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1

Surface plasmon resonance biosensors incorporating gold nanoparticles.  

PubMed

SPR biosensing is increasingly popular for the detection of a multitude of biomolecules. It offers label-free detection and study of proteins, nucleic acids, and other biomolecules in real time. A recent trend involves incorporation of AuNPs, either within the sensing surface itself or as signal enhancing tagging molecules. The importance of AuNP and detecting agent spacing is described and techniques using macromolecular spacing aids are highlighted. Recent methods to enhance SPR detection capabilities using gold nanoparticles are reviewed, as well as device fabrication and the results of incorporation. SPR detection is a highly versatile method for the detection of biomolecules and, with the incorporation of AuNPs, shows promise in extending it to a number of new applications. PMID:22416018

Bedford, Erin E; Spadavecchia, Jolanda; Pradier, Claire-Marie; Gu, Frank X

2012-06-01

2

Photoelectrochemical glucose biosensor incorporating CdS nanoparticles  

Microsoft Academic Search

A novel photoelectrochemical biosensor incorporating nanosized CdS semiconductor crystals with enzyme to enhance photochemical reaction has been investigated. CdS nanoparticles were synthesized by using dendrimer PAMAM as inner templates. The CdS nanoparticles and glucose oxidase (GOD) were immobilized on Pt electrode via layer-by-layer (LbL) technique to fabricate a biological–inorganic hybrid system. Under ultraviolet light, the photo-effect of the CdS nanoparticles

Jinjie Sun; Yihua Zhu; Xiaoling Yang; Chunzhong Li

2009-01-01

3

Antibacterial nano-structured titania coating incorporated with silver nanoparticles  

Microsoft Academic Search

Titanium (Ti) implants are widely used clinically but post-operation infection remains one of the most common and serious complications. A surface boasting long-term antibacterial ability is highly desirable in order to prevent implant associated infection. In this study, titania nanotubes (TiO2-NTs) incorporated with silver (Ag) nanoparticles are fabricated on Ti implants to achieve this purpose. The Ag nanoparticles adhere tightly

Lingzhou Zhao; Hairong Wang; Kaifu Huo; Lingyun Cui; Wenrui Zhang; Hongwei Ni; Yumei Zhang; Zhifen Wu; Paul K. Chu

2011-01-01

4

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

5

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 µM 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 µM (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 µM. 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 µM (p<0.001) and were toxic to sperm at equivalent melittin concentrations ?40 µM (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.

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

2014-01-01

6

A review on the dietary flavonoid kaempferol.  

PubMed

Epidemiological studies have revealed that a diet rich in plant-derived foods has a protective effect on human health. Identifying bioactive dietary constituents is an active area of scientific investigation that may lead to new drug discovery. 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). Some epidemiological studies have found a positive association between the consumption of foods containing kaempferol and a reduced risk of developing several disorders such as cancer and cardiovascular diseases. Numerous preclinical studies have shown that kaempferol and some glycosides of kaempferol have a wide range of pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial, anticancer, cardioprotective, neuroprotective, antidiabetic, anti-osteoporotic, estrogenic/antiestrogenic, anxiolytic, analgesic and antiallergic activities. In this article, the distribution of kaempferol in the plant kingdom and its pharmacological properties are reviewed. The pharmacokinetics (e.g. oral bioavailability, metabolism, plasma levels) and safety of kaempferol are also analyzed. This information may help understand the health benefits of kaempferol-containing plants and may contribute to develop this flavonoid as a possible agent for the prevention and treatment of some diseases. PMID:21428901

Calderón-Montaño, J M; Burgos-Morón, E; Pérez-Guerrero, C; López-Lázaro, M

2011-04-01

7

Antibacterial nano-structured titania coating incorporated with silver nanoparticles.  

PubMed

Titanium (Ti) implants are widely used clinically but post-operation infection remains one of the most common and serious complications. A surface boasting long-term antibacterial ability is highly desirable in order to prevent implant associated infection. In this study, titania nanotubes (TiO(2)-NTs) incorporated with silver (Ag) nanoparticles are fabricated on Ti implants to achieve this purpose. The Ag nanoparticles adhere tightly to the wall of the TiO(2)-NTs prepared by immersion in a silver nitrate solution followed by ultraviolet light radiation. The amount of Ag introduced to the NTs can be varied by changing processing parameters such as the AgNO(3) concentration and immersion time. The TiO(2)-NTs loaded with Ag nanoparticles (NT-Ag) can kill all the planktonic bacteria in the suspension during the first several days, and the ability of the NT-Ag to prevent bacterial adhesion is maintained without obvious decline for 30 days, which are normally long enough to prevent post-operation infection in the early and intermediate stages and perhaps even late infection around the implant. Although the NT-Ag structure shows some cytotoxicity, it can be reduced by controlling the Ag release rate. The NT-Ag materials are also expected to possess satisfactory osteoconductivity in addition to the good biological performance expected of TiO(2)-NTs. This controllable NT-Ag structure which provides relatively long-term antibacterial ability and good tissue integration has promising applications in orthopedics, dentistry, and other biomedical devices. PMID:21565401

Zhao, Lingzhou; Wang, Hairong; Huo, Kaifu; Cui, Lingyun; Zhang, Wenrui; Ni, Hongwei; Zhang, Yumei; Wu, Zhifen; Chu, Paul K

2011-08-01

8

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

9

Etoposide-incorporated tripalmitin nanoparticles with different surface charge: Formulation, characterization, radiolabeling, and biodistribution studies  

Microsoft Academic Search

Etoposide-incorporated tripalmitin nanoparticles with negative (ETN) and positive charge (ETP) were prepared by melt emulsification\\u000a and high-pressure homogenization techniques. Spray drying of nanoparticles led to free flowing powder with excellent redispersibility.\\u000a The nanoparticles were characterized by size analysis, zeta potential measurements, and scanning electron microscopy. The\\u000a mean diameter of ETN and ETP nanoparticles was 391 nm and 362 nm, respectively,

Lakkireddy Harivardhan Reddy; Rakesh Kumar Sharma; Krishna Chuttani; Anil Kumar Mishra; Rayasa Ramachandra Murthy

2004-01-01

10

Quantum dots incorporated magnetic nanoparticles for imaging colon carcinoma cells  

PubMed Central

Background Engineered multifunctional nanoparticles (NPs) have made a tremendous impact on the biomedical sciences, with advances in imaging, sensing and bioseparation. In particular, the combination of optical and magnetic responses through a single particle system allows us to serve as novel multimodal molecular imaging contrast agents in clinical settings. Despite of essential medical imaging modalities and of significant clinical application, only few nanocomposites have been developed with dual imaging contrast. A new method for preparing quantum dots (QDs) incorporated magnetic nanoparticles (MNPs) based on layer-by-layer (LbL) self-assembly techniques have developed and used for cancer cells imaging. Methods Here, citrate - capped negatively charged Fe3O4 NPs were prepared and coated with positively - charged hexadecyltrimethyl ammonium bromide (CTAB). Then, thiol - capped negatively charged CdTe QDs were electrostatically bound with CTAB. Morphological, optical and magnetic properties of the fluorescent magnetic nanoparticles (FMNPs) were characterized. Prepared FMNPs were additionally conjugated with hCC49 antibodies fragment antigen binding (Fab) having binding affinity to sialylated sugar chain of TAG-72 region of LS174T cancer cells, which was prepared silkworm expression system, and then were used for imaging colon carcinoma cells. Results The prepared nanocomposites were magnetically responsive and fluorescent, simultaneously that are useful for efficient cellular imaging, optical sensing and magnetic separation. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) revealed that the particle size is around 50 nm in diameter with inner magnetic core and outer CdTe QDs core-shell structure. Cytotoxicity test of prepared FMNPs indicates high viability in Vero cells. NPs conjugated with anti cancer antibodies were successfully labeled on colon carcinoma cells (LS174) in vitro and showed significant specificity to target cells. Conclusion The present report demonstrates a simple synthesis of CdTe QDs-Fe3O4 NPs. The surface of the prepared FMNPs was enabled simple conjugation to monoclonal antibodies by electrostatic interaction. This property further extended their in vitro applications as cellular imaging contrast agents. Such labeling of cells with new fluorescent-magneto nanoprobes for living detection is of interest to various biomedical applications and has demonstrated the potential for future medical use.

2013-01-01

11

Drug-incorporating calcium carbonate nanoparticles for a new delivery system  

Microsoft Academic Search

We devised a simple method for incorporating drugs into solid calcium carbonate nanoparticles (nano-CaCO3). The size of nano-CaCO3 was controlled by mixing speed. Washing the nanoparticles released little incorporated drug but much drug that was adsorbed on the surface. In an in vitro releasing test, granulocyte colony-stimulating factor incorporated in nano-CaCO3 was chemically stable and released very slowly. Subcutaneous injection

Y. Ueno; H. Futagawa; Y. Takagi; A. Ueno; Y. Mizushima

2005-01-01

12

A magnetic poly(dimethylesiloxane) composite membrane incorporated with uniformly dispersed, coated iron oxide nanoparticles  

Microsoft Academic Search

We report a new magnetic polymer membrane for MEMS application. The polymeric magnetic composite has coated iron oxide nanoparticles incorporated in a polydimethylsiloxane (PDMS) matrix. Existing magnetic polymeric materials have particle agglomeration problems, which result in rough surfaces and uneven mechanical and optical properties. We show that the use of iron oxide nanoparticles (10 nm in diameter) with fatty acid

Luna Cheng; Mu Chiao

2010-01-01

13

Tuning of optical properties of PMMA by incorporating silver nanoparticles  

NASA Astrophysics Data System (ADS)

Nanocomposite films of Poly (methylmethacrylate) filled with different concentration of silver nanoparticles were prepared by ex-situ method. Firstly, silver nanoparticles were obtained by reducing the aqueous solution of silver nitrate with sodium borohydride then Ag/PMMA films were prepared by mixing colloidal solution of silver nanoparticles with solution of polymer. From absorption and specular reflection spectra, the optical band gap and refractive index (n) have been calculated. The decrease in optical bandgap and increase in refractive index has been indicative of the modifications in optical band structure of the PMMA matrix.

Alisha; Rozra, Jyoti; Saini, Isha; Sharma, Annu; Sharma, Pawan

2012-06-01

14

Effect of incorporated PVP/Ag nanoparticles on ZnPc/C60 organic solar cells.  

PubMed

Various sizes of PVP-capped Ag nanoparticles were incorporated in the PEDOT:PSS layer of ZnPc/C60-based small-molecule organic solar cells. The incorporated nanoparticles partially block the incident light, but this was offset by the scattering effect and consequent increase in path lengths through the active organic layers. As a result, the overall power conversion efficiency of the cell increased by approximately 15% when nanoparticles with an average diameter of 24 nm were used. PMID:23862493

Heo, Ilsu; Kim, Jinhyun; Yim, Sanggyu

2013-06-01

15

Magneto-optical Kerr effects of yttrium-iron garnet thin films incorporating gold nanoparticles.  

PubMed

We report an experimental study on magneto-optical (MO) Kerr effects of yttrium-iron garnet (YIG) thin films incorporating Au nanoparticles. The polar MO Kerr spectra in the wavelength between 400 and 800 nm show that, by incorporating the Au nanoparticles, Kerr rotation angles become negative values in the region, where the localized surface plasmon polariton (SPP) resonance of the Au nanoparticles is located. The anomalous Kerr rotation indicates a possible coupling between the MO Kerr effect of YIG and the SPP. A mechanism for the coupling is discussed. PMID:16712274

Tomita, Satoshi; Kato, Takeshi; Tsunashima, Shigeru; Iwata, Satoshi; Fujii, Minoru; Hayashi, Shinji

2006-04-28

16

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

17

Comparison of post-detonation combustion in explosives incorporating aluminum nanoparticles: Influence of the passivation layer  

NASA Astrophysics Data System (ADS)

Aluminum nanoparticles and explosive formulations that incorporate them have been a subject of ongoing interest due to the potential of aluminum particles to dramatically increase energy content relative to conventional organic explosives. We have used time-resolved atomic and molecular emission spectroscopy to monitor the combustion of aluminum nanoparticles within the overall chemical dynamics of post-detonation fireballs. We have studied the energy release dynamics of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) charges incorporating three types of aluminum nanoparticles: commercial oxide-passivated nanoparticles, oleic acid-capped aluminum nanoparticles (AlOA), and nanoparticles in which the oxide shell of the particle has been functionalized with an acrylic monomer and copolymerized into a fluorinated acrylic matrix (AlFA). The results indicate that the commercial nanoparticles and the AlFA nanoparticles are oxidized at a similar rate, while the AlOA nanoparticles combust more quickly. This is most likely due to the fact that the commercial nano-Al and the AlFA particles are both oxide-passivated, while the AlOA particles are protected by an organic shell that is more easily compromised than an oxide layer. The peak fireball temperatures for RDX charges containing 20 wt. % of commercial nano-Al, AlFA, or AlOA were ~3900 K, ~3400 K, and ~4500 K, respectively.

Lewis, W. K.; Rumchik, C. G.; Smith, M. J.; Fernando, K. A. S.; Crouse, C. A.; Spowart, J. E.; Guliants, E. A.; Bunker, C. E.

2013-01-01

18

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

19

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

20

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

21

Highly Catalytically Active Palladium Nanoparticles Incorporated Inside Metal-Organic Framework Pores by Double Solvents Method  

NASA Astrophysics Data System (ADS)

Highly monodispersed palladium (Pd) nanoparticles have been successfully incorporated inside the mesopores of a metal-organic framework (MOF), MIL-101, without deposition of Pd nanoparticles on the external surfaces of framework by using the "double solvents" method, in which cyclohexane is used as a hydrophobic solvent to disperse the mesoporous MOF and an aqueous solution of Pd precursor is used as a hydrophilic solvent to fill the mesopores. The resulting Pd@MIL-101 composite is highly catalytically active for the reduction of 4-nitrophenol (4-NPh) by sodium borohydride (NaBH4). The observed excellent catalytic performances are attributed to the small Pd nanoparticles within the pores of MIL-101.

Yadav, Mahendra; Aijaz, Arshad; Xu, Qiang

2012-12-01

22

Development and characterization of solid oral dosage form incorporating candesartan nanoparticles.  

PubMed

Sparingly water-soluble drugs such as candesartan cilexetil offer challenges in developing a drug product with adequate bioavailability. The objective of the present study was to develop a tablet dosage form of candesartan cilexetil incorporating drug nanoparticles to increase its saturation solubility and dissolution rate for enhancing bioavailability while reducing variability in systemic exposure. The bioavailability of candesartan cilexetil is dissolution limited following oral administration. To enhance bioavailability and overcome variability in systemic exposure, a nanoparticle formulation of candesartan cilexetil was developed. Candesartan cilexetil nanoparticles were prepared using a wet bead milling technique. The milled nanosuspension was converted into solid intermediate using a spray drying process. The nanosuspensions were characterized for particle size before and after spray drying. The spray dried nanoparticles were blended with excipients for tableting. The saturation solubility and dissolution characteristics of the nanoparticle formulation were investigated and compared with commercial candesartan cilexetil formulation. The drug nanoparticles were evaluated for solid-state transitions before and after milling. This study demonstrated that tablet formulation incorporating drug nanoparticles showed significantly faster rate of drug dissolution in a discriminating dissolution medium as compared to commercially available tablet formulation. Systemic exposure studies in rats indicated a significant increase in the rate and extent of drug absorption. PMID:19235553

Nekkanti, Vijaykumar; Pillai, Raviraj; Venkateshwarlu, Vobalaboina; Harisudhan, T

2009-01-01

23

Optofluidics incorporating actively controlled micro- and nano-particles  

PubMed Central

The advent of optofluidic systems incorporating suspended particles has resulted in the emergence of novel applications. Such systems operate based on the fact that suspended particles can be manipulated using well-appointed active forces, and their motions, locations and local concentrations can be controlled. These forces can be exerted on both individual and clusters of particles. Having the capability to manipulate suspended particles gives users the ability for tuning the physical and, to some extent, the chemical properties of the suspension media, which addresses the needs of various advanced optofluidic systems. Additionally, the incorporation of particles results in the realization of novel optofluidic solutions used for creating optical components and sensing platforms. In this review, we present different types of active forces that are used for particle manipulations and the resulting optofluidic systems incorporating them. These systems include optical components, optofluidic detection and analysis platforms, plasmonics and Raman systems, thermal and energy related systems, and platforms specifically incorporating biological particles. We conclude the review with a discussion of future perspectives, which are expected to further advance this rapidly growing field.

Kayani, Aminuddin A.; Khoshmanesh, Khashayar; Ward, Stephanie A.; Mitchell, Arnan; Kalantar-zadeh, Kourosh

2012-01-01

24

Influence of Tb incorporation on the structural and the optical properties of ZnO nanoparticles  

NASA Astrophysics Data System (ADS)

Structural and optical properties of the Tb doped ZnO nanoparticles are systematically studied as a function of the Tb mole-fraction. Our study suggests that the Tb incorporates mostly on the surface and affects the optical properties of the ZnO nanoparticles by influencing the attachment of certain adsorbed groups, which are found to be responsible for the appearance of a broad green luminescence (GL) band in the photoluminescence spectra recorded for these nanoparticles. It has been found that the accumulation of Tb on the surface of the nanoparticles not only enhances the band edge to green luminescence intensity ratio under the vacuum condition but also increases the band gap energy by introducing a hydrostatic compressive strain in individual nanoparticles, which provides a unique opportunity to study the pressure dependence of the optical properties of nanoparticles without applying any external pressure. The hydrostatic compressive strain is explained in terms of the increase of the surface strain energy as a result of the Tb accumulation on the surface of the nanoparticles. The average value of the surface energy density for the particles has been estimated as a function of Tb mole-fraction. The pressure coefficient of the band gap which is obtained from the variation of the band gap energy with the hydrostatic strain has been found to decrease significantly with the particle size for the ZnO nanoparticles.

Sharma, A.; Dhar, S.; Singh, B. P.; Kundu, T.

2011-12-01

25

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 (?nsat) 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 ?nsat as high as 1.6×10-2 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, Jürgen; Pruner, Christian; Fally, Martin; Tomita, Yasuo

2014-06-15

26

Electrocatalytic oxygen reduction on functionalized gold nanoparticles incorporated in a hydrophobic environment.  

PubMed

The electrocatalytic properties of gold nanoparticles covalently capped with a monolayer film of 1,4-decylphenyl groups for oxygen reduction in an alkaline solution have been studied. Functionalized nanoparticles were adsorbed on a film of the same capping ligand previously grafted to a glassy carbon electrode. The molecular film-nanoparticle assembly was characterized by cyclic voltammetry and XPS. It is shown that although the attachment of the capping ligand to the electrode surface blocks direct electron transfer, the metal centers of the incorporated nanoparticles provide sites for electron tunneling from the electrode surface thus leading to sites where oxygen reduction can take place. Rotating disk voltammetry shows that the oxygen reduction reaction follows mainly a peroxide formation channel on these nanostructured surfaces. The capping ligand greatly influences the reduction mechanism by establishing a local hydrophobic environment at the reaction centers within the film. PMID:20799698

Mirkhalaf, Fakhradin; Schiffrin, David J

2010-09-21

27

Drug incorporation and release of water soluble drugs from novel functionalized poly(glycerol adipate) nanoparticles.  

PubMed

We have previously demonstrated the ability of poly(glycerol adipate) backbone (PGA) and PGA polymer backbone substituted with varying amounts of pendant C(18) chain length acyl groups to yield Dexamethasone phosphate DXMP loaded nanoparticles. The aim of this study was to obtain a deeper understanding of the underlying principles responsible for good drug incorporation and controlled release of drugs from poly (glycerol adipate) (PGA) nanoparticles. We compared the incorporation of the water soluble drugs DXMP and Cytosine arabinoside (CYT-ARA) in both unmodified and substituted PGA polymers. We investigated the effect of change in acyl group chain length and the degree of substitution on the physicochemical properties, drug loading and release of DXMP and CYT-ARA. Nanoparticles were prepared by the interfacial deposition technique and the simultaneous emulsification method. Amongst the nanoparticles prepared using acylated polymers with varying chain lengths (C(2) to C(10)) for DXMP incorporation, polymers with acyl group chain lengths containing 8 carbon atoms (C(8)) showed maximum drug incorporation. Amongst the C(8) series, polymers with 100% acylation provided both good drug incorporation and a controlled release for DXMP while for CYT-ARA it was the unsubstituted polymer backbone that had maximum drug loading and slower release. A number of inter-related factors are responsible for producing particles with particular size, zeta potential, drug loading and release characteristics. Drug loading and release from nanoparticles are primarily influenced by the nature of interactions between the drug and polymers which in turn depend upon the type of drug used and the physical chemistry of the polymer. PMID:18035443

Puri, Sanyogita; Kallinteri, Paraskevi; Higgins, Sean; Hutcheon, Gillian A; Garnett, Martin C

2008-01-01

28

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

29

Preparation and characterization of whey protein film incorporated with TiO2 nanoparticles.  

PubMed

Biodegradable titanium dioxide (TiO(2))/whey protein isolate (WPI) blend films were made by casting denatured WPI film solutions incorporated with TiO(2) nanoparticles. X-ray diffraction, UV-vis spectra, and fluorescence spectra of the films showed the successful incorporation of TiO(2) nanoparticles into the WPI matrix and indicated the interactions between TiO(2) and WPI. Mechanical tests revealed the antiplasticizing effect of TiO(2) nanoparticles on the WPI/TiO(2) film. Small amounts (<1 wt%) of added TiO(2) nanoparticles significantly increase the tensile properties of WPI film, but also decrease the moisture barrier properties. The addition of higher amounts (>1 wt%) of TiO(2) improves moisture barrier properties but lowers the tensile properties of the film. Microstructural evaluation confirmed the aggregation and distribution of TiO(2) nanoparticles within the WPI matrix and validated the results of functional properties of the WPI/TiO(2) film. PMID:19895492

Zhou, J J; Wang, S Y; Gunasekaran, S

2009-09-01

30

Production and in vitro characterization of solid dosage form incorporating drug nanoparticles.  

PubMed

The objective of this study was to develop a tablet formulation of ketoconazole incorporating drug nanoparticles to enhance saturation solubility and dissolution velocity for enhancing bioavailability and reducing variability in systemic exposure. The bioavailability of ketoconazole is dissolution limited following oral administration. To enhance bioavailability and overcome variability in systemic exposure, a nanoparticle formulation of ketoconazole was developed. Ketoconazole nanoparticles were prepared using a media-milling technique. The nanosuspension was layered onto water-soluble carriers using a fluid bed processor. The nanosuspensions were characterized for particle size before and after layering onto water-soluble carriers. The saturation solubility and dissolution characteristics were investigated and compared with commercial ketoconazole formulation to ascertain the impact of particle size on drug dissolution. The drug nanoparticles were evaluated for solid-state transitions before and after milling using differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). This study demonstrated that tablet formulation incorporating ketoconazole nanoparticles showed significantly faster rate of drug dissolution in a discriminating dissolution medium as compared with commercially available tablet formulation. There was no affect on solid-state properties of ketoconazole following milling. The manufacturing process used is relatively simple and scalable indicating general applicability to enhance dissolution and bioavailability of many sparingly soluble compounds. PMID:18720147

Basa, Shradhanjali; Muniyappan, Thilekkumar; Karatgi, Pradeep; Prabhu, Raghavendra; Pillai, Ravi

2008-11-01

31

The improvement of characteristics of biodegradable films made from kefiran-whey protein by nanoparticle incorporation.  

PubMed

Biodegradable kefiran-whey protein isolate (WPI) nanocomposites were produced using montmorillonite (MMT) and nano-TiO2 as nanoparticles in the percentage of 1, 3, and 5% (w/w) by a casting and solvent-evaporation method. Physical, mechanical, and water-vapor permeability (WVP) properties were determined as a function of nanoparticle concentration. The results revealed that the effect of these nanoparticles was different according to their nature and percentage. The films incorporated with 5% (w/w) MMT showed the highest tensile strength, Young's modulus, puncture strength, and the lowest WVP compared with the control and TiO2 added films. In contrast to MMT, addition of TiO2 nanoparticles due to the plasticizing effect led to a significant change in color and transparency of nanocomposite. Scanning electron microscopy (SEM) observations demonstrated the films' properties in relation to their microstructures. The surface topography results also showed a considerable increase in roughness parameters by incorporating the nanoparticles in kefiran-WPI matrix. PMID:24815408

Zolfi, Mohsen; Khodaiyan, Faramarz; Mousavi, Mohammad; Hashemi, Maryam

2014-08-30

32

Synthesis and characterization of Eu(III)-incorporated silica nanoparticles for application to UV-LED.  

PubMed

A tetrakis(dibenzylmethanido) Eu(III) complex as a ultraviolet (UV) excited phosphor was synthesized, and incorporated with mesoporous silica as core-shell (CS), outer-shell (OS) and intermediate-shell (IS) architectures, using a combination of the self-organization process and the Stöber method. Exciting the Eu(III) complex at UV light produced a strong sensitized red-emission from Eu(III) by energy transfer from the ligand. Phosphor-converted light-emitting diodes (pc-LEDs) were fabricated by casting the powdered complex and the incorporated silica nanoparticles onto a 365-nm InGaN chip, and their optical properties and thermal stability were investigated in terms of the chromaticity index and the intensity decay, respectively. The CS silica nanoparticle casted UV-LED exhibited the best perfomence with strong intensity and excellent thermal stability. PMID:24703666

Jeong, Yong-Kwang; Sohn, Youngku; Kang, Jun-Gill

2014-06-01

33

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

34

Study on the Electrical and Thermal Conductivity of Ordered Mesoporous TiO2 Thin Film Incorporated with Pt Nanoparticles  

Microsoft Academic Search

Ordered mesoporous TiO2 films with incorporated Pt nanoparticles were prepared using titanium tetraisopropoxide, hexachloroplatinic acid hexahydrate, and Pluronic P-123 as a titania precursor, a Pt precursor, and a structure-directing agent, respectively. Pt nanoparticles were introduced to enhance the electrical properties of the mesoporous films, which have excellent thermal insulation properties. We confirmed that the synthesized composite films with Pt nanoparticles

Tae-Jung Ha; Yong-June Choi; Sin-Young Jung; Won-Seon Seo; Young Soo Lim; Sangwoo Shin; Hyung Hee Cho; Hyung-Ho Park

2011-01-01

35

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.

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

2013-01-01

36

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

37

Incorporation of Ag metallic nanoparticles in 3D gelatin matrix via the green strategy solution plasma.  

PubMed

The environmental concern pays much attention to the recent cause of the global warming effect. The reduction of the chemical uses is one of many ways to avoid this crucial problem. Herein, the green process for silver nanometallic particle formation and incorporation in gelatin are proposed. By using a novel discharge process in solution named solution plasma, the silver nanometallic particle formation and its incorporation in gelatin could be accomplished in one-batch reactor during discharge by using silver nitrate (AgNO3) solution as the precursor and controlling systematical parameters. The three-dimensional scaffolds of gelatin/silver biocomposite were fabricated using lyophilizer and the water-soluble property of gelatin was improved by irradiation of ultraviolet ray. The well dispersed silver nanoparticles with the mean particle size 10-20 nm in the good texture of gelatin matrix were obtained. The density of micropore in gelatin/silver scaffold was proportional to the gelatin concentration. In addition, thermal stability of prepared samples had no change comparing with pure gelatin, indicating that the incorporation of silver nanoparticles in gelatin matrix did not affect to the nature of gelatin. PMID:23646779

Pootawang, Panuphong; Kim, Seong Cheol; Kim, Jung Wan; Lee, Sang Yul

2013-01-01

38

Incorporating functionalized polyethylene glycol lipids into reprecipitated conjugated polymer nanoparticles for bioconjugation and targeted labeling of cells  

NASA Astrophysics Data System (ADS)

We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG) lipids by reprecipitation. These nanoparticles retain the fundamental spectroscopic properties of conjugated polymer nanoparticles prepared without PEG lipid, but demonstrate greater hydrophilicity and quantum yield compared to unmodified conjugated polymer nanoparticles. The sizes of these nanoparticles, as determined by TEM, were 21-26 nm. Notably, these nanoparticles were prepared with several PEG lipid functional end groups, including biotin and carboxy moieties that can be easily conjugated to biomolecules. We have demonstrated the availability of these end groups for functionalization using the interaction of biotin PEG lipid conjugated polymer nanoparticles with streptavidin. Biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-linked magnetic beads, while carboxy and methoxy PEG lipid modified nanoparticles did not. Similarly, biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-coated glass slides and could be visualized as diffraction-limited spots, while nanoparticles without PEG lipid or with non-biotin PEG lipid end groups were not bound. To demonstrate that nanoparticle functionalization could be used for targeted labelling of specific cellular proteins, biotinylated PEG lipid conjugated polymer nanoparticles were bound to biotinylated anti-CD16/32 antibodies on J774A.1 cell surface receptors, using streptavidin as a linker. This work represents the first demonstration of targeted delivery of conjugated polymer nanoparticles and demonstrates the utility of these new nanoparticles for fluorescence based imaging and sensing.We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG) lipids by reprecipitation. These nanoparticles retain the fundamental spectroscopic properties of conjugated polymer nanoparticles prepared without PEG lipid, but demonstrate greater hydrophilicity and quantum yield compared to unmodified conjugated polymer nanoparticles. The sizes of these nanoparticles, as determined by TEM, were 21-26 nm. Notably, these nanoparticles were prepared with several PEG lipid functional end groups, including biotin and carboxy moieties that can be easily conjugated to biomolecules. We have demonstrated the availability of these end groups for functionalization using the interaction of biotin PEG lipid conjugated polymer nanoparticles with streptavidin. Biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-linked magnetic beads, while carboxy and methoxy PEG lipid modified nanoparticles did not. Similarly, biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-coated glass slides and could be visualized as diffraction-limited spots, while nanoparticles without PEG lipid or with non-biotin PEG lipid end groups were not bound. To demonstrate that nanoparticle functionalization could be used for targeted labelling of specific cellular proteins, biotinylated PEG lipid conjugated polymer nanoparticles were bound to biotinylated anti-CD16/32 antibodies on J774A.1 cell surface receptors, using streptavidin as a linker. This work represents the first demonstration of targeted delivery of conjugated polymer nanoparticles and demonstrates the utility of these new nanoparticles for fluorescence based imaging and sensing. Electronic supplementary information (ESI) available: Additional TEM data, supplemental light scattering measurements, absorbance and fluorescence emission spectra, and photostability measurements. See DOI: 10.1039/c0nr00746c

Kandel, Prakash K.; Fernando, Lawrence P.; Ackroyd, P. Christine; Christensen, Kenneth A.

2011-03-01

39

Incorporation and release of drug into/from superparamagnetic iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

The aim of this study was to attach a model drug (naproxen) onto superparamagnetic iron oxide nanoparticles (SPION). First, SPION were coated with thin layer of silica that contained micropores. We demonstrated that such surface functionalization could be optimized by the use of citric acid which prevented SPION agglomeration during the procedure. HRTEM investigation showed a uniform 1-2-nm-thick silica coating around SPION. This coating did not affect significantly the magnetic properties of the SPION. Into the coated SPION we successfully incorporated about 30 wt% of naproxen. The latter was readily released after immersion into a testing solution. The composites could be interesting for potential use in diagnostics.

Maver, Uroš; Bele, Marjan; Makovec, Darko; ?ampelj, Stanislav; Jamnik, Janko; Gaberš?ek, Miran

2009-10-01

40

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

41

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 ?69–173 nm upon selenium incorporation from ?41–132 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.

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

2013-01-01

42

Memory Effects in MetalOxideSemiconductor Capacitors Incorporating Dispensed Highly Monodisperse One-Nanometer Silicon Nanoparticles  

Microsoft Academic Search

MOS capacitors incorporating ex-situ produced, colloidal, highly mono-disperse, spherical, 1 nm Si nanoparticles were fabricated and evaluated for potential use as charge storage elements in future non-volatile memory devices. The CV characteristics are well behaved and agree with similarly fabricated zero-nanoparticle control samples and with an ideal simulation. Unlike larger particle systems, the demonstrated memory effect exhibits effectively pure hole

O. M. Nayfeh; D. A. Antoniadis; K. Mantey; M. H. Nayfeh

2007-01-01

43

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; Bünger, Carsten M; Schareck, Wolfgang; Schmitz, Klaus-Peter; Sternberg, Katrin

2013-08-01

44

Incorporation and controlled release of silyl ether prodrugs from PRINT nanoparticles.  

PubMed

Asymmetric bifunctional silyl ether (ABS) prodrugs of chemotherapeutics were synthesized and incorporated within 200 nm × 200 nm particles. ABS prodrugs of gemcitabine were selected as model compounds because of the difficulty to encapsulate a water-soluble drug within a hydrogel. The resulting drug delivery systems were degraded under acidic conditions and were found to release only the parent or active drug. Furthermore, changing the steric bulk of the alkyl substituents on the silicon atom could regulate the rate of drug release and, therefore, the intracellular toxicity of the gemcitabine-loaded particles. This yielded a family of novel nanoparticles that could be tuned to release drug over the course of hours, days, or months. PMID:22545784

Parrott, Matthew C; Finniss, Mathew; Luft, J Chris; Pandya, Ashish; Gullapalli, Anuradha; Napier, Mary E; DeSimone, Joseph M

2012-05-01

45

Incorporation and Controlled Release of Silyl Ether Prodrugs from PRINT Nanoparticles  

PubMed Central

Asymmetric bifunctional silyl ether (ABS) prodrugs of chemotherapeutics were synthesized and incorporated within 200 nm x 200 nm particles. ABS prodrugs of gemcitabine were selected as model compounds because of the difficulty to encapsulate a water soluble drug within a hydrogel. The resulting drug delivery systems were degraded under acidic conditions and were found to release only the parent or active drug. Furthermore, changing the steric bulk of the alkyl substituents on the silicon atom could regulate the rate of drug release and therefore the intracellular toxicity of the gemcitabine-loaded particles. This yielded a family of novel nanoparticles that could be tuned to release drug over the course of hours, days, or months.

Parrott, Matthew C.; Finniss, Mathew; Luft, J. Chris; Pandya, Ashish; Gullapalli, Anuradha; Napier, Mary E.; DeSimone, Joseph M.

2012-01-01

46

The influence of incorporating organic molecules or inorganic nanoparticles on the optical and electrical properties of carbon nanotube films  

Microsoft Academic Search

Organic molecules and inorganic nanoparticles were incorporated into transparent and conductive single- or double-wall carbon nanotube (SWNT or DWNT) films, and their electrical and optical properties were measured. When organic tetrafluoro-tetracyanoquinodimethane (F4TCNQ) molecules were incorporated into the nanotube films, sheet resistance was reduced to ?50% of those from the pristine SWNT and DWNT films. Larger improvements were observed with Au

Yeontack Ryu; Choongho Yu

2011-01-01

47

Core-shell nano-architectures: the incorporation mechanism of hydrophobic nanoparticles into the aqueous core of a microemulsion.  

PubMed

This work presents an in-depth investigation of the molecular interactions in the incorporation mechanism of colloidal hydrophobic-capped nanoparticles into the hydrophilic core of reverse microemulsions. (1)H Nuclear Magnetic Resonance (NMR) was employed to obtain molecular level details of the interaction between the nanoparticles capping amphiphiles and the microemulsion surfactants. The model system of choice involved oleic acid (OAC) and oleylamine (OAM) as capping molecules, while igepal-CO520 was the surfactant. The former were studied both in their "free" state and "ligated" one, i.e., bound to nanoparticles. The latter was investigated either in cyclohexane (micellar solution) or in water/cyclohexane microemulsions. The approach was extremely useful to gain a deeper understanding of the equilibria involved in this complex system (oleic acid capped-Bi2S3 in igepal/water/cyclohexane microemulsions). In difference to previously proposed mechanisms, the experimental data showed that the high affinity of the capping ligands for the reverse micelle interior was the drivingforce for the incorporation of the nanoparticles. A simple ligand-exchange mechanism could be ruled out. The collected information about the nanoparticle incorporation mechanism is extremely useful to develop new synthetic routes with an improved/tuned coating efficiency, in order to tailor the core-shell structure preparation. PMID:23910706

Scorciapino, Mariano A; Sanna, Roberta; Ardu, Andrea; Orrù, Federica; Casu, Mariano; Musinu, Anna; Cannas, Carla

2013-10-01

48

Three-Dimensional Model for Determining Inhomogeneous Thermal Dosage in a Liver Tumor During Arterial Embolization Hyperthermia Incorporating Magnetic Nanoparticles  

Microsoft Academic Search

Hyperthermia treatment incorporating magnetic nanoparticles (MNPs) is a hopeful therapy for cancers. Acquiring information about the MNPs' deposition in tumor tissues and modeling magnetic heating in vivo are essential for successful treatment. In this paper, we discuss the inhomogeneous heat generation by MNPs distributed heterogeneously in a liver tumor during arterial embolization hyperthermia (AEH) treatments. In order to more accurately

Ruizhi Xu; Hui Yu; Yu Zhang; Ming Ma; Zhongping Chen; Changling Wang; Gaojun Teng; Jun Ma; Xinchen Sun; Ning Gu

2009-01-01

49

Study on the Electrical and Thermal Conductivity of Ordered Mesoporous TiO2 Thin Film Incorporated with Pt Nanoparticles  

NASA Astrophysics Data System (ADS)

Ordered mesoporous TiO2 films with incorporated Pt nanoparticles were prepared using titanium tetraisopropoxide, hexachloroplatinic acid hexahydrate, and Pluronic P-123 as a titania precursor, a Pt precursor, and a structure-directing agent, respectively. Pt nanoparticles were introduced to enhance the electrical properties of the mesoporous films, which have excellent thermal insulation properties. We confirmed that the synthesized composite films with Pt nanoparticles had an ordered pore structure with anatase phase TiO2 by both small-angle and wide-angle X-ray diffraction analyses. Although the porosity of the composite film decreased from 37.6 to 29.3% when Pt nanoparticles were included, the conductivity ratio (?/?) of the film increased greatly, up to approximately 1370 K V-2, due to the greater increase in electrical conductivity than thermal conductivity. Based on our results, we conclude that by incorporating Pt nanoparticles into ordered mesoporous TiO2 film, the thermoelectric properties of the mesoporous films can be improved.

Ha, Tae-Jung; Choi, Yong-June; Jung, Sin-Young; Seo, Won-Seon; Lim, Young Soo; Shin, Sangwoo; Cho, Hyung Hee; Park, Hyung-Ho

2011-07-01

50

Incorporation of functionalized gold nanoparticles into nanofibers for enhanced attachment and differentiation of mammalian cells  

PubMed Central

Background Electrospun nanofibers have been widely used as substrata for mammalian cell culture owing to their structural similarity to natural extracellular matrices. Structurally consistent electrospun nanofibers can be produced with synthetic polymers but require chemical modification to graft cell-adhesive molecules to make the nanofibers functional. Development of a facile method of grafting functional molecules on the nanofibers will contribute to the production of diverse cell type-specific nanofiber substrata. Results Small molecules, peptides, and functionalized gold nanoparticles were successfully incorporated with polymethylglutarimide (PMGI) nanofibers through electrospinning. The PMGI nanofibers functionalized by the grafted AuNPs, which were labeled with cell-adhesive peptides, enhanced HeLa cell attachment and potentiated cardiomyocyte differentiation of human pluripotent stem cells. Conclusions PMGI nanofibers can be functionalized simply by co-electrospinning with the grafting materials. In addition, grafting functionalized AuNPs enable high-density localization of the cell-adhesive peptides on the nanofiber. The results of the present study suggest that more cell type-specific synthetic substrata can be fabricated with molecule-doped nanofibers, in which diverse functional molecules are grafted alone or in combination with other molecules at different concentrations.

2012-01-01

51

The delivery of thrombi-specific nanoparticles incorporating oligonucleotides into injured cerebrovascular endothelium.  

PubMed

In acute vascular events, the endothelium derived tissue factor (TF) is the trigger of the coagulation cascade. In this study, EGFP-EGF1 protein-conjugated PEG-PLGA nanoparticle was employed as a TF targeting vehicle, the NF-?B decoy oligonucleotides (ODNs) was incorporated into it and the resulting EGF1-EGFP-NP-ODNs were evaluated as a vector for therapy of cortex infarction. At 2 h after transfection of TF expressed rat brain capillary endothelial cell, EGF1-EGFP-NP-ODNs was more efficiently internalized and located in the cytoplasm than NP-ODNs. At 4 h and 6 h after administration, ODNs were present in the nuclei and obviously inhibited the TF expression. At 6 h after i.v. administration in vivo, most EGF1-EGFP-NP were accumulated in the embolism vessels, distributed in the damaged endothelial cells and lowered the TF expression. At 24 h after i.v. administration, MR imaging of cortex infarcts were predominantly dwindled. PMID:23465828

Shi, Wei; Mei, Heng; Deng, Jun; Chen, Chen; Wang, Huafang; Guo, Tao; Zhang, Bo; Pang, Zhiqing; Jiang, Xinguo; Wang, Xuxia; Lei, Hao; Hu, Yu

2013-05-01

52

Designer nanoparticles: Incorporating size, shape, and triggered release into nanoscale drug carriers  

PubMed Central

Importance of the field Although significant progress has been made in delivering therapeutic agents through micro and nanocarriers, precise control over in vivo biodistribution and disease-responsive drug release has been difficult to achieve. This is critical for the success of next generation drug delivery devices, since newer drugs, designed to interfere with cellular functions, must be efficiently and specifically delivered to diseased cells. The major constraint in achieving this has been our limited repertoire of particle synthesis methods, especially at the nanoscale. Recent developments in generating shape-specific nanocarriers and the potential to combine stimuli-responsive release with nanoscale delivery devices show great promise in overcoming these limitations. Areas covered in this review Here we discuss how recent advancements in fabrication technology allow synthesis of highly monodisperse, stimuli-responsive, drug-carrying nanoparticles of precise geometries. We also review how particle properties, specifically shape and stimuli responsiveness, affect biodistribution, cellular uptake, and drug release. What the reader will gain The reader is introduced to recent developments in intelligent drug nanocarriers and new nanofabrication approaches that can be combined with disease-responsive biomaterials. This will provide insight into the importance of controlling particle geometry and incorporating stimuli responsive materials into drug delivery.

Caldorera-Moore, Mary; Guimard, Nathalie; Shi, Li; Roy, Krishnendu

2009-01-01

53

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 Stöber'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 Förster 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.; Diógenes, Izaura C. N.; de Sousa, Eduardo H. S.; Longhinotti, Elisane

2014-05-01

54

Performance and tribofilm formation of a low-friction coating incorporating inorganic fullerene like nano-particles  

Microsoft Academic Search

A new tribological coating with potential as a coating for components for low-friction applications is tested and compared to three, state of the art, commercial low-friction PVD coatings. The new coating is an electrodeposited coating composed by a Ni–P matrix incorporating fullerene like nanoparticles of WS2. The performance of the new coating is compared with three reference coatings in a

B. André; F. Gustavsson; F. Svahn; S. Jacobson

55

Lapatinib-incorporated lipoprotein-like nanoparticles: preparation and a proposed breast cancer-targeting mechanism.  

PubMed

Aim:Lapatinib is a dual inhibitor of EGFR and human epidermal growth factor receptor 2 (HER2), and used to treat advanced breast cancer. To overcome its poor water solubility, we constructed lapatinib-incorporated lipoprotein-like nanoparticles (LTNPs), and evaluated the particle characteristics and possible anti-breast cancer mechanisms.Methods:LTNPs (lapatinib bound to albumin as a core, and egg yolk lecithin forming a lipid corona) were prepared. The particle characteristics were investigated using transmission electron microscopy (TEM) and atomic force microscopy (AFM). The uptake and subcellular localization of LTNPs, as well as the effects of LTNPs on cell cycle were examined in BT-474 human breast cancer cells in vitro. Mice bearing BT-474 subcutaneous xenograft were intravenously injected with coumarin-6 loaded LTNPs (30 mg/kg) to study the targeting mechanisms in vivo.Results:The LTNPs particles were generally spherical but flexible under TEM and AFM, and approximately 62.1 nm in size with a zeta potential of 22.80 mV. In BT-474 cells, uptake of LTNPs was mediated by endosomes through energy-dependent endocytosis involving clathrin-dependent pinocytosis and macropinocytosis, and they could effectively escape from endosomes to the cytoplasm. Treatment of BT-474 cells with LTNPs (20 ?g/mL) induced a significant cell arrest at G0/G1 phase compared with the same concentration of lapatinib suspension. In mice bearing BT-474 xenograft, intravenously injected LTNPs was found to target and accumulate in tumors, and colocalized with HER2 and SPRAC (secreted protein, acidic and rich in cysteine).Conclusion:LTNPs can be taken up into breast cancer cells through specific pathways in vitro, and targeted to breast cancer xenograft in vivo via enhanced permeability and retention effect and SPARC. PMID:24902791

Zhang, Li; Zhang, Shuang; Ruan, Shao-Bo; Zhang, Qian-Yu; He, Qin; Gao, Hui-le

2014-06-01

56

Characterization of natural organic matter treated by iron oxide nanoparticle incorporated ceramic membrane-ozonation process.  

PubMed

In this study, changes in the physical and structural properties of natural organic matter (NOM) were observed during hybrid ceramic membrane processes that combined ozonation with ultrafiltration ceramic membrane (CM) or with a reactive ceramic membrane (RM), namely, an iron oxide nanoparticles (IONs) incorporated-CM. NOM from feed water and NOM from permeate treated with hybrid ceramic membrane processes were analyzed by employing several NOM characterization techniques. Specific ultraviolet absorbance (SUVA), high-performance size exclusion chromatography (HPSEC) and fractionation analyses showed that the hybrid ceramic membrane process effectively removed and transformed relatively high contents of aromatic, high molecular weight and hydrophobic NOM fractions. Fourier transform infrared spectroscopy (FTIR) and 3-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy revealed that this process caused a significant decrease of the aromaticity of humic-like structures and an increase in electron withdrawing groups. The highest removal efficiency (46%) of hydroxyl radical probe compound (i.e., para-Chlorobenzoic acid (pCBA)) in RM-ozonation process compared with that in CM without ozonation process (8%) revealed the hydroxyl radical formation by the surface-catalyzed reaction between ozone and IONs on the surface of RM. In addition, experimental results on flux decline showed that fouling of RM-ozonation process (15%) was reduced compared with that of CM without ozonation process (30%). These results indicated that the RM-ozonation process enhanced the destruction of NOM and reduced the fouling by generating hydroxyl radicals from the catalytic ozonation in the RM-ozonation process. PMID:22944203

Park, Hosik; Kim, Yohan; An, Byungryul; Choi, Heechul

2012-11-15

57

CCMR: Incorporating Surface Plasmons into Hybrid Core-Shell Fluorescent Silica Nanoparticles  

NSDL National Science Digital Library

Fluorescent silica nanoparticles are widely used in bioimaging, bioassay, and nanomedicine applications.[1] In such applications the control of fluorescence intensity is desirable. It is known that introducing a metallic particle or shell to such fluorescent silica nanoparticles can create a surface plasmon interaction between the metal and the fluorescent dye, potentially allowing for enhancement of the fluorescence intensity. This paper describes the synthesis of two types of hybrid nanoparticles with a fluorescent dye core-shell silica structure coated with small gold nanoparticles and a gold core surrounded by a silica shell of pure silica with Oregon green-488 dye in a second silica shell attached to the surface. The structure of these nanoparticles was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS), while their optical properties were investigated by spectrophotometry and fluorometry.

Belgrave, Akeisha

2007-08-29

58

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

PubMed

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 (ZO-1) 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

59

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 (ZO–1) 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.

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

2013-01-01

60

Memory effects in metal-oxide-semiconductor capacitors incorporating dispensed highly monodisperse 1 nm silicon nanoparticles  

Microsoft Academic Search

Metal-oxide-semiconductor capacitors containing various densities of ex situ produced, colloidal, highly monodisperse, spherical, 1 nm silicon nanoparticles were fabricated and evaluated for potential use as charge storage elements in future nonvolatile memory devices. The capacitance-voltage characteristics are well behaved and agree with similarly fabricated zero-nanoparticle control samples and with an ideal simulation. Unlike larger particle systems, the demonstrated memory effect

Osama M. Nayfeh; Dimitri A. Antoniadis; Kevin Mantey; Munir H. Nayfeh

2007-01-01

61

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.

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

62

Effects of Kaempferol on the Oxidative Properties of Intact Plant Mitochondria  

PubMed Central

The effects of kaempferol on the oxidative and phosphorylative properties of plant mitochondria from potato tubers and etiolated mung bean (Phaseolus aureus Roxb.) hypocotyls were investigated. Kaempferol inhibited the state 3 oxidation rate of malate, NADH, and succinate, but was without effect on the ascorbate-tetramethyl p-phenylenediamine oxidation rate. The inhibition was almost the same whether the mitochondria were in state 3 or in an uncoupled state 3. When 180 micromolar kaempferol was added during state 4, the tight coupling of succinate or NADH oxidation was not released. The results obtained indicate that kaempferol inhibits the mitochondrial electron flow at, or just after, the flavoprotein site.

Ravanel, Patrick; Tissut, Michel; Douce, Roland

1982-01-01

63

TiO 2 nanoparticles incorporated with CuInS 2 clusters: preparation and photocatalytic activity for degradation of 4-nitrophenol  

Microsoft Academic Search

TiO2 nanoparticles incorporated with CuInS2 clusters were prepared in a solvothermal process and characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersion X-ray analysis (EDX). Compared with pure TiO2 nanoparticles, the TiO2 nanoparticles incorporated with CuInS2 clusters display higher photocatalytic activity with 99.9% of degradation ratio of 4-nitrophenol after 2h irradiation. In order to investigate the effect of

Shi-Zhao Kang; Yi-Kai Yang; Wenbo Bu; Jin Mu

2009-01-01

64

The influence of incorporating organic molecules or inorganic nanoparticles on the optical and electrical properties of carbon nanotube films  

NASA Astrophysics Data System (ADS)

Organic molecules and inorganic nanoparticles were incorporated into transparent and conductive single- or double-wall carbon nanotube (SWNT or DWNT) films, and their electrical and optical properties were measured. When organic tetrafluoro-tetracyanoquinodimethane (F 4TCNQ) molecules were incorporated into the nanotube films, sheet resistance was reduced to ˜50% of those from the pristine SWNT and DWNT films. Larger improvements were observed with Au nanoparticle decoration or HNO 3/SOCl 2 dipping processes. The sheet resistances were measured to be 42 ?/sq at 75% of transmittance for HNO 3/SOCl 2-treated DWNT films and 64 ?/sq at 77% for Au-incorporated DWNT films, making their electrical conductivities 200%-300% better than those of the pristine DWNT films. It was observed that DWNTs have better electrical/optical performance than SWNTs. The relative influence of various dopants, F 4TCNQ, Au, and HNO 3/SOCl 2 as well as microwave irradiation on the optical and electrical properties was identified by using Raman and UV-vis-NIR spectra.

Ryu, Yeontack; Yu, Choongho

2011-12-01

65

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

NASA Astrophysics Data System (ADS)

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

2013-11-01

66

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 2–3-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.

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

2010-01-01

67

Antibacterial properties of composite resins incorporating silver and zinc oxide nanoparticles on Streptococcus mutans and Lactobacillus  

PubMed Central

Objectives Recurrent caries was partly ascribed to lack of antibacterial properties in composite resin. Silver and zinc nanoparticles are considered to be broad-spectrum antibacterial agents. The aim of the present study was to evaluate the antibacterial properties of composite resins containing 1% silver and zinc-oxide nanoparticles on Streptococcus mutans and Lactobacillus. Materials and Methods Ninety discoid tablets containing 0%, 1% nano-silver and 1% nano zinc-oxide particles were prepared from flowable composite resin (n = 30). The antibacterial properties of composite resin discs were evaluated by direct contact test. Diluted solutions of Streptococcus mutans (PTCC 1683) and Lactobacillus (PTCC 1643) were prepared. 0.01 mL of each bacterial species was separately placed on the discs. The discs were transferred to liquid culture media and were incubated at 37? for 8 hr. 0.01 mL of each solution was cultured on blood agar and the colonies were counted. Data was analyzed with Kruskall-Wallis and Mann-Whitney U tests. Results Composites containing nano zinc-oxide particles or silver nanoparticles exhibited higher antibacterial activity against Streptococcus mutans and Lactobacillus compared to the control group (p < 0.05). The effect of zinc-oxide on Streptococcus mutans was significantly higher than that of silver (p < 0.05). There were no significant differences in the antibacterial activity against Lactobacillus between composites containing silver nanoparticles and those containing zinc-oxide nanoparticles. Conclusions Composite resins containing silver or zinc-oxide nanoparticles exhibited antibacterial activity against Streptococcus mutans and Lactobacillus.

Kasraei, Shahin; Sami, Lida; Hendi, Sareh; AliKhani, Mohammad-Yousef; Rezaei-Soufi, Loghman

2014-01-01

68

Incorporation of Magnetic Nanoparticles in New Hybrid Networks Based on Heteropolyanions and Polyacrylamide.  

PubMed

The copolymerization of acrylamide with the tetrafunctionalized polyanion [gamma-SiW(10)O(36)(RSiO)(4)](4-) (R=C(3)H(6)OC(O)C(Me)=CH(2)), which acts as a cross-linker, is performed in an aqueous dispersion of maghemite (gamma-Fe(2)O(3)) nanoparticles. It results in a magnetic hybrid hydrogel with superabsorption properties (see scheme). The magnetic properties of the nanoparticles enables their mobility inside the network to be estimated and their release during the swelling of the hydrogel to be observed. PMID:10649320

Mayer; Cabuil; Lalot; Thouvenot

1999-12-16

69

Sonoelectrochemical synthesis of highly photoelectrochemically active TiO2 nanotubes by incorporating CdS nanoparticles  

NASA Astrophysics Data System (ADS)

Self-organized anodic TiO2 nanotube arrays (TiO2NTs) are functionalized with CdS nanoparticle based perfusion and deposition through a single-step sonoelectrodeposition method. Even controlled at 50 °C, CdS nanoparticles with smaller size and more homogeneous distribution are successfully synthesized in dimethyl sulfoxide (DMSO) under ultrasonic irradiation. Moreover, TiO2 nanotubes can be filled with nanoparticles because of the ultrasonic effect. The CdS incorporated TiO2NTs (CdS-TiO2NTs) effectively harvest solar light in the UV as well as the visible light (up to 480 nm) region. Compared with pure TiO2NTs, a more than ninefold enhancement in photocurrent response is observed using the CdS-TiO2NTs. Maximum incident photon to charge carrier efficiency (IPCE) values of 99.95% and 9.85% are observed respectively for CdS-TiO2 nanotubes and pure TiO2NTs. The high value of IPCE observed with the CdS-TiO2NTs is attributed to the increased efficiency of charge separation and transport of electrons. A schematic diagram is proposed to illustrate the possible process of CdS formation in nanotubes under sonochemical and electrochemical conditions.

Wang, Cheng Lin; Sun, Lan; Yun, Hong; Li, Jing; Lai, Yue Kun; Lin, Chang Jian

2009-07-01

70

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

71

Generating High Modulus Fibers by Nanoparticle Incorporation with Potential to Introduce Multifunctionality.  

National Technical Information Service (NTIS)

The aim of this project is to develop the technology of stabilizing and controlling nanoparticle dispersion in polymers and in particular to apply this technology to the production of high modulus fibers which can be designed to have a variety of multifun...

M. E. Mackay P. M. Duxbury

2008-01-01

72

Kaempferol improves carcase characteristics in broiler chickens by regulating ANGPTL3 gene expression.  

PubMed

1. The objective of this study was to examine the beneficial effects of kaempferol, a naturally occurring polyphenol, on carcase characteristics in broiler chickens and the mechanisms involved in this regulation. 2. Broiler chickens were randomly divided into 7 groups: control, carrier control, kaempferol (0·3%), kaempferol (0·6%), hypercholesterolemic (HLD), HLD and kaempferol (0·3%), HLD and kaempferol (0·6%). 3. Seven weeks after treatment, carcase characteristics, lipid levels in the blood and liver, expression of hepatic Angiopoietin-like protein 3 (ANGPTL3) mRNA, and expression of adipose lipoprotein lipase (LPL) protein were determined. 4. Treatment with kaempferol (0·3 or 0·6%) significantly increased plasma high-density lipoprotein cholesterol levels, decreased percentage of abdominal fat, thickness of subcutaneous fat, plasma and hepatic total cholesterol and triglyceride concentrations, muscle malondialdehyde level and down-regulated expression of ANGPTL3 mRNA concomitantly with up-regulated expression of LPL protein in normal and hypercholesterolemic broiler chickens. 5. Kaempferol (0·3 or 0·6%) treatment had no significant effect on the values of percentage of breast muscle, percentage of leg muscle, carcase weight and eviscerated percentage. 6. The results suggest that kaempferol improves carcase characteristics by decreasing expression of ANGPTL3 in broiler chickens. PMID:23398429

Xiao, H-B; Fang, J; Lu, X-Y; Sun, Z-L

2012-01-01

73

Gold nanoparticles incorporated 3-(trimethoxysilyl)propyl methacrylate modified electrode for non-enzymatic electro-sensing of urea.  

PubMed

We describe non-enzymatic electrochemical sensor for urea based on the electrocatalytic activity of gold nanoparticle (AuNPs) incorporated in 3-(Trimethoxysilyl)propyl methacrylate (TMSPMA) network. AuNPs incorporated in TMSPMA network on poly crystalline gold electrode show excellent electrocatalytic activity towards urea sensing. Uniform distribution and interaction of Au nanoparticles in nanospace of TMSPMA network are probably the key factors for catalytic effect of the nanocomposite. Nanocomposite is characterized by UV-visible diffuse reflectance spectroscopy, cyclic voltammetry, field emission scanning electron microscopy and X-ray photoelectron spectroscopy before using as urea sensor. The sensing platform is found to be highly sensitive and shows linear response in wide range for urea concentration with a sensitivity of 1.13 microA/microM and limit of detection as 2.08 microM respectively at S/N (signal-to-noise ratio): 3. It is also observed that the sensor does not suffer interference from phosphate and sulphate ions. Further, a possible mechanism for electro-sensing of urea with modified electrode has also been proposed. PMID:24734691

Gupta, Sandeep; Tiwari, Madhu; Prakash, Rajiv

2014-04-01

74

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

PubMed

Research on incorporation of both growth factors and silver (Ag) into hydroxyapatite (HA) coatings on metallic implant surfaces for enhancing osteoinductivity and antibacterial properties is a challenging work. Generally, Ag nanoparticles are easy to agglomerate and lead to a large increase in local Ag concentration, which could potentially affect cell activity. On the other hand, growth factors immobilization requires mild processing conditions so as to maintain their activities. In this study, bone morphology protein-2 (BMP-2) and Ag nanoparticle contained HA coatings were prepared on Ti surfaces by combining electrochemical deposition (ED) of Ag and electrostatic immobilization of BMP-2. During the ED process, chitosan (CS) was selected as the stabilizing agent to chelate Ag ions and generate Ag nanoparticles that are uniformly distributed in the coatings. CS also reduces Ag toxicity while retaining its antibacterial activity. Afterwards, a BMP/heparin solution was absorbed on the CS/Ag/HA coatings. Consequently, BMP-2 was immobilized on the coatings by the electrostatic attraction between CS, heparin, and BMP-2. Sustained release of BMP-2 and Ag ions from HA coatings was successfully demonstrated for a long period. Results of antibacterial tests indicate that the CS/Ag/HA coatings have high antibacterial properties against both Staphylococcus epidermidis and Escherichia coli. Osteoblasts (OB) culture reveals that the CS/Ag/HA coatings exhibit good biocompatibility. Bone marrow stromal cells (BMSCs) culture indicates that the BMP/CS/Ag/HA coatings have good osteoinductivity and promote the differentiation of BMSCs. Ti bars with BMP/CS/Ag/HA coatings were implanted into the femur of rabbits to evaluate the osteoinductivity of the coatings. Results indicate that BMP/CS/Ag/HA coatings favor bone formation in vivo. In summary, this study presents a convenient and effective method for the incorporation of growth factors and antibacterial agents into HA coatings. This method can be utilized to modify a variety of metallic implant surfaces. PMID:24720634

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

2014-06-11

75

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

76

TiO 2 nanoparticles incorporated with CuInS 2 clusters: preparation and photocatalytic activity for degradation of 4-nitrophenol  

NASA Astrophysics Data System (ADS)

TiO 2 nanoparticles incorporated with CuInS 2 clusters were prepared in a solvothermal process and characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersion X-ray analysis (EDX). Compared with pure TiO 2 nanoparticles, the TiO 2 nanoparticles incorporated with CuInS 2 clusters display higher photocatalytic activity with 99.9% of degradation ratio of 4-nitrophenol after 2 h irradiation. In order to investigate the effect of the CuInS 2 clusters on the photocatalytic activity of TiO 2 nanoparticles, diffuse reflectance UV-Vis spectra (DRS), photoluminescence (PL) spectra, and photocurrent action spectra were measured. The results indicate that the enhanced photocatalytic activity is probably due to the interface between TiO 2 and CuInS 2 as a trap of the photogenerated electrons to decrease the recombination of electrons and holes.

Kang, Shi-Zhao; Yang, Yi-Kai; Bu, Wenbo; Mu, Jin

2009-11-01

77

Preparation and characterization of cisplatin-incorporated chitosan hydrogels, microparticles, and nanoparticles  

Microsoft Academic Search

Three different, polymer-platinum conjugates (hydrogels, microparticles, and nanoparticles) were synthesized by complexation\\u000a of cis-dichlorodiammineplatinum(II) (cisplatin) with partially succinylated glycol chitosan (PSGC). Succinic anhydride was\\u000a used as a linker to introduce cisplatin to glycol chitosan (GC). Succinylation of GC was investigated systematically as a\\u000a function of the molar ratio of succinic anhydride to glucosamine, the methanol content in the reaction media,

Jueun Cha; Won Bum Lee; Chong Rae Park; Yong Woo Cho; Cheol-Hee Ahn; Ick Chan Kwon

2006-01-01

78

Cytotoxicity of anticancer drugs incorporated in solid lipid nanoparticles on HT29 colorectal cancer cell line  

Microsoft Academic Search

Solid lipid nanoparticles (SLN) carrying cholesteryl butyrate (chol-but), doxorubicin and paclitaxel had previously been developed, and the antiproliferative effect of SLN formulations versus conventional drug formulations was here evaluated on HT-29 cells. The 50% inhibitory concentration (IC50) values were interpolated from growth curves obtained by trypan blue exclusion assay. In vitro cytotoxicity of SLN carrying chol-but (IC5072h 0.3±0.03 mM vs

L. Serpe; M. G. Catalano; R. Cavalli; E. Ugazio; O. Bosco; R. Canaparo; E. Muntoni; R. Frairia; M. R. Gasco; M. Eandi; G. P. Zara

2004-01-01

79

Kaempferol Inhibits Angiogenesis and VEGF Expression Through Both HIF Dependent and Independent Pathways in Human Ovarian Cancer Cells  

Microsoft Academic Search

Ovarian cancer is 1 of the most significant malignancies in the Western world, and the antiangiogenesis strategy has been postulated for prevention and treatment of ovarian cancers. Kaempferol is a natural flavonoid present in many fruits and vegetables. The antiangiogenesis potential of kaempferol and its underlying mechanisms were investigated in two ovarian cancer cell lines, OVCAR-3 and A2780\\/CP70. Kaempferol mildly

Haitao Luo; Gary O. Rankin; Lingzhi Liu; Matthew K. Daddysman; Bing-Hua Jiang; Yi Charlie Chen

2009-01-01

80

Improved photovoltaic performance of silicon nanowire/organic hybrid solar cells by incorporating silver nanoparticles  

PubMed Central

Silicon nanowire (SiNW) arrays show an excellent light-trapping characteristic and high mobility for carriers. Surface plasmon resonance of silver nanoparticles (AgNPs) can be used to increase light scattering and absorption in solar cells. We fabricated a new kind of SiNW/organic hybrid solar cell by introducing AgNPs. Reflection spectra confirm the improved light scattering of AgNP-decorated SiNW arrays. A double-junction tandem structure was designed to manufacture our hybrid cells. Both short-circuit current and external quantum efficiency measurements show an enhancement in optical absorption of organic layer, especially at lower wavelengths.

2013-01-01

81

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 °C 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

82

Size selective incorporation of gold nanoparticles in diblock copolymer vesicle wall.  

PubMed

A systematic study is conducted to reveal how far the polymeric vesicle wall can embed gold nanoparticles (AuNPs) with different sizes by combining experiments and self-consistent field simulations. Both the experimental and simulative results indicate that the location of AuNPs in vesicle wall or in spherical micelle is heavily size dependent. Whether the AuNPs enter the vesicle wall or not is determined by a ratio of the diameter of AuNPs (D0) to the thickness of the vesicle wall (d(w0)). The 1-dodecanethiol-coated AuNPs (Au(x)R) with D0/d(w0) < 0.3 will stably disperse in the vesicle walls. For polystyrene-coated AuNPs (Au(x)S), a criterion of D0/d(w0) is proposed based on the phase diagram; i.e., the Au(x)S with D0/d(w0) < 0.5 can be located in the vesicle wall. Otherwise, the Au(x)R and the Au(x)S prefer to locate in spherical micelles. Moreover, the contributions of enthalpy and entropy to the total free energy of the system are respectively calculated to reveal the mechanism of the size selective distribution of AuNPs. The results demonstrate that the escape of AuNPs from vesicle walls and their selective distribution in spherical micelles is an entropy-driven process. Our study provides an important guideline for fabricating nanoparticle/block copolymer hybrid vesicles in dilute solution. PMID:23875535

Xu, Jiangping; Han, Yuanyuan; Cui, Jie; Jiang, Wei

2013-08-20

83

Characterization and properties of portland cement composites incorporating zinc-iron oxide nanoparticles  

Microsoft Academic Search

The present work exposes preliminary results concerning ordinary Portland cement (OPC) blended with oxide fumes produced in steel smelting plants and known as electric arc furnace dust (EAFD). After acid treatment of the EAFD, the powder obtained was formed basically of nanometric particles of ZnFe2O4. The incorporation of EAFD to OPC produced a small retardation of the setting process. Nevertheless,

L. Ma. Flores-Velez; O. Dominguez

2002-01-01

84

Hybrid organic-inorganic nanoparticles: controlled incorporation of gold nanoparticles into virus-like particles and application in surface-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

A capsid is the protein coat surrounding a virus' genome that ensures its protection and transport. The capsid of murine polyomavirus (muPy) consists of one major (VP1) and two minor (VP2/3) proteins, from which just VP1 is sufficient to form the capsid when expressed recombinantly (1). From a material engineering point of view, viral capsids are of interest because they present a paradigm for complex self-assembly on the nanometer scale. Understanding and controlling these assembly dynamics will allow the construction of nanoscale structures using a self-assembly process. The first step in this direction was the discovery that capsids of several viruses can be reversibly disassembled into their building blocks and reassembled using the same building blocks by simply changing the buffer conditions (2, 3). Such capsids already find applications as targeted in vivo delivery vectors for genes, proteins or small molecular drugs (4, 5), as optical probes for biomedical imaging and sensing purposes with unprecedented resolution and sensitivity and can potentially be used as templates for nanoelectronics (6, 7). Here we show the controlled incorporation of inorganic gold nanoparticles into the capsid shell of muPy. This incorporation is mediated by covalent sulfide bonds between the capsid proteins cysteine residues and the molecular gold. The number of incorporated gold particles can be controlled during the assembly process and the capsids retain their ability to transduce cells. These particles provide new tools for tracking of viral particles in cells, and simultaneously allow the delivery of genes packages in the hollow capsid.

Niebert, Marcus; Riches, James; Howes, Mark; Ferguson, Charles; Parton, Robert G.; Middelberg, Anton P. J.; Rintoul, Llew; Fredericks, Peter M.

2007-01-01

85

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.

2014-01-01

86

Kaempferol, a new nutrition-derived pan-inhibitor of human histone deacetylases.  

PubMed

Kaempferol is a natural polyphenol belonging to the group of flavonoids. Different biological functions like inhibition of oxidative stress in plants or animal cells and apoptosis induction have been directly associated with kaempferol. The underlying mechanisms are only partially understood. Here we report for the first time that kaempferol has a distinct epigenetic activity by inhibition of histone deacetylases (HDACs). In silico docking analysis revealed that it fits into the binding pocket of HDAC2, 4, 7 or 8 and thereby binds to the zinc ion of the catalytic center. Further in vitro profiling of all conserved human HDACs of class I, II and IV showed that kaempferol inhibited all tested HDACs. In clinical oncology, HDAC inhibitors are currently under investigation as new anticancer compounds. Therefore, we studied the effect of kaempferol on human-derived hepatoma cell lines HepG2 and Hep3B as well as on HCT-116 colon cancer cells and found that it induces hyperacetylation of histone complex H3. Furthermore, kaempferol mediated a prominent reduction of cell viability and proliferation rate. Interestingly, toxicity assays revealed signs of relevant cellular toxicity in primary human hepatocytes only starting at 50 ?M as well as in an in vivo chicken embryotoxicity assay at 200 ?M. In conclusion, the identification of a novel broad inhibitory capacity of the natural compound kaempferol for human-derived HDAC enzymes opens up the perspective for clinical application in both tumor prevention and therapy. Moreover, kaempferol may serve as a novel lead structure for chemical optimization of pharmacokinetics, pharmacology or inhibitory activities. PMID:23159065

Berger, Alexander; Venturelli, Sascha; Kallnischkies, Mascha; Böcker, Alexander; Busch, Christian; Weiland, Timo; Noor, Seema; Leischner, Christian; Weiss, Thomas S; Lauer, Ulrich M; Bischoff, Stephan C; Bitzer, Michael

2013-06-01

87

Preparation of liposomal nanoparticles incorporating terbinafine in vitro drug release studies.  

PubMed

Terbinafine hydrochloride (TBH) (E)-N-(6,6-dimethyl-2-hepten-4-inyl)-N-methyl-1-naphthaline-methanamine(-hydrochloride) is an effective antifungal agent already existing on the market in the form of topical formulations. The present study deals with the preparation and physicochemical characterization (size, polydispersity, zeta-potential) of 1,2-Diacyl-sn-glycero-3-phosphocholine (EggPC) incorporating TBH in two different dispersion media (tris-buffered saline (TBS) of pH 7.4 or in phosphate buffer solution (PS) of pH 5.5) in order to investigate how pH of dispersion media affects the incorporation efficiency of TBH into liposomes. There were further prepared three Carbopol 934 hydrogels of different concentrations (0.5, 1 and 2%) and their viscosity was measured and evaluated. Moreover, the in vitro drug release from three liposomal gels was studied, in order to investigate the ability of liposomes to act as carriers for TBH in a gel. All formulations were found to retain their original physicochemical properties at least for three weeks. These early studies on the release kinetics from liposomal gel show that Korsmeyer-Peppas model could be the best fitted model concerning the TBH release profile and could be supported biophysically from extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. PMID:24738424

Koutsoulas, Charalampos; Pippa, Natassa; Demetzos, Costas; Zabka, Marian

2014-06-01

88

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 kaempferol’s angioprevention effects in ovarian cancer cells. This data supplements our comprehension of the mechanisms behind kaempferol’s biological influence in ovarian cancer cells, and better characterized kaempferol toward chemoprevention.

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

2011-01-01

89

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

90

Monodisperse magnetic core/shell microspheres with Pd nanoparticles-incorporated-carbon shells.  

PubMed

This work reports a hard self-template method to synthesize core/shell like Fe3O4@C microparticles, in which the Pd nanocrystals can be alternatively incorporated into the carbon shells. The Fe3O4@polyaniline core/shell microspheres were first synthesized as the precursor by in situ polymerization of aniline onto the surface of the Fe3O4 microspheres. In a subsequent carbonization of the precursor under a vacuum oven, the Fe3O4 core was preserved and the polyaniline shell transferred into carbon shells enveloping the magnetic sphere, forming magnetic Fe3O4@C microspheres. The Pd ions could be impregnated into the polyaniline shell, and thus the obtained composites were transformed into Fe3O4@C/Pd microspheres under the same vacuum heating progress. The as-obtained system demonstrates superparamagnetic characteristics, which would benefit its potential application in nanocatalysts. This strategy provides an efficient approach for tailoring core/shell materials with desired functionalities and structures by adjusting the precursors and structure-directing agents. PMID:24323164

Fang, Qunling; Cheng, Qing; Xu, Huajian; Xuan, Shouhu

2014-02-14

91

Synthesis of a labeled RGD-lipid, its incorporation into liposomal nanoparticles, and their trafficking in cultured endothelial cells.  

PubMed

The use of targeting ligands to enhance the delivery of liposomal nanoparticles (LNs) has moved slowly toward clinical application. This relative lack of clinical progression is further complicated by the existence of conflicting in vivo results in the literature. In this work, we describe new formulations of LNs that are targeted with an arginine-glycine-aspartic acid-containing peptide, cRGDfK, conjugated to the lipid distearoyl phosphatidylethanolamine (DSPE). These formulations may be able to circumvent some of the challenges encountered during the development of targeted-LNs. Of the constructs studied, a fluorescently labeled peptide-lipid conjugate was incorporated into LNs with high yield and accuracy. It is shown that the resulting targeted-LNs bind to human umbilical vein endothelial cells (HUVECs) with increasing avidity as the amount of peptide displayed on the LN surface increases. We specifically demonstrate the ability of targeted-LNs loaded with doxorubicin and incubated with HUVECs to deliver the drug to the cytosol. The cell does not internalize nontargeted LNs, supporting the notion that the RGD motif is associated with internalization of the targeted LN. PMID:19534457

Cressman, Sonya; Dobson, Ian; Lee, Justin B; Tam, Yuen Yi C; Cullis, Pieter R

2009-07-01

92

Electrochemical behavior of gold nanoparticles modified nitrogen incorporated tetrahedral amorphous carbon and its application in glucose sensing.  

PubMed

Gold nanoparticles (NPs) with 10-50 nm in diameter were synthesized on nitrogen incorporated tetrahedral amorphous carbon (ta-C:N) thin film electrode by electrodeposition. The deposition and nucleation processes of Au on ta-C:N surface were investigated by cyclic voltammetry and chronoamperometry. The morphology of Au NPs was characterized by scanned electron microscopy. The electrochemical properties of Au NPs modified ta-C:N (ta-C:N/Au) electrode and its ability to sense glucose were investigated by voltammetric and amperometric measurements. The potentiostatic current-time transients showed a progressive nucleation process and diffusion growth of Au on the surface of ta-C:N film according to the Scharifker-Hills model. The Au NPs acted as microelectrodes improved the electron transfer and electrocatalytic oxidation of glucose on ta-C:N electrode. The ta-C:N/Au electrode exhibited fast current response, a linear detection range of glucose from 0.5 to 25 mM and a detection limit of 120 microM, which hinted its potential application as a glucose biosensor. PMID:22409057

Liu, Aiping; Wu, Huaping; Qiu, Xu; Tang, Weihua

2011-12-01

93

Blockade of Airway Inflammation by Kaempferol via Disturbing Tyk-STAT Signaling in Airway Epithelial Cells and in Asthmatic Mice  

PubMed Central

Asthma is characterized by bronchial inflammation causing increased airway hyperresponsiveness and eosinophilia. The interaction between airway epithelium and inflammatory mediators plays a key role in the asthmatic pathogenesis. The in vitro study elucidated inhibitory effects of kaempferol, a flavonoid found in apples and many berries, on inflammation in human airway epithelial BEAS-2B cells. Nontoxic kaempferol at ?20??M suppressed the LPS-induced IL-8 production through the TLR4 activation, inhibiting eotaxin-1 induction. The in vivo study explored the demoting effects of kaempferol on asthmatic inflammation in BALB/c mice sensitized with ovalbumin (OVA). Mouse macrophage inflammatory protein-2 production and CXCR2 expression were upregulated in OVA-challenged mice, which was attenuated by oral administration of ?10?mg/kg kaempferol. Kaempferol allayed the airway tissue levels of eotaxin-1 and eotaxin receptor CCR3 enhanced by OVA challenge. This study further explored the blockade of Tyk-STAT signaling by kaempferol in both LPS-stimulated BEAS-2B cells and OVA-challenged mice. LPS activated Tyk2 responsible for eotaxin-1 induction, while kaempferol dose-dependently inhibited LPS- or IL-8-inflamed Tyk2 activation. Similar inhibition of Tyk2 activation by kaempferol was observed in OVA-induced mice. Additionally, LPS stimulated the activation of STAT1/3 signaling concomitant with downregulated expression of Tyk-inhibiting SOCS3. In contrast, kaempferol encumbered STAT1/3 signaling with restoration of SOCS3 expression. Consistently, oral administration of kaempferol blocked STAT3 transactivation elevated by OVA challenge. These results demonstrate that kaempferol alleviated airway inflammation through modulating Tyk2-STAT1/3 signaling responsive to IL-8 in endotoxin-exposed airway epithelium and in asthmatic mice. Therefore, kaempferol may be a therapeutic agent targeting asthmatic diseases.

Gong, Ju-Hyun; Shin, Daekeun; Han, Seon-Young; Park, Sin-Hye; Kang, Min-Kyung; Kim, Jung-Lye; Kang, Young-Hee

2013-01-01

94

Kaempferol induces apoptosis in two different cell lines via Akt inactivation, Bax and SIRT3 activation, and mitochondrial dysfunction.  

PubMed

Kaempferol (3,4',5,7-tetrahydroxyflavone) is a flavonoid with anti- and pro-oxidant activity present in various natural sources. Kaempferol has been shown to posses anticancer properties through the induction of the apoptotic program. Here we report that treatment of the chronic myelogenous leukemia cell line K562 and promyelocitic human leukemia U937 with 50 microM kaempferol resulted in an increase of the antioxidant enzymes Mn and Cu/Zn superoxide dismutase (SOD). Kaempferol treatment induced apoptosis by decreasing the expression of Bcl-2 and increasing the expressions of Bax. There were also induction of mitochondrial release of cytochrome c into cytosol and significant activation of caspase-3, and -9 with PARP cleavage. Kaempferol treatment increased the expression and the mitochondria localization of the NAD-dependent deacetylase SIRT3. K562 cells stably overexpressing SIRT3 were more sensitive to kaempferol, whereas SIRT3 silencing did not increase the resistance of K562 cells to kaempferol. Inhibition of PI3K and de-phosphorylation of Akt at Ser473 and Thr308 was also observed after treating both K562 and U937 cells with kaempferol. In conclusion our study shows that the oxidative stress induced by kaempferol in K562 and U937 cell lines causes the inactivation of Akt and the activation of the mitochondrial phase of the apoptotic program with an increase of Bax and SIRT3, decrease of Bcl-2, release of cytochrome c, caspase-3 activation, and cell death. PMID:19160423

Marfe, Gabriella; Tafani, Marco; Indelicato, Manuela; Sinibaldi-Salimei, Paola; Reali, Valentina; Pucci, Bruna; Fini, Massimo; Russo, Matteo Antonio

2009-03-01

95

Production of kaempferol 3-O-rhamnoside from glucose using engineered Escherichia coli.  

PubMed

Flavonoids are ubiquitous phenolic compounds and at least 9,000 have been isolated from plants. Most flavonoids have been isolated and assessed in terms of their biological activities. Microorganisms such as Escherichia coli and Saccharomyces cerevisiae are efficient systems for the synthesis of flavonoids. Kaempferol 3-O-rhamnoside has notable biological activities such as the inhibition of the proliferation of breast cancer cells, the absorption of glucose in the intestines, and the inhibition of the self-assembly of beta amyloids. We attempted to synthesize kaempferol 3-O-rhamnoside from glucose in E. coli. Five flavonoid biosynthetic genes [tyrosine ammonia lyase (TAL), 4-coumaroyl CoA ligase (4CL), chalcone synthase (CHS), flavonol synthase (FLS), and flavonol 3-O-rhamnosyltransferase (UGT78D1)] from tyrosine were introduced into E. coli that was engineered to increase tyrosine production. By using this approach, the production of kaempferol 3-O-rhamnoside increased to 57 mg/L. PMID:24879482

Yang, So-Mi; Han, So Hyun; Kim, Bong-Gyu; Ahn, Joong-Hoon

2014-08-01

96

Electrospun magnetic poly(L-lactide) (PLLA) nanofibers by incorporating PLLA-stabilized Fe3O4 nanoparticles.  

PubMed

Magnetic poly(L-lactide) (PLLA)/Fe3O4 composite nanofibers were prepared with the purpose to develop a substrate for bone regeneration. To increase the dispersibility of Fe3O4 nanoparticles (NPs) in the PLLA matrix, a modified chemical co-precipitation method was applied to synthesize Fe3O4 NPs in the presence of PLLA. Trifluoroethanol (TFE) was used as the co-solvent for all the reagents, including Fe(II) and Fe(III) salts, sodium hydroxide, and PLLA. The co-precipitated Fe3O4 NPs were surface-coated with PLLA and demonstrated good dispersibility in a PLLA/TFE solution. The composite nanofiber electrospun from the solution displayed a homogeneous distribution of Fe3O4 NPs along the fibers using various contents of Fe3O4 NPs. X-ray diffractometer (XRD) and vibration sample magnetization (VSM) analysis confirmed that the co-precipitation process had minor adverse effects on the crystal structure and saturation magnetization (Ms) of Fe3O4 NPs. The resulting PLLA/Fe3O4 composite nanofibers showed paramagnetic properties with Ms directly related to the Fe3O4 NP concentration. The cytotoxicity of the magnetic composite nanofibers was determined using in vitro culture of osteoblasts (MC3T3-E1) in extracts and co-culture on nanofibrous matrixes. The PLLA/Fe3O4 composite nanofibers did not show significant cytotoxicity in comparison with pure PLLA nanofibers. On the contrary, they demonstrated enhanced effects on cell attachment and proliferation with Fe3O4 NP incorporation. The results suggested that this modified chemical co-precipitation method might be a universal way to produce magnetic biodegradable polyester substrates containing well-dispersed Fe3O4 NPs. This new strategy opens an opportunity to fabricate various kinds of magnetic polymeric substrates for bone tissue regeneration. PMID:23706239

Shan, Dingying; Shi, Yuzhou; Duan, Shun; Wei, Yan; Cai, Qing; Yang, Xiaoping

2013-08-01

97

Osteoblasts on rod shaped hydroxyapatite nanoparticles incorporated PCL film provide an optimal osteogenic niche for stem cell differentiation.  

PubMed

After the clinical insertion of a bone biomaterial, the surrounding osteoblasts would migrate and attach to the implant surface and foster a microenvironment that largely determines the differentiation fate of the comigrated mesenchymal stem cells. Whether the fostered microenvironment is suitable for osteogenic differentiation of mesenchymal stem cells is critical for the subsequent osseointegration. In this study, we determined (1) how the spherical or rod-shaped hydroxyapatite nanoparticles (nHA) incorporated poly(?-caprolactone) (PCL) films (PCL-spherical nHA, PCL-rod nHA) interact with primary human osteoblasts (HOBs); (2) how the microenvironment rendered by their interaction affects osteogenic differentiation of adipose tissue-derived mesenchymal stem cells (ASCs). HOBs were seeded on PCL, PCL-spherical nHA, and PCL-rod nHA films, respectively. When cultured alone, the HOBs on PCL-rod nHA films showed most efficient osteoblastic differentiation compared with those on PCL or PCL-spherical nHA films. When cocultured with ASCs in an indirect coculture system, only the HOBs on PCL-rod nHA films up-regulated the gene expression of Runx2, bone sialoprotein, and osteocalcin of ASCs. Additionally, the HOBs on PCL-rod nHA films showed significant up-regulation of bone morphogenic protein 2 gene and protein expression and induced highest phosphorylated Smad1/5 protein level in ASCs. Treatment of the coculture medium with bone morphogenic protein 2 inhibitor (Noggin) largely abolished the osteogenic differentiation of the ASCs induced by the HOBs on PCL-rod nHA films. In conclusion, HOBs can not only best display their osteoblastic phenotype by culturing on PCL-rod nHA films but also render an optimal osteogenic niche for the differentiation of stem cells. PMID:21306280

Lu, ZuFu; Roohani-Esfahani, Seyed-Iman; Kwok, Philip Chi Lip; Zreiqat, Hala

2011-06-01

98

In situ incorporation of nickel nanoparticles into the mesopores of MCM-41 by manipulation of solvent-solute interaction and its activity toward adsorptive desulfurization of gas oil.  

PubMed

In this contribution, different amounts of nickel were incorporated into the mesopores of MCM-41 via an in situ approach. A hydrophobic nickel precursor was incorporated into the nanochannels of mesoporous silica by manipulation of solvent-solute interaction. The synthesized material was characterized using X-ray diffraction, nitrogen physisorption, temperature programmed reduction, and transmission electron microscopy. The results implicate the formation of MCM-41 with well-ordered hexagonal structure and establish also the presence of nickel nanoparticles inside the nanochannels of mesoporous silica. Adsorptive desulfurization of gas oil was conducted using the nickel-incorporated MCM-41 samples. The effects of nickel concentration, temperature of process and feed flow rate on the desulfurization process were examined. The MCM-41 containing 6 wt.% of nickel had both the highest breakthrough sulfur adsorption capacity and total sulfur adsorption capacity, which were 0.69 and 1.67 mg sulfur/g adsorbent, respectively. The breakthrough sulfur adsorption capacity was almost regained after reductive regeneration of spent adsorbent. The obtained results suggest that the method applied for the synthesis of Niy/MCM resulted in formation of well-dispersed, accessible and small nickel nanoparticles incorporated into the pores of MCM-41 which might be an advantage for adsorption of refractory sulfur compounds from low sulfur gas oil. PMID:21820806

Samadi-Maybodi, Abdolraouf; Teymouri, Mohammad; Vahid, Amir; Miranbeigi, Aliakbar

2011-09-15

99

Antidepressant-like Effect of Kaempferol and Quercitirin, Isolated from Opuntia ficus-indica var. saboten  

PubMed Central

Opuntia ficus-indica var. saboten. is widely cultivated in Jeju Island (South Korea) for use in manufacture of health foods. This study described antidepressant effect of two flavonoids (kaempferol and quercitrin) isolated from the Opuntia ficus-indica var. saboten. The expression of the hypothalamic POMC mRNA or plasma ?-endorphin levels were increased by extract of Opuntia ficus-indica var. saboten or its flavoniods administered orally. In addition, antidepressant activity was studied using tail suspension test (TST), forced swimming test (FST) and rota-rod test in chronically restraint immobilization stress group in mice. After restraint stress (2 hrs/day for 14 days), animals were kept in cage for 14 days without any further stress, bet with drugs. Mice were fed with a diet supplemented for 14 days and during the behavioral test period with kaempferol or quercitrin (30 mg/kg/day). POMC mRNA or plasma ?-endorphin level was increased by extract of Opuntia ficus-indica var. saboten and its flavoniods. In addition, immobility time in TST and FST was significantly reduced by kaempferol or quercitrin. In rota-rod test, the time of permanence was maintained to the semblance of control group in turning at 15 rpm. Our results suggest that two flavonoids (kaempferol and quercitrin) isolated from the Opuntia ficus-indica var. saboten. show a potent antidepressant effect.

Park, Soo-Hyun; Sim, Yun-Beom; Han, Pyung-Lim; Lee, Jin-Koo

2010-01-01

100

Determination of kaempferol and quercetin in Xindakang tablet by ?-cyclodextrin modified micellar electrokinetic capillary chromatography.  

PubMed

A method was proposed to determine kaempferol and quercetin in Hippophae rhamnoides L medicinal preparation xindakang tablet by ?-cyclodextrin modified micellar electrokinetic capillary chromatography. Under the optimized conditions: buffer solution of 20 mmol/L Na(2)B(4)O(7)-KH(2)PO(4) (pH 9.0)-20mmol/L SDS-6mmol/L ?-CD-5%(v/v) MeCN, applied voltage of 16 kV and injection time of 8s, the two analytes were separated well within 10 minutes. The calibration was linear in the 0.02-0.80 and 0.02-0.70 mg/mL range for kaempferol and quercetin, respectively. The reproducibility based on migration time and peak height were 0.47% and1.87% for kaempferol, 0.55% and 2.02% for quercetin. The detection limits based on three times noise were 0.010 mg/mL and 0.008 mg/mL for kaempferol and quercetin, respectively. The developed method was utilized to analyze real samples and running recovery experiments with satisfactory results. PMID:24811806

Lu, Yuanqi; Wang, Dunqing; Ning, Zhihua; Yao, Qingqiang

2014-05-01

101

The effects of curing medium on flexural strength and water permeability of concrete incorporating TiO 2 nanoparticles  

Microsoft Academic Search

The effect of limewater on flexural strength and water permeability of TiO2 nanoparticles binary blended concrete has been investigated. TiO2 nanoparticles with partial replacement of cement by 0.5, 1.0, 1.5 and 2.0 weight percent have been used as reinforcement.\\u000a Curing of the specimens has been carried out in water and saturated limewater for 7, 28 and 90 days after casting. The

Ali Nazari

2011-01-01

102

Antimicrobial and antioxidant activity of kaempferol rhamnoside derivatives from Bryophyllum pinnatum  

PubMed Central

Background Bryophyllum pinnatum (Lank.) Oken (Crassulaceae) is a perennial succulent herb widely used in traditional medicine to treat many ailments. Its wide range of uses in folk medicine justifies its being called "life plant" or "resurrection plant", prompting researchers' interest. We describe here the isolation and structure elucidation of antimicrobial and/or antioxidant components from the EtOAc extract of B. pinnatum. Results The methanol extract displayed both antimicrobial activities with minimum inhibitory concentration (MIC) values ranging from 32 to 512 ?g/ml and antioxidant property with an IC50 value of 52.48 ?g/ml. Its partition enhanced the antimicrobial activity in EtOAc extract (MIC = 16-128 ?g/ml) and reduced it in hexane extract (MIC = 256-1024 ?g/ml). In addition, this process reduced the antioxidant activity in EtOAc and hexane extracts with IC50 values of 78.11 and 90.04 ?g/ml respectively. Fractionation of EtOAc extract gave seven kaempferol rhamnosides, including; kaempferitrin (1), kaempferol 3-O-?-L-(2-acetyl)rhamnopyranoside-7-O-?-L-rhamnopyranoside (2), kaempferol 3-O-?-L-(3-acetyl)rhamnopyranoside-7-O-?-L-rhamnopyranoside (3), kaempferol 3-O-?-L-(4-acetyl)rhamnopyranoside-7-O-?-L-rhamnopyranoside (4), kaempferol 3-O-?-D- glucopyranoside-7-O-?-L-rhamnopyranoside (5), afzelin (6) and ?-rhamnoisorobin (7). All these compounds, except 6 were isolated from this plant for the first time. Compound 7 was the most active, with MIC values ranging from 1 to 2 ?g/ml and its antioxidant activity (IC50 = 0.71 ?g/ml) was higher than that of the reference drug (IC50 = 0.96 ?g/ml). Conclusion These findings demonstrate that Bryophyllum pinnatum and some of its isolated compounds have interesting antimicrobial and antioxidant properties, and therefore confirming the traditional use of B. pinnatum in the treatment of infectious and free radical damages.

2012-01-01

103

Evaluation of in vitro macrophage response and in vivo host response to growth factors incorporated chitosan nanoparticle impregnated collagen-chitosan scaffold.  

PubMed

The purpose of this study was to evaluate the in vitro macrophage compatibility, the inflammatory response and in vivo host response to a novel collagen-chitosan (COL-CS) scaffold containing growth factors incorporated Chitosan Nanoparticle (CNP). The scaffold was obtained by freezing a blend of COL-CS solution and growth factor incorporated CNP followed by lyophilization. High Resolution Transmission Electron Micrograph (HR-TEM) indicated that growth factors incorporated CNP were in the size range of 50-100 nm, while Scanning Electron Microscopic (SEM) analysis of the scaffold surface suggests that the pores of the scaffolds (COL-CS) were well interconnected, with a mean diameter of 75-150 microm. Macrophages grown on growth factors containing scaffold exhibited poor inflammatory response compared to scaffold without growth factors. In vivo biocompatibility and host response study of scaffold was performed by subcutaneous implantation and examination of the implanted material on day 3 and 15 post implant. The dual growth factors viz. EGF (Epidermal Growth Factor) and FGF (Fibroblast Growth Factor) incorporated implant showed a distinct fibrous capsule boundary on the surface. Secondly, the immunofluoresence assay and zymography respectively for TNFalpha and MMP9 exhibited low expression of these inflammatory markers. These observations divulge that the growth factors when incorporated, can suppress the inflammatory properties of the scaffolds and thus such scaffolds could be used in tissue engineering for minimal host response and enhanced tissue-scaffold interaction. PMID:24730246

Rajam, A Merlin; Jithendral, P; Mandal, A B; Rose, C

2014-03-01

104

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

105

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

106

Sustained release of PTX-incorporated nanoparticles synergized by burst release of DOX?HCl from thermosensitive modified PEG/PCL hydrogel to improve anti-tumor efficiency.  

PubMed

As drug therapies become increasingly sophisticated, the synergistic benefits of two or more drugs are often required. In this study, we aimed at improving anti-tumor efficiency of paclitaxel (PTX)-incorporated thermo-sensitive injectable hydrogel by the synergy of burst release of doxorubicin hydrochloride (DOX?HCl). Thermosensitive injectable hydrogel composed of nanoparticles assembled from amphiphilic copolymer poly(?-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone)-poly(ethylene glycol)-poly(?-caprolaone-co-1,4,8-trioxa[4.6]spiro-9-undecanone) (PECT) was fabricated. Hydrophobic PTX and hydrophilic DOX?HCl were loaded simultaneously in the thermo-sensitive injectable hydrogel by a two-stage entrapment. Thermosensitive gelling behaviors of drug-loading PECT nanoparticle aqueous dispersions were studied. In vitro release profiles of PTX and DOX?HCl and in vivo anti-tumor effect by dual drugs from PECT hydrogel were investigated. The results showed that hydrophilic and hydrophobic drugs could be successfully entrapped in PECT hydrogel simultaneously without affecting its thermo-sensitive behavior. In vitro release profiles demonstrated the burst release of DOX?HCl and the sustained release of PTX. Anti-tumor effect was improved by a fast and tense attack caused by the burst release of hydrophilic DOX?HCl from hydrogel, which was continued by the sequent sustained release of PTX-incorporated nanoparticles and remnant DOX?HCl. Unintentionally, entrapped in PECT hydrogel, hydrophilic DOX?HCl was observed to have a sustained releasing pattern in vitro and in vivo. PMID:24931190

Xu, Shuxin; Wang, Weiwei; Li, Xijing; Liu, Jianping; Dong, Anjie; Deng, Liandong

2014-10-01

107

Two-electron electrochemical oxidation of quercetin and kaempferol changes only the flavonoid C-ring.  

PubMed

Bulk electrolysis of the antioxidant flavonoids quercetin and kaempferol in acetonitrile both yield a single oxidation product in two-electron processes. The oxidation products are more polar than their parent compounds, with an increased molecular weight of 16g/mol, and were identified as 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone and 2-(4-hydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone for quercetin and kaempferol, respectively. Two-electron oxidation of the parent flavonoid is suggested to yield a 3,4-flavandione with unchanged substitution pattern in the A- and B-ring, which may rearrange to form the substituted 3(2H)-benzofuranone through the chalcan-trione ring-chain tautomer. The acidity of the 3-OH group is suggested to determine the fate of the flavonoid phenoxyl radical, originally formed by one-electron oxidation, as no well-defined oxidation product of luteolin (lacking the 3-OH group) could be isolated despite rather similar half-peak potentials: Ep/2 = 0.97V, 0.98 V and 1.17 V vs. NHE for quercetin, kaempferol and luteolin, respectively, as measured by cyclic voltammetry in acetonitrile. PMID:9860049

Jørgensen, L V; Cornett, C; Justesen, U; Skibsted, L H; Dragsted, L O

1998-10-01

108

The flavonols quercetin, kaempferol, and myricetin inhibit hepatocyte growth factor-induced medulloblastoma cell migration.  

PubMed

Medulloblastoma, the most common malignant brain tumor in children, is a highly metastatic disease, with up to 30% of children having evidence of disseminated disease at presentation. Recently, the hepatocyte growth factor (HGF) and its receptor, the tyrosine kinase Met, have emerged as key components of human medulloblastoma growth and metastasis, suggesting that inhibition of this pathway may represent an attractive target for the prevention and treatment of this disease. Using immunoblotting procedures, we observed that the dietary-derived flavonols quercetin, kaempferol, and myricetin inhibited HGF/Met signaling in a medulloblastoma cell line (DAOY), preventing the formation of actin-rich membrane ruffles and resulting in the inhibition of Met-induced cell migration in Boyden chambers. Furthermore, quercetin and kaempferol also strongly diminished HGF-mediated Akt activation. Interestingly, the inhibitory effects of quercetin on the tyrosine kinase receptor Met [half-maximal inhibitory effect (IC(50)) of 12 micromol/L] or on the Met-induced activation of Akt (IC(50) of 2.5 micromol/L) occurred at concentrations achievable through dietary approaches. These results highlight quercetin, kaempferol, and myricetin as dietary-derived inhibitors of Met activity and suggest that this inhibitory effect may contribute to the chemopreventive properties of these molecules. PMID:19244381

Labbé, David; Provençal, Mathieu; Lamy, Sylvie; Boivin, Dominique; Gingras, Denis; Béliveau, Richard

2009-04-01

109

Nanomolar concentrations determination of hydrazine by a modified carbon paste electrode incorporating TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

In the present paper, the use of a carbon paste electrode modified by quinizarine (QZ) and TiO2 nanoparticles prepared by a simple and rapid method was described. The heterogeneous electron-transfer properties of quinizarine coupled to TiO2 nanoparticles at a carbon paste electrode was investigated using cyclic voltammetry and chronoamperometry in aqueous buffer solutions. The modified electrode showed excellent character for the electrocatalytic oxidization of hydrazine (HZ). Differential pulse voltammetric peak currents of HZ increased linearly with their concentrations at the range of 0.5 µM to 1900.0 µM and the detection limit (2?) was determined to be 77 nM. Finally, this method was used for the determination of HZ in water samples, using a standard addition method.

Mazloum-Ardakani, Mohammad; Taleat, Zahra; Beitollahi, Hadi; Naeimi, Hossein

2011-04-01

110

The dietary flavonoid kaempferol effectively inhibits HIF-1 activity and hepatoma cancer cell viability under hypoxic conditions  

SciTech Connect

Research highlights: {yields} Kaempferol inhibits HIF-1 activity in hepatocarcinoma cells; {yields} Kaempferol causes cytoplasmic mislocalization of HIF-1{alpha} by impairing the MAPK pathway. {yields} Viability of hepatocarcinoma cells under hypoxia is reduced by kaempferol. -- Abstract: Hepatocellular carcinoma (HCC) is characterized by high mortality rates and resistance to conventional treatment. HCC tumors usually develop local hypoxia, which stimulates proliferation of cancer cells and renders them resilient to chemotherapy. Adaptation of tumor cells to the hypoxic conditions depends on the hypoxia-inducible factor 1 (HIF-1). Over-expression of its regulated HIF-1{alpha} subunit, an important target of anti-cancer therapy, is observed in many cancers including HCC and is associated with severity of tumor growth and poor patient prognosis. In this report we investigate the effect of the dietary flavonoid kaempferol on activity, expression levels and localization of HIF-1{alpha} as well as viability of human hepatoma (Huh7) cancer cells. Treatment of Huh7 cells with kaempferol under hypoxic conditions (1% oxygen) effectively inhibited HIF-1 activity in a dose-dependent manner (IC{sub 50} = 5.16 {mu}M). The mechanism of this inhibition did not involve suppression of HIF-1{alpha} protein levels but rather its mislocalization into the cytoplasm due to inactivation of p44/42 MAPK by kaempferol (IC{sub 50} = 4.75 {mu}M). Exposure of Huh7 cells to 10 {mu}{Mu} kaempferol caused significant reduction of their viability, which was remarkably more evident under hypoxic conditions. In conclusion, kaempferol, a non-toxic natural food component, inhibits both MAPK and HIF-1 activity at physiologically relevant concentrations (5-10 {mu}M) and suppresses hepatocarcinoma cell survival more efficiently under hypoxia. It has, therefore, potential as a therapeutic or chemopreventive anti-HCC agent.

Mylonis, Ilias; Lakka, Achillia; Tsakalof, Andreas [Laboratory of Biochemistry, School of Medicine, University of Thessaly, BIOPOLIS, 41110 Larissa (Greece) [Laboratory of Biochemistry, School of Medicine, University of Thessaly, BIOPOLIS, 41110 Larissa (Greece); Institute of Biomedical Research and Technology (BIOMED), 51 Papanastasiou str., 41222 Larissa (Greece); Simos, George, E-mail: simos@med.uth.gr [Laboratory of Biochemistry, School of Medicine, University of Thessaly, BIOPOLIS, 41110 Larissa (Greece) [Laboratory of Biochemistry, School of Medicine, University of Thessaly, BIOPOLIS, 41110 Larissa (Greece); Institute of Biomedical Research and Technology (BIOMED), 51 Papanastasiou str., 41222 Larissa (Greece)

2010-07-16

111

Kaempferol modulates pro-inflammatory NF-?B activation by suppressing advanced glycation endproducts-induced NADPH oxidase  

PubMed Central

Advanced glycation endproducts (AGE) are oxidative products formed from the reaction between carbohydrates and a free amino group of proteins that are provoked by reactive species (RS). It is also known that AGE enhance the generation of RS and that the binding of AGE to a specific AGE receptor (RAGE) induces the activation of the redox-sensitive, pro-inflammatory transcription factor, nuclear factor-kappa B (NF-?B). In this current study, we investigated the anti-oxidative effects of short-term kaempferol supplementation on the age-related formation of AGE and the binding activity of RAGE in aged rat kidney. We further investigated the suppressive action of kaempferol against AGE's ability to stimulate activation of pro-inflammatory NF-?B and its molecular mechanisms. For this study, we utilized young (6 months old), old (24 months old), and kaempferol-fed (2 and 4 mg/kg/day for 10 days) old rats. In addition, for the molecular work, the rat endothelial cell line, YPEN-1 was used. The results show that AGE and RAGE were increased during aging and that these increases were blunted by kaempferol. In addition, dietary kaempferol reduced age-related increases in NF-?B activity and NF-?B-dependant pro-inflammatory gene activity. The most significant new finding from this study is that kaempferol supplementation prevented age-related NF-?B activation by suppressing AGE-induced nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase). Taken together, our results demonstrated that dietary kaempferol exerts its anti-oxidative and anti-inflammatory actions by modulating the age-related NF-?B signaling cascade and its pro-inflammatory genes by suppressing AGE-induced NADPH oxidase activation. Based on these data, dietary kaempferol is proposed as a possible anti-AGE agent that may have the potential for use in anti-inflammation therapies.

Kim, Ji Min; Lee, Eun Kyeong; Kim, Dae Hyun; Yu, Byung Pal

2010-01-01

112

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.

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

2013-01-01

113

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

PubMed

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. PMID:24604238

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

2014-05-21

114

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; Samorì, Paolo

2014-04-01

115

Colorimetric Assay for Determination of Lead (II) Based on Its Incorporation into Gold Nanoparticles during Their Synthesis  

PubMed Central

In this report, we present a new method for visual detection of Pb2+. Gold nanoparticles (Au-NPs) were synthesized in one step at room temperature, using gallic acid (GA) as reducer and stabilizer. Pb2+ is added during the gold nanoparticle formation. Analysis of Pb2+ is conducted by a dual strategy, namely, colorimetry and spectrometry. During Au-NPs synthesis, addition of Pb2+ would lead to formation of Pb-GA complex, which can induce the aggregation of newly-formed small unstable gold nanoclusters. Consequently, colorimetric detection of trace Pb2+ can be realized. As the Pb2+ concentration increases, the color turns from red-wine to purple, and finally blue. This method offers a sensitive linear correlation between the shift of the absorption band (??) and logarithm of Pb2+ concentration ranging from 5.0 × 10?8 to 1.0 × 10?6 M with a linear fit coefficient of 0.998, and a high selectivity for Pb2+ detection with a low detection limit down to 2.5 × 10?8 M.

Ding, Nan; Cao, Qian; Zhao, Hong; Yang, Yimin; Zeng, Lixi; He, Yujian; Xiang, Kaixiang; Wang, Guangwei

2010-01-01

116

In-situ electrochemically deposited polypyrrole nanoparticles incorporated reduced graphene oxide as an efficient counter electrode for platinum-free dye-sensitized solar cells.  

PubMed

This paper reports a rapid and in-situ electrochemical polymerization method for the fabrication of polypyrrole nanoparticles incorporated reduced graphene oxide (rGO@PPy) nanocomposites on a ITO conducting glass and its application as a counter electrode for platinum-free dye-sensitized solar cell (DSSC). The scanning electron microscopic images show the uniform distribution of PPy nanoparticles with diameter ranges between 20 and 30?nm on the rGO sheets. The electrochemical studies reveal that the rGO@PPy has smaller charge transfer resistance and similar electrocatalytic activity as that of the standard Pt counter electrode for the I3(-)/I(-) redox reaction. The overall solar to electrical energy conversion efficiency of the DSSC with the rGO@PPy counter electrode is 2.21%, which is merely equal to the efficiency of DSSC with sputtered Pt counter electrode (2.19%). The excellent photovoltaic performance, rapid and simple fabrication method and low-cost of the rGO@PPy can be potentially exploited as a alternative counter electrode to the expensive Pt in DSSCs. PMID:24930387

Lim, Su Pei; Pandikumar, Alagarsamy; Lim, Yee Seng; Huang, Nay Ming; Lim, Hong Ngee

2014-01-01

117

In-situ electrochemically deposited polypyrrole nanoparticles incorporated reduced graphene oxide as an efficient counter electrode for platinum-free dye-sensitized solar cells  

PubMed Central

This paper reports a rapid and in-situ electrochemical polymerization method for the fabrication of polypyrrole nanoparticles incorporated reduced graphene oxide (rGO@PPy) nanocomposites on a ITO conducting glass and its application as a counter electrode for platinum-free dye-sensitized solar cell (DSSC). The scanning electron microscopic images show the uniform distribution of PPy nanoparticles with diameter ranges between 20 and 30?nm on the rGO sheets. The electrochemical studies reveal that the rGO@PPy has smaller charge transfer resistance and similar electrocatalytic activity as that of the standard Pt counter electrode for the I3?/I? redox reaction. The overall solar to electrical energy conversion efficiency of the DSSC with the rGO@PPy counter electrode is 2.21%, which is merely equal to the efficiency of DSSC with sputtered Pt counter electrode (2.19%). The excellent photovoltaic performance, rapid and simple fabrication method and low-cost of the rGO@PPy can be potentially exploited as a alternative counter electrode to the expensive Pt in DSSCs.

Lim, Su Pei; Pandikumar, Alagarsamy; Lim, Yee Seng; Huang, Nay Ming; Lim, Hong Ngee

2014-01-01

118

Modulation of the cyclooxygenase pathway via inhibition of nitric oxide production contributes to the anti-inflammatory activity of kaempferol.  

PubMed

Kaempferol has been reported to inhibit nitric oxide synthase and cyclooxygenase enzymes in animal models. The present study was designed to investigate whether kaempferol modulates the cyclooxygenase pathway via inhibition of nitric oxide production, which in turn contributes to its anti-inflammatory activity. Investigations were performed using carrageenan induced rat air pouch model. Inflammation was assessed by measurement of nitrites (nitrite, a breakdown product of nitric oxide), prostaglandin-E(2) levels and cellular infiltration in the pouch fluid exudates. To assess the anti-inflammatory effect of the extract, rat air pouch linings were examined histologically. The levels of nitrite and prostaglandin-E(2) in pouch fluid were measured by using Griess assay and ELISA respectively. Cell counts and differential counts were performed using a Coulter counter and Wright-Giemsa stain respectively. Kaempferol when administered orally at 50 and 100mg/kg dose showed significant inhibition of carrageenan induced production of nitrite (40.12 and 59.74%, respectively) and prostaglandin-E(2) generation (64.23 and 78.55%, respectively). Infiltration of the cells into the rat granuloma air pouch was also significantly inhibited by kaempferol. Modulation of cyclooxygenase pathway via inhibition of nitric oxide synthesis significantly contributes to kaempferol's anti-inflammatory activity. The present study characterizes the effects and mechanisms of naturally occurring phenolic flavonoid kaempferol, on inducible nitric oxide synthase expression and nitric oxide production. These results partially explain the pharmacological efficacy of flavonoids in general and kaempferol in particular as anti-inflammatory compounds. PMID:20558157

Mahat, Mahamad Yunnus A; Kulkarni, Nagaraj M; Vishwakarma, Santosh L; Khan, Farhin R; Thippeswamy, B S; Hebballi, Vijay; Adhyapak, Anjana A; Benade, Vijay S; Ashfaque, Saudagar Mohammad; Tubachi, Suraj; Patil, Basangouda M

2010-09-10

119

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.

2013-01-01

120

In Vitro Biocompatibility and Antibacterial Efficacy of a Degradable Poly(L-lactide-co-epsilon-caprolactone) Copolymer Incorporated with Silver Nanoparticles.  

PubMed

Silver nanoparticles (Ag-nps) are currently used as a natural biocide to prevent undesired bacterial growth in clothing, cosmetics and medical products. The objective of the study was to impart antibacterial properties through the incorporation of Ag-nps at increasing concentrations to electrospun degradable 50:50 poly(L-lactide-co-epsilon-caprolactone) scaffolds for skin tissue engineering applications. The biocompatibility of the scaffolds containing Ag-nps was evaluated with human epidermal keratinocytes (HEK); cell viability and proliferation were evaluated using Live/Dead and alamarBlue viability assays following 7 and 14 days of cell culture on the scaffolds. Significant decreases in cell viability and proliferation were noted for the 1.0 mg(Ag) g(scaffold)(-1) after 7 and 14 days on Ag-nps scaffolds. After 14 days, scanning electron microscopy revealed a confluent layer of HEK on the surface of the 0.0 and 0.1 mg(Ag) g(scaffold)(-1). Both 0.5 and 1.0 mg(Ag) g(scaffold)(-1) were capable of inhibiting both Gram positive and negative bacterial strains. Uniaxial tensile tests revealed a significant (p < 0.001) decrease in the modulus of elasticity following Ag-nps incorporation compared to control. These findings suggest that a scaffold containing between 0.5 and 1.0 mg(Ag) g(scaffold)(-1) is both biocompatible and antibacterial, and is suitable for skin tissue engineering graft scaffolds. PMID:24150238

Samberg, Meghan E; Mente, Peter; He, Ting; King, Martin W; Monteiro-Riviere, Nancy A

2014-07-01

121

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

122

Hybrid polymer:colloidal nanoparticle photovoltaic cells incorporating a solution-processed, multi-functioned ZnO nanocrystal layer  

NASA Astrophysics Data System (ADS)

We report significant improvement in both the power conversion efficiency and the environmental stability of solution-processed hybrid organic-inorganic solar cells by including a solution-processed ZnO nanocrystal layer between the photoactive layer and the cathode. For devices based on blends of poly(3-hexylthiophene) (P3HT) and mostly-spherical CdSe nanocrystals, incorporation of the ZnO layer leads to an up to 70% increase in the power conversion efficiency. Compared to only a few hours of shelf lifetime for unencapsulated devices with the metal cathode directly deposited on the hybrid active layer, devices with the ZnO layer can retain approximately 70% of the original efficiency when they are exposed to the laboratory ambient without encapsulation for more than two months. We attribute the function of this ZnO nanocrystal layer to a combination of optical, electronic, morphological, and chemical effects, including blocking leakage of photogenerated holes to the cathode, optimizing the optical intensity profile in the hybrid active layer, minimizing recombination or quenching of photogenerated excitons and charge carriers, significantly reducing the transport rate of oxygen and water molecules to the active layer and reducing degradation/oxidation of any low work function layer at the cathode interface.

Yang, Jihua; Qian, Lei; Zhou, Renjia; Zheng, Ying; Tang, Aiwei; Holloway, Paul H.; Xue, Jiangeng

2012-02-01

123

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

124

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.

2010-01-01

125

Production of quercetin, kaempferol and their glycosidic derivatives from the aqueous-organic extracted residue of litchi pericarp with Aspergillus awamori.  

PubMed

Our previous work exhibited Aspergillus awamori fermentation of the litchi pericarp increased significantly antioxidant activity and DNA protection effect. In this present study, the litchi pericarp and its aqueous-organic extracted residues were fermented by A. awamori in order to elucidate the enhanced beneficial effects. The study identified that rutin which present in litchi pericarp could be deglycosylated to form quercetin and quercetin-3-glucoside after the fermentation. Application the standard compounds (rutin, quercetin 3-glucoside, quercetin, kaempferol-3-glucoside and kaempferol) further revealed the effective biotransformation by A. awamori fermentation. It was hypothesised that rutin was initially dehydroxylated to form kaempferol-3-rutinoside and then deglycosylated to form kaempferol-3-glucoside and kaempferol. To our best knowledge, it is the first report on dehydroxylated effect of polyphenols caused by A. awamori fermentation. Thus, A. awamori fermentation can provide an effective way to produce health benefiting value-added products from litchi pericarp in food industry. PMID:24128471

Lin, Sen; Zhu, Qinqin; Wen, Lingrong; Yang, Bao; Jiang, Guoxiang; Gao, Haiyan; Chen, Feng; Jiang, Yueming

2014-02-15

126

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

127

Effect of kaempferol on lipid peroxidation and antioxidant status in 1,2-dimethyl hydrazine induced colorectal carcinoma in rats.  

PubMed

Colorectal cancer, a common cause of cancer related deaths in both sexes in western population is often due to persistent oxidative stress leading to DNA damage. Antioxidants scavenge free radicals and inhibit neoplastic process. Kaempferol, a flavonol widely distributed in tea, broccoli, grape fruit, brussels sprouts and apple, is claimed to have chemopreventive action in colon cancer. The aim of our study was to evaluate the effect of kaempferol on tissue lipid peroxidation and antioxidant status in 1,2-dimethyl hydrazine induced colorectal cancer in male Wistar rats and to compare its efficacy with irinotecan. Experimental colon cancer induced by 1,2-dimethyl hydrazine in rats mimic human colon cancer and therefore is an ideal model for chemoprevention studies. The rats were divided into six groups. Group 1 served as control. Group 2 received 1,2-dimethyl hydrazine (20 mg/kg body weight) subcutaneously once a week for four weeks. Group 3 received irinotecan (100 mg/kg body weight) intravenously once a week for four weeks with 1,2-dimethyl hydrazine. Groups 4 to 6 were given a daily oral dose of 50, 100, 200 mg/kg body weight of kaempferol with 1,2-dimethyl hydrazine. The total study period was 16 weeks. Kaempferol supplementation lowered 1,2-dimethyl hydrazine induced erythrocyte lysate and liver thiobarbituric acid reactive substances level and rejuvenated anti oxidant enzymes catalase, super oxide dismutase and glutathione peroxidase. The recovery of enzyme status was maximum at the dose of 200 mg/kg body weight and was comparable to irinotecan. Our study reveals that kaempferol could be safely used as a chemopreventive agent in colorectal cancer. PMID:21172346

Nirmala, Parthasarathy; Ramanathan, Manickam

2011-03-01

128

The attenuation of restenosis following arterial gene transfer using carbon nanotube coated stent incorporating TAT/DNA(Ang1+Vegf) nanoparticles.  

PubMed

This study report the development of a nanobiohybrid hydrogel based endovascular stent device capable of preventing postangioplasty in-stent restenosis (ISR) by promoting significant vascular endothelial recovery in a site-specific manner. The hydrogel is comprised of fibrin matrices, assembled layer-by-layer (LbL) on stent surface with alternate layers carrying endosomolytic Tat peptide/DNA nanoparticles (NPs) or NPs hybridized to polyacrylic acid (PAA) wrapped single-walled carbon nanotubes (NP-CNT). Here, the hydrogel works as a reservoir to carry, protect, and simultaneously deliver pro-angiogenic, vascular endothelial growth factor (Vegf) and Angiopoietin-1(Ang1), gene carrying NPs to the target site. In vitro results demonstrated that CNTs incorporated in the hydrogel layers play a major role in tuning the bioactivity of the stent. In addition, the developed stent formulation can significantly reduce the loss of therapeutics while traversing through the vessel and during deployment. In vivo experiments in balloon-injured canine femoral artery demonstrated that the NCS (+) group, carrying NP(vegf+Ang1), can significantly enhance re-endothelialization of injured artery compared to control NCS (-), carrying NP(Null), and bare metal stent (BMS) groups, attenuate stenosis (18.5±9.03% vs 39.56±13.8 vs 45.34±8.3%; n=8, p<0.05) and prevent neointima formation (1.53±0.36 mm(2) vs 2.51±0.27 mm(2) vs 2.66±0.14 mm(2); n=8, p<0.05) as analyzed angiography and histomorphometric analysis. These data collectively implicate that this new technology can be useful for stent and other biomedical devices through controlled delivery of multiple biotherapeutics. PMID:22818986

Paul, Arghya; Shao, Wei; Shum-Tim, Dominique; Prakash, Satya

2012-10-01

129

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.

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

2013-01-01

130

Nanoparticles  

NASA Astrophysics Data System (ADS)

Nanostructured bulk materials are regarded as a means of enhancing the performance of thermoelectric (TE) materials and devices. Powder metallurgy has the distinct advantage over conventional synthesis that it can start directly from nanosized particles. However, further processing, for example extrusion, usually requires elevated temperatures, which lead to grain growth. We have found that introduction of semiconductor nanoparticles of molybdenum disulfide (MoS2), a well-known solid lubricant, suppresses grain growth in bismuth telluride-based alloys, thus improving the extrusion process. Scanning electron microscope images show that adding MoS2 particles at concentrations of 0.2, 0.4, and 0.8 wt% to p-type (Bi0.2Sb0.8)2Te3, under otherwise identical extrusion conditions, reduces average grain size by a factor of four. Scherer's formula applied to x-ray diffraction data indicates that average crystallite sizes (˜17 nm) of powders are not significantly different from those of alloys extruded with MoS2 (˜18 nm), which is in stark contrast with those for conventional alloy (Bi0.2Sb0.8)2Te3 extruded under the same conditions (˜80 nm). Harman measurements of TE properties reveal a decrease of the thermal conductivity accompanied by reduction of the room-temperature figure of merit ( ZT) from 0.9 to 0.7, because of a lower power factor. Above 370 K, however, the performance of alloys containing MoS2 surpasses that of (Bi0.2Sb0.8)2Te3, with reduction of the thermal conductivity which is more significant at temperatures above the cross point of the ZT values.

Keshavarz, Mohsen K.; Vasilevskiy, Dimitri; Masut, Remo A.; Turenne, Sylvain

2014-06-01

131

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-Méndez, Sion F.; Santillán-Rodríguez, Carlos R.; González-Valenzuela, Ricardo A.; Espinosa-Magaña, Francisco; Matutes-Aquino, José A.

2014-04-01

132

Simultaneous determination of the flavonoids robinin and kaempferol in human breast cancer cells by liquid chromatography-tandem mass spectrometry  

Microsoft Academic Search

An accurate, precise and sensitive method was developed and validated for the simultaneous quantification of the flavonoid glycoside robinin, and its algycone kaempferol in human breast cancer MCF-7 cells. The application of liquid chromatography-tandem mass spectrometry (LC\\/MS\\/MS) with a TurboIonspray interface in negative mode under multiple reactions monitoring was investigated. Chromatographic separation was achieved on a C18 column using a

Lia Tsiklauri; Guohua An; Donna M. Ruszaj; Mary Alaniya; Ether Kemertelidze; Marilyn E. Morris

2011-01-01

133

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 µM against JEV in cells pretreated before infection, whereas in cells infected before treatment, EC50 was 21.5 and 40.4 µM, 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.

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

2012-01-01

134

Micelle-like nanoparticles of block copolymer poly(ethylene oxide)-block-poly(methacrylic acid) incorporating fluorescently substituted metallacarboranes designed as HIV protease inhibitor interaction probes.  

PubMed

We prepared nanoparticles differing in morphology from double-hydrophilic block copolymer poly(ethylene oxide)-block-poly(methacrylic acid), PEO-PMA, and two types of fluorescein-[3-cobalt(III) bis(1,2-dicarbollide)] conjugates, GB176 and GB179, in alkaline buffer. GB176 molecule consists of fluorescein attached to the metallacarborane anion. In GB179 molecule, the fluorescein moiety connects two metallacarborane anions. The self-assembly is based on the unusual interaction of metallacarborane clusters with PEO blocks which form insoluble micellar cores. The GB176 containing nanoparticles are loose and irregular, while the GB179 ones are rigid and spherical. The structure of nanoparticles depends to some extent on a procedure of preparation. The micelles were studied by static and dynamic light scattering, fluorometry and atomic force microscopy. Since the metallacarborane conjugates act as potent inhibitors of HIV protease, the presented system is important from the point of view of drug delivery. PMID:20447643

Uchman, Mariusz; Cígler, Petr; Grüner, Bohumír; Procházka, Karel; Matejícek, Pavel

2010-08-01

135

Aceriphyllum rossii Extract and Its Active Compounds, Quercetin and Kaempferol Inhibit IgE-mediated Mast Cell Activation and Passive Cutaneous Anaphylaxis.  

PubMed

Aceriphyllum rossii contains an abundant source of natural flavonoids with potential antioxidant, anticancer and anti-inflammatory properties. However, the effect of A. rossii extract (ARE) on immunoglobulin E(IgE)-mediated allergic responses remains unknown. In the present study, the effects of ARE and its active compounds, quercetin and kaempferol, on IgE-mediated rat basophilic leukemia mast cell activation and passive cutaneous anaphylaxis (PCA) were investigated. ARE, quercetin, and kaempferol inhibited secretion of ?-hexosaminidase and histamine, and reduced the production and mRNA expression of interleukin-4 and tumor necrosis factor-?. ARE also decreased the production of prostaglandin E2 and leukotriene B4 and expression of cyclooxygenase 2 and 5-lipoxygenase. Furthermore, ARE, quercetin, and kaempferol inhibited IgE-mediated phosphorylation of Syk, phospholipase C?, protein kinase C (PKC)?, and the mitogen-activated protein kinases, extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase. ARE, quercetin, and kaempferol markedly suppressed mast cell-dependent PCA in IgE-sensitized mice. These results indicate that ARE and its active constituents, quercetin and kaempferol, may be a useful therapy for immediate-type hypersensitivity. PMID:24702030

Kim, Myungsuk; Lim, Sue Ji; Kang, Suk Woo; Um, Byung-Hun; Nho, Chu Won

2014-04-30

136

Simultaneous determination of the flavonoids robinin and kaempferol in human breast cancer cells by liquid chromatography-tandem mass spectrometry.  

PubMed

An accurate, precise and sensitive method was developed and validated for the simultaneous quantification of the flavonoid glycoside robinin, and its algycone kaempferol in human breast cancer MCF-7 cells. The application of liquid chromatography-tandem mass spectrometry (LC/MS/MS) with a TurboIonspray interface in negative mode under multiple reactions monitoring was investigated. Chromatographic separation was achieved on a C(18) column using a mobile phase consisting of (A) water with 0.025% formic acid and 1mM ammonium formate and (B) acetonitrile with 0.025% formic acid. Rutin was used as the internal standard for robinin and fisetin as the internal standard for kaempferol. The assay had a limit of detection of 0.1ng/ml for both compounds when present in cell lysate. The calibration curves were linear from 1 to 250ng/ml (r>0.999) for each compound. The intra- and inter-day coefficients of variation were less than 10% and intra- and inter-day accuracies were within 11%. This assay was successfully applied in a robinin cellular uptake study to determine the intracellular concentrations of robinin in MCF-7 cells. PMID:21232900

Tsiklauri, Lia; An, Guohua; Ruszaj, Donna M; Alaniya, Mary; Kemertelidze, Ether; Morris, Marilyn E

2011-04-28

137

Selective detection of dopamine in the presence of uric acid using a gold nanoparticles-poly(luminol) hybrid film and multi-walled carbon nanotubes with incorporated ?-cyclodextrin modified glassy carbon electrode.  

PubMed

Gold nanoparticles-poly(luminol) (Plu-AuNPs) hybrid film and multi-walled carbon nanotubes with incorporated ?-cyclodextrin modified glassy carbon electrode (?-CD-MWCNTs/Plu-AuNPs/GCE) was successfully prepared for simultaneous determination of dopamine (DA) and uric acid (UA). The surface of the modified electrode has been characterized by X-ray photo-electron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscope (SEM) and transmission electron microscope (TEM). Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) have been used to investigate the ?-CD-MWCNTs/Plu-AuNPs composite film. Gold nanoparticles anchored into poly(luminol) film exhibited catalytic activity for DA. MWCNTs with incorporated ?-CD can greatly promote the direct electron transfer. In 0.10 M phosphate buffer solution (PBS, pH 7.0), the DPV response of the ?-CD-MWCNTs/Plu-AuNPs/GCE sensor to DA is about 8-fold as compared with the Plu-AuNPs/GCE sensor, and the detection limit for DA is about one order of magnitude lower than the Plu-AuNPs/GCE sensor. The steady-state current response increases linearly with DA concentration from 1.0 × 10(-6) to 5.6 × 10(-5)M with a low detection limit (S/N=3) of 1.9 × 10(-7)M. Moreover, the interferences of ascorbic acid (AA) and uric acid (UA) are effectively diminished. The applicability of the prepared electrode has been demonstrated by measuring DA contents in dopamine hydrochloride injection. PMID:21962652

Jia, Dong; Dai, Jianyuan; Yuan, Hongyan; Lei, Ling; Xiao, Dan

2011-10-15

138

Carrier transport mechanism of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) films by incorporating ZnO nanoparticles  

NASA Astrophysics Data System (ADS)

The carrier transport mechanism of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) having ZnO nanoparticles, denoted ZnO-doped PEDOT:PSS, is investigated. Conductivity proportional to ZnO doping was observed at 300 K. The improved electrical conductivity is considered to mainly come from the mobility enhancement. The carrier mobility in ZnO-doped PEDOT:PSS samples exhibits unexpectedly strong temperature dependence, implying the domination of tunneling in the whole range of temperatures. An exhibition of high mobility of ZnO-doped PEDOT:PSS samples is attributed to a combined effect of the weak electron-phonon couplings and changes in the chemical structure of PEDOT:PSS.

Lin, Yow-Jon; Tsai, Cheng-Lung; Su, Yu-Chao; Liu, Day-Shan

2012-06-01

139

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 Wagner–Nelson 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 50–100 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 vitro–in 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 vitro–in 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.

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

140

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.

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

141

Simultaneous determination of catechin, rutin, quercetin kaempferol and isorhamnetin in the extract of sea buckthorn ( Hippophae rhamnoides L.) leaves by RP-HPLC with DAD  

Microsoft Academic Search

A rapid and specific reversed-phase high performance liquid chromatography (RP-HPLC) method with diode array detection (DAD) at room temperature was used and validated for the simultaneous determination of five flavonoids (catechin, CA; rutin, RU; quercetin, QU; kaempferol, KA; isorhamnetin, IS) in the extract of sea buckthorn (Hippophae rhamnoides L.) leaves. The sample pretreatment process involved ultrasonic extraction with 85% ethanol

Yuangang Zu; Chunying Li; Yujie Fu; Chunjian Zhao

2006-01-01

142

Nanocomposite incorporating v2 o5 nanowires and gold nanoparticles for mimicking an enzyme cascade reaction and its application in the detection of biomolecules.  

PubMed

Artificial enzyme mimics are a current research interest, and many nanomaterials have been found to display enzyme-mimicking activity. However, to the best of our knowledge, there have not hitherto been any reports on the use of pure nanomaterials to construct a system capable of mimicking an enzyme cascade reaction. Herein, we describe the construction of a novel nanocomposite consisting of V2 O5 nanowires and gold nanoparticles (AuNPs) through a simple and facile chemical method, in which V2 O5 and AuNPs possess intrinsic peroxidase and glucose oxidase (GOx)-like activity, respectively. Results suggest that this material can mimic the enzyme cascade reaction of horseradish peroxidase (HRP) and GOx. Based on this mechanism, a direct and selective colorimetric method for the detection of glucose has been successfully designed. Because single-strand and double-strand DNA (ssDNA and dsDNA) have different deactivating effects on the GOx-like activity of AuNPs, the sensing of target complementary DNA can also be realized and disease-associated single-nucleotide polymorphism of DNA can be easily distinguished. Our study opens a new avenue for the use of nanomaterials in enzyme mimetics, and holds promise for the further exploration of nanomaterials in creating alternative catalytic systems to natural enzymes. PMID:24825488

Qu, Konggang; Shi, Peng; Ren, Jinsong; Qu, Xiaogang

2014-06-10

143

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

144

Vascularization and bone regeneration in a critical sized defect using 2-N,6-O-sulfated chitosan nanoparticles incorporating BMP-2.  

PubMed

An ideal bone tissue engineering graft should have both excellent pro-osteogenesis and pro-angiogenesis to rapidly realize the bone regeneration in vivo. To meet this goal, 2-N,6-O-sulfated chitosan (26SCS) based nanoparticle (S-NP) was successfully developed and showed a dose-dependent enhancement on angiogenesis in vitro. For the repair of a critical sized defect in rabbit radius, we developed BMP-2 loaded S-NP (BMP-2/S-NP) with protein loading efficiency of 1.4 ± 0.2% and fabricated a gelatin sponge (G) based implant loaded with BMP-2/S-NP (BMP-2/S-NP/G). This implant exerted a delivery of BMP-2 with an initial burst release of 15.3 ± 4.1% in first 24 h and a gradual release for 21 days to 77.8 ± 3.6%. The in vitro ALP assay revealed that the activity of released BMP-2 from BMP-2/S-NP/G was maintained after 3-d and 7-d delivery and further enhanced after 14-d delivery compared with the original BMP-2. Furthermore, the in vivo effects of BMP-2/S-NP/G on the bone regeneration and vessel formation in the critical sized defect (18 mm) of rabbit radius were investigated by synchrotron radiation-based micro-computed tomography (SR?CT) imaging, three dimensional micro-computed tomographic (?CT) imaging, histological analysis, immunohistochemistry and biomechanical measurement. Based on the results, both peripheral vessel and new vessel formation were significantly increased by the BMP-2/S-NP/G treatment, along with the bridged defects at as early as 2 weeks, the healed defects at 8 weeks and the reunion of bone marrow cavity at 12 weeks. The results indicated that both controlled release of active BMP-2 and favorable vascularization at the defect site contributed by BMP-2/S-NP/G played a crucial role in accelerating and promoting bone augmentation. This study suggests that BMP-2/S-NP/G demonstrates promise for vascularization and bone regeneration in clinical case of large defect. PMID:24140042

Cao, Lingyan; Wang, Jing; Hou, Juan; Xing, Wanli; Liu, Changsheng

2014-01-01

145

Hypoglycemic effect and antioxidant potential of kaempferol-3,7-O-(alpha)-dirhamnoside from Bauhinia forficata leaves.  

PubMed

In vivo and in vitro treatments were carried out to investigate the effects of kaempferol-3,7-O-(alpha)-dirhamnoside (kaempferitrin), a major flavonoid compound of the n-butanol fraction from Bauhiniaforficata leaves, on serum glucose levels, as well as its antioxidant potential. Oral administration of kaempferitrin led to a significant hypoglycemic effect in normal and in alloxan-induced diabetic rats. In normal rats, blood glucose lowering was observed only with the higher dose of kaempferitrin (200 mg/kg) at 1 h after treatment. However, the hypoglycemic effect of kaempferitrin in diabetic rats was evident at all doses tested (50, 100, and 200 mg/kg), and this profile was maintained throughout the period studied for both higher doses. Additionally, in glucose-fed hyperglycemic normal rats, the kaempferitrin failed to decrease blood glucose levels. In vitro antioxidant properties or action against reactive oxygen species of this compound was also evaluated. The compound showed high reactivity with 1,1-diphenyl-2-picryl hydrazyl (DPPH), IC(50) of 84.0 +/- 7.8 microM, inhibited myeloperoxidase activity with K(0.5) = 86 +/- 9.9 microM, and decreased lipid peroxidation, induced by ascorbyl radical either in microsomes or in asolectin and phosphatidylcholine liposomes, with IC(50)'s of 320 +/- 14.1, 223 +/- 8.3, and 112 +/- 8.8 microM, respectively. PMID:15165145

de Sousa, Eliandra; Zanatta, Leila; Seifriz, Ilana; Creczynski-Pasa, Tânia Beatriz; Pizzolatti, Moacir Geraldo; Szpoganicz, Bruno; Silva, Fátima Regina Mena Barreto

2004-05-01

146

13C CP MAS NMR and GIAO-CHF/DFT calculations of flavonoids: Morin, kaempferol, tricin, genistein, formononetin and 3,7-dihydroxyflavone  

NASA Astrophysics Data System (ADS)

13C CP MAS NMR spectra of the flavonoids: morin, kaempferol, 3,7-dihydroxyflavone, tricin and isoflavones: genistein and formononetin were recorded to characterize solid-state conformations. Intramolecular hydrogen bonds forming five-, six- and seven-membered rings are present in the two morin molecules in the crystals - their 13C resonances have been assigned with the aid of the calculated shielding constants. Linear relationships between the calculated shielding constants ?DFT (ppm) and chemical shifts ( ?CPMAS, ppm) were obtained for all studied compounds. Higher correlation coefficients suggest that the conformation with "clockwise" orientation of both OH groups is more probable in the solid 3,7-dihydroxyflavone, whereas in the solid formononetin the OH and OCH 3 substituents are directed "anticlockwise". The barrier to the rotation of phenyl ring B decreases in the order: morin (2'-OH, 3-OH) > kaempferol (3-OH) > tricin.

Zieli?ska, Agnieszka; Paradowska, Katarzyna; Jakowski, Jacek; Wawer, Iwona

2008-02-01

147

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

PubMed

An ultra performance liquid chromatography-mass spectrometric (UPLC-MS) 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 liquid-liquid extraction, and chromatographic separation was performed on a C(18) column using a linear gradient of methanol and formic acid (0.1%). The pharmacokinetic parameters of isorhamnetin, kaempferol and quercetin from TFH in rats were quantitatively determined by UPLC with photodiode array detection (PDA). The qualitative detection of the three flavones was accomplished by selected ion monitoring in negative ion mode ESI-MS. Results of the pharmacokinetic study indicate that the three flavones in TFH were absorbed by passive diffusion in rats, and no "double-peak" phenomenon was observed in C-t curves of the three flavones from TFH except for quercetin. Results of this study indicate that the pharmacokinetic behaviors of isorhamnetin, kaempferol and quercetin when administered together in a complex herbal extract might be different than the individual behaviors of the same compounds administered in their pure forms. Results of this study also demonstrate that UPLC-MS is a rapid and practical method to determine the pharmacokinetic parameters of flavones present in an herbal extract. PMID:22056665

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

2012-01-01

148

Kaempferol attenuates the glutamate-induced oxidative stress in mouse-derived hippocampal neuronal HT22 cells.  

PubMed

It is thought that the neuronal cell loss caused by oxidative stress is the primary mechanism underlying the pathogenesis of several neurodegenerative disorders. Glutamate is an endogenous neurotransmitter, but at high concentrations it can act as a neurotoxicant by increasing the intracellular levels of reactive oxygen species (ROS). Therefore, the development of factors that can attenuate glutamate-induced oxidative stress in neuronal cells is a good strategy by which new drugs could be discovered that may treat or prevent neurodegenerative diseases. Here, the neuroprotective effects of kaempferol (KF) isolated from the stems of butterbur (Petasites japonicus) were examined in glutamate-treated hippocampal neuronal cells (HT22). The administration of KF (25 ?M) resulted in a significant increase in cell viability (105.18 ± 7.48%) compared with the control (100.00 ± 3.05%), while glutamate (5 mM) reduced cell viability by 39.94 ± 1.61%. The glutamate-induced calcium (Ca(2+)) influx (1.93 ± 0.08-fold) was significantly reduced by 0.89 ± 0.02-fold following the administration of 25 ?M KF. Additionally, when HT22 cells were stressed with excessive glutamate, there was a 3.70 ± 0.01-fold increase in intracellular ROS generation, even though this was effectively attenuated by KF (25 ?M, 0.72 ± 0.01-fold). The protective effects of KF in HT22 cells were later confirmed using a lactate dehydrogenase (LDH) assay and a FITC-annexin V/propidium iodide double staining procedure. These findings also revealed that the neuroprotective effects of KF are a result of the regulation of the expression levels of proteins, such as Bcl-2, Bid, apoptosis-inducing factor (AIF), and mitogen-activated protein kinase (MAPK). This is the first report to investigate the neuroprotective influence of KF in glutamate-treated HT22 cells. These data demonstrate that KF may be a useful candidate for pharmacological therapies that can prevent and treat neurodegenerative diseases such as Alzheimer's disease (AD). PMID:24770605

Yang, Eun-Ju; Kim, Geum-Soog; Jun, Mira; Song, Kyung-Sik

2014-06-25

149

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

150

Engineering biofunctional magnetic nanoparticles for biotechnological applications  

Microsoft Academic Search

Synthesis and characterization of magnetic nanoparticles with excellent size control are showed here. Their functionalization using an amphiphilic polymer is also described. This strategy allows the stabilization of magnetic nanoparticles in aqueous solvents and in addition, the polymer shell serves as a platform to incorporate relevant biomolecules, such as poly(ethylene glycol) and a number of carbohydrates. Nanoparticles functionalized with carbohydrates

Maria Moros; Beatriz Pelaz; Pilar López-Larrubia; Maria L. García-Martin; Valeria Grazú; Jesus M. de La Fuente

2010-01-01

151

A tough nanofiber hydrogel incorporating ferritin  

Microsoft Academic Search

We have developed tough nanofiber hydrogels incorporating ferritin nanoparticles with a core-shell structure that is suitable for stress concentration reduction. The swelling properties of the nanocomposite hydrogel under external forces were enhanced, leading to fast water absorption. The elastic modulus, tensile strength, and elongation at break of the nanocomposite hydrogel measured in solutions were dramatically enhanced as compared to those

Min Kyoon Shin; Sun I. Kim; Seon Jeong Kim; Byung Joo Kim; Insuk So; Mikhail E. Kozlov; Jiyoung Oh; Ray H. Baughman

2008-01-01

152

Improved barrier and mechanical properties of novel hydroxypropyl methylcellulose edible films with chitosan\\/tripolyphosphate nanoparticles  

Microsoft Academic Search

Chitosan\\/tripolyphosphate nanoparticles were prepared and incorporated in hydroxypropyl methylcellulose (HPMC) films. FT-IR and transmission electron microscopy (TEM) analyses of the nanoparticles, mechanical properties, water vapor permeability, thermal stability, scanning electron microscopy (SEM) of the films were analyzed. Incorporation of chitosan nanoparticles in the films improved their mechanical and film barrier properties significantly. The chitosan nanoparticles tend to occupy the empty

Márcia R. de Moura; Fauze A. Aouada; Roberto J. Avena-Bustillos; Tara H. McHugh; John M. Krochta; Luiz H. C. Mattoso

2009-01-01

153

Magnetic, fluorescent, and thermo-responsive Fe(3)O(4)/rare earth incorporated poly(St-NIPAM) core-shell colloidal nanoparticles in multimodal optical/magnetic resonance imaging probes.  

PubMed

Multifunctional colloidal nanoparticles which exhibit fluorescence, superparamagnetism, and thermosensitivity are produced by two step seed emulsifier-free emulsion polymerization in the presence of oleic acid (OA) and sodium undecylenate (NaUA) modified Fe(3)O(4) nanoparticles. In the first step, St and NIPAM polymerize the NaUA on the surface of Fe(3)O(4) nanoparticles to form Fe(3)O(4)/poly(St-NIPAM) nanoparticles which act as seeds for the polymerization of Eu(AA)(3)Phen with the remaining St and NIPAM in the second step to form an outer fluorescent layer. The core-shell composite nanoparticles show reversible dimensional changes in response to external temperature stimuli. Fluorescence spectra acquired from the composites exhibit characteristic emission peaks of Eu(3+) at 594 and 619 nm and vivid red luminescence can be observed by 2-photon confocal scanning laser microscopy (CLSM). In vitro cytotoxicity tests based on the MTT assay demonstrate good cytocompatibility and the composites also possess paramagnetic properties with a maximum saturation magnetization of 6.45 emu/g and high transverse relaxivity rates (r(2)) of 411.78 mM(-1) s(-1). In vivo magnetic resonance imaging (MRI) studies show significant liver and spleen contrast with relative signal intensity reduction of about 86% 10 min after intravenous injection of the composites. These intriguing properties suggest that these nanocarriers have large clinical potential as multimodal optical/MRI probes. PMID:23274069

Zhu, Haie; Tao, Juan; Wang, Wenhao; Zhou, Yingjie; Li, Penghui; Li, Zheng; Yan, Kai; Wu, Shuilin; Yeung, Kelvin W K; Xu, Zushun; Xu, Haibo; Chu, Paul K

2013-03-01

154

Kaempferol 3-O-Galactoside, 7-O-Rhamnoside is the Major Green Fluorescing Compound in the Epidermis of Vicia faba1  

PubMed Central

The vacuoles of lower epidermal strips from Vicia faba exhibit an intrinsic green fluorescence when incubated in alkaline buffers. Using an alkaline-induced absorbance change as a spectrophotometric assay, the major pigment responsible for this fluorescence was isolated and identified as the flavonoid: kaempferol 3-O-galactoside, 7-O-rhamnoside. The aqueous absorption maxima were 394 and 341 nanometers at pH 10.0 and 6.0, respectively, with a pKa of 8.3 and the fluorescence emission maximum was 494 nanometers at pH 10.0. The in vivo concentration was estimated to be between 3 and 10 micromolar. The absorption spectrum of this flavonoid is different from the action spectrum for stomatal opening indicating that this compound is not the photoreceptor pigment for the blue light response of Vicia faba guard cells.

Vierstra, Richard D.; John, Theodore R.; Poff, Kenneth L.

1982-01-01

155

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; Küpeli, E; Terzio?lu, S; Yesilada, E

2007-10-01

156

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.

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

2012-01-01

157

Antiplasmodial properties of kaempferol-3-O-rhamnoside isolated from the leaves of Schima wallichii against chloroquine-resistant Plasmodium falciparum  

PubMed Central

Previous intervention studies have shown that the most effective agents used in the treatment of malaria were isolated from natural sources. Plants consumed by non-human primates serve as potential drug sources for human disease management due to the similarities in anatomy, physiology and disease characteristics. The present study investigated the antiplasmodial properties of the primate-consumed plant, Schima wallichii (S. wallichii) Korth. (family Theaceae), which has already been reported to have several biological activities. The ethanol extract of S. wallichii was fractionated based on polarity using n-hexane, ethyl acetate and water. The antiplasmodial activity was tested in vitro against chloroquine-resistant Plasmodium falciparum (P. falciparum) at 100 ?g/ml for 72 h. The major compound of the most active ethyl acetate fraction was subsequently isolated using column chromatography and identified by nuclear magnetic resonance. The characterized compound was also tested against chloroquine-resistant P. falciparum in culture to evaluate its antiplasmodial activity. The ethanol extract of S. wallichii at 100 ?g/ml exhibited a significant parasite shrinkage after 24 h of treatment. The ethyl acetate fraction at 100 ?g/ml was the most active fraction against chloroquine-resistant P. falciparum. Based on the structural characterization, the major compound isolated from the ethyl acetate fraction was kaempferol-3-O-rhamnoside, which showed promising antiplasmodial activity against chloroquine-resistant P. falciparum with an IC50 of 106 ?M after 24 h of treatment. The present study has provided a basis for the further investigation of kaempferol-3-O-rhamnoside as an active compound for potential antimalarial therapeutics.

BARLIANA, MELISA I.; SURADJI, EKA W.; ABDULAH, RIZKY; DIANTINI, AJENG; HATABU, TOSHIMITSU; NAKAJIMA-SHIMADA, JUNKO; SUBARNAS, ANAS; KOYAMA, HIROSHI

2014-01-01

158

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

159

Effects of Parsley (Petroselinum crispum) and its Flavonol Constituents, Kaempferol and Quercetin, on Serum Uric Acid Levels, Biomarkers of Oxidative Stress and Liver Xanthine Oxidoreductase Aactivity inOxonate-Induced Hyperuricemic Rats  

PubMed Central

Increased serum uric acid is known to be a major risk related to the development of several oxidative stress diseases. The aim of this study was to investigate the effect of parsley, quercetin and kaempferol on serum uric acid levels, liver xanthine oxidoreductase activity and two non-invasive biomarkers of oxidative stress (total antioxidant capacity and malondialdehyde concentration) in normal and oxonate-induced hyperuricemic rats. A total of 60 male Wistar rats were randomly divided into ten equal groups; including 5 normal groups (vehicle, parsley, quercetin, kaempferol and allopurinol) and 5 hyperuricemic groups (vehicle, parsley, quercetin, kaempferol and allopurinol). Parsley (5 g/Kg), quercetin (5 mg/Kg), kaempferol (5 mg/Kg) and allopurinol (5 mg/Kg) were administrated to the corresponding groups by oral gavage once a day for 2 weeks. The results showed that parsley and its flavonol did not cause any significant reduction in the serum uric acid levels in normal rats, but significantly reduced the serum uric acid levels of hyperuricemic rats in a time-dependent manner. All treatments significantly inhibited liver xanthine oxidoreductase activity. Parsley, kaempferol and quercetin treatment led also to a significant increase in total antioxidant capacity and decrease in malondialdehyde concentration in hyperuricemic rats. Although the hypouricemic effect of allopurinol was much higher than that of parsley and its flavonol constituents, it could not significantly change oxidative stress biomarkers. These features of parsley and its flavonols make them as a possible alternative for allopurinol, or at least in combination therapy to minimize the side effects of allopurinol to treat hyperuricemia and oxidative stress diseases.

Haidari, Fatemeh; Keshavarz, Seid Ali; Mohammad Shahi, Majid; Mahboob, Soltan-Ali; Rashidi, Mohammad-Reza

2011-01-01

160

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

161

Photoluminescence properties of sonochemically synthesized gold nanoparticles for DNA biosensing  

Microsoft Academic Search

The electronic interactions of sonochemically synthesized gold (Au) nanoparticles with AT- and GC-DNA were studied by measuring photoluminescence (PL) spectral properties and the inherent PL images of the Au nanoparticles incorporated with the single DNA molecules using a laser scanning confocal microscope. The Au-nanoparticles incorporated AT-DNA and GC-DNA exhibit confocal PL image. These results suggest a Lewis acid (Au)–Lewis base

Sambandam Anandan; Seung-Do Oh; Minjoong Yoon; Muthupandian Ashokkumar

2010-01-01

162

Kaempferol7- O-?- d-glucoside (KG) isolated from Smilax china L. rhizome induces G 2\\/M phase arrest and apoptosis on HeLa cells in a p53-independent manner  

Microsoft Academic Search

Kaempferol-7-O-?-d-glucoside (KG), a flavonoid glycoside, isolated from Smilax china L. rhizome, displayed marked anticancer activity on a panel of established cancer cells, of which, HeLa human cervix carcinoma cells were the most sensitive. Meanwhile, the cytotoxic effects of KG on normal human cells (HEK293 embryonic kidney cells and L-02 embryonic liver cells) were much smaller than on cancer cells. This

Wen Xu; Jianwen Liu; Changlong Li; He-Zhen Wu; Yan-Wen Liu

2008-01-01

163

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

164

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...

165

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.

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

2011-01-01

166

Incorporation effect of nanosized perovskite LaFe0.7Co0.3O3 on the electrochemical activity of Pt nanoparticles-multi walled carbon nanotube composite toward methanol oxidation  

NASA Astrophysics Data System (ADS)

Nanosized perovskite LaFe0.7Co0.3O3 (LFCO) is synthesized through conventional co-precipitation method and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques. The incorporation effect of the mentioned perovskite to catalytic activity of the PtNPs-MWCNTs-nafion (or -chitosan) catalyst toward methanol oxidation has been studied by cyclic voltammetry. Based on the electrochemical studies, all MWCNTs-PtNPs-nafion (or chitosan) and MWCNTs-PtNPs-LFCO-nafion (or chitosan) catalysts show a considerable activity for methanol oxidation. However, a synergistic effect is observed when LFCO is added to the catalyst by decreasing the poisoning rate of the Pt catalyst.

Noroozifar, Meissam; Khorasani-Motlagh, Mozhgan; Khaleghian-Moghadam, Roghayeh; Ekrami-Kakhki, Mehri-Saddat; Shahraki, Mohammad

2013-05-01

167

Synthesis of nano-sized mesoporous silicas with metal incorporation  

Microsoft Academic Search

The metal oxide-incorporated or -grafted mesoporous silica nanoparticles and nanotubes have been prepared efficiently via a two-step synthetic process, which includes a pre-hydrolysis of the TEOS and metal alkoxides or salts in acidic solution (pH

Man-Chien Chao; Hong-Ping Lin; Chung-Yuan Mou; Bo-Wen Cheng; Chi-Feng Cheng

2004-01-01

168

Fabrication, characterization and microwave properties of polyurethane nanocomposites reinforced with iron oxide and barium titanate nanoparticles  

Microsoft Academic Search

Polyurethane (PU) nanocomposites reinforced with magnetic iron oxide nanoparticles and\\/or dielectric barium titanate nanoparticles fabricated by the surface-initiated-polymerization approach were investigated. The polymer matrix incorporated with different nanoparticles shows different presenting status surrounding the nanoparticles, i.e., chemical bonding, physical entanglement and bulk polymer chain. The nanoparticles have a different effect on the thermal stability of the polymer nanocomposites. By embedding

Z. Guo; S.-E. Lee; H. Kim; H. T. Hahn; A. B. Karki; D. P. Young

2009-01-01

169

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

170

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.

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

2011-01-01

171

Engineering biofunctional magnetic nanoparticles for biotechnological applications  

NASA Astrophysics Data System (ADS)

Synthesis and characterization of magnetic nanoparticles with excellent size control are showed here. Their functionalization using an amphiphilic polymer is also described. This strategy allows the stabilization of magnetic nanoparticles in aqueous solvents and in addition, the polymer shell serves as a platform to incorporate relevant biomolecules, such as poly(ethylene glycol) and a number of carbohydrates. Nanoparticles functionalized with carbohydrates show the ability to avoid unspecific interactions between proteins present in the working medium and the nanoparticles, so can be used as an alternative to poly(ethylene glycol) molecules. Results confirm these nanoparticles as excellent contrast agents for magnetic resonance imaging. Changes in the spin-spin transversal relaxation times of the surrounding water protons due to nanoparticle aggregation demonstrates the bioactivity of these nanoparticles functionalized with carbohydrates. To finish with, nanoparticle toxicity is evaluated by means of MTT assay. The obtained results clearly indicate that these nanoparticles are excellent candidates for their further application in nanomedicine or nanobiotechnology.Synthesis and characterization of magnetic nanoparticles with excellent size control are showed here. Their functionalization using an amphiphilic polymer is also described. This strategy allows the stabilization of magnetic nanoparticles in aqueous solvents and in addition, the polymer shell serves as a platform to incorporate relevant biomolecules, such as poly(ethylene glycol) and a number of carbohydrates. Nanoparticles functionalized with carbohydrates show the ability to avoid unspecific interactions between proteins present in the working medium and the nanoparticles, so can be used as an alternative to poly(ethylene glycol) molecules. Results confirm these nanoparticles as excellent contrast agents for magnetic resonance imaging. Changes in the spin-spin transversal relaxation times of the surrounding water protons due to nanoparticle aggregation demonstrates the bioactivity of these nanoparticles functionalized with carbohydrates. To finish with, nanoparticle toxicity is evaluated by means of MTT assay. The obtained results clearly indicate that these nanoparticles are excellent candidates for their further application in nanomedicine or nanobiotechnology. Electronic supplementary information (ESI) available: Chemical, physical and magnetic characterization; R2 maps; stability of NPs at different conditions; size of glucose NPs in the presence of Concanavalin A; MTT assays of the samples are shown in figures S1-S10. Table S1 represents the hydrodynamic size of PMAO NPs after being washed with different solvents. See DOI: 10.1039/c0nr00104j

Moros, Maria; Pelaz, Beatriz; López-Larrubia, Pilar; García-Martin, Maria L.; Grazú, Valeria; de La Fuente, Jesus M.

2010-09-01

172

Design and characterization of protein-quercetin bioactive nanoparticles  

PubMed Central

Background The synthesis of bioactive nanoparticles with precise molecular level control is a major challenge in bionanotechnology. Understanding the nature of the interactions between the active components and transport biomaterials is thus essential for the rational formulation of bio-nanocarriers. The current study presents a single molecule of bovine serum albumin (BSA), lysozyme (Lys), or myoglobin (Mb) used to load hydrophobic drugs such as quercetin (Q) and other flavonoids. Results Induced by dimethyl sulfoxide (DMSO), BSA, Lys, and Mb formed spherical nanocarriers with sizes less than 70 nm. After loading Q, the size was further reduced by 30%. The adsorption of Q on protein is mainly hydrophobic, and is related to the synergy of Trp residues with the molecular environment of the proteins. Seven Q molecules could be entrapped by one Lys molecule, 9 by one Mb, and 11 by one BSA. The controlled releasing measurements indicate that these bioactive nanoparticles have long-term antioxidant protection effects on the activity of Q in both acidic and neutral conditions. The antioxidant activity evaluation indicates that the activity of Q is not hindered by the formation of protein nanoparticles. Other flavonoids, such as kaempferol and rutin, were also investigated. Conclusions BSA exhibits the most remarkable abilities of loading, controlled release, and antioxidant protection of active drugs, indicating that such type of bionanoparticles is very promising in the field of bionanotechnology.

2011-01-01

173

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 ...

174

Semiconductor Nanoparticles  

NASA Astrophysics Data System (ADS)

Semiconductor nanoparticles exhibit size dependent properties, when their size is comparable to the size of Bohr diameter for exciton. This can be exploited to increase fluorescence efficiency or increase the internal magnetic field strength in doped semiconductors. Nanoparticles are usually unstable and can aggregate. It is therefore necessary to protect them. Surface passivation using capping molecules or by making core-shell particles are some useful ways. Here synthesis and results on doped and un-doped nanoparticles of ZnS, CdS and ZnO will be discussed. We shall present results on core-shell particles using some of these nanoparticles and also discuss briefly the effect of Mn doping on hyperfine interactions in case of CdS nanoparticles.

Bangal, M.; Ashtaputre, S.; Marathe, S.; Ethiraj, A.; Hebalkar, N.; Gosavi, S. W.; Urban, J.; Kulkarni, S. K.

2005-01-01

175

Incorporated evaporative condenser  

Microsoft Academic Search

The incorporated evaporative condenser developed in this work comprises of a system of fins, basin of water condensates, circuit pump and system of drop cloud via spraying. In the whole provision a system of drop collector is also included for the minimisation of water escapes now essential for the operation of system. Actually, the present work aims on the development

Michalis Gr. Vrachopoulos; Andronikos E. Filios; Georgios T. Kotsiovelos; Eleftherios D. Kravvaritis

2007-01-01

176

DNA templated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Recent discoveries in nanoscience are predicted to potentially revolutionize future technologies in an extensive number of fields. These developments are contingent upon discovering new and often unconventional methods to synthesize and control nanoscale components. Nature provides several examples of working nanotechnology such as the use of programmed self assembly to build and deconstruct complex molecular systems. We have adopted a method to control the one dimensional assembly of magnetic nanoparticles using DNA as a scaffold molecule. With this method we have demonstrated the ability to organize 5 nm particles into chains that stretch up to ˜20 mum in length. One advantage of using DNA compared is the ability of the molecule to interact with other biomolecules. After assembling particles onto DNA we have been able to cleave the molecule into smaller fragments using restriction enzymes. Using ligase enzymes we have re-connected these fragments, coated with either gold or iron oxide, to form long one-dimensional arrangements of the two different types of nanoparticles on a single molecular guide. We have also created a sensitive magnetic field sensor by incorporating magnetic nanoparticle coated DNA strands with microfabricated electrodes. The IV characteristics of the aligned nanoparticles are dependant on the magnitude of an externally applied magnetic field. This transport phenomenon known as tunneling magnetoresistance (TMR) shows room temperature resistance of our devices over 80% for cobalt ferrite coated DNA when a field of 20 kOe is applied. In comparison, studies using two dimensional nanoparticle films of irox oxides xii only exhibit a 35% MR effect. Confinement into one dimension using the DNA guide produces a TMR mechanism which produces significant increases in magnetoresistance. This property can be utilized for applications in magnetic field sensing, data storage, and logic elements.

Kinsella, Joseph M.

177

Engineering biofunctional magnetic nanoparticles for biotechnological applications.  

PubMed

Synthesis and characterization of magnetic nanoparticles with excellent size control are showed here. Their functionalization using an amphiphilic polymer is also described. This strategy allows the stabilization of magnetic nanoparticles in aqueous solvents and in addition, the polymer shell serves as a platform to incorporate relevant biomolecules, such as poly(ethylene glycol) and a number of carbohydrates. Nanoparticles functionalized with carbohydrates show the ability to avoid unspecific interactions between proteins present in the working medium and the nanoparticles, so can be used as an alternative to poly(ethylene glycol) molecules. Results confirm these nanoparticles as excellent contrast agents for magnetic resonance imaging. Changes in the spin-spin transversal relaxation times of the surrounding water protons due to nanoparticle aggregation demonstrates the bioactivity of these nanoparticles functionalized with carbohydrates. To finish with, nanoparticle toxicity is evaluated by means of MTT assay. The obtained results clearly indicate that these nanoparticles are excellent candidates for their further application in nanomedicine or nanobiotechnology. PMID:20676420

Moros, Maria; Pelaz, Beatriz; López-Larrubia, Pilar; García-Martin, Maria L; Grazú, Valeria; de la Fuente, Jesus M

2010-09-01

178

Modulation of flavonoid metabolites in Arabidopsis thaliana through overexpression of the MYB75 transcription factor: role of kaempferol-3,7-dirhamnoside in resistance to the specialist insect herbivore Pieris brassicae  

PubMed Central

Anthocyanins and flavonols are secondary metabolites that can function in plant defence against herbivores. In Arabidopsis thaliana, anthocyanin and flavonol biosynthesis are regulated by MYB transcription factors. Overexpression of MYB75 (oxMYB75) in Arabidopsis results in increasing anthocyanin and flavonol levels which enhances plant resistance to generalist caterpillars. However, how these metabolites affect specialist herbivores has remained unknown. Performance of a specialist aphid (Brevicoryne brassicae) was unaffected after feeding on oxMYB75 plants, whereas a specialist caterpillar (Pieris brassicae) gained significantly higher body mass when feeding on this plant. An increase in anthocyanin and total flavonol glycoside levels correlated negatively with the body mass of caterpillars fed on oxMYB75 plants. However, a significant reduction of kaempferol-3,7-dirhamnoside (KRR) corresponded to an increased susceptibility of oxMYB75 plants to caterpillar feeding. Pieris brassicae caterpillars also grew less on an artificial diet containing KRR or on oxMYB75 plants that were exogenously treated with KRR, supporting KRR’s function in direct defence against this specialist caterpillar. The results show that enhancing the activity of the anthocyanin pathway in oxMYB75 plants results in re-channelling of quercetin/kaempferol metabolites which has a negative effect on the accumulation of KRR, a novel defensive metabolite against a specialist caterpillar.

Dicke, Marcel

2014-01-01

179

Boron incorporation into mullite  

NASA Astrophysics Data System (ADS)

Boron-doped mullites were synthesized using aluminium nitrate-nonahydrate, tetraethoxysilane and boric acid in a sol gel process with subsequent annealing at 950 and 1300 °C for five hours. Two different bulk compositions with constant Al2O3 contents (60 and 70 mol%, respectively) and varying SiO2 plus B2O3 contents were investigated. X-ray powder diffraction analyses yielded a linear decrease of the lattice parameters with increasing bulk B2O3 content, which was interpreted as to be due to boron incorporation. Related to the increasing boron content, corresponding infrared spectra revealed a slight and continuous shift for most of the absorption bands. These data show that mullite is able to incorporate large amounts of boron into its structure (up to about 20 mol% B2O3 depending on the bulk composition of the starting materials). Infrared analyses suggest that boron is incorporated into the mullite structure in form of planar three-fold coordinated BO3 groups.

Griesser, K. J.; Beran, A.; Voll, D.; Schneider, H.

2008-03-01

180

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

181

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

182

Superparamagnetic Nanoparticles  

Microsoft Academic Search

\\u000a Nanoscaled magnetic materials are great candidates for fundamental and applied research. 0D, 1D and 2D magnetic nanostructures\\u000a have been extensively studied previously. One of the unique phenomena that only exists in nanoscaled magnetic structure (below\\u000a a certain critical size) is superparamagnetism. In this chapter, various chemical synthesis methods to obtain superparamagnetic\\u000a nanoparticles are compared. Strategies to prevent agglomeration of nanoparticles

Boon Hoong Ong; Nisha Kumari Devaraj

183

Improving the Dielectric Properties of Polymers by Incorporating Nanoparticles  

Microsoft Academic Search

The paper presents a brief review of the promise of nanotechnology applied to polymeric insulation materials and discusses the electrical properties found. For a variety of nanocomposites, the dielectric behaviour has shown that the interface between the embedded particles and host matrix holds the key to the understanding of the bulk phenomena being observed. Dielectric spectroscopy verified the motion of

C Zou; J C Fothergill; M Fu; J K Nelson

184

Effect of filler incorporation route on the properties of polysulfone–silver nanocomposite membranes of different porosities  

Microsoft Academic Search

Flat sheet porous polysulfone–silver nanocomposite membranes were synthesized by the wet phase inversion process. The effects of casting mixture composition and nanoparticle incorporation route on the morphological and separation properties of prepared membranes were studied by comparing nanocomposites of different preparations with silver-free controls. Silver nanoparticles were either synthesized ex situ and then added to the casting solution as an

Julian S. Taurozzi; Hari Arul; Volodymyr Z. Bosak; Anatoliy F. Burban; Thomas C. Voice; Merlin L. Bruening; Volodymyr V. Tarabara

2008-01-01

185

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

186

Trimetallic Ag@AuPt Neapolitan nanoparticles  

NASA Astrophysics Data System (ADS)

Trimetallic Ag@AuPt Neapolitan nanoparticles were prepared by two sequential galvanic exchange reactions of 1-hexanethiolate-capped silver nanoparticles (AgC6, 5.70 +/- 0.82 nm in diameter) with gold(i)-thiomalic acid (AuITMA) and platinum(ii)-hexanethiolate (PtIIC6) complexes. The first reaction was carried out at the air-water interface by the Langmuir method where the AgC6 nanoparticles formed a compact monolayer and water-soluble AuITMA was injected into the water subphase; the nanoparticles were then deposited onto a substrate surface in the up-stroke fashion and immersed into an acetone solution of PtIIC6. As both reactions were confined to an interface, the Au and Pt elements were situated on two opposite poles of the original Ag nanoparticles. The tripatchy structure was clearly manifested in elemental mapping of the nanoparticles, and consistent with the damping and red-shift of the nanoparticle surface plasmon resonance. Further characterizations by X-ray photoelectron spectroscopy showed that the reactions were mostly confined to the top layers of the Ag metal cores, and contact angle and infrared spectroscopic measurements confirmed the incorporation and segregated distribution of the organic capping ligands on the nanoparticle surface.

Song, Yang; Chen, Shaowei

2013-07-01

187

Identification of regioisomers of methylated kaempferol and quercetin by ultra high performance liquid chromatography quadrupole time-of-flight (UHPLC-QTOF) tandem mass spectrometry combined with diagnostic fragmentation pattern analysis.  

PubMed

The O-methylation of active flavonoids can enhance their antiallergic, anticancerous, and cardioprotective effects depending on the methylation position. Thus, it is biologically and pharmacologically important to differentiate methylated flavonoid regioisomers. In this study, we examined the regioisomers of methylated kaempferol and quercetin using ultra high performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry. The methyl groups on the flavonoids can generally be cleaved as methyl radicals in a position-independent manner. We found that methyl groups can be cleaved as methane. If there are protons adjacent the methoxy on the flavonol rings, intra-molecule proton transfer can occur via collision-induced dissociation, and one molecule of methane can then be eliminated. The remaining charged fragment ([M+H-CH4](+)) reflects the adjacent structure and is specific to the methoxy position. Furthermore, the retro Diels-Alder (RDA) fragmentation of methylated flavonols can generate fragments with the methoxy at the original methylated ring. Combining the position-specific [M+H-CH4](+) fragment with the RDA fragments provides a diagnostic pattern for rapidly identifying methylated regioisomeric flavonols. Along with their retention behaviour, we have successfully identified ten regioisomers of methylated kaempferol and quercetin, which include six compounds previously reported in plants and shown to be biologically active. The developed approach is sensitive, rapid, reliable, and requires few standard compounds. It is highly efficient for characterising the specificity of novel flavonoid O-methyltransferases and can help direct enzymatic or chemical syntheses during the early stages of drug discovery. This method also has potential for use in identifying other methylated isomeric flavonoids. PMID:23998533

Ma, Chengying; Lv, Haipeng; Zhang, Xinzhong; Chen, Zongmao; Shi, Jiang; Lu, Meiling; Lin, Zhi

2013-09-17

188

Nanoparticles for bioanalysis  

Microsoft Academic Search

This review covers the emerging field of nanobiotechnology, in which nanoparticles are applied to the analysis of biomolecules. Nanoparticles can be used in a variety of bioanalytical formats, and this review discusses four classes of use. First, nanoparticles as quantitation tags, such as the optical detection of quantum dots and the electrochemical detection of metallic nanoparticles. Second, encoded nanoparticles as

Sharron G Penn; Lin He; Michael J Natan

2003-01-01

189

Hybrid Nanoparticles for Detection and Treatment of Cancer  

PubMed Central

There is currently considerable effort to incorporate both diagnostic and therapeutic functions into a single nanoscale system for the more effective treatment of cancer. Nanoparticles have great potential to achieve such dual functions, particularly if more than one type of nanostructure can be incorporated in a nanoassembly—referred to in this review as a hybrid nanoparticle. Here we review recent developments in the synthesis and evaluation of such hybrid nanoparticles based on two design strategies (barge vs. tanker), in which liposomal, micellar, porous silica, polymeric, viral, noble metal, and nanotube systems are incorporated either within (barge) or at the surface of (tanker) a nanoparticle. We highlight the design factors that should be considered to obtain effective nanodevices for cancer detection and treatment.

Sailor, Michael J.; Park, Ji-Ho

2012-01-01

190

Nanoparticles and the control of oral infections.  

PubMed

The potential of antimicrobial nanoparticles to control oral infections is reviewed. Such particles can be classified as having a size no greater than 100 nm and are produced using traditional or more novel techniques. Exploitation of the toxic properties of nanoparticles to bacteria, fungi and viruses, in particular metals and metal oxides, as well as their incorporation into polymeric materials have increased markedly over the past decade. The potential of nanoparticles to control the formation of biofilms within the oral cavity, as a function of their biocidal, anti-adhesive and delivery capabilities, is now receiving close attention. Latest insights into the application of nanoparticles within this field, including their use in photodynamic therapy, will be reviewed. Possible approaches to alter biocompatibility and desired function will also be covered. PMID:24388116

Allaker, Robert P; Memarzadeh, Kaveh

2014-02-01

191

Incorporation of pyrene in polypyrrole/polystyrene magnetic beads.  

PubMed

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. PMID:24854245

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

2014-10-15

192

Nepal CRS project incorporates.  

PubMed

The Nepal Contraceptive Retail Sales (CRS) Project, 5 years after lauching product sales in June 1978, incorporated as a private, nonprofit company under Nepalese management. The transition was finalized in August 1983. The Company will work through a cooperative agreement with USAID/Kathmandu to complement the national family planning goals as the program continues to provide comtraceptives through retail channels at subsidized prices. Company objectives include: increase contraceptive sales by at least 15% per year; make CRS cost effective and move towards self sufficiency; and explore the possibility of marketing noncontraceptive health products to improve primary health care. After only5 years the program can point to some impressive successes. The number of retial shops selling family planning products increased from 100 in 1978 to over 8000, extending CRS product availability to 66 of the country's 75 districts. Retail sales have climbed dramatically in the 5-year period, from Rs 46,817 in 1978 to Rs 271,039 in 1982. Sales in terms of couple year protection CYP) have grown to 24,451 CYP(1982), a 36% increase over 1980 CYP. Since the beginning of the CRS marketing program, total distribution of contraceptives--through both CRS and the Family Planning Maternal and Child Haelth (FP/MCH) Project--has been increasing. While the FP/MCH program remains the largest distributor,contribution of CRS Products is increasing, indicating that CRS is creating new product acceptors. CRS market share in 1982 was 43% for condoms and 16% for oral contraceptives (OCs). CRS markets 5 products which are subsidized in order to be affordable to consumers as well as attractive to sellers. The initial products launched in June 1978 were Gulaf standard dose OCs and Dhaal lubricated colored condoms. A less expensive lubricates, plain Suki-Dhaal condom was introduced in June 1980 in an attempt to reach poorer rural populations, but rural distribution costs are excessive and Suki-Dhaal sales have never been high. In 1982 2 additional products were introduced--Nilocan (Norminest) low does OCs and Kamal Neo Sampoon foaming tablets. The CRS program recruited and trained its own sales representatives who work shop to shop, promoting products and educating retailers and consumers. An important part of the communication starategy includes consumer and retailer education. Advertising messages were developed to increase brand awareness, create demand, educate consumers about side effects of OCs, and to identify contraceptives as a means of adequately space children. PMID:12312964

1983-01-01

193

Multifunctional mesoporous silica nanocomposite nanoparticles for theranostic applications.  

PubMed

Clever combinations of different types of functional nanostructured materials will enable the development of multifunctional nanomedical platforms for multimodal imaging or simultaneous diagnosis and therapy. Mesoporous silica nanoparticles (MSNs) possess unique structural features such as their large surface areas, tunable nanometer-scale pore sizes, and well-defined surface properties. Therefore, they are ideal platforms for constructing multifunctional materials that incorporate a variety of functional nanostructured materials. In this Account, we discuss recent progress by our group and other researchers in the design and fabrication of multifunctional nanocomposite nanoparticles based on mesoporous silica nanostructures for applications to simultaneous diagnosis and therapy. Versatile mesoporous silica-based nanocomposite nanoparticles were fabricated using various methods. Here, we highlight two synthetic approaches: the encapsulation of functional nanoparticles within a mesoporous silica shell and the assembly of nanoparticles on the surface of silica nanostructures. Various nanoparticles were encapsulated in MSNs using surfactants as both phase transfer agents and pore-generating templates. Using MSNs as a scaffold, functional components such as magnetic nanoparticles and fluorescent dyes have been integrated within these systems to generate multifunctional nanocomposite systems that maintain their individual functional characteristics. For example, uniform mesoporous dye-doped silica nanoparticles immobilized with multiple magnetite nanocrystals on their surfaces have been fabricated for their use as a vehicle capable of simultaneous magnetic resonance (MR) and fluorescence imaging and drug delivery. The resulting nanoparticle-incorporated MSNs were then tested in mice with tumors. These in vivo experiments revealed that these multifunctional nanocomposite nanoparticles were delivered to the tumor sites via passive targeting. These nanocomposite nanoparticles served as successful multimodal imaging probes and also delivered anticancer drugs to the tumor site. With innumerable combinations of imaging modalities and drug delivery available within these vehicles, multifunctional nanocomposite nanoparticles provide new opportunities for clinical diagnostics and therapeutics. PMID:21848274

Lee, Ji Eun; Lee, Nohyun; Kim, Taeho; Kim, Jaeyun; Hyeon, Taeghwan

2011-10-18

194

Development of white antibacterial pigment based on silver chloride nanoparticles and mesoporous silica and its polymer composite  

Microsoft Academic Search

We report the synthesis of silver chloride nanoparticles inside the pores of a mesoporous silica, SBA-15. The nanoparticles were formed by an ion exchange reaction of AgNO3 incorporated inside the pores with a HCl vapor. The incorporation of AgNO3 into the SBA-15 pores and its conversion into silver nanoparticles were proven by low angle X-ray diffraction, infrared spectroscopy, nitrogen adsorption–desorption

Seung-Hyun Min; Jae-Hun Yang; Joon Young Kim; Young-Uk Kwon

2010-01-01

195

Apoferritin-Templated Synthesis of Encoded Metallic Phosphate Nanoparticle Tags  

SciTech Connect

Encoded metallic-phosphate nanoparticle tags, with distinct encoding patterns, have been prepared using an apoferritin template. A center-cavity structure as well as the disassociation and reconstructive characteristics of apoferritin at different pH environments provide a facile route for preparing such encoded nanoparticle tags. Encapsulation and diffusion approaches have been investigated during the preparation. The encapsulation approach, which is based on the dissociation and reconstruction of apoferritin at different pHs, exhibits an effective route to prepare such encoded metallic-phosphate nanoparticle tags. The compositionally encoded nanoparticle tag leads to a high coding capacity with a large number of distinguishable voltammetric signals, reflecting the predetermined composition of the metal mixture solution (and hence the nanoparticle composition). Releasing the metal components from the nanoparticle tags at pH 4.6 acetate buffer avoids harsh dissolution conditions, such as strong acids. Such a synthesis of encoded nanoparticle tags, including single-component and compositionally encoded nanoparticle tags, is substantially simple, fast, and convenient compared to that of encoded metal nanowires and semiconductor nanoparticle (CdS, PbS, and ZnS) incorporated polystyrene beads. The encoded metallic-phosphate nanoparticle tags thus show great promise for bioanalytical or product-tracking/identification/protection applications.

Liu, Guodong; Wu, Hong; Dohnalkova, Alice; Lin, Yuehe

2007-07-31

196

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

197

Nanoparticle-host interactions in natural systems  

NASA Astrophysics Data System (ADS)

Natural nanoparticles are attracting a great deal of attention due to their unique role as agents of elemental transport and their increased reactivity in geologic systems. Although significant progress has been made in understanding their behavior in the Earth's critical zone (i.e. near-surface environments), there is a severe lack of information on their stability for a wider range of geologically relevant temperatures. Here, we describe the first direct observations of the dynamic behavior of natural nanoparticles at near atomic scale, revealing that their thermal stability is not only dependent on particle size, but also on the surrounding host mineral. Native Au nanoparticles (mean diameter ~4 nm) incorporated in an As-rich pyrite from "invisible" Au ores were observed during in-situ heating up to 650°C. While isolated Au nanoparticles melt, with their melting point being a function of size, we show that when incorporated in a sulfide host, Au nanoparticles react to increased temperature by dissolving into the pyrite matrix and forming larger particles in an Ostwald-type ripening process. The dissolution temperatures are much lower than melting temperatures of isolated nanoparticles and are as well strongly size-dependent. These findings provide new insights into the fate of nanoparticulate Au and other metals during geological processes and throughout their metallurgical recovery from refractory ores. The size distribution of the particles may be an indicator of the geologic history of the ore because, as we show, the mean particle diameter sets un upper limit to the maximum temperature of the host rock. Furthermore, results suggest that nanoparticulate minerals, usually documented in low-temperature (T<100°C) aqueous environments, can also occur and survive at higher temperatures when incorporated into refractory host phases.

Becker, U.; Reich, M.; Utsunomiya, S.; Wang, J.; Kesler, S.; Wang, L.; Ewing, R. C.

2007-12-01

198

Nanoparticles for bioanalysis.  

PubMed

This review covers the emerging field of nanobiotechnology, in which nanoparticles are applied to the analysis of biomolecules. Nanoparticles can be used in a variety of bioanalytical formats, and this review discusses four classes of use. First, nanoparticles as quantitation tags, such as the optical detection of quantum dots and the electrochemical detection of metallic nanoparticles. Second, encoded nanoparticles as substrates for multiplexed bioassays, such as striped metallic nanoparticles. Third, nanoparticles that leverage signal transduction, for example in colloidal gold-based aggregation assays. Fourth, functional nanoparticles that exploit specific physical or chemical properties of nanoparticles to carry out novel functions, such as the catalysis of a biological reaction. In addition, the review discusses the next generation of nanoparticles that will be utilized in the life sciences, such as nanodots and carbon nanotubes. PMID:14580566

Penn, Sharron G; He, Lin; Natan, Michael J

2003-10-01

199

Controlled Synthesis of Nanoparticles in Microheterogeneous Systems  

NASA Astrophysics Data System (ADS)

Because of their structural and dynamical properties, microheterogeneous systems have been employed as solvent and reaction media both to synthesize and stabilize nanoparticles. Following this route, inside their nanometer-sized heterogeneities the nanoparticles of many different substances have been incorporated. The book shows the distinct advantages of this synthetic strategy over that of many other methods. Moreover, it furnishes to the reader a collection of theoretical and experimental facts allowing him to reduce the number of trial and errors necessary to arrive at an optimal synthetic protocol.

Turco Liveri, Vincenzo

200

Grain boundary engineering with gold nanoparticles  

NASA Astrophysics Data System (ADS)

We investigated high-TC grain boundary Josephson junctions with and without incorporated gold nanoparticles. Pulsed laser deposition was used for the deposition of YBa2Cu3O7?? thin films on SrTiO3 bicrystal substrates with different grain boundary angles. During the deposition process, single-crystalline nanoparticles self-assembled from a thin gold layer which was sputtered on the substrate before the YBCO deposition. The interaction between nanoparticles and thin film growth significantly influences the quality of the YBCO films [1]. The critical current density and the critical temperature of the superconducting films can be increased in a defined manner. Furthermore, the nanoparticles influence the growth conditions in the region of the grain boundary and thus the properties of the later patterned Josephson junctions. The comparison between Josephson junctions with and without nanoparticles on the same substrate shows a reduction of the critical current IC and an increase of the normal state resistance RN for all investigated types of grain boundaries in the areas with gold nanoparticles. In some cases we even found an increase of the resulting ICRN product. We present the influence of light irradiation on the properties of the Josephson junctions.

Schmidl, F.; Katzer, C.; Michalowski, P.; Koch, S.; Tympel, V.

2014-05-01

201

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

202

Porous Collagen Scaffold Reinforced with Surfaced Activated PLLA Nanoparticles  

PubMed Central

Porous collagen scaffold is integrated with surface activated PLLA nanoparticles fabricated by lyophilizing and crosslinking via EDC treatment. In order to prepare surface-modified PLLA nanoparticles, PLLA was firstly grafted with poly (acrylic acid) (PAA) through surface-initiated polymerization of acrylic acid. Nanoparticles of average diameter 316?nm and zeta potential ?39.88?mV were obtained from the such-treated PLLA by dialysis method. Porous collagen scaffold were fabricated by mixing PLLA nanoparticles with collagen solution, freeze drying, and crosslinking with EDC. SEM observation revealed that nanoparticles were homogeneously dispersed in collagen matrix, forming interconnected porous structure with pore size ranging from 150 to 200??m, irrespective of the amount of nanoparticles. The porosity of the scaffolds kept almost unchanged with the increment of the nanoparticles, whereas the mechanical property was obviously improved, and the degradation was effectively retarded. In vitro L929 mouse fibroblast cells seeding and culture studies revealed that cells infiltrated into the scaffolds and were distributed homogeneously. Compared with the pure collagen sponge, the number of cells in hybrid scaffolds greatly increased with the increment of incorporated nanoparticles. These results manifested that the surface-activated PLLA nanoparticles effectively reinforced the porous collagen scaffold and promoted the cells penetrating into the scaffold, and proliferation.

Xu, Cancan; Lu, Wei; Bian, Shaoquan; Liang, Jie; Fan, Yujiang; Zhang, Xingdong

2012-01-01

203

Porous collagen scaffold reinforced with surfaced activated PLLA nanoparticles.  

PubMed

Porous collagen scaffold is integrated with surface activated PLLA nanoparticles fabricated by lyophilizing and crosslinking via EDC treatment. In order to prepare surface-modified PLLA nanoparticles, PLLA was firstly grafted with poly (acrylic acid) (PAA) through surface-initiated polymerization of acrylic acid. Nanoparticles of average diameter 316 nm and zeta potential -39.88 mV were obtained from the such-treated PLLA by dialysis method. Porous collagen scaffold were fabricated by mixing PLLA nanoparticles with collagen solution, freeze drying, and crosslinking with EDC. SEM observation revealed that nanoparticles were homogeneously dispersed in collagen matrix, forming interconnected porous structure with pore size ranging from 150 to 200 ?m, irrespective of the amount of nanoparticles. The porosity of the scaffolds kept almost unchanged with the increment of the nanoparticles, whereas the mechanical property was obviously improved, and the degradation was effectively retarded. In vitro L929 mouse fibroblast cells seeding and culture studies revealed that cells infiltrated into the scaffolds and were distributed homogeneously. Compared with the pure collagen sponge, the number of cells in hybrid scaffolds greatly increased with the increment of incorporated nanoparticles. These results manifested that the surface-activated PLLA nanoparticles effectively reinforced the porous collagen scaffold and promoted the cells penetrating into the scaffold, and proliferation. PMID:22448137

Xu, Cancan; Lu, Wei; Bian, Shaoquan; Liang, Jie; Fan, Yujiang; Zhang, Xingdong

2012-01-01

204

HPMC reinforced with different cellulose nano-particles  

Microsoft Academic Search

Three different types of cellulose nanoparticles: (i) nano-fibrils cellulose (NFC), (ii) nano-fibrils cellulose oxidized using the tempo reaction (NFCt) and (iii) cellulose whiskers, were incorporated into HPMC edible films at different concentrations. The films were examined for mechanical and moisture barrier properties verifying how the addition of cellulose nano-particles affected the water affinities (water adsorption\\/desorption isotherms) and the diffusion coefficients.

Cristina Bilbao-Sainz; Julien Bras; Tina Williams; Tangi Sénechal; William Orts

2011-01-01

205

Formation and characterization of nanoparticles via laser ablation in solution  

NASA Astrophysics Data System (ADS)

The work presented in this thesis encompassed laser ablation of various transition metals within a liquid environment. Through an improved understanding of the ablation process, control over the properties of the resultant nanoparticles can be obtained, and thusly nanoparticles can be tailored with specific properties. Creation of nanoparticles via laser ablation in solution is a relatively youngtechnique for nanoparticle synthesis, and the work presented should prove useful in guiding further exploration in ablation processes in liquids for nanomaterial production. When a laser is focused onto a target under a liquid environment, the target material and its surrounding liquid are vaporized. The concoction of vapor is ejected normal to the surface as a bubble. The bubble has a temperature reaching the boiling point of the metal, and has a gradient to the boiling point of the solvent. The bubble expands until it reaches a critical volume, and then subsequently collapses. It is within this bubble that nanoparticle formation occurs. As the bubble expands, the vapor cools and nanoparticle growth transpires. During the bubble collapse, pressures reaching GigaPascals have been reported, and a secondary nanoparticle formation occurs as a result of these high pressures. Chapter 1 delves a little more into the nanoparticle formation mechanisms, as well as an introduction to the analytical techniques used for characterization. Ablation of titanium took place in isopropanol, ethanol, water, and n-hexane, under various fluences, with a 532 nm Nd:YAG operating at 10 Hz. It was found that a myriad of nanoparticles could be made with vastly different compositions that were both solvent and fluence dependent. Nanoparticles were made that incorporated carbon and oxygen from the solvent, showing how solvent choice is an important factor in nanoparticle creation. Chapter 3 discusses the results of the titanium work in great detail and demonstrates carbide production with ablation in isopropyl alcohol. Ablation in n-hexane also showed diffraction patterns correlating with carbides, and water showed oxygen incorporation. These results showed the ability to utilize the solvent in tailoring nanoparticles to achieve desired properties. Zirconium and nickel were ablated with the Nd:YAG at 532 nm. These studies utilized a stainless steel chamber designed and built to improve control over the experimental variables. The nickel study showcased the new chamber's ability for reproducibility in a size dependence study based upon laser fluence. The results of ablation with the Nd:YAG were compared to femtosecond ablation experiments performed with a titanium:sapphire femtosecond laser system. The Ti:sapphire femtosecond laser operated at 10 Hz, produced femtosecond pulses centered at ˜795 nm. The pulse duration was varied from 100 fs to 390 fs, the nanoparticles created from each condition were characterized, and the results are presented in chapters 5 and 6. Aluminum nanoparticles were made using both nanosecond and femtosecond laser ablation techniques. Aluminum nanoparticles have a great deal of potential for use as fuel additives as well as in paints and coatings. The nanosecond ablation process rendered large nanoparticles (over 200 nm) and the results are briefly shown in Appendix A. The femtosecond system produced a much smaller distribution of nanoparticles, with nanoparticles remaining in suspension for over a month's time, as evidenced by their unique UV-Vis absorbance. These nanoparticles were produced in isopropyl alcohol, and were stabilized by the solvent, as TEM analysis showed nanoparticles with very little oxygen incorporation. The solvent is bound to the nanoparticles as a result of the formation process and as a result forms a protective coating, which prevents further oxidation over time. The remarkable stability of these aluminum nanoparticles is a testament of employing the high energy scheme of the laser ablation process in a manner to tailor the production of novel nanomaterials. (Abstract shortened by UMI.)

Golightly, Justin Samuel

206

Formation and material analysis of plasma polymerized carbon nitride nanoparticles  

NASA Astrophysics Data System (ADS)

This paper deals with the analysis of nanoparticles polymerized in nitrogen/acetylene and argon/acetylene gas mixtures in low temperature rf discharges. The polymerization process was monitored by means of mass spectroscopy. The chemical characteristics of the material were obtained in situ by infrared absorption spectroscopy and ex situ by means of near edge x-ray absorption fine structure spectroscopy. These data were supported by complimentary elemental analyses such as deuteron induced gamma emission, Rutherford backscattering, and nuclear reaction analysis. Although morphology showed no differences, further material analysis shows clearly nitrogen incorporation in the nanoparticles, mostly by multiple bonds. In comparison with the nanoparticles from argon/acetylene plasma, the amount of carbon in carbon-nitride nanoparticles remains unchanged, whereas hydrogen content strongly decreases. The results of mass spectroscopy on neutrals and ions lead to the assumption that carbon-nitride nanoparticles are formed by copolymerization of two kinds of precursors: hydrocarbon and nitrogen containing hydrocarbon species.

Kova?evi?, E.; Berndt, J.; Stefanovi?, I.; Becker, H.-W.; Godde, C.; Strunskus, Th.; Winter, J.; Boufendi, L.

2009-05-01

207

Crystallization and Thermal Conductivity of CaCO3 Nanoparticle Filled Polypropylene  

Microsoft Academic Search

Isotactic polypropylene (PP) and calcium carbonate (CaCO3) nanocomposites were prepared by melt extrusion in a twin screw extruder. The effect of CaCO3 nanoparticles on the crystallization and thermal conductivity (TC) of PP was studied by thermal analysis (DSC) and thermal conductivity analysis (TCA). The introduction of CaCO3 nanoparticles resulted in an increase in crystallinity. The incorporation of this nanoparticle (up

M. H. VAKILI; H. EBADI-DEHAGHANI; M. HAGHSHENAS-FARD

2011-01-01

208

Influence of nanoparticle surface modification on the electrical behaviour of polyethylene nanocomposites  

Microsoft Academic Search

In this study, we present the results of the influence of surface modification of TiO2 nanoparticles on the short-term breakdown strength and space charge distribution of low-density polyethylene (LDPE). A polar silane coupling agent N-(2-aminoethyl) 3-aminopropyl-trimethoxysilane (AEAPS) was used for the nanoparticle surface modification. Despite agglomeration and a poor interface compared to untreated nanoparticles, it was found that the incorporation

Dongling Ma; Treese A. Hugener; Richard W. Siegel; Anna Christerson; Eva Mårtensson; Carina Önneby; Linda S. Schadler

2005-01-01

209

In Situ Formation of Silver Nanoparticles within Chitosan-attached Cotton Fabric for Antibacterial Property  

Microsoft Academic Search

This work involves chemical modification of cotton fabrics by natural, biocompatible, and biodegradable polysaccharide — chitosan — followed by incorporating silver nanoparticles in the fabrics. The excellent chelating property of chitosan binds the silver metal ions that are later on reduced to nanoparticles giving rise to chitosan-attached nanosilver-loaded fabrics. The silver nanoparticles-loaded chitosan-attached fabric has been characterized by surface plasmon

Varsha Thomas; M. Bajpai; S. K. Bajpai

2011-01-01

210

Chemical and structural investigation of lipid nanoparticles: drug-lipid interaction and molecular distribution.  

PubMed

Lipid nanoparticles are a promising alternative to existing carriers in chemical or drug delivery systems. A key challenge is to determine how chemicals are incorporated and distributed inside nanoparticles, which assists in controlling chemical retention and release characteristics. This study reports the chemical and structural investigation of gamma-oryzanol loading inside a model lipid nanoparticle drug delivery system composed of cetyl palmitate as solid lipid and Miglyol 812 as liquid lipid. The lipid nanoparticles were prepared by high pressure homogenization at varying liquid lipid content, in comparison with the gamma-oryzanol free systems. The size of the lipid nanoparticles, as measured by the photon correlation spectroscopy, was found to decrease with increased liquid lipid content from 200 to 160 nm. High-resolution proton nuclear magnetic resonance ((1)H-NMR) measurements of the medium chain triglyceride of the liquid lipid has confirmed successful incorporation of the liquid lipid in the lipid nanoparticles. Differential scanning calorimetric and powder x-ray diffraction measurements provide complementary results to the (1)H-NMR, whereby the crystallinity of the lipid nanoparticles diminishes with an increase in the liquid lipid content. For the distribution of gamma-oryzanol inside the lipid nanoparticles, the (1)H-NMR revealed that the chemical shifts of the liquid lipid in gamma-oryzanol loaded systems were found at rather higher field than those in gamma-oryzanol free systems, suggesting incorporation of gamma-oryzanol in the liquid lipid. In addition, the phase-separated structure was observed by atomic force microscopy for lipid nanoparticles with 0% liquid lipid, but not for lipid nanoparticles with 5 and 10% liquid lipid. Raman spectroscopic and mapping measurements further revealed preferential incorporation of gamma-oryzanol in the liquid part rather than the solid part of in the lipid nanoparticles. Simple models representing the distribution of gamma-oryzanol and lipids (solid and liquid) inside the lipid nanoparticle systems are proposed. PMID:20182010

Anantachaisilp, Suranan; Smith, Siwaporn Meejoo; Treetong, Alongkot; Pratontep, Sirapat; Puttipipatkhachorn, Satit; Ruktanonchai, Uracha Rungsardthong

2010-03-26

211

Development, Optimization and Characterization of Nanoparticle Drug Delivery System of Cisplatin  

Microsoft Academic Search

Purpose: Polymeric nanoparticles are frequently employed for drug delivery systems to perform a sustained release behavior\\u000a of incorporated drug. These polymeric nanoparticles can be used for site specific targeting of encapsulated drug. The objective\\u000a of present study was to develop a poly (lactide-co-glycolide) (PLGA) nanoparticles drug delivery system of anticancer drug\\u000a cisplatin with higher therapeutic efficacy, lesser side effects, and

V. Agrahari; V. Kabra; P. Trivedi

212

Multi-Functionalization of Silicon by Nanoparticles Through 'Plug and Play' Approach.  

National Technical Information Service (NTIS)

In this paper, we demonstrate a 'Plug and Play' approach, whereby externally synthesized nanoparticles of desired functions and size are incorporated into the semiconductor. followed by the manipulation of surface chemical bonds in order to achieve multip...

A. Ulman K. Prabhakaran K. V. Shafi T. Ogino

2001-01-01

213

Pegylated siRNA-loaded calcium phosphate nanoparticle-driven amplification of cancer cell internalization in vivo  

PubMed Central

The cell membrane is a critical barrier to effective delivery for many therapeutics, including those which are nanoparticle-based. Improving nanoparticle transport across the cell membrane remains a fundamental challenge. Cancer cells preferentially internalized pegylated calcium phosphate nanoparticles over normal epithelial cells. Furthermore, non-cytotoxic levels of doxorubicin markedly amplified this difference by increasing free unbound caveolin-1 and resulted in enhanced caveolin-mediated nanoparticle endocytosis in cancer cells. Engineered pegylated siRNA-loaded triple-shell calcium phosphate nanoconstructs incorporating ultra-low levels of doxorubicin recapitulated these effects and delivered increased numbers of siRNA into cancer cells with target-specific results. Systemic administration of nanoparticles in vivo demonstrated highly preferential entry into tumors, little bystander organ biodistribution, and significant tumor growth arrest. In conclusion, siRNA-loaded calcium phosphate nanoparticles incorporating non-cytotoxic amounts of doxorubicin markedly enhances nanoparticle internalization and results in increased payload delivery with concomitant on-target effects.

Tobin, Lisa A.; Xie, Yili; Tsokos, Maria; Chung, Su I.; Merz, Allison A.; Arnold, Michael A.; Li, Guang; Malech, Harry L.; Kwong, King F.

2013-01-01

214

Molecular imaging and therapy of cancer with radiolabeled nanoparticles  

PubMed Central

Summary This review summarizes the current state-of-the-art of radiolabeled nanoparticles for molecular imaging and internal radiotherapy applications targeting cancer. With the capacity to provide enormous flexibility, radiolabeled nanoparticles have the potential to profoundly impact disease diagnosis and patient management in the near future. Currently, the major challenges facing the research on radiolabeled nanoparticles are desirable (tumor) targeting efficacy, robust chemistry for both radionuclide encapsulation/incorporation and targeting ligand conjugation, favorable safety profile, as well as certain commercial and regulatory hurdles.

Hong, Hao; Zhang, Yin; Sun, Jiangtao; Cai, Weibo

2009-01-01

215

Independent optically addressable nanoparticle-polymer optomechanical composites  

NASA Astrophysics Data System (ADS)

We report the fabrication and characterization of optomechanically active composite materials consisting of a thermally responsive poly(NIPAAm-co-AAm) hydrogel matrix incorporating a dilute concentration of Au or silica-Au core-shell nanoparticles. Under optical illumination at the resonance absorption wavelength of the nanoparticle dopant, a dramatic volume collapse of the composite occurs due to local photothermal heating of the NIPAAm matrix. Nanoparticle dopants were chosen so that each composite was specifically optically addressable, exhibiting optomechanical behavior at independent wavelengths. Such materials can be useful as independently addressable remotely triggerable switches and gates in a wide variety of micromechanical applications.

Sershen, S. R.; Westcott, S. L.; Halas, N. J.; West, J. L.

2002-06-01

216

Varying nanoparticle pseudostationary phase plug length during capillary electrophoresis.  

PubMed

Capillary electrophoresis based separations of the hypothesized Parkinson's disease biomarkers dopamine, epinephrine, pyrocatechol, L-3,4-dihydroxyphenylalanine (L-DOPA), glutathione, and uric acid are performed in the presence of a 1 nM 11-mercaptoundecanoic acid functionalized gold (Au@MUA) nanoparticle pseudostationary phase plug. Au@MUA nanoparticles are monitored in the capillary and remain stable in the presence of electrically-driven flow. Migration times, peak areas, and relative velocity changes (vs. no pseudostationary) are monitored upon varying (1) the Au@MUA nanoparticle pseudostationary phase plug length at a fixed separation voltage and (2) the separation voltage for a fixed Au@MUA nanoparticle pseudostationary phase plug length. For instance, the migration times of positively charged dopamine and epinephrine increase slightly as the nanoparticle pseudostationary phase plug length increases with concomitant decreases in peak areas and relative velocities as a result of attractive forces between the positively charged analytes and the negatively charged nanoparticles. Migration times for neutral pyrocatechol and slightly negative L-DOPA did not exhibit significant changes with increasing nanoparticle pseudostationary plug length; however, reduction in peak areas for these two molecules were evident and attributed to non-specific interactions (i.e. hydrogen bonding and van der Waals interactions) between the biomarkers and nanoparticles. Moreover, negatively charged uric acid and glutathione displayed progressively decreasing migration times and peak areas and as a result, increased relative velocities with increasing nanoparticle pseudostationary phase plug length. These trends are attributed to partitioning and exchanging with 11-mercaptoundecanoic acid on nanoparticle surfaces for uric acid and glutathione, respectively. Similar trends are observed when the separation voltage decreased thereby suggesting that nanoparticle-biomarker interaction time dictates these trends. Understanding these analyte migration time, peak area, and velocity trends will expand our insight for incorporating nanoparticles in separations. PMID:21465053

Subramaniam, Varuni; Griffith, Lindsay; Haes, Amanda J

2011-09-01

217

Drug targeting using solid lipid nanoparticles.  

PubMed

The present review aims to show the features of solid lipid nanoparticles (SLNs) which are at the forefront of the rapidly developing field of nanotechnology with several potential applications in drug delivery and research. Because of some unique features of SLNs such as their unique size dependent properties it offers possibility to develop new therapeutics. A common denominator of all these SLN-based platforms is to deliver drugs into specific tissues or cells in a pathological setting with minimal adverse effects on bystander cells. SLNs are capable to incorporate drugs into nanocarriers which lead to a new prototype in drug delivery which maybe used for drug targeting. Hence solid lipid nanoparticles hold great promise for reaching the goal of controlled and site specific drug delivery and hence attracted wide attention of researchers. This review presents a broad treatment of targeted solid lipid nanoparticles discussing their types such as antibody SLN, magnetic SLN, pH sensitive SLN and cationic SLN. PMID:24717692

Rostami, Elham; Kashanian, Soheila; Azandaryani, Abbas H; Faramarzi, Hossain; Dolatabadi, Jafar Ezzati Nazhad; Omidfar, Kobra

2014-07-01

218

Controlled cobalt doping in biogenic magnetite nanoparticles.  

PubMed

Cobalt-doped magnetite (CoxFe3 -xO4) nanoparticles have been produced through the microbial reduction of cobalt-iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mössbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe(2+) site with Co(2+), with up to 17 per cent Co substituted into tetrahedral sites. PMID:23594814

Byrne, J M; Coker, V S; Moise, S; Wincott, P L; Vaughan, D J; Tuna, F; Arenholz, E; van der Laan, G; Pattrick, R A D; Lloyd, J R; Telling, N D

2013-06-01

219

Insertion of nanoparticle clusters into vesicle bilayers.  

PubMed

A major contemporary concern in developing effective liposome-nanoparticle hybrids is the present inclusion size limitation of nanoparticles between vesicle bilayers, which is considered to be around 6.5 nm in diameter. In this article, we present experimental observations backed by theoretical considerations which show that greater structures can be incorporated within vesicle membranes by promoting the clustering of nanoparticles before liposome formation. Cryo-transmission electron microscopy and cryo-electron tomography confirm these observations at unprecedented detail and underpin that the liposome membranes can accommodate flexible structures of up to 60 nm in size. These results imply that this material is more versatile in terms of inclusion capabilities and consequently widens the opportunities in developing multivalent vesicles for nanobiotechnology applications. PMID:24611878

Bonnaud, Cécile; Monnier, Christophe A; Demurtas, Davide; Jud, Corinne; Vanhecke, Dimitri; Montet, Xavier; Hovius, Ruud; Lattuada, Marco; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

2014-04-22

220

Controlled cobalt doping in biogenic magnetite nanoparticles  

PubMed Central

Cobalt-doped magnetite (CoxFe3 ?xO4) nanoparticles have been produced through the microbial reduction of cobalt–iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mössbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe2+ site with Co2+, with up to 17 per cent Co substituted into tetrahedral sites.

Byrne, J. M.; Coker, V. S.; Moise, S.; Wincott, P. L.; Vaughan, D. J.; Tuna, F.; Arenholz, E.; van der Laan, G.; Pattrick, R. A. D.; Lloyd, J. R.; Telling, N. D.

2013-01-01

221

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.

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

2012-01-01

222

Design of rolipram-loaded nanoparticles: comparison of two preparation methods  

Microsoft Academic Search

The aim of the present work was to investigate the preparation of nanoparticles as a potential drug carrier and targeting system for the treatment of inflammatory bowel disease. Rolipram was chosen as the model drug to be incorporated within nanoparticles. Pressure homogenization–emulsification (PHE) with a microfluidizer or a modified spontaneous emulsification solvent diffusion method (SESD) were used in order to

Alf Lamprecht; Nathalie Ubrich; Hiromitsu Yamamoto; Ulrich Schäfer; Hirofumi Takeuchi; Claus-Michael Lehr; Philippe Maincent; Yoshiaki Kawashima

2001-01-01

223

Lipid nanoparticles for transdermal delivery of flurbiprofen: formulation, in vitro, ex vivo and in vivo studies  

Microsoft Academic Search

The aim of the study is to prepare aqueous dispersions of lipid nanoparticles – flurbiprofen solid lipid nanoparticles (FLUSLN) and flurbiprofen nanostructured lipid carriers (FLUNLC) by hot homogenization followed by sonication technique and then incorporated into the freshly prepared hydrogels for transdermal delivery. They are characterized for particle size, for all the formulations, more than 50% of the particles were

Kesavan Bhaskar; Jayaraman Anbu; Velayutham Ravichandiran; Vobalaboina Venkateswarlu; Yamsani Madhusudan Rao

2009-01-01

224

Natural Rubber Blended with Polystyrene Nanoparticles Prepared by Differential Microemulsion Polymerization  

Microsoft Academic Search

Blends of natural rubber (NR) and polystyrene (PS) nanoparticles at 3—9 phr by latex compounding were investigated for their tensile properties, dynamic mechanical behaviors, and flammability. The nanolatex of PS was synthesized via differential microemulsion polymerization. The properties of NR were improved as a result of the incorporation of PS nanoparticles at 3 phr for tensile properties except the %

Saowaroj Chuayjuljit; Anyaporn Boonmahithisud

2010-01-01

225

Design of biodegradable nanoparticles: a novel approach to encapsulating poorly soluble phytochemical ellagic acid  

NASA Astrophysics Data System (ADS)

Nanosizing of poorly water soluble drugs or incorporating them into nanoparticles to increase their solubility and thereby the bioavailability has become a favoured approach today. This work describes a novel method for encapsulating poorly water soluble phytochemical ellagic acid that is also sparingly soluble/insoluble in routine solvents used to prepare nanoparticles.

Bala, I.; Bhardwaj, V.; Hariharan, S.; Sitterberg, J.; Bakowsky, U.; Kumar, M. N. V. Ravi

2005-12-01

226

YAG:Ce nanoparticle lightsources  

NASA Astrophysics Data System (ADS)

We investigate the luminescence properties of 10 nm yttrium aluminum garnet (YAG) nanoparticles doped with Ce ions at 0.2%, 4% and 13% that are designed as active probes for scanning near-field optical microscopy. They are produced by a physical method without any subsequent treatment, which is imposed by the desired application. The structural analysis reveals the amorphous nature of the particles, which we relate to some compositional defects as indicated by the elemental analysis. The optimum emission is obtained with a doping level of 4%. The emission of the YAG nanoparticles doped at 0.2% is strongly perturbed by the crystalline disorder whereas the 13% doped particles hardly exhibit any luminescence. In the latter case, the presence of Ce4+ ions is confirmed, indicating that the Ce concentration is too high to be incorporated efficiently in YAG nanoparticles in the trivalent state. By a unique procedure combining cathodoluminescence and Rutherford backscattering spectrometry, we demonstrate that the enhancement of the particle luminescence yield is not proportional to the doping concentration, the emission enhancement being larger than the Ce concentration increase. Time-resolved photoluminescence reveals the presence of quenching centres likely related to the crystalline disorder as well as the presence of two distinct Ce ion populations. Eventually, nano-cathodoluminescence indicates that the emission and therefore the distribution of the doping Ce ions and of the defects are homogeneous.

Masenelli, B.; Mollet, O.; Boisron, O.; Canut, B.; Ledoux, G.; Bluet, J.-M.; Mélinon, P.; Dujardin, Ch; Huant, S.

2013-04-01

227

Zirconia nanoparticles prepared by laser vaporization as fillers for dental adhesives  

Microsoft Academic Search

Zirconia nanoparticles prepared by laser vaporization were incorporated into the primer or into the adhesive of a commercial adhesive system in order to evaluate its effect on bond strength to dentin. Zirconia nanoparticles (20–50nm) were prepared using a particular laser vaporization technique and incorporated into the primer (P) or into the adhesive (A) of the Adper Scotchbond Multi-Purpose (SBMP) system

Ulrich Lohbauer; Andrea Wagner; Renan Belli; Christian Stoetzel; Andrea Hilpert; Heinz-Dieter Kurland; Janet Grabow; Frank A. Müller

2010-01-01

228

Fabrication and optical characteristics of a novel optical fiber doped with the Au nanoparticles.  

PubMed

Optical fibers containing gold metal nanoparticles were developed by modified chemical vapor deposition, in which Au(OH)3 and tetraethyl-orthosilicate (TEOS) was used via sol-gel process to incorporate gold metals by providing the reduction atmosphere. The absorption peak appeared near 490 nm was found to be due to the surface plasmon resonance of the gold nanoparticles incorporated in the fiber core. PMID:17252810

Ju, Seongmin; Nguyen, Viet Linh; Watekar, Pramod R; Kim, Bok Hyeon; Jeong, Chaehwan; Boo, Seongjae; Kim, Cheol Jin; Han, Won-Taek

2006-11-01

229

Efficacy of nanoparticles in achieving hemostasis  

NASA Astrophysics Data System (ADS)

Uncontrollable hemorrhage is significant cause of preventable death in the military and civilian setting. Hemostatic wound dressings have been created in an attempt to rectify this problem, but none currently on the market are highly effective at controlling hemorrhage resulting in a need for an effective hemostatic wound dressing. This study investigated the effects of gold, silver, and silica nanoparticles on blood coagulation time in order to determine if nanoparticle incorporation into a hemostatic wound dressing would effectively achieve hemostasis. Gold, silver, and silica nanoparticles were experimented with two different ex vivo studies to determine their effects on coagulation. A modified Lee White Method and a rotational viscometer were utilized to assess the nanoparticles ability to clot blood. Results obtained from the modified Lee White Method proved inconsistent and inconclusive demonstrating a need for improved testing methods. Results acquired from viscometer testing demonstrated that silica was effective in decreasing coagulation time indicating its potential use as a hemostatic agent and its prospective incorporation into a hemostatic wound dressing.

Schmitt, Carrie Catherine

230

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

231

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

232

Iron Nanoparticles in Reactive Environmental Barriers  

SciTech Connect

Zero-valent iron is cheap, environmentally innocuous, and effective at reducing chlorinated organics. It has, as a result, become a popular candidate for remediating aquifers contaminated with trichloroethylene and other halogenated pollutants. In this paper, we discuss one such system, where iron nanoparticles are synthesized and incorporated into polyvinyl alcohol membranes, forming water-permeable barriers to these pollutants. These barriers are tested against a variety of contaminants, including carbon tetrachloride, copper, and chromate.

Nuxoll, Eric E.; Shimotori, Tsutomu; Arnold, William A.; Cussler, Edward L.

2003-09-23

233

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.

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

2013-01-01

234

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

PubMed

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 (Fe(2)O(3), Co(2)O(3), 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

2013-01-15

235

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.

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

2009-01-01

236

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

237

Electrostatic assembly of binary nanoparticle superlattices using protein cages.  

PubMed

Binary nanoparticle superlattices are periodic nanostructures with lattice constants much shorter than the wavelength of light and could be used to prepare multifunctional metamaterials. Such superlattices are typically made from synthetic nanoparticles, and although biohybrid structures have been developed, incorporating biological building blocks into binary nanoparticle superlattices remains challenging. Protein-based nanocages provide a complex yet monodisperse and geometrically well-defined hollow cage that can be used to encapsulate different materials. Such protein cages have been used to program the self-assembly of encapsulated materials to form free-standing crystals and superlattices at interfaces or in solution. Here, we show that electrostatically patchy protein cages--cowpea chlorotic mottle virus and ferritin cages--can be used to direct the self-assembly of three-dimensional binary superlattices. The negatively charged cages can encapsulate RNA or superparamagnetic iron oxide nanoparticles, and the superlattices are formed through tunable electrostatic interactions with positively charged gold nanoparticles. Gold nanoparticles and viruses form an AB(8)(fcc) crystal structure that is not isostructural with any known atomic or molecular crystal structure and has previously been observed only with large colloidal polymer particles. Gold nanoparticles and empty or nanoparticle-loaded ferritin cages form an interpenetrating simple cubic AB structure (isostructural with CsCl). We also show that these magnetic assemblies provide contrast enhancement in magnetic resonance imaging. PMID:23241655

Kostiainen, Mauri A; Hiekkataipale, Panu; Laiho, Ari; Lemieux, Vincent; Seitsonen, Jani; Ruokolainen, Janne; Ceci, Pierpaolo

2013-01-01

238

Synthesis and applications of novel silver nanoparticle structures  

NASA Astrophysics Data System (ADS)

The field of nanotechnology is rapidly expanding across disciplines as each new development is realized. New exciting technologies are being driven by advances in the application of nanotechnology; including biochemical, optical, and semiconductors research. This thesis will focus on the use of silver nanoparticles as optical labels on cells, methods of forming different small structures of silver nanoparticles, as well as the use of silver nanoparticles in the development of a photovoltaic cell. Silver nanoparticles have been modified with self-assembled monolayers of hydroxyl-terminated long chain thiols and encapsulated with a silica shell. The resulting core-shell nanoparticles were used as optical labels for cell analysis using flow cytometry and microscopy. The excitation of plasmon resonances in nanoparticles results in strong depolarized scattering of visible light permitting detection at the single nanoparticle level. The nanoparticles were modified with neutravidin via epoxide-azide coupling chemistry and biotinylated antibodies targeting cell surface receptors were bound to the nanoparticle surface. The nanoparticle labels exhibited long-term stability under physiological conditions without aggregation or silver ion leaching. Labeled cells exhibited two orders of magnitude enhancement of the scattering intensity compared to unlabeled cells. Dimers of silver nanoparticles have been fabricated by first immobilizing a monolayer of single silver nanoparticles onto poly(4-vinylpyridine) covered glass slides. The monolayer was then exposed to adenine, which has two amines which will bind to silver. The nanoparticle monolayer, now modified with adenine, is exposed to a second suspension of nanoparticles which will bind with the amine modified monolayer. Finally, a thin silica shell is formed about the structure via solgel chemistry to prevent dissolution or aggregation upon sonication/striping. Circular arrays of silver nanoparticels are developed using a template base self assembly. A 1.5 micron silica sphere is bound to poly(4-vinylpyridine) coated glass and used as a template. a mask of silica monoxide is vacuum deposited atop the spheres/glass leaving a ring just below the sphere untouched and able to bind silver nanoparticles. Optical microscopy reveal interesting results under depolarized light conditions, but ultimate structural analysis has proven elusive. Semiconducting p-type cuprous oxide was electrochemically deposited on both silver and indium tin oxide electrodes. Silver nanoparticles were incorporated into the architecture either atop the cuprous oxide or sandwiched between cuprous oxide and n-type material. Increases in photocurrent were observed in both cases and further work must be conducted to optimize a solid state device for photovoltaic applications.

Dukes, Kyle

239

Biosynthesis of silver nanoparticles.  

PubMed

Metal nanoparticles have unique optical, electronic, and catalytic properties. There exist well-defined physical and chemical processes for their preparation. Those processes often yield small quantities of nanoparticles having undesired morphology, and involve high temperatures for the reaction and the use of hazardous chemicals. Relatively, the older technique of bioremediation of metals uses either microorganisms or their components for the production of nanoparticles. The nanoparticles obtained from bacteria, fungi, algae, plants and their components, etc. appear environment-friendly, as toxic chemicals are not used in the processes. In addition to this, the formation of nanoparticles takes place at almost normal temperature and pressure. Control of the shape and size of the nanoparticles is possible by appropriate selection of the pH and temperature. Three important steps are the bioconversion of Ag+ ions, conversion of desired crystals to nanoparticles, and nanoparticle stability. Generally, nanoparticles are characterized by the UV-visible spectroscopy and use of the electron microscope. Silver nanoparticles are used as antimicrobial agents and they possess antifungal, anti-inflammatory, and anti-angiogenic properties. This review highlights the biosynthesis of silver nanoparticles by various organisms, possible mechanisms of their synthesis, their characterization, and applications of silver nanoparticles. PMID:24749472

Poulose, Subin; Panda, Tapobrata; Nair, Praseetha P; Théodore, Thomas

2014-02-01

240

CCMR: Bimetallic Nanoparticle Catalysis  

NSDL National Science Digital Library

Bimetallic nanoparticles are of great interest in scientific research due to their large surface to volume ratios and surface restructuring that may occur during catalysis. Our goals were to synthesize different bimetallic nanoparticles and test their catalytic abilities for use in future experiments. The nanoparticles we concentrated on were Au/Ag alloy, Au/Cu alloy, and Au/Pd core-shell.

Chong, Hahn

2010-08-15

241

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

242

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

243

Core-Shell Composite Nanoparticles: Synthesis, Characterization, and Applications  

NASA Astrophysics Data System (ADS)

Nanoparticles are ubiquitous in various fields due to their unique properties not seen in similar bulk materials. Among them, core-shell composite nanoparticles are an important class of materials which are attractive for their applications in catalysis, sensing, electromagnetic shielding, drug delivery, and environmental remediation. This dissertation focuses on the study of core-shell type of nanoparticles where a polymer serves as the core and inorganic nanoparticles are the shell. This is an interesting class of supramolecular building blocks and can "exhibit unusual, possibly unique, properties which cannot be obtained simply by co-mixing polymer and inorganic particles". The one-step Pickering emulsion polymerization method was successfully developed and applied to synthesize polystyrene-silica core-shell composite particles. Possible mechanisms of the Pickering emulsion polymerization were also explored. The silica nanoparticles were thermodynamically favorable to self-assemble at liquid-liquid interfaces at the initial stage of polymerization and remained at the interface to finally form the shells of the composite particles. More importantly, Pickering emulsion polymerization was employed to synthesize polystyrene/poly(N-isopropylacrylamide) (PNIPAAm)-silica core-shell nanoparticles with N-isopropylacrylamide incorporated into the core as a co-monomer. The composite nanoparticles were temperature sensitive and could be up-taken by human prostate cancer cells and demonstrated effectiveness in drug delivery and cancer therapy. Similarly, by incorporating poly-2-(N,N)-dimethylamino)ethyl methacrylate (PDMA) into the core, pH sensitive core-shell composite nanoparticles were synthesized and applied as effective carriers to release a rheological modifier upon a pH change. Finally, the research focuses on facile approaches to engineer the transition of the temperature-sensitive particles and develop composite core-shell nanoparticles with a metallic shell.

Sanyal, Sriya

244

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

245

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.

Hansen, Steffi; Lehr, Claus-Michael

2012-01-01

246

Enhanced efficiency of solution-processed small-molecule solar cells upon incorporation of gold nanospheres and nanorods into organic layers.  

PubMed

The significantly enhanced performance upon incorporation of Au nanoparticles in solution-processed small-molecule solar cells is demonstrated. Simultaneously incorporating Au nanospheres into the hole transport layer and Au-silica nanorods into the active layer results in superior broadband absorption improvement in the device with a power conversion efficiency of 8.72% with 31% enhancement. PMID:24652441

Xu, Xiaoyan; Kyaw, Aung Ko Ko; Peng, Bo; Du, Qingguo; Hong, Lei; Demir, Hilmi Volkan; Wong, Terence K S; Xiong, Qihua; Sun, Xiao Wei

2014-05-01

247

Electrostatic method for the production of polymer nanofibers blended with metal-oxide nanoparticles  

NASA Astrophysics Data System (ADS)

The paper presents investigations of a method of the production of non-woven polymer fabrics with incorporated metal oxide nanoparticles based on electrospinning and electrospraying. Two main configurations of electrospraying/electrospinning systems have been tested: two-step process of electrospinning of polymer solution followed by electrospraying of nanoparticle suspension, and simultaneous electrospinning of polymer solution and electrospraying of nanoparticle suspension. By this method TiO2, MgO, or Al2O3 nanoparticles of the size from 20 to 100 nm were deposited onto electrospun PVC nanofibers.

Jaworek, A.; Krupa, A.; Lackowski, M.; Sobczyk, A. T.; Czech, T.; Ramakrishna, S.; Sundarrajan, S.; Pliszka, D.

2009-01-01

248

CTAB capped silver nanoparticles for plasmonic dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

To improve the light harvesting efficiency of Dye-sensitized solar cell (DSSC), we have explored the surface plasmon property of metal nanoparticles in this paper. Cetyl trimethylammonium bromide (CTAB) capped silver nanoparticles have been synthesized by wet chemical method and studied for spectroscopic and structural investigations. FTIR confirms the capping of CTAB on silver nanoparticles occurs via their head group. Williamson Hall plot revealed the presence of tensile strain. Finally, these particles have been incorporated in DSSC to study the plasmonic effect of nanoparticles on performance of DSSC.

Tanvi, Mahajan, Aman; Bedi, R. K.; Kumar, Subodh

2014-04-01

249

Synthesis, characterization and UV-shielding property of polystyrene-embedded CeO2 nanoparticles  

NASA Astrophysics Data System (ADS)

A cerium-triethanolamine (TEA) complex was prepared and used as the precursor to synthesize CeO2 nanoparticles. It was mixed with styrene (St) in aqueous solution and hydrolysized to generate CeO2 nanoparticles. In situ emulsion polymerization of the monomer was followed in one pot. The CeO2 nanoparticles were incorporated into polystyrene (PS) matrix and dispersed homogeneously, with an average crystallite size of 3-5 nm and a band gap at 3.01 eV. Meanwhile, the embedding of the CeO2 nanoparticles can enhance UV-shielding property of PS.

Liu, Kang-Qiang; Kuang, Cheng-Xiu; Zhong, Ming-Qiang; Shi, Yan-Qin; Chen, Feng

2013-10-01

250

Novel hybrid organic-inorganic monolithic column containing mesoporous nanoparticles for capillary electrochromatography.  

PubMed

The rod-shaped SBA-15-C(18) mesoporous nanoparticles were incorporated into hybrid organic-inorganic monolithic column with aminopropyl moiety to develop novel stationary phases with mixing mechanism of reverse phase and ion exchange. Experimental conditions including dispersion pattern, nanoparticles percentage were optimized for simple and stable column preparation. The monolithic columns were evaluated with mixture of organic acids in capillary electrochromatography (CEC) mode and the column efficiency reaches 280, 000 plates/m. The results indicate that the column containing nanoparticles enhances both selectivity and column efficiency due to high specific surface area of nanoparticles and mixing separation mechanism. PMID:22939160

Wan, Li; Zhang, Lingyi; Lei, Wen; Zhu, Yaxian; Zhang, Weibing; Wang, Yanqin

2012-08-30

251

Nitrogen incorporation into WTi films  

Microsoft Academic Search

The nitrogen incorporation into WTi films for diffusion barrier applications in microelectronics was investigated. Reactive\\u000a sputtering and ion implatation were used to obtain nitrogen containing films. XPS depth profiling and peak deconvolution yielded\\u000a chemical composition and information on the reactions involving N. No reaction between W and N was observed, whereas Ti and\\u000a N did react. The ratio of Ti

J. Burschik; B. Adolphi

1999-01-01

252

Tailored Composite Polymer-Metal Nanoparticles by Miniemulsion Polymerization and Thiol-ene Functionalization  

PubMed Central

A simple and modular synthetic approach, based on miniemulsion polymerization, has been developed for the fabrication of composite polymer-metal nanoparticle materials. The procedure produces well-defined composite structures consisting of gold, silver or MnFe2O4 nanoparticles (?10 nm in diameter) encapsulated within larger spherical nanoparticles of poly(divinylbenzene) (?100 nm in diameter). This methodology readily permits the incorporation of multiple metal domains into a single polymeric particle, while still preserving the useful optical and magnetic properties of the metal nanoparticles. The morphology of the composite particles is retained upon increasing the inorganic content, and also upon redispersion in organic solvents. Finally, the ability to tailor the surface chemistry of the composite nanoparticles and incorporate steric stabilizing groups using simple thiol-ene chemistry is demonstrated.

van Berkel, Kim Y.

2010-01-01

253

In Vivo Sustained Release of siRNA from Solid Lipid Nanoparticles  

PubMed Central

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 weight percent 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.

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

2011-01-01

254

De-alloyed platinum nanoparticles  

DOEpatents

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

255

Effect of Nanoparticle Size on Nanoparticle Spatial Distribution in a Diblock Copolymer Supramolecular Thin Film  

NASA Astrophysics Data System (ADS)

The self-assembly of nanoparticles (NPs) opens many pathways towards generation of functional nanostructured materials with desirable optical, mechanical and electrical properties. A great challenge in this field is the effective control of NP spatial distribution within the block copolymer matrix, which is crucial in tailoring the macroscopic properties of the polymer/nanoparticle composites. We systematically investigated the effect of NP size on the spatial distribution of nanoparticles upon blending with a diblock copolymer based supramolecule in thin film. The spatial distribution of NPs in thin film was observed to be strongly dependent on NP size. These observations can be explained by the increase in entropic penalty of incorporating larger NPs associated with the deformation of the BCP block to accommodate the NPs. This effect is observed for NPs with different chemistries and could serve as a promising route to creating multifunctional thin film nanocomposites.

Bai, Peter; Kao, Joseph; Lucas, Matthew; Alivisatos, Paul; Xu, Ting

2012-02-01

256

Peptide-Directed Self-Assembly of Functionalized Polymeric Nanoparticles Part I: Design and Self-Assembly of Peptide-Copolymer Conjugates into Nanoparticle Fibers and 3D Scaffolds.  

PubMed

A robust self-assembly of nanoparticles into fibers and 3D scaffolds is designed and fabricated by functionalizing a RAFT-polymerized amphiphilic triblock copolymer with designer ionic complementary peptides so that the assembled core-shell polymeric nanoparticles are directed by peptide assembly into continuous "nanoparticle fibers," ultimately leading to 3D fiber scaffolds. The assembled nanostructure is confirmed by FESEM and optical microscopy. The assembly is not hindered when a protein (insulin) is incorporated within the nanoparticles as an active ingredient. MTS cytotoxicity tests on SW-620 cell lines show that the peptides, copolymers, and peptide-copolymer conjugates are biocompatible. The methodology of self-assembled nanoparticle fibers and 3D scaffolds is intended to combine the advantages of a flexible hydrogel scaffold with the versatility of controlled release nanoparticles to offer unprecedented ability to incorporate desired drug(s) within a self-assembled scaffold system with individual control over the release of each drug. PMID:24610743

Ding, Xiaochu; Janjanam, Jagadeesh; Tiwari, Ashutosh; Thompson, Martin; Heiden, Patricia A

2014-06-01

257

Nanoparticle Surface Functionalization for Improved Dispersion in Network Composites  

NASA Astrophysics Data System (ADS)

Incorporation of inorganic nanoparticles into crosslinked networks has resulted in greater toughening behavior with lower filler content compared to traditional composites. The characteristics that provide these desirable qualities are also responsible for their poor dispersion and, consequently, limiting wide commercial use. This work aims to demonstrate how excellent dispersion can be obtained easily and efficiently in different networks through nanoparticle surface modification. Both epoxy/Jeffamine and thiol-ene based networks were examined with differing molecular weight and chemical functionality tethers. The aggregation behavior of nanocomposite samples were monitored optically and using TEM. Thermomechanical properties were studied using DSC, DMA and MTS. The Tg was dependent on both nanoparticle incorporation and functionality. Toughening was observed in some, but not all, cases.

Richardson, Adam; McNair, Olivia; Strange, Gregory; Early, Mark; Savin, Daniel

2011-03-01

258

Terminal supraparticle assemblies from similarly charged protein molecules and nanoparticles.  

PubMed

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. PMID:24845400

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

2014-01-01

259

Reversible photoswitching of dye-doped core-shell nanoparticles.  

PubMed

We present a simple and versatile mechanism for the reversible photoswitching of dye-doped core-shell nanoparticles. Photochromic dithienylethenes are incorporated into the outer shell, close enough to the dyes entrapped in the core to efficiently quench them by energy transfer when photoconverted with UV light. The emission can be switched back on by irradiation with ? > 450 nm. PMID:21909549

Genovese, Damiano; Montalti, Marco; Prodi, Luca; Rampazzo, Enrico; Zaccheroni, Nelsi; Tosic, Oliver; Altenhöner, Kai; May, Florian; Mattay, Jochen

2011-10-21

260

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°C 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

261

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

262

Targeted nanoparticle enhanced proapoptotic peptide as potential therapy for glioblastoma  

PubMed Central

Antiangiogenic therapy can produce transient tumor regression in glioblastoma (GBM), but no prolongation in patient survival has been achieved. We have constructed a nanosystem targeted to tumor vasculature that incorporates three elements: (i) a tumor-homing peptide that specifically delivers its payload to the mitochondria of tumor endothelial cells and tumor cells, (ii) conjugation of this homing peptide with a proapoptotic peptide that acts on mitochondria, and (iii) multivalent presentation on iron oxide nanoparticles, which enhances the proapoptotic activity. The iron oxide component of the nanoparticles enabled imaging of GBM tumors in mice. Systemic treatment of GBM-bearing mice with the nanoparticles eradicated most tumors in one GBM mouse model and significantly delayed tumor development in another. Coinjecting the nanoparticles with a tumor-penetrating peptide further enhanced the therapeutic effect. Both models used have proven completely resistant to other therapies, suggesting clinical potential of our nanosystem.

Agemy, Lilach; Friedmann-Morvinski, Dinorah; Kotamraju, Venkata Ramana; Roth, Lise; Sugahara, Kazuki N.; Girard, Olivier M.; Mattrey, Robert F.; Verma, Inder M.; Ruoslahti, Erkki

2011-01-01

263

Spiropyran-based Photochromic Polymer Nanoparticles with Optically Switchable Luminescence  

PubMed Central

Emulsion polymerization yields 40–400 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.

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

2008-01-01

264

Modulating nanoparticle film assembly using amphiphiles  

NASA Astrophysics Data System (ADS)

Nanocomposite thin films comprised of nanoparticles have shown great promise for use in electronics, photonics, biomedical as well as energy storage and conversion devices. One versatile method for fabricating such thin films is layer-by-layer (LbL) assembly, a process that involves sequential deposition of oppositely charged species to create conformal thin films. The advantage of LbL assembly lies in the fact that the properties and structure of films can be tuned by varying assembly conditions such as pH and ionic strength. Furthermore, a variety of nanomaterials with useful properties can be incorporated within LbL assembled thin films. Despite these advantages, there are a few limitations to using LbL assembly to fabricate nanoparticle films: (1) Favorable film growth of all-nanoparticle LbL assembly in aqueous phase occurs within a narrow processing window thus limiting the versatility of LbL assembly. (2) nanoparticle LbL assembly has generally been limited to aqueous phase due to the ease of charging nanomaterials in water. (3) The fabrication of nanoparticle films via LbL assembly is slow and typically takes several hours to complete. In this thesis, amphiphiles will be used to address these three limitations of nanoparticle LbL assembly. The first limitation is addressed by using a small amphiphilic molecule, hexylamine to broaden the narrow nanoparticle LbL assembly window. In addition, an array of experimental techniques is used to reveal the mechanism leading to a broad processing window. It will be demonstrated that the second limitation of nanoparticle LbL assembly to aqueous phase can be overcome by using a surfactant Aerosol-OT (AOT) to charge stabilize particles in toluene for non-polar LbL assembly. Furthermore, the effect of the surface chemistry of particles and dispersion moisture content on the charge of particles in non-polar media is probed along with the role of relative humidity on the LbL assembly process in non-polar media. Lastly, electrophoretic deposition (EPD) of surfactant-charged particles in a non-polar solvent is used to rapidly assemble nanocomposite films, thus overcoming the third limitation of nanoparticle LbL assembly.

Tettey, Kwadwo E.

265

Preparation, characterisation and application of europium(III) chelate-dyed polystyrene–acrylic acid nanoparticle labels  

Microsoft Academic Search

Preparation, characterisation and application of europium(III) chelate-incorporated polystyrene–acrylic acid (AAc) nanoparticle labels featuring diverse AAc proportions is described. Emulsion copolymerisation of styrene and AAc was used to synthesise uniform-sized nanoparticles, approximately 50nm in diameter. The structural, fluorescence and functional properties of the nanoparticles were characterised to obtain the optimal polymer composition of particulate labels. The AAc content had only a

Petri Huhtinen; Mirja Kivelä; Tero Soukka; Heikki Tenhu; Timo Lövgren; Harri Härmä

2008-01-01

266

Functionalized Fe?O?@Au superparamagnetic nanoparticles: in vitro bioactivity.  

PubMed

The interaction of nanoparticles with cells has been a focus of interest during the past decade. We report the fabrication and characterization of hydrosoluble Fe?O?@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 Fe?O?@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. PMID:22802157

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

2012-08-10

267

Hydrophobically modified glycol chitosan nanoparticles as carriers for paclitaxel.  

PubMed

Self-assembled nanoparticles based on hydrophobically modified glycol chitosan (HGC) were prepared as a carrier for paclitaxel. HGC conjugates were prepared by chemically linking 5beta-cholanic acid to glycol chitosan chains using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide chemistry. In phosphate-buffered saline (PBS; pH 7.4), the synthesized HGC conjugates formed nano-sized particles with a diameter of 200 nm and exhibited high thermodynamic stability as reflected by their low critical aggregation concentration (0.03 mg/ml). Paclitaxel was efficiently loaded into HGC nanoparticles up to 10 wt.% using a dialysis method. The paclitaxel-loaded HGC (PTX-HGC) nanoparticles were 400 nm in diameter and were stable in PBS for 10 days. These PTX-HGC nanoparticles also showed sustained release of the incorporated of paclitaxel (80% of the loaded dose was released in 8 days at 37 degrees C in PBS). Owing to sustained release, the PTX-HGC nanoparticles were less cytotoxic to B16F10 melanoma cells than free paclitaxel formulated in Cremophor EL. Injection of PTX-HGC nanoparticles into the tail vein of tumor-bearing mice prevented increases in tumor volume for 8 days. Finally, PTX was less toxic to the tumor-bearing mice when formulated in HGC nanoparticles than when formulated with Cremophor EL. PMID:16458988

Kim, Jong-Ho; Kim, Yoo-Shin; Kim, Sungwon; Park, Jae Hyung; Kim, Kwangmeyung; Choi, Kuiwon; Chung, Hesson; Jeong, Seo Young; Park, Rang-Woon; Kim, In-San; Kwon, Ick Chan

2006-03-10

268

Nanoparticle-modified monolithic pipette tips for phosphopeptide enrichment.  

PubMed

We have developed nanoparticle-modified monoliths in pipette tips for selective and efficient enrichment of phosphopeptides. The 5 ?L monolithic beds were prepared by UV-initiated polymerization in 200 ?L polypropylene pipette tips and either iron oxide or hydroxyapatite nanoparticles were used for monolith modification. Iron oxide nanoparticles were prepared by a co-precipitation method and stabilized by citrate ions. A stable coating of iron oxide nanoparticles on the pore surface of the monolith was obtained via multivalent electrostatic interactions of citrate ions on the surface of nanoparticles with a quaternary amine functionalized poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) monolith. Hydroxyapatite nanoparticles were incorporated into the poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) monolith by simply admixing them in the polymerization mixture followed by in situ polymerization. The nanoparticle-modified monoliths were compared with commercially available titanium dioxide pipette tips. Performance of the developed and commercially available sorbents was demonstrated with the efficient and selective enrichment of phosphopeptides from peptide mixtures of ?-casein and ?-casein digests followed by off-line MALDI/MS analysis. PMID:22926133

Krenkova, Jana; Foret, Frantisek

2013-03-01

269

Colloidal Polymers via Dipolar Assembly of Magnetic Nanoparticle Monomers.  

PubMed

In this Spotlight on Applications, we describe our recent progress in the preparation of hierarchical one-dimensional (1-D) materials constructed from polymer-coated ferromagnetic cobalt nanoparticles. We begin with a general discussion of nanoparticles capable of 1-D self-organization to form 1-D assemblies, which we term colloidal polymers. The need for efficient, highly directional interactions prompted our investigation with polymer-coated ferromagnetic nanoparticles, which spontaneously form linear assemblies through coupling of north and south magnetic poles present in these single-domain ferromagnetic nanoparticles. These highly directional N-S interactions and the resulting formation of 1-D assemblies can be understood in the context of traditional polymer-forming reactions. The dipolar assembly of these ferromagnetic nanoparticles into chains and binary assemblies while dispersed in organic media has been investigated as a key foundation to form novel magnetic materials and heterostructured nanocomposites. These studies enabled the fabrication of magnetic nanoactuating systems resembling "artificial cilia and flagella". We then discuss our recent efforts to prepare cobalt oxide nanowires using various nanoparticle conversion reactions through a process termed colloidal polymerization. A series of novel functional "colloidal monomers" based on dipolar cobalt nanoparticles were also prepared, incorporating noble metal or semiconductor nanoinclusions to form heterostructured cobalt oxide nanocomposites. PMID:24467583

Hill, Lawrence J; Pyun, Jeffrey

2014-05-14

270

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.

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

2013-01-01

271

Inflammatory and genotoxic effects of sanding dust generated from nanoparticle-containing paints and lacquers.  

PubMed

Nanoparticles are increasingly used in paints and lacquers. Little is known of the toxicity of nanoparticles incorporated in complex matrices and released during different phases of the life cycle. DNA damaging activity and inflammogenicity of sanding dust sampled during standardised sanding of boards painted with paints with and without nanoparticles were determined 24 h after intratracheal instillation of a single dose of 54 ?g in mice. Dusts from nanoparticle-containing paints and lacquers did not generate pulmonary inflammation or oxidative stress. Sanding dust from both the nanoparticle-containing and the conventional lacquer and the outdoor acrylic-based reference paint increased the level of DNA strand breaks in bronchoalveolar fluid cells. In conclusion, addition of nanoparticles to paint or lacquers did not increase the potential of sanding dust for causing inflammation, oxidative stress or DNA damage, suggesting that the paint/lacquer matrix is more important as determinant of DNA damage than the nanomaterial. PMID:21995293

Saber, Anne Thoustrup; Koponen, Ismo Kalevi; Jensen, Keld Alstrup; Jacobsen, Nicklas Raun; Mikkelsen, Lone; Møller, Peter; Loft, Steffen; Vogel, Ulla; Wallin, Håkan

2012-11-01

272

Thermosensitive Gold Nanoparticles  

SciTech Connect

Nanotechnology has experienced a rapid growth recently because nanoparticles exhibit physical and chemical properties that are quite different from those of the bulk solid. Typically, an organic layer comprised of a surfactant or a polymer is anchored at the interface to both localize the nanoparticle and stabilize its properties. Of particular interest is the conjugation of gold nanoparticles with functional macromolecules such as saccharide and oligo deoxyribonucleic acid (DNA). The combination of organic functionality coupled with the dielectric properties of gold nanoparticles has resulted in a new material that provides for sensitive colorimetric detection of polynucleotides. We report here the introduction of thermosensitive polymers onto Au nanoparticles so that the polymer-bound gold nanoparticles now become responsive to temperature.

Zhu, Ming-Qiang; Wang, Li Q.; Exarhos, Gregory J.; Li, Alexander D.

2004-03-10

273

Silica nanoparticles for micro-particle imaging velocimetry: fluorosurfactant improves nanoparticle stability and brightness of immobilized iridium(III) complexes.  

PubMed

To establish highly luminescent nanoparticles for monitoring fluid flows, we examined the preparation of silica nanoparticles based on immobilization of a cyclometalated iridium(III) complex and an examination of the photophysical studies provided a good insight into the Ir(III) microenvironment in order to reveal the most suitable silica nanoparticles for micro particle imaging velocimetry (?-PIV) studies. Iridium complexes covalently incorporated at the surface of preformed silica nanoparticles, [Ir-4]@Si500-Z, using a fluorinated polymer during their preparation, demonstrated better stability than those without the polymer, [Ir-4]@Si500, as well as an increase in steady state photoluminescence intensity (and therefore particle brightness) and lifetimes which are increased by 7-fold compared with nanoparticles with the same metal complex attached covalently throughout their core, [Ir-4]?Si500. Screening of the nanoparticles in fluid flows using epi-luminescence microscopy also confirm that the brightest, and therefore most suitable particles for microparticle imaging velocimetry (?-PIV) measurements are those with the Ir(III) complex immobilized at the surface with fluorosurfactant, that is [Ir-4]@Si500-Z. ?-PIV studies demonstrate the suitability of these nanoparticles as nanotracers in microchannels. PMID:24164285

Lewis, David J; Dore, Valentina; Rogers, Nicola J; Mole, Thomas K; Nash, Gerard B; Angeli, Panagiota; Pikramenou, Zoe

2013-11-26

274

Magnetic Nanoparticles and Biosciences  

Microsoft Academic Search

Summary.  ?Magnetic nanoparticles represent an interesting material both present in various living organisms and usable for a variety\\u000a of bioapplications. This review paper will summarize the information about biogenic magnetic nanoparticles, the ways to synthesize\\u000a biocompatible magnetic nano- particles and complexes containing them, and the applications of magnetic nanoparticles in various\\u000a areas of biosciences and biotechnologies.

Ivo Šafa?ík

2002-01-01

275

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. For further resources related to this article, please visit the WIREs website. Conflict of interest: The authors declare no competing financial interest. PMID:24616442

Srikar, R; Upendran, Anandhi; Kannan, Raghuraman

2014-05-01

276

Comb Polymer Architectures for Versatile Nanoparticle Assembly  

NASA Astrophysics Data System (ADS)

Nanoparticles are a material of interest in photovoltaic research due to their optical absorption properties. However, there have been many challenges for device fabrication. It has been difficult to produce continuous, homogenous films, and successes in this area have been highly dependent on the actual nanoparticles used, and have thus been hard to apply generally to different materials of interest. We show how this challenge can be overcome using a comb polymer architecture. Here, pentadecyl phenol small molecules are hydrogen bonded to polyvinyl pyridine. This alkyl moiety produced is compatible with the ligand shells of many nanomaterials. We incorporated these small molecules and nanoparticles into polystrene-polyvinyl pyridine block copolymers. This strategy was successful for assembling nanoparticles made out of a variety of materials, without special considerations for the actual core material or morphology. Following these successes in bulk samples we extended our studies to thin films of these composites. Here, the morphology is controlled by the interfacial interactions. These materials have the potential to be used for photovoltaic devices, as they are easily solution-processible. This strategy is generally applicable with the choice of small molecule mediating interactions with any desired nanomaterial.

Mastroianni, Alexander; Thorkelsson, Kari; Zhao, Yue; Luther, Joseph; Millstone, Jill; Alivisatos, Paul; Frechet, Jean; Xu, Ting

2009-03-01

277

Aptamer conjugated magnetic nanoparticles as nanosurgeons  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have shown promise in the fields of targeted drug delivery, hyperthermia and magnetic resonance imaging (MRI) in cancer therapy. The ability of magnetic nanoparticles to undergo surface modification and the effect of external magnetic field in the dynamics of their movement make them an excellent nanoplatform for cancer destruction. Surgical removal of cancerous or unwanted cells selectively from the interior of an organ or tissue without any collateral damage is a serious problem due to the highly infiltrative nature of cancer. To address this problem in surgery, we have developed a nanosurgeon for the selective removal of target cells using aptamer conjugated magnetic nanoparticles controlled by an externally applied three-dimensional rotational magnetic field. With the help of the nanosurgeon, we were able to perform surgical actions on target cells in in vitro studies. LDH and intracellular calcium release assay confirmed the death of cancer cells due to the action of the nanosurgeon which in turn nullifies the possibility of proliferation by the removed cells. The nanosurgeon will be a useful tool in the medical field for selective surgery and cell manipulation studies. Additionally, this system could be upgraded for the selective removal of complex cancers from diverse tissues by incorporating various target specific ligands on magnetic nanoparticles.

Nair, Baiju G.; Nagaoka, Yutaka; Morimoto, Hisao; Yoshida, Yasuhiko; Maekawa, Toru; Sakthi Kumar, D.

2010-11-01

278

Nanoparticle based boolean logic  

NASA Astrophysics Data System (ADS)

Arrays of passivated gold nanoparticles have been shown to exhibit single electron transport behavior at room temperature. The ratio of the self-capacitance to the interparticle capacitance is very different to that reported for single electron devices fabricated using traditional methods. This ratio suggests that novel device behavior may be possible in organized arrays of nanoparticles. We report on simulations of single electron logic circuits designed using parameters expected for circuits made using passivated gold nanoparticles. We will show AND- and NAND-gate behavior from an electron-pump gated one-dimensional array of nanoparticles.

Berven, C. A.; Wybourne, M. N.; Longstreth, L.; Hutchison, J. E.

2003-07-01

279

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.

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

2011-01-01

280

Radiolabelling of engineered nanoparticles for in vitro and in vivo tracing applications using cyclotron accelerators.  

PubMed

We present in this article an outline of some cyclotron-based irradiation techniques that can be used to directly radiolabel industrially manufactured nanoparticles, as well as two techniques for synthesis of labelled nanoparticles using cyclotron-generated radioactive precursor materials. These radiolabelled nanoparticles are suitable for a range of different in vitro and in vivo tracing studies of relevance to the field of nanotoxicology. A basic overview is given of the relevant physics of nuclear reactions regarding both ion-beam and neutron production of radioisotopes. The various issues that determine the practicality and usefulness of the different methods are discussed, including radioisotope yield, nuclear reaction kinetics, radiation and thermal damage, and radiolabel stability. Experimental details are presented regarding several techniques applied in our laboratories, including direct light-ion activation of dry nanoparticle samples, neutron activation of nanoparticles and suspensions using an ion-beam driven activator, spark-ignition generation of nanoparticle aerosols using activated electrode materials, and radiochemical synthesis of nanoparticles using cyclotron-produced isotopes. The application of these techniques is illustrated through short descriptions of some selected results thus far achieved. It is shown that these cyclotron-based methods offer a very useful range of options for nanoparticle radiolabelling despite some experimental difficulties associated with their application. For direct nanoparticle radiolabelling, if care is taken in choosing the experimental conditions applied, useful activity levels can be achieved in a wide range of nanoparticle types, without causing substantial thermal or radiation damage to the nanoparticle structure. Nanoparticle synthesis using radioactive precursors presents a different set of issues and offers a complementary and equally valid approach when laboratory generation of the nanoparticles is acceptable for the proposed studies, and where an appropriate radiolabel can be incorporated into the nanoparticles during synthesis. PMID:21479952

Gibson, N; Holzwarth, U; Abbas, K; Simonelli, F; Kozempel, J; Cydzik, I; Cotogno, G; Bulgheroni, A; Gilliland, D; Ponti, J; Franchini, F; Marmorato, P; Stamm, H; Kreyling, W; Wenk, A; Semmler-Behnke, M; Buono, S; Maciocco, L; Burgio, N

2011-07-01

281

Influence of ferrite nanoparticle type and content on the crystallization kinetics and electroactive phase nucleation of poly(vinylidene fluoride).  

PubMed

This work reports on the nucleation of the ?-phase of poly(vinylidene fluoride) (PVDF) by incorporating CoFe(2)O(4) and NiFe(2)O(4) nanoparticles, leading in this way to the preparation of magnetoelectric composites. The fraction of filler nanoparticles needed to produce the same ?- to ?-phase ratio in crystallized PVDF is 1 order of magnitude lower in the cobalt ferrite nanoparticles. The interaction between nanoparticles and PVDF chains induce the all-trans conformation in PVDF segments, and this structure then propagates in crystal growth. The nucleation kinetics is enhanced by the presence of nanoparticles, as corroborated by the increasing number of spherulites with increasing nanoparticle content and by the variations of the Avrami's exponent. Further, the decrease of the crystalline fraction of PVDF with increasing nanoparticle content indicates that an important fraction of polymer chains are confined in interphases with the filler particle. PMID:21545124

Sencadas, Vitor; Martins, Pedro; Pitães, Alexandre; Benelmekki, Maria; Gómez Ribelles, José Luis; Lanceros-Mendez, Senentxu

2011-06-01

282

Dilation and degradation of the brain extracellular matrix enhances penetration of infused polymer nanoparticles  

PubMed Central

This study investigates methods of manipulating the brain extracellular matrix (ECM) to enhance the penetration of nanoparticle drug carriers in convection-enhanced delivery (CED). A probe was fabricated with two independent microfluidic channels to infuse, either simultaneously or sequentially, nanoparticles and ECM-modifying agents. Infusions were performed in the striatum of the normal rat brain. Monodisperse polystyrene particles with a diameter of 54 nm were used as a model nanoparticle system. Because the size of these particles is comparable to the effective pore size of the ECM, their transport may be significantly hindered compared with the transport of low molecular weight molecules. To enhance the transport of the infused nanoparticles, we attempted to increase the effective pore size of the ECM by two methods: dilating the extracellular space and degrading selected constituents of the ECM. Two methods of dilating the extracellular space were investigated: co-infusion of nanoparticles and a hyperosmolar solution of mannitol, and pre-infusion of an isotonic buffer solution followed by infusion of nanoparticles. These treatments resulted in an increase in the nanoparticle distribution volume of 50% and 123%, respectively. To degrade hyaluronan, a primary structural component of the brain ECM, a pre-infusion of hyaluronidase (20,000 U/mL) was followed after 30 min by infusion of nanoparticles. This treatment resulted in an increase in the nanoparticle distribution of 64%. Our results suggest that both dilation and enzymatic digestion can be incorporated into CED protocols to enhance nanoparticle penetration.

Neeves, Keith B.; Sawyer, Andrew J.; Foley, Conor P.; Saltzman, W. Mark; Olbricht, William L.

2007-01-01

283

Malonamide-functionalized gold nanoparticles for selective, colorimetric sensing of trivalent lanthanide ions.  

PubMed

A selective and sensitive molecular sensor for trivalent lanthanide (Ln(3+)) ions based upon a malonamide-functionalized gold nanoparticle was developed for colorimetric detection in water. A new synthetic approach permits nanoparticle synthesis, stabilization, and incorporation of a selective lanthanide binding site in a single, direct step. The design incorporates a specifically tailored dual function precursor ligand that bears a sodium thiosulfate (Bunte salt) group that links to the gold nanoparticle core and a tetramethylmalonamide (TMMA) group that serves as a selective Ln(3+) binding site. The sensor's colorimetric response to lanthanide ions is immediate, and it is sensitive down to approximately 50 nM for Eu(3+) and Sm(3+). This study demonstrates a general strategy for direct, convenient nanoparticle synthesis that enables the incorporation of analyte binding groups directly to the nanoparticle surface, allowing colorimetric sensors to be developed for widespread use. The one-step synthesis offers uniform surface ligand composition, reduces the volume of waste generated during nanoparticle synthesis and purification, produces functionalized gold nanoparticles that are stable in nonmodified aqueous environments, and offers colorimetric detection at ambient temperature. PMID:19904966

Lisowski, Carmen E; Hutchison, James E

2009-12-15

284

75 FR 51845 - Diebold, Incorporated, Hebron, OH; Diebold, Incorporated, North Canton, OH; Amended Certification...  

Federal Register 2010, 2011, 2012, 2013

...Administration [TA-W-70,993; TA-W-70,993A] Diebold, Incorporated, Hebron, OH; Diebold, Incorporated, North Canton, OH; Amended...on April 1, 2010, applicable to workers of Diebold, Incorporated, North Canton, Ohio. The...

2010-08-23

285

Numeral Incorporation in Japanese Sign Language  

ERIC Educational Resources Information Center

This article explores the morphological process of numeral incorporation in Japanese Sign Language. Numeral incorporation is defined and the available research on numeral incorporation in signed language is discussed. The numeral signs in Japanese Sign Language are then introduced and followed by an explanation of the numeral morphemes which are…

Ktejik, Mish

2013-01-01

286

Nanoparticles in forensic science  

Microsoft Academic Search

Nanoparticles appear in several areas of forensic science including security documents, paints, inks, and reagents that develop latent prints. One reagent (known as the silver physical developer) that visualizes the water insoluble components of latent print residue is based on the formation of highly charged silver nanoparticles. These attach to and grow on the residue and generate a silver image.

Antonio A. Cantu

2008-01-01

287

Cubic colloidal platinum nanoparticles  

SciTech Connect

Cubic platinum nanoparticles (4-18 nm) have been synthesized for the first time in solution by the controlled reduction of K{sub 2}PtCl{sub 4} with hydrogen gas in the presence of sodium polyacrylate as a capping material. The nanoparticles are found to have fcc structures, similar to the bulk metal with (100) facets.

Ahmadi, T.S.; Wang, Z.L.; Henglein, A.; El-Sayed, M.A. [Georgia Institute of Technology, Atlanta, GA (United States)] [Georgia Institute of Technology, Atlanta, GA (United States)

1996-06-01

288

Nanoparticle Deposition onto Biofilms  

PubMed Central

We develop a mathematical model of nanoparticles depositing onto and penetrating into a biofilm grown in a parallel-plate flow cell. We carry out deposition experiments in a flow cell to support the modeling. The modeling and the experiments are motivated by the potential use of polymer nanoparticles as part of a treatment strategy for killing biofilms infecting the deep passages in the lungs. In the experiments and model, a fluid carrying polymer nanoparticles is injected into a parallel-plate flow cell in which a biofilm has grown over the bottom plate. The model consists of a system of transport equations describing the deposition and diffusion of nanoparticles. Standard asymptotic techniques that exploit the aspect ratio of the flow cell are applied to reduce the model to two coupled partial differential equations. We perform numerical simulations using the reduced model. We compare the experimental observations with the simulation results to estimate the nanoparticle sticking coefficient and the diffusion coefficient of the nanoparticles in the biofilm. The distributions of nanoparticles through the thickness of the biofilm are consistent with diffusive transport, and uniform distributions through the thickness are achieved in about four hours. Nanoparticle deposition does not appear to be strongly influenced by the flow rate in the cell for the low flow rates considered.

Miller, J.K.; Neubig, R.; Clemons, C.B.; Kreider, K.L.; Wilber, J.P.; Young, G.W.; Ditto, A.J.; Yun, Y.H.; Milsted, A.; Badawy, H.T.; Panzner, M.J.; Youngs, W.J.; Cannon, C.L.

2012-01-01

289

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

290

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.

Hansen, Mikkel Fougt; Frandsen, Cathrine

2010-01-01

291

Toxicology of nanoparticles.  

PubMed

While nanotechnology and the production of nanoparticles are growing exponentially, research into the toxicological impact and possible hazard of nanoparticles to human health and the environment is still in its infancy. This review aims to give a comprehensive summary of what is known today about nanoparticle toxicology, the mechanisms at the cellular level, entry routes into the body and possible impacts to public health. Proper characterisation of the nanomaterial, as well as understanding processes happening on the nanoparticle surface when in contact with living systems, is crucial to understand possible toxicological effects. Dose as a key parameter is essential in hazard identification and risk assessment of nanotechnologies. Understanding nanoparticle pathways and entry routes into the body requires further research in order to inform policy makers and regulatory bodies about the nanotoxicological potential of certain nanomaterials. PMID:21925220

Elsaesser, Andreas; Howard, C Vyvyan

2012-02-01

292

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

293

Functional Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields. Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy is a critical component in dispersion. Oleic acid is used to alter the surface of magnetite nanoparticles and successfully achieve good dispersion in a PMMA thin film. Polypyrrole is then coated onto the PMMA composite layer. The bilayer is characterized using cross-sectional TEM, cross-sectional SEM, magnetic characterization, and low frequency conductivity. The results show that the superparmagnetic properties of the as synthesized particles are maintained in the composite. With further study of the properties of these nanoparticles for real and functional uses, MCE is studied on a variety of magnetic nanoparticle systems. Magnetite, manganese zinc ferrite, and cobalt ferrite systems show significant broadening of the MCE and the ability to tune the peak temperature of MCE by varying the size of the nanoparticles. Four distinct systems are studied including cobalt, cobalt core silver shell nanoparticles, nickel ferrite, and ball milled zinc ferrite. The results demonstrate the importance of surface characteristics on MCE. Surface spin disorder appears to have a large influence on the low temperature magnetic and magnetocalorie characteristics of these nanoparticle systems.

Gass, James

294

Paramagnetic Liposome Nanoparticles for Cellular and Tumour Imaging  

PubMed Central

In this review we discuss the development of paramagnetic liposomes incorporating MRI contrast agents and show how these are utilized in cellular imaging in vitro. Bi-functional, bi-modal imaging paramagnetic liposome systems are also described. Next we discuss the upgrading of paramagnetic liposomes into bi-modal imaging neutral nanoparticles for in vivo imaging applications. We discuss the development of such systems and show how paramagnetic liposomes and imaging nanoparticles could be developed as platforms for future multi-functional, multi-modal imaging theranostic nanodevices tailor-made for the combined imaging of early stage disease pathology and functional drug delivery.

Kamaly, Nazila; Miller, Andrew D.

2010-01-01

295

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

296

Nanoparticle Effects on Polymer Crystallization and Dynamics  

NASA Astrophysics Data System (ADS)

Polymer mixtures, copolymers, and structurally designed polymers have been joined by the incorporation of nanoparticles as a method of tuning material properties. The research presented here examines the properties of polymer nanocomposites in terms of nanoparticle effects on polymer crystallization and dynamics. The objective of this work is to further the understanding of the ways in which nanoparticles affect polymer properties in order to enhance development of polymer nanocomposites with desired properties through the controlled addition of appropriate nanoparticles. In examining the effect of single-walled carbon nanotubes (SWNTs) and organically-modified layered silicates (OMLS) on the crystallization process and final morphology of the semi-crystalline polymer poly(vinylidene fluoride), a synergistic result is observed wherein the piezoelectrically active beta-phase is promoted while the native alpha-phase is hindered. Furthermore, the resultant electrical properties indicate further benefit from optimized in and out of plane dielectric vs. conductive behavior. The second part of the work attempts to distinguish between nano-confinement and interfacial interactions as the dominating factor in the observed phenomenon wherein polymer glass transition temperatures (Tg) are shifted up or down in glass-forming amorphous liquid and polymer systems. A new approach is used involving different nanoparticle geometries to represent different modes of interaction with the polymer. Behavior is distinguished between what occurs at different length scales and temperatures. Near and above Tg, neutron scattering experiments reveal that the dynamics are dominated by the confinement of the polymer chains rather than by their interactions with nearby interfaces.

AbdulBaki, Mansour K.

297

Targeting intracellular compartments by magnetic polymeric nanoparticles.  

PubMed

Superparamagnetic iron oxide nanoparticles (SPIONs) show a great promise for a wide specter of bioapplications, due to their characteristic magnetic properties exhibited only in the presence of magnetic field. Their advantages in the fields of magnetic drug targeting and imaging are well established and their safety is assumed, since iron oxide nanoparticles have already been approved for in vivo application, however, according to many literature reports the bare metal oxide nanoparticles may cause toxic effects on treated cells. Therefore, it is reasonable to prevent the direct interactions between metal oxide core and surrounding environment. In the current research ricinoleic acid coated maghemite nanoparticles were successfully synthesized, characterized and incorporated in the polymeric matrix, resulting in nanosized magnetic polymeric particles. The carrier system was shown to exhibit superparamagnetic properties and was therefore responsive towards external magnetic field. Bioevaluation using T47-D breast cancer cells confirmed internalization of magnetic polymeric nanoparticles (MNPs) and their intracellular localization in various subcellular compartments, depending on presence/absence of external magnetic field. However, the number of internalized MNPs observed by fluorescent and transmission electron microscopy was relatively low, making such way of targeting effective only for delivery of highly potent drugs. The scanning electron microscopy of treated cells revealed that MNPs influenced the cell adhesion, when external magnetic field was applied, and that treatment resulted in damaged apical plasma membrane right after exposure to the magnetic carrier. On the other hand, MNPs showed only reversibly reduced cellular metabolic activity in concentrations up to 200 ?g/ml and, in the tested concentration the cell cycle distribution was within the normal range, indicating safety of the established magnetic carrier system for the treated cells. PMID:23603023

Kocbek, Petra; Kralj, Slavko; Kreft, Mateja Erdani; Kristl, Julijana

2013-09-27

298

Tracer-incorporated X-ray imaging of biofluid flow phenomena  

NASA Astrophysics Data System (ADS)

Particle-traced X-ray imaging technologies have been developed by combining the merits of the X-ray radiography and particle image velocimetry (PIV) technique. The developed X-ray imaging technology has strong potential in the noninvasive analysis of various flows such as non-transparent fluid flows or fluids flowing in opaque conduits. In this study, tracer-incorporated X-ray imaging technology was developed. In addition, new- concepted tracer particles were designed for in vitro and in vivo X-ray imaging analysis of various biofluids. As tracer particles in X-ray image, X-ray contrast enhancer Iopamidol was encapsulated into bio-compatible polymeric chitosan microparticles and gold nanoparticles with high X-ray absorption efficiency were directly incorporated into cells. The Iopamidol-incorporated polymeric microparticles were successfully applied for in vivo blood flow measurement in a rat. The gold nanoparticles were selectively incorporated into cancer cells, by which cancer cells can be detected in situ. The developed X-ray imaging technology would have a great potential in biomedical applications such as in situ analysis of blood flow and cancer detection.

Jung, Sung Yong; Ahn, Sungsook; Lee, Sang Joon

2011-11-01

299

Shaped gold and silver nanoparticles  

Microsoft Academic Search

Advance in the synthesis of shaped nanoparticles made of gold and silver is reviewed in this article. This review starts with\\u000a a new angle by analyzing the relationship between the geometrical symmetry of a nanoparticle shape and its internal crystalline\\u000a structures. According to the relationship, the nanoparticles with well-defined shapes are classified into three categories:\\u000a nanoparticles with single crystallinity, nanoparticles

Yugang Sun; Changhua An

2011-01-01

300

Preparation and evaluation of thiomer nanoparticles via high pressure homogenization.  

PubMed

The aim of this study was to establish and evaluate a high pressure homogenization method for the preparation of thiomer nanoparticles. Particles were formulated by incorporation of the model protein horseradish peroxidase in chitosan-glutathione (Ch-GSH) and poly(acrylic acid)-glutathione (PAA-GSH) via co-precipitation followed by air jet milling. The resulting microparticles were suspended in distilled water using an Ultraturax and subsequently micronized by high pressure homogenization. Finally, resulting particles were evaluated regarding size distribution, shape, zeta potential, drug load, protein activity and release behaviour. The mean particle size after 30 cycles with a pressure of 1500 bar was 538 +/- 94 nm for particles consisting of Ch-GSH and 638 +/- 94 nm for particles consisting of PAA-GSH. Nanoparticles of Ch-GSH had a positive zeta-potential of +1.03 mv, whereas nanoparticles from PAA-GSH had a negative zeta potential of -6.21 mv. The maximum protein load for nanoparticles based on Ch-GSH and based on PAA-GSH was 45 +/- 2% and 37 +/- %, respectively. The release profile of nanoparticles followed a first order release kinetic. Thiolated nanoparticles prepared by a high pressure homogenization technique were shown to be stable and provide controlled drug release characteristics. The preparation method described here might be a useful tool for a more upscaled production of nanoparticulate drug delivery systems. PMID:20367028

Hoyer, Herbert; Schlocker, Wolfgang; Greindl, Melanie; Ostermann, Thomas; Bernkop-Schnürch, Andreas

2010-01-01

301

Modulating electron transfer properties of gold nanoparticles for efficient biosensing.  

PubMed

Present study concerns modulating the electron transfer properties of gold nanoparticles through amino acid induced coupling among them. In addition to conductivity, the amino functionalization of the nanoparticles results in enhanced activity and operational stability of the biosensor fabricated using the same. Nanoparticles synthesized using amino acid as reducing agent (average diameter-20 nm), incorporate the natural coupling property of amino acids and are seen to align in a chain-like arrangement. The coupling of the individual nanoparticles to form chain like structure was confirmed by both absorption spectroscopy as well as transmission electron microscopy. The glucose biosensor developed by adsorption of glucose oxidase (GOx) enzyme onto these coupled gold nanoparticles showed enhanced efficiency as compared to the one with glucose oxidase immobilized onto gold nanoparticles synthesized using the conventional method (trisodium citrate as reducing agent). The fabricated biosensor demonstrated a wide linear concentration range from 1 ?M-5mM and a high sensitivity of 47.2 ?A mM(-1) cm(-2). Also, an enhanced selectivity to glucose was observed with negligible interference in the physiological range, from easily oxidizable biospecies, e.g. uric acid and ascorbic acid. Furthermore, the electrochemical biosensor has excellent long term stability- retaining greater than 85% of the biosensor activity up to 60 days. PMID:22608576

Sharma, Shikha; Gupta, Nidhi; Srivastava, Sudha

2012-01-01

302

A comprehensive review of the application of chalcogenide nanoparticles in polymer solar cells  

NASA Astrophysics Data System (ADS)

In this review the use of solution-processed chalcogenide quantum dots (CdS, CdSe, PbS, etc.) in hybrid organic-inorganic solar cells is explored. Such devices are known as potential candidates for low-cost and efficient solar energy conversion, and compose the so-called third generation solar cells. The incorporation of oxides and metal nanoparticles has also been successfully achieved in this new class of photovoltaic devices; however, we choose to explore here chalcogenide quantum dots in light of their particularly attractive optical and electronic properties. We address herein a comprehensive review of the historical background and state-of-the-art comprising the incorporation of such nanoparticles in polymer matrices. Later strategies for surface chemistry manipulation, in situ synthesis of nanoparticles, use of continuous 3D nanoparticles network (aerogels) and ternary systems are also reviewed.

Freitas, Jilian N.; Gonçalves, Agnaldo S.; Nogueira, Ana F.

2014-05-01

303

A comprehensive review of the application of chalcogenide nanoparticles in polymer solar cells.  

PubMed

In this review the use of solution-processed chalcogenide quantum dots (CdS, CdSe, PbS, etc.) in hybrid organic-inorganic solar cells is explored. Such devices are known as potential candidates for low-cost and efficient solar energy conversion, and compose the so-called third generation solar cells. The incorporation of oxides and metal nanoparticles has also been successfully achieved in this new class of photovoltaic devices; however, we choose to explore here chalcogenide quantum dots in light of their particularly attractive optical and electronic properties. We address herein a comprehensive review of the historical background and state-of-the-art comprising the incorporation of such nanoparticles in polymer matrices. Later strategies for surface chemistry manipulation, in situ synthesis of nanoparticles, use of continuous 3D nanoparticles network (aerogels) and ternary systems are also reviewed. PMID:24839190

Freitas, Jilian N; Gonçalves, Agnaldo S; Nogueira, Ana F

2014-05-29

304

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.

Han, Han; Davis, Mark E.

2013-01-01

305

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

306

Nanoparticle flotation collectors II: the role of nanoparticle hydrophobicity.  

PubMed

The ability of polystyrene nanoparticles to facilitate the froth flotation of glass beads was correlated to the hydrophobicity of the nanoparticles. Contact angle measurements were used to probe the hydrophobicity of hydrophilic glass surfaces decorated with hydrophobic nanoparticles. Both sessile water drop advancing angles, ?(a), and attached air bubble receding angle measurements, ?(r), were performed. For glass surfaces saturated with adsorbed nanoparticles, flotation recovery, a measure of flotation efficiency, increased with increasing values of each type of contact angle. As expected, the advancing water contact angle on nanoparticle-decorated, dry glass surfaces increased with surface coverage, the area fraction of glass covered with nanoparticles. However, the nanoparticles were far more effective at raising the contact angle than the Cassie-Baxter prediction, suggesting that with higher nanoparticle coverages the water did not completely wet the glass surfaces between the nanoparticles. A series of polystyrene nanoparticles was prepared to cover a range of surface energies. Water contact angle measurements, ?(np), on smooth polymer films formed from organic solutions of dissolved nanoparticles were used to rank the nanoparticles in terms of hydrophobicity. Glass spheres were saturated with adsorbed nanoparticles and were isolated by flotation. The minimum nanoparticle water contact angle to give high flotation recovery was in the range of 51° < ?(np(min)) ? 85°. PMID:21830818

Yang, Songtao; Pelton, Robert

2011-09-20

307

Dynamics of nanoparticle adhesion.  

PubMed

We performed molecular dynamics simulations and theoretical analysis of nanoparticle pulling off from adhesive substrates. Our theoretical model of nanoparticle detachment is based on the Kramers' solution of the stochastic barrier crossing in effective one-dimensional potential well. The activation energy, ?E, for nanoparticle detachment first decreases linearly with increasing the magnitude of the applied force, f, then it follows a power law ?E [proportionality] (f* - f)(3/2) as magnitude of the pulling force f approaches a critical detachment force value, f*. These two different regimes in activation energy dependence on magnitude of the applied force are confirmed by analyzing nanoparticle detachment in effective one-dimensional potential obtained by weighted histogram analysis method. Simulations show that detachment of nanoparticle proceeds through neck formation such that magnitude of the activation energy is determined by balancing surface energy of the neck connecting particle to a substrate with elastic energy of nanoparticle deformation. In this regime the activation energy at zero applied force, ?E(0), for nanoparticle with radius, R(p), shear modulus, G, surface energy, ?(p), and work of adhesion, W, is a universal function of the dimensionless parameter ? [proportionality] ?(p)W(-2/3)(GR(p))(-1/3). Simulation data are described by a scaling function ?E(0) [proportionality] ?(p) (5/2)R(p)(1/2)G(-3/2)?(-3.75). Molecular dynamics simulations of nanoparticle detachment show that the Kramers' approach fails in the vicinity of the critical detachment force f* where activation energy barrier becomes smaller than the thermal energy k(B)T. In the interval of the pulling forces f > f* nanoparticle detachment becomes a deterministic process. PMID:23231258

Carrillo, Jan-Michael Y; Dobrynin, Andrey V

2012-12-01

308

Recent advances in lipid nanoparticle formulations with solid matrix for oral drug delivery.  

PubMed

Lipid nanoparticles based on solid matrix have emerged as potential drug carriers to improve gastrointestinal (GI) absorption and oral bioavailability of several drugs, especially lipophilic compounds. These formulations may also be used for sustained drug release. Solid lipid nanoparticle (SLN) and the newer generation lipid nanoparticle, nanostructured lipid carrier (NLC), have been studied for their capability as oral drug carriers. Biodegradable, biocompatible, and physiological lipids are generally used to prepare these nanoparticles. Hence, toxicity problems related with the polymeric nanoparticles can be minimized. Furthermore, stability of the formulations might increase than other liquid nano-carriers due to the solid matrix of these lipid nanoparticles. These nanoparticles can be produced by different formulation techniques. Scaling up of the production process from lab scale to industrial scale can be easily achieved. Reasonably high drug encapsulation efficiency of the nanoparticles was documented. Oral absorption and bioavailability of several drugs were improved after oral administration of the drug-loaded SLNs or NLCs. In this review, pros and cons, different formulation and characterization techniques, drug incorporation models, GI absorption and oral bioavailability enhancement mechanisms, stability and storage condition of the formulations, and recent advances in oral delivery of the lipid nanoparticles based on solid matrix will be discussed. PMID:21174180

Das, Surajit; Chaudhury, Anumita

2011-03-01

309

PLGA Micro and Nanoparticles Loaded Into Gelatin Scaffold for Controlled Drug Release  

Microsoft Academic Search

Curcumin and bovine serum albumin (BSA) were used as model drugs and loaded into micro- and nanoparticles of biodegradable poly(lactic-co-glycolic acid) (PLGA). The PLGA was incorporated into hydrophilic and biocompatible gelatin scaffolds to design a controlled drug release system. The gelatin scaffolds were cross-linked using glutaraldehyde. The controlled delivery of drugs from biologically active PLGA micro- and nanoparticles was measured

Waseem Asghar; Muhymin Islam; Aniket S. Wadajkar; Yuan Wan; Azhar Ilyas; Kytai T. Nguyen; Samir M. Iqbal

2012-01-01

310

Efficiency enhancement in DSSC using metal nanoparticles: A size dependent study  

Microsoft Academic Search

The photoelectrode of Eosin-Y sensitised DSSC was modified by incorporating Au-nanoparticles to enhance the power conversion efficiency via scattering from surface plasmon polaritons. Size dependence of Au nanoparticle on conversion efficiency was performed in DSSC for the first time by varying the particle size from 20 to 94nm. It was found that, the conversion efficiency is highly dependent on the

K. G. Deepa; P. Lekha; S. Sindhu

311

A new numerical approach for the simulation of the growth of inorganic nanoparticles  

Microsoft Academic Search

In this paper we derive and test an extended mass-flow type stochastic particle algorithm for simulating the growth of nanoparticles that are formed in flames and reactors. The algorithm incorporates the effects of coagulation that dominates such systems, along with a particle source and surface growth. We simulate three different configurations for the creation of nanoparticles. The oxidation of SiH4

N. M. Morgan; C. G. Wells; M. J. Goodson; M.. Kraft; W. Wagner

2006-01-01

312

Blue shift in the luminescence spectra of MEH-PPV films containing ZnO nanoparticles  

Microsoft Academic Search

Luminescence properties of nanocomposites consisting of ZnO nanoparticles in a conjugated polymer, poly [2-methoxy-5-(2?-ethyl hexyloxy)-phenylene vinylene] (MEH-PPV), were investigated. Photoluminescence measurements reveal a blue shift in the emission spectrum of MEH-PPV upon incorporation of ZnO nanoparticles into the polymer film while the emission is increasingly quenched with increasing ZnO concentration. In contrast, the structure of the polymer and its conjugation

Cuong Ton-That; Matthew R. Phillips; Thien-Phap Nguyen

2008-01-01

313

Peptide antisense nanoparticles  

PubMed Central

We have designed a heterofunctionalized nanoparticle conjugate consisting of a 13-nm gold nanoparticle (Au NP) containing both antisense oligonucleotides and synthetic peptides. The synthesis of this conjugate is accomplished by mixing thiolated oligonucleotides and cysteine-terminated peptides with gold nanoparticles in the presence of salt, which screens interactions between biomolecules, yielding a densely functionalized nanomaterial. By controlling the stoichiometry of the components in solution, we can control the surface loading of each biomolecule. The conjugates are prepared easily and show perinuclear localization and an enhanced gene regulation activity when tested in a cellular model. This heterofunctionalized structure represents a new strategy for preparing nanomaterials with potential therapeutic applications.

Patel, Pinal C.; Giljohann, David A.; Seferos, Dwight S.; Mirkin, Chad A.

2008-01-01

314

Synthesis of Silver Nanoparticles  

NSDL National Science Digital Library

This series of videos, presented by the Materials Research Science and Engineering Center at the University of Wisconsin-Madison, deals with the synthesis of silver nanoparticles. The experiment allows students to view the formation of silver nanoparticles that can be detected by the reflection of a laser beam. Silver nanoparticles are used in the creation of yellow stained glass in churches around the country, an interesting, but little known fact. This is a fairly inexpensive activity as it involves stock solutions, and equipment present in any science laboratory. Overall, students will enjoy this basic, but still challenging, experiment.

Johnson, Chris; Ng, Steve

2009-01-21

315

Design parameters for voltage-controllable directed assembly of single nanoparticles  

NASA Astrophysics Data System (ADS)

Techniques to reliably pick-and-place single nanoparticles into functional assemblies are required to incorporate exotic nanoparticles into standard electronic circuits. In this paper we explore the use of electric fields to drive and direct the assembly process, which has the advantage of being able to control the nano-assembly process at the single nanoparticle level. To achieve this, we design an electrostatic gating system, thus enabling a voltage-controllable nanoparticle picking technique. Simulating this system with the nonlinear Poisson-Boltzmann equation, we can successfully characterize the parameters required for single particle placement, the key being single particle selectivity, in effect designing a system that can achieve this controllably. We then present the optimum design parameters required for successful single nanoparticle placement at ambient temperature, an important requirement for nanomanufacturing processes.

Porter, Benjamin F.; Abelmann, Leon; Bhaskaran, Harish

2013-10-01

316

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.

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

2013-01-01

317

Active targeting of cancer cells using folic acid-conjugated platinum nanoparticles  

NASA Astrophysics Data System (ADS)

Interaction of nanoparticles with human cells is an interesting topic for understanding toxicity and developing potential drug candidates. Water soluble platinum nanoparticles were synthesized via reduction of hexachloroplatinic acid using sodium borohydride in the presence of capping agents. The bioactivity of folic acid and poly(vinyl pyrrolidone) capped platinum nanoparticles (Pt-nps) has been investigated using commercially available cell lines. In the cell viability experiments, PVP-capped nanoparticles were found to be less toxic (>80% viability), whereas, folic acid-capped platinum nanoparticles showed a reduced viability down to 24% after 72 h of exposure at a concentration of 100 ?g ml-1 for MCF7 breast cancer cells. Such toxicity, combined with the possibility to incorporate functional organic molecules as capping agents, can be used for developing new drug candidates.

Teow, Yiwei; Valiyaveettil, Suresh

2010-12-01

318

Design parameters for voltage-controllable directed assembly of single nanoparticles.  

PubMed

Techniques to reliably pick-and-place single nanoparticles into functional assemblies are required to incorporate exotic nanoparticles into standard electronic circuits. In this paper we explore the use of electric fields to drive and direct the assembly process, which has the advantage of being able to control the nano-assembly process at the single nanoparticle level. To achieve this, we design an electrostatic gating system, thus enabling a voltage-controllable nanoparticle picking technique. Simulating this system with the nonlinear Poisson-Boltzmann equation, we can successfully characterize the parameters required for single particle placement, the key being single particle selectivity, in effect designing a system that can achieve this controllably. We then present the optimum design parameters required for successful single nanoparticle placement at ambient temperature, an important requirement for nanomanufacturing processes. PMID:24029752

Porter, Benjamin F; Abelmann, Leon; Bhaskaran, Harish

2013-10-11

319

Improvement of thermal stability of polypropylene using DOPO-immobilized silica nanoparticles  

PubMed Central

After the surface silylation with 3-methacryloxypropyltrimethoxysilane, silica nanoparticles were further modified by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The immobilization of DOPO on silica nanoparticles was confirmed by Fourier transform infrared spectroscopy, UV–visible spectroscopy, magic angle spinning nuclear magnetic resonance, and thermogravimetric analysis. By incorporating the DOPO-immobilized silica nanoparticles (5 wt%) into polypropylene matrix, the thermal oxidative stability exhibited an improvement of 62 °C for the half weight loss temperature, while that was only 26 °C increment with incorporation of virgin silica nanoparticles (5 wt%). Apparent activation energies of the polymer nanocomposites were estimated via Flynn–Wall–Ozawa method. It was found that the incorporation of DOPO-immobilized silica nanoparticles improved activation energies of the degradation reaction. Based on the results, it was speculated that DOPO-immobilized silica nanoparticles could inhibit the degradation of polypropylene and catalyze the formation of carbonaceous char on the surface. Thus, thermal stability was significantly improved.

Dong, Quanxiao; Ding, Yanfen; Wen, Bin; Wang, Feng; Dong, Huicong; Zhang, Shimin

2014-01-01

320

Preparation and characterization of methyltrimethoxysilane-Ag nanoparticles using chemical reduction at room temperature  

NASA Astrophysics Data System (ADS)

A new, direct, simple and high yield solution phase synthesis for preparing narrow-sized silver nanoparticles by chemical reduction in aqueous solution of AgNO3 in the presence of incorporated Sn particles in methyltrimethoxysilane (MTMS) at room temperature is reported. The resulting MTMS-silver nanoparticles were characterized by means of powder X-ray diffraction and transmission electron microscopy. The produced Ag particles present a tight size distribution with an average diameter of about 15 nm. Dispersed silver nanoparticles in tetrahydrofuran-dimethylformamide (1:1) mixture exhibit some broad surface plasmon resonance bands in UV-visible spectrum.

Farasat, Mahshid; Golzan, Mir Maqsood

2014-03-01

321

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

PubMed

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%. PMID:24666992

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

2014-01-01

322

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, Jérôme; Haas, Fernando; Manfredi, Giovanni; Hervieux, Paul-Antoine

2014-04-01

323

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

324

Blue luminescence from amorphous GaN nanoparticles synthesized {ital in situ} in a polymer  

SciTech Connect

Amorphous GaN nanoparticles were synthesized by the {ital in situ} thermal decomposition of cyclotrigallazane incorporated into a polystyrene{endash}poly({ital N,N}-dimethyl-4-vinylaniline) copolymer. Transmission electron microscopy, energy dispersive x-ray spectrometry, and x-ray photoelectron spectroscopy show that the composite material consists of amorphous GaN nanoparticles (average diameter {approximately}40 nm) well dispersed in the copolymer. The photoluminescence spectra show blue light emission from the amorphous GaN nanoparticles, peaked at {approximately}426 nm. {copyright} {ital 1999 American Institute of Physics.}

Yang, Y.; Leppert, V.J.; Risbud, S.H. [Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616 (United States)] [Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616 (United States); Twamley, B.; Power, P.P. [Department of Chemistry, University of California, Davis, California 95616 (United States)] [Department of Chemistry, University of California, Davis, California 95616 (United States); Lee, H.W. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

1999-04-01

325

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

326

Magnetic nanoparticle temperature estimation  

SciTech Connect

The authors present a method of measuring the temperature of magnetic nanoparticles that can be adapted to provide in vivo temperature maps. Many of the minimally invasive therapies that promise to reduce health care costs and improve patient outcomes heat tissue to very specific temperatures to be effective. Measurements are required because physiological cooling, primarily blood flow, makes the temperature difficult to predict a priori. The ratio of the fifth and third harmonics of the magnetization generated by magnetic nanoparticles in a sinusoidal field is used to generate a calibration curve and to subsequently estimate the temperature. The calibration curve is obtained by varying the amplitude of the sinusoidal field. The temperature can then be estimated from any subsequent measurement of the ratio. The accuracy was 0.3 deg. K between 20 and 50 deg. C using the current apparatus and half-second measurements. The method is independent of nanoparticle concentration and nanoparticle size distribution.

Weaver, John B.; Rauwerdink, Adam M.; Hansen, Eric W. [Department of Radiology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756 (United States) and Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755-8000 (United States); Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755-8000 (United States)

2009-05-15

327

Poly(amino acid) functionalized maghemite and gold nanoparticles  

NASA Astrophysics Data System (ADS)

Bimodal MRI/OI imaging probes are of great interest in nanomedicine. Although many organic polymers have been studied thoroughly for in vivo applications, reports on the use of poly(amino acid)s as coating polymers are scarce. In this paper, poly-(d-glutamic acid, d-lysine) (PGL) has been used for coating maghemite and gold nanoparticles. An advantage of this flexible and biocompatible polymer is that, once anchored to the nanoparticle surface, dangling lysine amino groups are available for the incorporation of new functionalities. As an example, Alexa Fluor derivatives have been attached to PGL-coated maghemite nanoparticles to obtain magnetic/fluorescent materials. These dual-property materials could be used as bimodal MRI/OI probes for in vivo imaging.

Perego, Davide; Masciocchi, Norberto; Guagliardi, Antonietta; Domínguez-Vera, José Manuel; Gálvez, Natividad

2013-02-01

328

Oxidation state and coordination of gold deposited on titania nanoparticles  

NASA Astrophysics Data System (ADS)

We perform XANES(X-Ray absorption near edge structure) and EXAFS( extended x-ray absorption fine structure) measurements on gold/titania interfaces.The possible oxidation of metallic gold by holes generated in titanium oxide by UV light is explored. Gold nanoparticles of diamter 8-10 nm are deposited on Titania nanoparticles of diameter 30 nm by an electrophoretic technique. As UV light is shone on the composite, gold nanoparticles get oxidized by photogenerated holes at the metal/semiconductor interface and the metallic ions diffuse into the titanium oxide. The undiffused gold is leached off, thereby leaving only the gold ions inside the titanium oxide. We explore the chemical state of this remnant gold by XANES, which does show a clear change of valence state from metallic gold. The coordination geometry of gold incorporated in titania is also explored by the EXAFS technique.

Lahiri, Debdutta; Subramanian, Vaidyanathan; Shibata, Tomohiro; Boyanov, Maxim; Stuckey, Aaron; Mishra, Bhoopesh; Kamat, Prashant; Bunker, Bruce

2002-03-01

329

Highly quasi-monodisperse ag nanoparticles on titania nanotubes by impregnative aqueous ion exchange.  

PubMed

Silver nanoparticles were homogenously dispersed on titania nanotubes (NT), which were prepared by alkali hydrothermal methodology and dried at 373 K. Ag(+) incorporation was done by impregnative ion exchange of aqueous silver nitrate onto NT. First, Ag(+) ions incorporate into the layers of nanotube walls, and then, upon heat treatment under N(2) at 573 and 673 K, they migrate and change into Ag(2)O and Ag(0) nanoparticles, respectively. In both cases, Ag nanoparticles are highly dispersed, decorating the nanotubes in a polka-dot pattern. The Ag particle size distribution is very narrow, being ca. 4 +/- 2 nm without any observable agglomeration. The reduction of Ag(2)O into Ag(0) octahedral nanoparticles occurs spontaneously and topotactically when annealing, without the aid of any reducing agent. The population of Ag(0) nanoparticles can be controlled by adjusting the annealing temperature. An electron charge transfer from NT support to Ag(0) nanoparticles, because of a strong interaction, is responsible for considerable visible light absorption in Ag(0) nanoparticles supported on NT. PMID:19485374

Toledo-Antonio, J A; Cortes-Jácome, M A; Angeles-Chavez, C; López-Salinas, E; Quintana, P

2009-09-01

330

Photosynthetic nanoparticle complexes  

NASA Astrophysics Data System (ADS)

We investigate structures composed of a photosynthetic molecule and a semiconductor (metal) nanoparticle [1]. The rate of optical generation of electron--hole pairs inside a photosynthetic system can be greatly increased through conjugation with nanoparticles. In the case of a semiconductor nanoparticle, the enhancement effect comes from the essentially larger optical absorption cross-section of a semiconductor nanoparticle compared to a photosynthetic system. In this hybrid complex, excitons are transferred via the Forster mechanism to the photosynthetic system, where charge separation takes place. For metal nanoparticles conjugated with a photosynthetic system, we predicted a strong enhancement effect due to the plasmon resonance. Such an enhancement effect was recently observed at Munich U. [2]. In summary, we have shown that one can use crystalline nanoparticles to create a 10-fold enhancement of the initial stage of photosynthesis, i.e. the absorption process. Potential applications of nanocrystal complexes are in light-harvesting. [1] A. O. Govorov and I. Carmeli, Nano Lett. 7, 620 (2007); A. O. Govorov, Adv. Materils, online, DOI: 10.1002/adma.200702999. [2] S.Mackowski, S. W"ormke, A.J. Maier, T.H.P. Brotosudarmo, H. Harutyunyan, A. Hartschuh, A.O. Govorov, H. Scheer, C. Br"auchle, Nano Lett. 8, 558 (2008).

Govorov, Alexander

2009-03-01

331

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.

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

2013-01-01

332

Nanoparticle flotation collectors III: the role of nanoparticle diameter.  

PubMed

The ability of polystyrene nanoparticles to promote glass bead flotation was measured as a function of nanoparticle diameter. In all cases, smaller nanoparticles were more effective flotation collectors, even when compared at constant nanoparticle number concentration. The superior performance of smaller particles was explained by two mechanisms, acting in parallel. First, smaller particles deposit more quickly giving more effective flotation in those cases where nanoparticle deposition kinetics is rate determining; the sensitivity of nanoparticle deposition rates to particle size was illustrated by kinetic measurements on a quartz crystal microbalance silica surface. Second, for a given coverage of nanoparticles on the glass beads, the mean distance between neighboring nanoparticle surfaces decreases with particle diameter. We propose that the expansion of the three phase contact line, after initial bead/bubble attachment, is favored with decreasing the distance between neighboring hydrophobic particles. PMID:22871900

Yang, Songtao; Pelton, Robert; Montgomery, Miles; Cui, Yuguo

2012-09-26

333

49 CFR 572.180 - Incorporated materials.  

Code of Federal Regulations, 2013 CFR

...No. 175-7000-2, Leg Assemblyâright incorporated by reference in § 572.181; (xiii) Drawing No. 175-8000, Neoprene Body Suit, incorporated by reference in §§ 572.181 and 572.185; and, (xiv) Drawing No. 175-9000, Headform...

2013-10-01

334

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

335

Ribonucleotide incorporation by yeast DNA polymerase ?.  

PubMed

During replication in yeast, the three B family DNA replicases frequently incorporate ribonucleotides (rNMPs) into DNA, and their presence in the nuclear genome can affect genome stability. This prompted us to examine ribonucleotide incorporation by the fourth B family member, Pol ?, the enzyme responsible for the majority of damage-induced mutagenesis in eukaryotes. We first show that Pol ? inserts rNMPs into DNA and can extend primer termini containing 3'-ribonucleotides. We then measure rNMP incorporation by Pol ? in the presence of its cofactors, RPA, RFC and PCNA and at normal cellular dNTP and rNTP concentrations that exist under unstressed conditions. Under these conditions, Pol ? stably incorporates one rNMP for every 200-300 dNMPs incorporated, a frequency that is slightly higher than for the high fidelity replicative DNA polymerases. Under damage-induced conditions wherein cellular dNTP concentrations are elevated 5-fold, Pol ? only incorporates one rNMP per 1300 dNMPs. Functional interaction of Pol ? with the mutasome assembly factor Rev1 gives comparable rNMP incorporation frequencies. These results suggest that ribonucleotide incorporation into DNA during Pol ?-mediated mutagenesis in vivo may be rare. PMID:24674899

Makarova, Alena V; Nick McElhinny, Stephanie A; Watts, Brian E; Kunkel, Thomas A; Burgers, Peter M

2014-06-01

336

Protein nanoparticles for intracellular delivery of therapeutic enzymes.  

PubMed

The use of enzymes as therapeutics is very promising because of their catalytic activity and specificity. However, intracellular delivery of active enzymes is challenging due to their low stability and large size. The production of protein-enzyme nanoparticles was investigated with the goal of developing a protein carrier for active enzyme delivery. ?-Galactosidase (?-gal), an enzyme whose deficiency is the cause of some lysosomal storage disorders, was incorporated into enhanced green fluorescent protein nanoparticles prepared via desolvation. Particle size was found to be sensitive to the type of cross-linker, cross-linking time, and the presence of imidazole. The results indicate that ?-gal activity is highly retained (>70%) after particle fabrication and >85% of protein is incorporated in the particles. Protein-enzyme nanoparticles exhibited higher internalization in multiple cell lines in vitro, compared with the soluble enzyme. Importantly, ?-gal retained its activity following intracellular delivery. These data demonstrate that protein nanoparticles are a biocompatible, high-efficiency alternative for intracellular delivery of active enzyme therapeutics. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci. PMID:24740820

Estrada, Lina Herrera; Chu, Stanley; Champion, Julie A

2014-06-01

337

Behavior of metal oxide nanoparticles in natural aqueous matrices  

Microsoft Academic Search

The increasing use of nanomaterials in consumer products that are exposed to environmental media has led to a need to understand their fate and transport. In particular, metal oxide (MeO) nanoparticles, such as TiO2, ZnO and CeO2, are increasingly incorporated into a wide range of products, from sunscreens to paints and other coatings, and catalysts. With regard to their transport,

A. A. Keller; D. Zhou; H. Wang

2009-01-01

338

CCMR: Metal Nanoparticles Architectures for Nanoplasmonics Applications: Synthesis and Characterizations  

NSDL National Science Digital Library

This summer my project was to increase the size of a nano particle called Cornell Dot or C. Dot. A C. Dot is a core-shell silica nanoparticles is the development of fluorescent particles based on organic dyes covalently incorporated into the silica matrix. Reactive dye molecules are cross-linked to a silica precursor which is reacted to form a dye-rich core particle. This core is then encapsulated in a layer of pure silica to create the coreshell particle.

Livenere, John

2009-08-15

339

Physical and chemical properties of superparamagnetic Fe-incorporated nano hydroxyapatite.  

PubMed

Nano hydroxyapatite (n-HA) crystals carrying incorporated Fe ions were designed and synthesized by a co-precipitation method. The microstructure and morphology as well as magnetic property of the Fe-incorporated n-HA crystals (denoted as n-Fe-HA) were characterized by TEM, XRD and VSM. The results showed that lattice substitution or incorporation had occurred between Fe ions and n-HA, which was quite different from the mechanical mixture of Fe3O4 nanoparticles and n-HA crystals. The n-Fe-HA with a synthetic molar ratio of 1:2 (calculated by Fe3O4:HA) exhibited a needle like crystal shape and relatively good crystallinity. However, when the molar ratio was up to 1:1, some Fe3O4 nanoparticles were separated from n-Fe-HA crystals. The magnetization measurements showed that n-Fe-HA crystals were in superparamagnetic state, proving that the existence of Fe ions in n-HA crystals contributed to the magnetic properties of n-Fe-HA crystals. As one component of biomedical composite, n-Fe-HA has a potential to promote bone regeneration. PMID:19908688

Jiang, Hong; Li, Yubao; Zuo, Yi; Yang, Weihu; Zhang, Li; Li, Jidong; Wang, Li; Zou, Qin; Cheng, Lin; Li, Junfeng

2009-12-01

340

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

341

MICROBIAL IMPACTS OF ENGINEERED NANOPARTICLES  

EPA Science Inventory

Reactivity at the nanometric scale is intimately linked to nanoparticle mobility and microbial sensitivity. Thus, first-order factors increasing nanoparticle reactivity should increase the rate of redox reactions with second-order effects on particle mobility and ecot...

342

Magnetic Nanoparticle Compositions and Methods.  

National Technical Information Service (NTIS)

A nanoparticle having a core comprising a magnetic material and surface to which are covalently coupled a plurality of silane moieties, wherein each silane moiety comprises a polyalkylene oxide moiety. The nanoparticle can further include a targeting agen...

J. W. Gunn M. Zhang N. Kohler

2006-01-01

343

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...

344

Transport measurements across single nanoparticles  

NASA Astrophysics Data System (ADS)

During this last decade, numerous progresses have been obtained in the chemical synthesis of nanoparticle. Various materials (oxides, chalcogenides) known for their peculiar electronic or magnetic properties -- superconductivity, Mott localization, topological protection -- can now be obtained as nanoparticles through chemical synthesis. These new nano-materials are offering a unique opportunity to study the effect of quantum confinement on unconventional electronic orders. To improve the preparation of samples with single nanoparticles trapped within a nanogap, we developed a new method where nanoparticles are projected in-vacuum on chip circuits covered by nanogap spaced electrodes. Continuous current measurements during the projection allow identifying the trapping of a single nanoparticle within the nanogap. We apply the method for trapping single gold nanoparticles, which led to the observation of Coulomb blockade. We also applied the method to magnetite (Fe3O4) nanoparticles, which allows to study the electric field induced insulator to metal transition in only a few nanoparticles.

Yu, Qian; Cui, Limin; Ulysse, Christian; Mottaghizadeh, Alireza; Zimmers, Alexandre; Aubin, Hervé.

2013-03-01

345

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

346

Microfluidic patterning of nanoparticle monolayers  

Microsoft Academic Search

A microfluidic technique was developed to pattern nanoparticle monolayer controllably in a tentative polydimethylsiloxane\\u000a (PDMS) microchannel. It was found that nanoparticle monolayer could be achieved in a two-step fluidic process: nanoparticle\\u000a sedimentation and DI water rinsing. When nanoparticle suspension flows through a tentative PDMS microchannel, the particles\\u000a will settle down due to the gravity effect and the Brownian motion and

Zhen Chen; Yu Zhao; Wei Wang; Zhihong Li

2009-01-01

347

Nanoparticles laden in situ gel for sustained ocular drug delivery.  

PubMed

Proper availability of drug on to corneal surface is a challenging task. However, due to ocular physiological barriers, conventional eye drops display poor ocular bioavailability of drugs (< 1%). To improve precorneal residence time and ocular penetration, earlier our group developed and evaluated in situ gel and nanoparticles for ocular delivery. In interest to evaluate the combined effect of in situ gel and nanoparticles on ocular retention, we combined them. We are the first to term this combination as "nanoparticle laden in situ gel", that is, poly lactic co glycolic acid nanoparticle incorporated in chitosan in situ gel for sparfloxacin ophthalmic delivery. The formulation was tested for various physicochemical properties. It showed gelation pH near pH 7.2. The observation of acquired gamma camera images showed good retention over the entire precorneal area for sparfloxacin nanoparticle laden in situ gel (SNG) as compared to marketed formulation. SNG formulation cleared at a very slow rate and remained at corneal surface for longer duration as no radioactivity was observed in systemic circulation. The developed formulation was found to be better in combination and can go up to the clinical evaluation and application. PMID:23833523

Gupta, Himanshu; Aqil, Mohammed; Khar, Roop K; Ali, Asgar; Bhatnagar, Aseem; Mittal, Gaurav

2013-04-01

348

Cell adhesion and proliferation on polyethylene grafted with Au nanoparticles  

NASA Astrophysics Data System (ADS)

Plasma treatment and subsequent Au nano-particles grafting of polyethylene (PE) lead to changes in surface morphology, roughness and wettability, significantly increasing the attractiveness of the material for cells. The PE samples were exposed to argon plasma. Plasma modified PE was chemically grafted by immersion to biphenyldithiol and consequently into solution of Au nano-particles. Changes in chemical structure of the modified PE were studied using X-ray Photoelectron Spectroscopy (XPS) and electrokinetic analysis ( ?-potential). The surface wettability of the modified PE samples was examined by measurement of the contact angle by standard goniometry. The surface morphology of the plasma modified PE and that grafted with Au nano-particles was studied by Atomic Force Microscopy (AFM). The modified PE samples were seeded with rat vascular smooth muscle cells (VSMCs) and their adhesion and proliferation were studied. Chemically bounded biphenyldithiol increases the number of the incorporated gold nano-particles and changes sample surface properties. The presence of the biphenyldithiol and the gold nano-particles on the PE surface influences dramatically adhesion and proliferation of VSMCs.

Kasálková, N. Slepi?ková; Slepi?ka, P.; Kolská, Z.; Sajdl, P.; Ba?áková, L.; Rimpelová, S.; Švor?ík, V.

2012-02-01

349

Nanoparticles laden in situ gel for sustained ocular drug delivery  

PubMed Central

Proper availability of drug on to corneal surface is a challenging task. However, due to ocular physiological barriers, conventional eye drops display poor ocular bioavailability of drugs (< 1%). To improve precorneal residence time and ocular penetration, earlier our group developed and evaluated in situ gel and nanoparticles for ocular delivery. In interest to evaluate the combined effect of in situ gel and nanoparticles on ocular retention, we combined them. We are the first to term this combination as “nanoparticle laden in situ gel”, that is, poly lactic co glycolic acid nanoparticle incorporated in chitosan in situ gel for sparfloxacin ophthalmic delivery. The formulation was tested for various physicochemical properties. It showed gelation pH near pH 7.2. The observation of acquired gamma camera images showed good retention over the entire precorneal area for sparfloxacin nanoparticle laden in situ gel (SNG) as compared to marketed formulation. SNG formulation cleared at a very slow rate and remained at corneal surface for longer duration as no radioactivity was observed in systemic circulation. The developed formulation was found to be better in combination and can go up to the clinical evaluation and application.

Gupta, Himanshu; Aqil, Mohammed; Khar, Roop K.; Ali, Asgar; Bhatnagar, Aseem; Mittal, Gaurav

2013-01-01

350

Antimicrobial properties of hydrated cellulose membranes with silver nanoparticles.  

PubMed

Microbial cellulose membranes have attracted a great deal of attention as novel wound-dressing materials, especially for the healing of skin burns and chronic wounds, because of their high water holding capacity and biocompatibility. However, the high humidity around the wound sometimes allows the growth of bacteria, as well as the regeneration of the tissue. In this study, silver nanoparticles were incorporated into the cellulose membranes via a chemical reduction method using a silver salt, silver nitrate (AgNO(3)) and a reducing agent, sodium borohydride (NaBH(4)). The silver nanoparticles were evenly adsorbed on the overall surface of the cellulose nanofibrils without any local aggregation and had a spherical shape with uniform size (8+/-2 nm) which allowed them to show antimicrobial properties. The interaction between the oxygen in cellulose and silver nanoparticles resulted in the stable adsorption of the silver nanoparticles on cellulose nanofibrils. The cellulose membrane with silver nanoparticles exhibited an antimicrobial activity of more than 99.99% against Escherichia coli and Staphylococcus aureus, so that it could be used as an antimicrobial wound-dressing material for chronic wounds and burns. PMID:19192358

Jung, Rira; Kim, Yeseul; Kim, Hun-Sik; Jin, Hyoung-Joon

2009-01-01

351

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

352

Cytotoxicity and anti-inflammatory activity of cyclosporine A loaded PLGA nanoparticles for ocular use.  

PubMed

Cyclosporine A loaded poly(lactide-co-glycolide) nanoparticles were prepared using the o/w emulsification solvent evaporation method and the effect of four preparation parameters on particle size and zeta potential was investigated. Release properties of the nanoparticles were examined and in vitro experiments were performed in order to evaluate the cytotoxicity and anti-inflammatory activity of the nanoparticles developed. Particle sizes varied between 191 and 303 nm depending on the different preparation parameters and all nanoparticle dispersions were monodisperse. The nanoparticles showed negative zeta potential values varying between -16 and -35 mV and 57 to 70 % of the amount of loaded cyclosporine A was released after 24 h. None of the nanoparticle formulations showed significant cytotoxicity compared to the negative control using human epithelial cells (HaCaT). Cyclosporine A incorporated in the various nanoparticle formulations retained its anti-inflammatory activity as significant suppression of interleukine-2 secretion in concanavalin A stimulated Jurkat T cells was measured. As the overall influence of the freeze-drying process on the characteristics of nanoparticles was limited, trehalose and carnitine should be preferred as cryoprotectants in ocular formulations for treatment of dry eye disease. PMID:24601220

Hermans, K; Van Den Plas, D; Schreurs, E; Weyenberg, W; Ludwig, A

2014-01-01

353

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; Müller-Buschbaum, Peter

2014-04-01

354

Plasmid DNA-entrapped nanoparticles engineered from microemulsion precursors: in vitro and in vivo evaluation.  

PubMed

Nonviral gene therapy has been a rapidly growing field. However, delivery systems that can provide protection for pDNA and potential targeting are still desired. A novel pDNA-nanoparticle delivery system was developed by entrapping hydrophobized pDNA inside nanoparticles engineered from oil-in-water (O/W) microemulsion precursors. Plasmid DNA was hydrophobized by complexing with cationic surfactants DOTAP and DDAB. Warm O/W microemulsions were prepared at 50-55 degrees C with emulsifying wax, Brij 78, Tween 20, and Tween 80. Nanoparticles were engineered by simply cooling the O/W microemulsions containing the hydrophobized pDNA in the oil phase to room temperature while stirring. The nanoparticles were characterized by particle sizing, zeta-potential, and TEM. Nanoparticles were challenged with serum nucleases to assess pDNA stability. In addition, the nanoparticles were coincubated with simulated biological media to assess their stability. In vitro hepatocyte transfection studies were completed with uncoated nanoparticles or nanoparticles coated with pullulan, a hepatocyte targeting ligand. In vivo biodistribution of the nanoparticles containing I-125 labeled pDNA was monitored 30 min after tail-vein injection to Balb/C mice. Depending on the hydrophobizing lipid agent employed, uniform pDNA-entrapped nanoparticles (100-160 nm in diameter) were engineered within minutes from warm O/W microemulsion precursors. The nanoparticles were negatively charged (-6 to -15 mV) and spherical. An anionic exchange column was used to separate unentrapped pDNA from nanoparticles. Gel permeation chromatography of pDNA-entrapped and serum-digested nanoparticles showed that the incorporation efficiency was approximately 30%. Free 'naked' pDNA was completely digested by serum nucleases while the entrapped pDNA remained intact. Moreover, in vitro transfection studies in Hep G2 cells showed that pullulan-coated nanoparticles resulted in enhanced luciferase expression, compared to both pDNA alone and uncoated nanoparticles. Preincubation of the cells with free pullulan inhibited the transfection. Finally, 30 min after tail vein injection to mice, only 16% of the 'naked' pDNA remained in the circulating blood compared to over 40% of the entrapped pDNA. Due to the apparent stability of these pDNA-entrapped nanoparticles in the blood, they may have potential for systemic gene therapy applications requiring cell and/or tissue-specific delivery. PMID:12440869

Cui, Zhengrong; Mumper, Russell J

2002-01-01

355

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

356

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°C 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°C 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°C. 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

357

Transport of NaYF4:Er3+, Yb3+ up-converting nanoparticles into HeLa cells.  

PubMed

An effective, simple and practically useful method to incorporate fluorescent nanoparticles inside live biological cells was developed. The internalization time and concentration dependence of a frequently used liposomal transfection factor (Lipofectamine 2000) was studied. A user friendly, one-step technique to obtain water and organic solvent soluble Er(3+) and Yb(3+) doped NaYF4 nanoparticles coated with polyvinylpyrrolidone was obtained. Structural analysis of the nanoparticles confirmed the formation of nanocrystals of the desired sizes and spectral properties. The internalization of NaYF4 nanoparticles in HeLa cervical cancer cells was determined at different nanoparticle concentrations and for incubation periods from 3 to 24 h. The images revealed a redistribution of nanoparticles inside the cell, which increases with incubation time and concentration levels, and depends on the presence of the transfection factor. The study identifies, for the first time, factors responsible for an effective endocytosis of the up-converting nanoparticles to HeLa cells. Thus, the method could be applied to investigate a wide range of future 'smart' theranostic agents. Nanoparticles incorporated into the liposomes appear to be very promising fluorescent probes for imaging real-time cellular dynamics. PMID:23669145

Sikora, Bo?ena; Fronc, Krzysztof; Kami?ska, Izabela; Koper, Kamil; Szewczyk, Sebastian; Paterczyk, Bohdan; Wojciechowski, Tomasz; Sobczak, Kamil; Minikayev, Roman; Paszkowicz, Wojciech; St?pie?, Piotr; Elbaum, Danek

2013-06-14

358

Transport of NaYF4:Er3+, Yb3+ up-converting nanoparticles into HeLa cells  

NASA Astrophysics Data System (ADS)

An effective, simple and practically useful method to incorporate fluorescent nanoparticles inside live biological cells was developed. The internalization time and concentration dependence of a frequently used liposomal transfection factor (Lipofectamine 2000) was studied. A user friendly, one-step technique to obtain water and organic solvent soluble Er3+ and Yb3+ doped NaYF4 nanoparticles coated with polyvinylpyrrolidone was obtained. Structural analysis of the nanoparticles confirmed the formation of nanocrystals of the desired sizes and spectral properties. The internalization of NaYF4 nanoparticles in HeLa cervical cancer cells was determined at different nanoparticle concentrations and for incubation periods from 3 to 24 h. The images revealed a redistribution of nanoparticles inside the cell, which increases with incubation time and concentration levels, and depends on the presence of the transfection factor. The study identifies, for the first time, factors responsible for an effective endocytosis of the up-converting nanoparticles to HeLa cells. Thus, the method could be applied to investigate a wide range of future ‘smart’ theranostic agents. Nanoparticles incorporated into the liposomes appear to be very promising fluorescent probes for imaging real-time cellular dynamics.

Sikora, Bo?ena; Fronc, Krzysztof; Kami?ska, Izabela; Koper, Kamil; Szewczyk, Sebastian; Paterczyk, Bohdan; Wojciechowski, Tomasz; Sobczak, Kamil; Minikayev, Roman; Paszkowicz, Wojciech; St?pie?, Piotr; Elbaum, Danek

2013-06-01

359

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

360

Virus templated metallic nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

361

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

362

Conductivity changes in zinc oxide and magnesium zinc oxide nanoparticle films annealed in hydrogen ambient  

NASA Astrophysics Data System (ADS)

This dissertation explores the physics of how the electrical properties of ZnO and MgZnO nanoparticle films are modified when exposed to hydrogen gas at high temperatures. Specifically, with the goal of quantifying the ease of incorporation of the hydrogen atom and its properties as a donor. The nanoparticles were grown on insulating silicon substrates and had an average diameter of 40 nm. The devices were of a two terminal design, where the terminals consisted of two 25 mum diameter gold wires laid parallel to each other on the nanoparticle film to measure the current passing through the film. For the first set of experiments when nanoparticles were exposed to H 2 gas at room temperature, no significant changes in the current-voltage behavior of the nanoparticles were observed relative to measurements done in vacuum. Annealing in H2 below 370K resulted in no significant change in the current. Both the ZnO and MgZnO nanoparticle films showed significant changes at about the same threshold temperatures when annealed to 400K. A second set of experiments were carried out in temperatures up to 500K following the same procedure that showed similar but more complex behavior. The formation energy of hydrogen incorporation was calculated by analysis of the solubility of hydrogen in ZnO at various temperatures. Donor energy level of the nanoparticle films was also calculated by analyzing the post-doping conductivity in vacuum as a function of temperature. The origin of the change in I-V characteristics of ZnO and MgZnO nanoparticles when annealed in H2 ambient, the reasons for the differences of hydrogen doping results between nanoscale and bulk, and the mechanism of hydrogen behavior in the nanoparticle films will be discussed in detail.

Chava, Sirisha

363

Engineered Nanoparticles and Their Identification Among Natural Nanoparticles  

NASA Astrophysics Data System (ADS)

The more nanotechnology develops, the more likely the release of engineered nanoparticles into the environment becomes. Due to a huge excess of natural nanoparticles, the identification and quantification of engineered nanoparticles pose a big challenge to analysts. Moreover, identification in a qualitative sense and quantification by mass concentration alone are not sufficient, because the potential environmental hazard arising from engineered nanoparticles is controlled by many other properties of the particles. We discuss the most important methods of fractionation and detection of both natural and engineered nanoparticles, with a focus on the chemical nature of the particles, particle concentration, and particle size. Analyses should not rely on only one method; instead, several complementary methods should, if possible, be used. Coupled techniques should be further developed and increasingly applied. Dedicated techniques that are tailored to the search for a particular sort of engineered nanoparticles are more promising than universal approaches that search for any engineered nanoparticles.

Zänker, H.; Schierz, A.

2012-07-01

364

Coupled cavity lasers incorporating Bragg mirrors  

Microsoft Academic Search

We report results on a coupled cavity semiconductor laser incorporating a photonic bandgap mirror. This enhances fabrication tolerances over standard cleaving. We present numerical results and describe preliminary experiments.

D. H. Brown; M. B. Flynn; L. O'Faolain; W. Sibbett; T. F. Krauss

2003-01-01

365

Incorporating Spatial Ability Instruction in Teacher Preparation  

ERIC Educational Resources Information Center

This article provides a picture of the learning environment that is created for the preservice mathematics teacher and how development of spatial abilities can be incorporated into courses for these students. (Contains 3 figures.)

Sundberg, Sue E.; Goodman, Terry A.

2005-01-01

366

Novel bioactive scaffolds incorporating nanogels as potential drug eluting devices.  

PubMed

Big advances are being achieved in the design of new implantable devices with enhanced properties. For example, synthetic porous three-dimensional structures can mimic the architecture of the tissues, and serve as templates for cell seeding. In addition, polymeric nanoparticles are able to provide a programmable and sustained local delivery of different types of biomolecules. In this study novel alternative scaffolds with controlled bioactive properties and architectures are presented. Two complementary approaches are described. Firstly, scaffolds with nanogels as active controlled release devices incorporated inside the three-dimensional structure are obtained using the thermally induced phase separation (TIPS) method. Secondly, a novel coating method using the spraying technique to load these nanometric crosslinked hydrogels on the surface of two-dimensional (2D) and three-dimensional (3D) biodegradable scaffolds is described. The scanning electron microscopy (SEM) images show the distribution of the nanogels on the surface of different substrates and also inside the porous structure of poly-alpha-hydroxy ester derivative foams. Both of them are compared in terms of manufacturability, dispersion and other processing variables. PMID:20355508

Saez-Martinez, Virginia; Olalde, Beatriz; Juan, Maria Jesus; Jurado, Maria Jesus; Garagorri, Nerea; Obieta, Isabel

2010-04-01

367

In vitro Evaluation of Doxorubicin-Incorporated Magnetic Albumin Nanospheres.  

PubMed

Magnetic albumin nanospheres that incorporate doxorubicin (M-DOX-BSA-NPs) were prepared previously by our research group to develop magnetically responsive drug carrier system. This nanocarrier was synthesized as a drug delivery system for targeted chemotherapy. In this work, cytotoxic effects of doxorubicin (DOX)-loaded/unloaded or magnetic/non-magnetic nanoparticles and free DOX against PC-3 cells and A549 cells were determined with the MTT test and the results were compared with each other. DOX-loaded magnetic albumin nanospheres (M-DOX-BSA-NPs) were found more cytotoxic than other formulations. The quantitative data obtained from flow cytometry analysis further verified the higher targeting and killing ability of M-DOX-BSA-NPs than free DOX on both of the cancer cell lines. Additionally, the results of cell cycle analysis have showed that M-DOX-BSA-NPs affected G1 and G2 phases. Finally, cell images were obtained using spin-disk confocal microscopy, and cellular uptake of M-DOX-BSA-NPs was visualized. The findings of this study suggest that M-DOX-BSA-NPs represent a potential doxorubicin delivery system for targeted drug transport into prostate and lung cancer cells. PMID:24524300

Zeybek, Ayça; Sanl?-Mohamed, Gül?ah; Ak, Güliz; Y?lmaz, Habibe; Sanl?er, Senay H

2014-07-01

368

The Smart Targeting of Nanoparticles  

PubMed Central

One major challenge in nanomedicine is how to selectively deliver nanoparticles to diseased tissues. Nanoparticle delivery system requires targeting for specific delivery to pathogenic sites when enhanced permeability and retention (EPR) is not suitable or inefficient. Functionalizing nanoparticles is a widely-used technique that allows for conjugation with targeting ligands, which possess inherent ability to direct selective binding to cell types or states and, therefore, confer “smartness” to nanoparticles. This review illustrates methods of ligand-nanoparticle functionalization, provides a cross-section of various ligand classes, including small molecules, peptides, antibodies, engineered proteins, or nucleic acid aptamers, and discusses some unconventional approaches currently under investigation.

Friedman, Adam D.; Claypool, Sarah E.; Liu, Rihe

2014-01-01

369

Chitosan microparticles incorporating a hydrophilic sunscreen agent  

Microsoft Academic Search

A microparticulate delivery system incorporating the hydrophilic sunscreen agent, phenylbenzimidazole sulphonic acid (PBSA) was prepared for better in-use performance. Chitosan, not adequately considered for sunscreen delivery, was used a matrix material. Emulsion crosslinking with glutaraldehyde generated microparticles (MPs) with good features in terms of yield (?76%), size (24–100?m) and % incorporation efficiency (29–74%). PBSA release was sustained over 8h according

Yasmine A. Gomaa; Labiba K. El-Khordagui; Nabila A. Boraei; Inas A. Darwish

2010-01-01

370

Antibacterial efficacy of triclosan-incorporated polymers  

Microsoft Academic Search

Triclosan (2, 4, 4’-trichloro-2’-hydroxydiphenyl ether) is a broad-spectrum antimicrobial agent, routinely used in various personal care products.1 It is also incorporated into polymers through melt-mixing, with the aim of providing persistent antibacterial action on the surface of the polymer.2,3 Such triclosan-incorporated polymers can be promoted for hospital use as fabric seat covers, tables, chairs, and clothing. We assessed the antibacterial

Bilgé D. Kalyon; Ugursoy Olgun

2001-01-01

371

Incorporation of thrombospondin into fibrin clots  

SciTech Connect

Thrombospondin is a major platelet glycoprotein which is released from platelets during blood coagulation. The authors examined the interaction of thrombospondin with polymerizing fibrin. Thrombospondin, purified from human platelets and labeled with /sup 125/I, became incorporated into clots formed from both plasma and purified fibrinogen. Plasma clots contained somewhat less thrombospondin than clots formed from equivalent concentrations of fibrinogen. In plasma clots and fibrin clots formed in the presence of factor XIII, thrombospondin was cross-linked in the clot; thrombospondin in the supernatant remained largely monomeric. Cross-linking of thrombospondin by factor XIII, however, only slightly increased the amount of thrombospondin which was incorporated into the clot. In contrast, incorporation of /sup 125/I-fibronectin into clots was dependent upon cross-linking. Most of the incorporation of /sup 125/I-thrombospondin occurred during fibrin polymerization as judged by parallel studies of the incorporation of /sup 125/I-fibrinogen. The amount of thrombospondin incorporated into a clot was directly related to thrombospondin concentration and was only weakly dependent on fibrinogen concentration. Incorporation was not saturated at thrombospondin:fibrin (mol/mol) ratios as high as 2/1. Thrombospondin, however, modified the final structure of fibrin clots in a concentration-dependent manner as monitored by opacity. When tryptic digests of /sup 125/I-thrombospondin were studied, the 270-kilodalton core became incorporated into fibrin whereas the 30-kilodalton heparin binding fragment was excluded. These results indicate that thrombospondin specifically co-polymerizes with fibrin during blood coagulation and may be an important modulator of clot structure.

Bale, M.D.; Westrick, L.G.; Mosher, D.F.

1985-06-25

372

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.; Carrière, M.

2012-05-01

373

Virus templated metallic nanoparticles.  

PubMed

Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. ?35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron. PMID:20877898

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

2010-12-01

374

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

375

TOPICAL REVIEW: Biopolymeric nanoparticles  

NASA Astrophysics Data System (ADS)

This review on nanoparticles highlights the various biopolymers (proteins and polysaccharides) which have recently revolutionized the world of biocompatible and degradable natural biological materials. The methods of their fabrication, including emulsification, desolvation, coacervation and electrospray drying are described. The characterization of different parameters for a given nanoparticle, such as particle size, surface charge, morphology, stability, structure, cellular uptake, cytotoxicity, drug loading and drug release, is outlined together with the relevant measurement techniques. Applications in the fields of medicine and biotechnology are discussed along with a promising future scope.

Sundar, Sushmitha; Kundu, Joydip; Kundu, Subhas C.

2010-02-01

376

Biocatalytic Single Enzyme Nanoparticles  

SciTech Connect

As an innovative way of enzyme stabilization, we recently developed a new enzyme composite of nano-meter scale that we call "single-enzyme nanoparticles (SENs)" (9). Each enzyme molecule is surrounded with a porous composite organic/inorganic network of less than a few nanometers think. This approach represents a new type of enzyme-containing nanostructure. In experiments with perotease (chymotrypsin, CT), the activity of single enzyme nanoparticle form of the enzyme was greatly stabilized compared to the free form, without imposing a serious mass transfer limitation of substrates. In this chapter we will describe the synthesis, characterization and catalytic activity of the new SENs.

Grate, Jay W.; Kim, Jungbae

2004-03-31

377

PEGylated Inorganic Nanoparticles  

SciTech Connect

Application of inorganic nanoparticles in diagnosis and therapy has become a critical component in targeted treatment of diseases. The surface modification of inorganic oxides is important for providing diversity in size, shape, solubility, long term stability and attachment of selective functional groups. PEGylation of surfaces is a key strategic approach for providing stealth characteristics to nanomaterials otherwise identified as foreign materials by human body. The current review describes the role of surface modification of oxides by polyethylene glycol (PEG) in providing versatile characteristics to inorganic oxide nanoparticles with a focus on their biomedical applications. The role of PEG as structure directing agent in synthesis of oxides is also captured in this short review.

Karakoti, Ajay S.; Das, Soumya; Thevuthasan, Suntharampillai; Seal, Sudipta

2011-02-25

378

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; Matamá, Teresa; Loureiro, Ana; Gomes, Andreia C; Cavaco-Paulo, Artur

2013-03-01

379

Dual drug-loaded nanoparticles on self-integrated scaffold for controlled delivery  

PubMed Central

Antioxidant (quercetin) and hypoglycemic (voglibose) drug-loaded poly-D,L-lactideco-glycolide nanoparticles were successfully synthesized using the solvent evaporation method. The dual drug-loaded nanoparticles were incorporated into a scaffold film using a solvent casting method, creating a controlled transdermal drug-delivery system. Key features of the film formulation were achieved utilizing several ratios of excipients, including polyvinyl alcohol, polyethylene glycol, hyaluronic acid, xylitol, and alginate. The scaffold film showed superior encapsulation capability and swelling properties, with various potential applications, eg, the treatment of diabetes-associated complications. Structural and light scattering characterization confirmed a spherical shape and a mean particle size distribution of 41.3 nm for nanoparticles in the scaffold film. Spectroscopy revealed a stable polymer structure before and after encapsulation. The thermoresponsive swelling properties of the film were evaluated according to temperature and pH. Scaffold films incorporating dual drug-loaded nanoparticles showed remarkably high thermoresponsivity, cell compatibility, and ex vivo drug-release behavior. In addition, the hybrid film formulation showed enhanced cell adhesion and proliferation. These dual drug-loaded nanoparticles incorporated into a scaffold film may be promising for development into a transdermal drug-delivery system.

Bennet, Devasier; Marimuthu, Mohana; Kim, Sanghyo; An, Jeongho

2012-01-01

380

Nanoparticle-Based Biosensors and Bioassays  

SciTech Connect

In this book chapter, we review the recent advances in nanoparticles based bioassay. The nanoparticles include quantum dots, silica nanoparticles and apoferritin nanoparticles. The new nanoparticles-based labels hold great promise for multiplex protein and DNA detection and for enhancing the sensitivity of other bioassays.

Liu, Guodong; Wang, Jun; Lin, Yuehe; Wang, Joseph

2007-10-11

381

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°C). 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

2011-09-01

382

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

383

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

PubMed

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. PMID:24632943

Gutjahr, Johann; Sakong, Sung; Kratzer, Peter

2014-04-11

384

Magnetization and actuation of polymeric microstructures with magnetic nanoparticles for application in microfluidics  

Microsoft Academic Search

An increasing number of lab-on-a-chip devices require advanced fluid manipulations. We intend to address this requirement by incorporating polymeric responsive materials on the walls of the microfluidic channels of such devices. In this paper we present a magnetic polymer made from commercially available functionalized magnetic nanoparticles and PDMS. Loadings of this polymer up to 5% volume of magnetic material were

F. Fahrni; M. W. J. Prins; L. J. van IJzendoorn

2009-01-01

385

Gene expression analysis in rat lungs after intratracheal exposure to nanoparticles doped with cadmium  

Microsoft Academic Search

Silica nanoparticles (NPs) incorporating cadmium (Cd) have been developed for a range of potential application including drug delivery devices. Occupational Cd inhalation has been associated with emphysema, pulmonary fibrosis and lung tumours. Mechanistically, Cd can induce oxidative stress and mediate cell-signalling pathways that are involved in inflammation.This in vivo study aimed at investigating pulmonary molecular effects of NPs doped with

Teresa Coccini; Marco Fabbri; Elisa Roda; Maria Grazia Sacco; Luigi Manzo; Laura Gribaldo

2011-01-01

386

Enhanced gas separation performance of nanocomposite membranes using MgO nanoparticles  

Microsoft Academic Search

Gas separation membranes with enhanced performance were developed by the introduction of nanosized magnesium oxide particles followed by treatment with silver ions. Firstly, nanocomposite membranes were fabricated by incorporating nanoscale magnesium oxide particles with different loadings into the Matrimid matrix. The addition of MgO nanoparticles led to an increase in gas permeability of membranes; the highest permeability was observed for

Seyed Saeid Hosseini; Yi Li; Tai-Shung Chung; Ye Liu

2007-01-01

387

Positive contrast magnetic resonance imaging of cells labeled with magnetic nanoparticles  

Microsoft Academic Search

Contrast agents incorporating superparamagnetic iron-oxide nanoparticles have shown promise as a means to visualize labeled cells using MRI. Labeled cells cause significant signal dephasing due to the magnetic field inhomogeneity induced in water molecules near the cell. With the resulting signal void as the means for detection, the particles behave as a negative contrast agent, which can suffer from partial-volume

Charles H. Cunningham; Takayasu Arai; Phillip C. Yang; Michael V. McConnell; John M. Pauly; Steven M. Conolly

2005-01-01

388

Metal-containing nanoparticles and nano-structured particles in fingermark detection  

Microsoft Academic Search

This article reviews the application of metal-containing nanoparticles and nano-structured particles to fingermark detection. This area of research is attracting significant interest as advances in nanoscience are being incorporated into the field of forensic fingermark detection. Although more research is needed before some of the techniques presented can be implemented in routine casework, nanotechnology is likely to play a major

Mi Jung Choi; Andrew M. McDonagh; Philip Maynard; Claude Roux

2008-01-01

389

Targeting nanoparticles to cancer  

Microsoft Academic Search

Nanotechnology applications in medicine, termed as nanomedicine, have introduced a number of nanoparticles of variable chemistry and architecture for cancer imaging and treatment. Nanotechnology involves engineering multifunctional devices with dimensions at the nanoscale, similar dimensions as those of large biological vesicles or molecules in our body. These devices typically have features just tens to hundred nanometers across and they can

M. Wang; M. Thanou

2010-01-01

390

Interfacing biology with nanoparticles  

Microsoft Academic Search

New approaches are constantly being developed for both the synthesis of inorganic nanomaterials and their surface modification for sensing and electronic applications. Insofar as surface modification of gold nanoparticles is concerned, thiol chemistry is the most popular approach to bind ligands to their surface. We have been pursuing the possibility of using amine functionality to bind ligands to the surface

Saikat Mandal; Sumant Phadtare; Murali Sastry

2005-01-01

391

Nanoparticles in forensic science  

NASA Astrophysics Data System (ADS)

Nanoparticles appear in several areas of forensic science including security documents, paints, inks, and reagents that develop latent prints. One reagent (known as the silver physical developer) that visualizes the water insoluble components of latent print residue is based on the formation of highly charged silver nanoparticles. These attach to and grow on the residue and generate a silver image. Another such reagent involves highly charged gold nanoparticles. These attach to the residue forming a weak gold image which can be amplified with a silver physical developer. Nanoparaticles are also used in items such as paints, printing inks, and writing inks. Paints and most printing inks consist of nano-sized pigments in a vehicle. However, certain modern ink jet printing inks now contain nano-sized pigments to improve their light fastness and most gel inks are also based on nano scale pigments. These nanoparticlecontaining materials often appear as evidence and are thus subject to forensic characterization. Both luminescent (quantum dots), up-converting nano scale phosphors, and non luminescent nanoparticles are used as security tags to label product, add security to documents, and as anti counterfeiting measures. These assist in determining if an item is fraudulently made.

Cantu, Antonio A.

2008-10-01

392

Health implications of nanoparticles  

Microsoft Academic Search

Nanoparticles are increasingly used in a wide range of applications in science, technology and medicine. Since they are produced for specific purposes which cannot be met by larger particles and bulk material they are likely to be highly reactive, in particular, with biological systems. On the other hand a large body of know-how in environmental sciences is available from toxicological

Wolfgang G. Kreyling; Manuela Semmler-Behnke; Winfried Möller

2006-01-01

393

Starch nanoparticles: a review.  

PubMed

Starch is a natural, renewable, and biodegradable polymer produced by many plants as a source of stored energy. It is the second most abundant biomass material in nature. The starch structure has been under research for years, and because of its complexity, an universally accepted model is still lacking (Buleon, A.; et al. Int. J. Biol. Macromol. 1998, 23, 85-112). However, the predominant model for starch is a concentric semicrystalline multiscale structure that allows the production of new nanoelements: (i) starch nanocrystals resulting from the disruption of amorphous domains from semicrystalline granules by acid hydrolysis and (ii) starch nanoparticles produced from gelatinized starch. This paper intends to give a clear overview of starch nanoparticle preparation, characterization, properties, and applications. Recent studies have shown that they could be used as fillers to improve mechanical and barrier properties of biocomposites. Their use for industrial packaging, continuously looking for innovative solutions for efficient and sustainable systems, is being investigated. Therefore, recently, starch nanoparticles have been the focus of an exponentially increasing number of works devoted to develop biocomposites by blending starch nanoparticles with different biopolymeric matrices. To our knowledge, this topic has never been reviewed, despite several published strategies and conclusions. PMID:20405913

Le Corre, Déborah; Bras, Julien; Dufresne, Alain

2010-05-10

394

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 2–5 ppm and 7.4–9.0 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.

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

395

Mechanisms of copper incorporation into human ceruloplasmin.  

PubMed

Ceruloplasmin is a multicopper oxidase essential for normal iron homeostasis. To elucidate the mechanisms of copper incorporation into this protein, holoceruloplasmin biosynthesis was examined by immunoblot analysis and (64)Cu metabolic labeling of Chinese hamster ovary cells transfected with cDNAs encoding wild-type or mutant ceruloplasmin. This analysis reveals that the incorporation of copper into newly synthesized apoceruloplasmin in vivo results in a detectable conformational change in the protein. Strikingly, despite the unique functional role of each copper site within ceruloplasmin, metabolic studies indicate that achieving this final conformation-driven state requires the occupation of all six copper-binding sites with no apparent hierarchy for copper incorporation at any given site. Consistent with these findings a missense mutation (G631R), resulting in aceruloplasminemia and predicted to alter the interactions at a single type I copper-binding site, results in the synthesis and secretion only of apoceruloplasmin. Analysis of copper incorporation into apoceruloplasmin in vitro reveals that this process is cooperative and that the failure of copper incorporation into copper-binding site mutants observed in vivo is intrinsic to the mutant proteins. These findings reveal a precise and sensitive mechanism for the formation of holoceruloplasmin under the limiting conditions of copper availability within the cell that may be generally applicable to the biosynthesis of cuproproteins within the secretory pathway. PMID:12351628

Hellman, Nathan E; Kono, Satoshi; Mancini, Grazia M; Hoogeboom, A J; De Jong, G J; Gitlin, Jonathan D

2002-11-29

396

Synthesis and Characterization of Thermo-Sensitive Nanoparticles for Drug Delivery Applications  

PubMed Central

The aim of this research project was to develop new temperature sensitive nanoparticles that have a lower critical solution temperature (LCST) that is above body temperature and can be incorporated with various molecules at the surface. The poly(N-isopropylacrylamide-co-acrylamide-co-allylamine) (NIPA-AAm-AH) nanoparticles were synthesized through a free radical polymerization method. NIPA was polymerized with AAm and AH to increase the LCST and to provide amine groups for functionalization, respectively. Using transmission electron microscopy (TEM) and laser scattering technology, the sizes of these nanoparticles were found to be inversely proportional to the surfactant concentrations. In addition, the LCST of the 100-nm NIPA-AAm-AH nanoparticles was approximately 40 °C measured by a spectrophotometer. The chemical composition of the NIPA-AAm-AH nanoparticles determined with Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) also confirmed the presence of functional groups of each monomer. The nanoparticles were also successfully conjugated to bovine anti-rabbit IgG-Texas Red as a model for future bioconjugation. Furthermore, nanoparticles did not show significant cytotoxicity activity against human fibroblast cells. Finally, doxorubicin (DOX) was used in order to investigate the drug release profiles of the NIPA-AAm-AH nanoparticles at different temperatures. The results indicated that DOX was released more at 41 °C compared to that of 37 °C and 4 °C, which is evidence for temperature sensitivity of the nanoparticles. Future work will investigate the pharmacological and targeted capabilities of the synthesized nanoparticles conjugated to antibodies for possible application in controlled and targeted drug delivery.

Rahimi, Maham; Kilaru, Sunitha; Sleiman, Ghida El Hajj; Saleh, Anas; Rudkevich, Dmitry

2010-01-01

397

The preparation of size-controlled functionalized polymeric nanoparticles in micelles  

NASA Astrophysics Data System (ADS)

The reverse micellar system of dioctyl-sulfosuccinate (AOT)/octane and toluene have been used as a template for polymerization of acrylamide (AA)/bisacrylamide (BAA)-based functionalized polymeric nanoparticles. Such nanoparticles are typically sized between 20 and 90 nm. They can be synthesized with different functional groups according to the monomers added to the polymerization mixture. In our experiments the nanoparticles carried amino and carboxyl groups following