Layer-by-layer assembled multilayers using catalase-encapsulated gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kim, Sungwoo; Park, Jeongju [School of Advanced Materials Engineering, Kookmin University, Jeongneung-dong, Seongbuk-gu, Seoul 136-702 (Korea, Republic of); Cho, Jinhan, E-mail: jinhan71@korea.ac.kr [Department of Chemical and Biological Engineering, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-701 (Korea, Republic of)

2010-09-17

We introduce a novel and versatile approach for the preparation of multilayers, based on catalase-encapsulated gold nanoparticles (CAT-Au{sub NP}), allowing electrostatic charge reversal and structural transformation through pH adjustment. CAT-Au{sub NP}, which are synthesized directly from CAT stabilizer, can be electrostatically assembled with anionic and cationic PEs as a result of the charge reversal of the catalase stabilizers through pH control. In particular, at pH 5.2, near the pI of catalase, dispersed CAT-Au{sub NP} are structurally transformed into colloidal or network CAT-Au{sub NP} nanocomposites. Furthermore, we demonstrate that the layer-by-layer assembled multilayers composed of PEs and CAT-Au{sub NP} induce an effective electron transfer between CAT and the electrode as well as a high loading of CAT and Au{sub NP}, and resultantly exhibit a highly catalytic activity toward H{sub 2}O{sub 2}.

Self-Assembled Polyelectrolyte Nanoparticles as Fluorophore-Free Contrast Agents for Multicolor Optical Imaging

Directory of Open Access Journals (Sweden)

Da Hye Shin

2015-03-01

Full Text Available In this work, we describe the fabrication of self-assembled polyelectrolyte nanoparticles that provide a multicolor optical imaging modality. Poly(γ-glutamic acid(γ-PGA formed self-assembled nanoparticles through electrostatic interactions with two different cationic polymers: poly(L-lysine(PLL and chitosan. The self-assembled γ-PGA/PLL and γ-PGA/chitosan nanoparticles were crosslinked by glutaraldehyde. Crosslinking of the ionic self-assembled nanoparticles with glutaraldehyde not only stabilized the nanoparticles but also generated a strong autofluorescence signal. Fluorescent Schiff base bonds (C=N and double bonds (C=C were generated simultaneously by crosslinking of the amine moiety of the cationic polyelectrolytes with monomeric glutaraldehyde or with polymeric glutaraldehyde. The unique optical properties of the nanoparticles that resulted from the crosslinking by glutaraldehyde were analyzed using UV/Vis and fluorescence spectroscopy. We observed that the fluorescence intensity of the nanoparticles could be regulated by adjusting the crosslinker concentration and the reaction time. The nanoparticles also exhibited high performance in the labeling and monitoring of therapeutic immune cells (macrophages and dendritic cells. These self-assembled nanoparticles are expected to be a promising multicolor optical imaging contrast agent for the labeling, detection, and monitoring of cells.

Self-assembly of inorganic nanoparticles: Ab ovo

Science.gov (United States)

Kotov, Nicholas A.

2017-09-01

There are numerous remarkable studies related to the self-organization of polymers, coordination compounds, microscale particles, biomolecules, macroscale particles, surfactants, and reactive molecules on surfaces. The focus of this paper is on the self-organization of nanoscale inorganic particles or simply nanoparticles (NPs). Although there are fascinating and profound discoveries made with other self-assembling structures, the ones involving NPs deserve particular attention because they (a) are omnipresent in Nature; (b) have relevance to numerous disciplines (physics, chemistry, biology, astronomy, Earth sciences, and others); (c) embrace most of the features, geometries, and intricacies observed for the self-organization of other chemical species; (d) offer new tools for studies of self-organization phenomena; and (e) have a large economic impact, extending from energy and construction industries, to optoelectronics, biomedical technologies, and food safety. Despite the overall success of the field it is necessary to step back from its multiple ongoing research venues and consider two questions: What is self-assembly of nanoparticles? and Why do we need to study it? The reason to bring them up is to achieve greater scientific depth in the understanding of these omnipresent phenomena and, perhaps, deepen their multifaceted impact. Contribution to the Focus Issue Self-assemblies of Inorganic and Organic Nanomaterials edited by Marie-Paule Pileni.

Real time monitoring of superparamagnetic nanoparticle self-assembly on surfaces of magnetic recording media

International Nuclear Information System (INIS)

Ye, L.; Pearson, T.; Crawford, T. M.; Qi, B.; Cordeau, Y.; Mefford, O. T.

2014-01-01

Nanoparticle self-assembly dynamics are monitored in real-time by detecting optical diffraction from an all-nanoparticle grating as it self-assembles on a grating pattern recorded on a magnetic medium. The diffraction efficiency strongly depends on concentration, pH, and colloidal stability of nanoparticle suspensions, demonstrating the nanoparticle self-assembly process is highly tunable. This metrology could provide an alternative for detecting nanoparticle properties such as colloidal stability

Supramolecular domains in mixed peptide self-assembled monolayers on gold nanoparticles.

Science.gov (United States)

Duchesne, Laurence; Wells, Geoff; Fernig, David G; Harris, Sarah A; Lévy, Raphaël

2008-09-01

Self-organization in mixed self-assembled monolayers of small molecules provides a route towards nanoparticles with complex molecular structures. Inspired by structural biology, a strategy based on chemical cross-linking is introduced to probe proximity between functional peptides embedded in a mixed self-assembled monolayer at the surface of a nanoparticle. The physical basis of the proximity measurement is a transition from intramolecular to intermolecular cross-linking as the functional peptides get closer. Experimental investigations of a binary peptide self-assembled monolayer show that this transition happens at an extremely low molar ratio of the functional versus matrix peptide. Molecular dynamics simulations of the peptide self-assembled monolayer are used to calculate the volume explored by the reactive groups. Comparison of the experimental results with a probabilistic model demonstrates that the peptides are not randomly distributed at the surface of the nanoparticle, but rather self-organize into supramolecular domains.

Self-assembled rosette nanotubes encapsulate and slowly release dexamethasone

Directory of Open Access Journals (Sweden)

Chen Y

2011-05-01

Full Text Available Yupeng Chen1,2, Shang Song2, Zhimin Yan3, Hicham Fenniri3, Thomas J Webster2,41Department of Chemistry, Brown University, Providence, RI, USA; 2School of Engineering, Brown University, Providence, RI, USA; 3National Institute for Nanotechnology and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada; 4Department of Orthopedics, Brown University, Providence, RI, USAAbstract: Rosette nanotubes (RNTs are novel, self-assembled, biomimetic, synthetic drug delivery materials suitable for numerous medical applications. Because of their amphiphilic character and hollow architecture, RNTs can be used to encapsulate and deliver hydrophobic drugs otherwise difficult to deliver in biological systems. Another advantage of using RNTs for drug delivery is their biocompatibility, low cytotoxicity, and their ability to engender a favorable, biologically-inspired environment for cell adhesion and growth. In this study, a method to incorporate dexamethasone (DEX, an inflammatory and a bone growth promoting steroid into RNTs was developed. The drug-loaded RNTs were characterized using diffusion ordered nuclear magnetic resonance spectroscopy (DOSY NMR and UV-Vis spectroscopy. Results showed for the first time that DEX can be easily and quickly encapsulated into RNTs and released to promote osteoblast (bone-forming cell functions over long periods of time. As a result, RNTs are presented as a novel material for the targeted delivery of hydrophobic drugs otherwise difficult to deliver.Keywords: nanotubes, drug delivery, self-assembly, physiological conditions

RT Self-assembly of Silica Nanoparticles on Optical Fibres

DEFF Research Database (Denmark)

Canning, John; Lindoy, Lachlan; Huyang, George

2013-01-01

The room temperature deposition of self-assembling silica nanoparticles onto D-shaped optical fibres x201c;D-fibrex201d;), drawn from milled preforms fabricated by modified chemical vapor deposition, is studied and preliminary results reported here.......The room temperature deposition of self-assembling silica nanoparticles onto D-shaped optical fibres x201c;D-fibrex201d;), drawn from milled preforms fabricated by modified chemical vapor deposition, is studied and preliminary results reported here....

Synthesis of self-assembly plasmonic silver nanoparticles with tunable luminescence color

International Nuclear Information System (INIS)

Al-Ghamdi, Haifa S.; Mahmoud, Waleed E.

2014-01-01

Assembly is an elegant and effective bottom-up approach to prepare arrays of nanoparticles from nobel metals. Noble metal nanoparticles are perfect building blocks because they can be prepared with an adequate functionalization to allow their assembly and with controlled sizes. Herein, we report a novel recipe for the synthesis of self-assembled silver nanoparticles with tunable optical properties and sizes. The synthetic route followed here based on the covalent binding among silver nanoparticles by means of poly vinyl alcohol for the first time. The size of silver nanoparticle is governed by varying the amount of sodium borohydride. The as-synthesized nanoparticles were characterized by transmission electron microscopy, x-ray diffraction, energy dispersive x-ray spectroscopy, selected area electron diffraction and UV–vis spectroscopy. Results depicted that self-assembly of mono-dispersed silver nanoparticles with different sizes have been achieved. The silver nanostructure has a single crystalline faced centered cubic structure with growth orientation along (1 1 1) facet. These nanoparticles exhibited localized surface plasmon resonance at 403 nm. The luminescence peaks were red-sifted from violet to green due to the increase of the particle sizes. -- Highlights: • Self-assembled silver nanoparticles based PVA were synthesized. • NaBH 4 amount was found particle size dependent. • Silver nanoparticles strongly affected the surface plasmon resonance. • Highly symmetric luminescence emission band narrow width is obtained. • Dark field image showed a tunable color change from violet to green

Polarized neutron reflectivity from monolayers of self-assembled magnetic nanoparticles.

Science.gov (United States)

Mishra, D; Petracic, O; Devishvili, A; Theis-Bröhl, K; Toperverg, B P; Zabel, H

2015-04-10

We prepared monolayers of iron oxide nanoparticles via self-assembly on a bare silicon wafer and on a vanadium film sputter deposited onto a plane sapphire substrate. The magnetic configuration of nanoparticles in such a dense assembly was investigated by polarized neutron reflectivity. A theoretical model fit shows that the magnetic moments of nanoparticles form quasi domain-like configurations at remanence. This is attributed to the dipolar coupling amongst the nanoparticles.

Dynamics of nanoparticle self-assembly into superhydrophobic liquid marbles during water condensation.

Science.gov (United States)

Rykaczewski, Konrad; Chinn, Jeff; Walker, Marlon L; Scott, John Henry J; Chinn, Amy; Jones, Wanda

2011-12-27

Nanoparticles adsorbed onto the surface of a drop can fully encapsulate the liquid, creating a robust and durable soft solid with superhydrophobic characteristics referred to as a liquid marble. Artificially created liquid marbles have been studied for about a decade but are already utilized in some hair and skin care products and have numerous other potential applications. These soft solids are usually formed in small quantity by depositing and rolling a drop of liquid on a layer of hydrophobic particles but can also be made in larger quantities in an industrial mixer. In this work, we demonstrate that microscale liquid marbles can also form through self-assembly during water condensation on a superhydrophobic surface covered with a loose layer of hydrophobic nanoparticles. Using in situ environmental scanning electron microscopy and optical microscopy, we study the dynamics of liquid marble formation and evaporation as well as their interaction with condensing water droplets. We demonstrate that the self-assembly of nanoparticle films into three-dimensional liquid marbles is driven by multiple coalescence events between partially covered droplets and is aided by surface flows causing rapid nanoparticle film redistribution. We also show that droplet and liquid marble coalescence can occur due to liquid-to-liquid contact or squeezing of the two objects into each other as a result of compressive forces from surrounding droplets and marbles. Irrelevant of the mechanism, coalescence of marbles and drops can cause their rapid movement across and rolling off the edge of the surface. We also demonstrate that the liquid marbles randomly moving across the surface can be captured and immobilized by hydrophilic surface patterns.

Thermomechanical Response of Self-Assembled Nanoparticle Membranes

Energy Technology Data Exchange (ETDEWEB)

Wang, Yifan [Department; James; Chan, Henry [Center; Narayanan, Badri [Center; McBride, Sean P. [Department; Sankaranarayanan, Subramanian K. R. S. [Center; Lin, Xiao-Min [Center; Jaeger, Heinrich M. [Department; James

2017-07-21

Monolayers composed of colloidal nanoparticles, with a thickness of less than 10 nm, have remarkable mechanical moduli and can suspend over micrometer-sized holes to form free-standing membranes. In this paper, we discuss experiment's and coarse-grained molecular dynamics simulations characterizing the thermomechanical properties of these self-assembled nanoparticle membranes. These membranes remain strong and resilient up to temperatures much higher than previous simulation predictions and exhibit an unexpected hysteretic behavior during the first heating cooling cycle. We show this hysteretic behavior can be explained by an asymmetric ligand configuration from the self assembly process and can be controlled by changing the ligand coverage or cross-linking the ligand molecules. Finally, we show the screening effect of water molecules on the ligand interactions can strongly affect the moduli and thermomechanical behavior.

Diversity oriented high-throughput screening of 1,3,4-oxadiazole modified chlorophenylureas and halogenobenzamides by HPLC with peptidomimetic calixarene-bonded stationary phases.

Science.gov (United States)

Bazylak, Grzegorz; Malak, Anna; Ali, Imran; Borowiak, Teresa; Dutkiewicz, Grzegorz

2008-06-01

Retention profiles in series of the neutral and highly hydrophobic 1,3,4-oxadiazoles containing chlorophenylurea and halogenobenzamide moiety and indicating analgesic activity were determined in the isocratic standard- and narrow-bore HPLC systems employing, respectively, various octadecylsilica and different calixarene bonded stationary phases. When acetonitrile - 2.65 mM phosphoric acid (55 : 45, %, v/v), pH* 3.25, mobile phase was applied retention of these compounds increased with decline of their overall hydrophobicity according to the general preference of more polar compounds by calixarene cavity in time of its non-specific host-guest supramolecular interactions with halogenated substances. The size of calixarene nanocavity and its upper-rim substitution did not change the observed retention order, resolution and selectivity of separation for oxadiazoles. Compared to the retention on the non-end-capped and the highly-end-capped octadecylsilica HPLC column a most improved separation of some regioisomers of halogenated 1,3,4-oxadiazoles were observed on both used calixarene-type HPLC supports. In addition, preliminary data on the self-assembled supramolecular crystal structure of exemplary 1,3,4-oxadiazolchlorophenylurea with cis-elongated conformation was reported and formation of the monovalent inclusion host-guest complexes between 1,3,4-oxadiazoles and each calixarene-type stationary phase was studied with molecular modelling MM+ and AM1 methods. The structural, isomeric and energetic factors leading to the hydrogen bond stabilized inclusion complexes between these species were considered and used for explanation of observed retention sequence and selectivity of 1,3,4-oxadiazoles separation in applied calixarene-based HPLC systems. All these data would be useful in future development of optimized procedures enabling encapsulation of 1,3,4-oxadiazolurea-type drugs with calixarenes.

Atomically Precise Nanocluster Assemblies Encapsulating Plasmonic Gold Nanorods.

Science.gov (United States)

Chakraborty, Amrita; Fernandez, Ann Candice; Som, Anirban; Mondal, Biswajit; Natarajan, Ganapati; Paramasivam, Ganesan; Lahtinen, Tanja; Häkkinen, Hannu; Nonappa, Nonappa; Pradeep, Thalappil

2018-04-01

We present the self-assembled structures of atomically precise, ligand-protected noble metal nanoclusters leading to encapsulation of plasmonic gold nanorods (GNRs). Unlike highly sophisticated DNA nanotechnology, our approach demonstrates a strategically simple hydrogen bonding-directed self-assembly of nanoclusters leading to octahedral nanocrystals encapsulating GNRs. Specifically, we use the p-mercaptobenzoic acid (pMBA) protected atomically precise nanocluster, Na4[Ag44(pMBA)30] and pMBA functionalized GNRs. High resolution transmission and scanning transmission electron tomographic reconstructions suggest that the geometry of the GNR surface is responsible for directing the assembly of silver nanoclusters via H-bonding leading to octahedral symmetry. Further, use of water dispersible gold nanoclusters, Au~250(pMBA)n and Au102(pMBA)44 also formed layered shells encapsulating GNRs. Such cluster assemblies on colloidal particles present a new category of precision hybrids with diverse possibilities. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two-dimensional nanoparticle self-assembly using plasma-induced Ostwald ripening

International Nuclear Information System (INIS)

Tang, J; Photopoulos, P; Tsoukalas, D; Tserepi, A

2011-01-01

In this work, a novel Ag nanoparticle self-assembly process based on plasma-induced two-dimensional Ostwald ripening is demonstrated. Ag nanoparticles are deposited on p-doped Si substrates using a DC magnetron sputtering process. With the assistance of O 2 /Ar plasma treatment, different sizes and patterns of Ag nanoparticles are formed, due to the Ostwald ripening. The evolution of plasma-induced nanoparticle ripening is studied and a clear increase in particle size and a decrease in particle density are observed with increasing plasma treatment. From the experiments, it is concluded that the initial nanoparticle density and the plasma gas mixture (Ar/O 2 ratio) are important factors that affect the ripening process. The proposed plasma-directed Ag nanoparticle self-assembly provides a rapid method of tailoring the nanoparticle distribution on substrates, with potential applications in the fields of solar cells, biosensors, and catalysis.

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

Science.gov (United States)

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

2016-02-17

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

Self-assembled nanoparticles based on amphiphilic chitosan derivative and arginine for oral curcumin delivery

Directory of Open Access Journals (Sweden)

Raja MA

2016-09-01

Full Text Available Mazhar Ali Raja, Shah Zeenat, Muhammad Arif, Chenguang Liu College of Marine Life Science, Ocean University of China, Qingdao, Shandong, People’s Republic of China Abstract: Curcumin (Cur is a striking anticancer agent, but its low aqueous solubility, poor absorption, hasty metabolism, and elimination limit its oral bioavailability and consequently hinder its development as a drug. To redress these limitations, amphiphilic chitosan (CS conjugate with improved mucoadhesion and solubility over a wider pH range was developed by modification with hydrophobic acrylonitrile (AN and hydrophilic arginine (Arg; the synthesized conjugate (AN–CS–Arg, which was well characterized by Fourier transform infrared and 1H nuclear magnetic resonance spectroscopy. Results of critical aggregation concentration revealed that the AN–CS–Arg conjugate had low critical aggregation concentration and was prone to form self-assembled nanoparticles (NPs in aqueous medium. Cur-encapsulated AN–CS–Arg NPs (AN–CS–Arg/Cur NPs were developed by a simple sonication method and characterized for the physicochemical parameters such as zeta potential, particle size, and drug encapsulation. The results showed that zeta potential of the prepared NPs was 40.1±2.81 mV and the average size was ~218 nm. A considerable improvement in the aqueous solubility of Cur was observed after encapsulation into AN–CS–Arg/Cur NPs. With the increase in Cur concentration, loading efficiency increased but encapsulation efficiency decreased. The in vitro release profile exhibited sustained release pattern from the AN–CS–Arg/Cur NPs in typical biological buffers. The ex vivo mucoadhesion study revealed that AN–CS–Arg/Cur NPs had greater mucoadhesion than the control CS NPs. Compared with free Cur solution, AN–CS–Arg/Cur NPs showed stronger dose-dependent cytotoxicity against HT-29 cells. In addition, it was observed that cell uptake of AN–CS–Arg/Cur NPs was much higher

Self-assembled fluorescent organic nanoparticles for live cell imaging

NARCIS (Netherlands)

Fischer, I.; Petkau, K.; Dorland, Y.L.; Schenning, A.P.H.J.; Brunsveld, L.

2013-01-01

Fluorescent, cell-permeable, organic nanoparticles based on self-assembled p-conjugated oligomers with high absorption cross-sections and high quantum yields have been developed. The nanoparticles are generated with a tuneable density of amino groups for charge-mediated cellular uptake by a

Enhanced catalysis and enantioselective resolution of racemic naproxen methyl ester by lipase encapsulated within iron oxide nanoparticles coated with calix[8]arene valeric acid complexes.

Science.gov (United States)

Sayin, Serkan; Akoz, Enise; Yilmaz, Mustafa

2014-09-14

In this study, two types of nanoparticles have been used as additives for the encapsulation of Candida rugosa lipase via the sol-gel method. In one case, the nanoparticles were covalently linked with a new synthesized calix[8]arene octa valeric acid derivative (C[8]-C4-COOH) to produce new calix[8]arene-adorned magnetite nanoparticles (NP-C[8]-C4-COOH), and then NP-C[8]-C4-COOH was used as an additive in the sol-gel encapsulation process. In the other case, iron oxide nanoparticles were directly added into the sol-gel encapsulation process in order to interact electrostatically with both C[8]-C4-COOH and Candida rugosa lipase. The catalytic activities and enantioselectivities of two novel encapsulated lipases (Enc-NP-C[8]-C4-COOH and Enc-C[8]-C4-COOH@Fe3O4) in the hydrolysis reaction of racemic naproxen methyl ester were evaluated. The results showed that the activity and enantioselectivity of the lipase were improved when the lipase was encapsulated in the presence of calixarene-based additives. Indeed, the encapsulated lipases have an excellent rate of enantioselectivity, with E = 371 and 265, respectively, as compared to the free enzyme (E = 137). The lipases encapsulated with C[8]-C4-COOH and iron oxide nanoparticles (Enc-C[8]-C4-COOH@Fe3O4) retained more than 86% of their initial activities after 5 repeated uses and 92% with NP-C[8]-C4-COOH.

COVALENTLY ATTACHED MULTILAYER ULTRA-THIN FILMS FROM DIAZORESIN AND CALIXARENES

Institute of Scientific and Technical Information of China (English)

Zhao-hui Yang; Wei-xiao Cao

2003-01-01

A kind of photosensitive ultra-thin film was fabricated from diazoresin (DR) and various calixarenes by using the self-assembly technique. Under UV irradiation both the ionic- and hydrogen bonds between the layers of the film will convert into covalent bonds. As a result, the stability of the film toward polar solvents increases dramatically.

Characterization of self-assembled electrodes based on Au-Pt nanoparticles for PEMFC application

Energy Technology Data Exchange (ETDEWEB)

Valenzuela, E. [Politecnica Univ. de Chiapas, Tuxtla Gutierrez, Chiapas (Mexico). Energia y Sustentabilidad; Sebastian, P.J. [Politecnica Univ. de Chiapas, Chiapas (Mexico). Energia y Sustentabilidad; Centro de Investigacion en Energia, UNAM, Morelos (Mexico); Gamboa, S.A. [Centro de Investigacion en Energia, UNAM, Morelos (Mexico); Pal, U. [Inst. de Fisica, Universidad Autonoma de Puebla Univ., Puebla (Mexico). Inst. de Fisica; Gonzalez, I. [Autonoma Metropolitana Univ. (Mexico). Dept. de Quimica

2008-07-01

This paper reported on a study in which membrane electrode assemblies (MEAs) were fabricated by depositing Au, Pt and AuPt nanoparticles on Nafion 115 membrane for use in a proton exchange membrane fuel cell (PEMFC). A Rotating Disc Electrode (RDE) was used to measure the nanoparticle catalyst activity. After deposition of the nanoparticles on the membrane, the surface was studied by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The membrane proton conduction process was studied by Electrochemical Impedance Spectroscopy (EIS) with the 4 probe technique. The MEAs fabricated with Nafion/Metal membranes were evaluated in a PEMFC under standard conditions. Colloidal solutions were used to prepare self-assembled electrodes with nanoparticles deposited on Nafion membrane. The particles deposited on Nafion showed good stability and had homogeneous distribution along the membrane surface. The impedance results revealed an increase in the membrane proton resistance of the self-assembled electrodes compared to unmodified Nafion. The Au-Pt nanoparticles were obtained by chemical reduction. The nanoparticle size in the three systems was about 2 nm. The self-assembled electrodes performed well in standard conditions. The optimum colloidal concentration and immersion time must be determined in order to obtain good catalytic activity and high membrane conductance. The self-assembled Nafion/AuPt had the best open circuit potential (887 mV). The Au and Pt self-assemblies showed a similar performance in terms of maximum power and maximum current density. The performance of the Nafion/Au self-assembly was influenced more by ohmic losses, particularly in the membrane. The maximum power generation was obtained at 0.35 V. The mass transport losses increased after this value, thereby affecting the efficiency of the PEMFC. 2 figs.

The effect of Au amount on size uniformity of self-assembled Au nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Chen, S-H; Wang, D-C; Chen, G-Y; Chen, K-Y [Graduate School of Engineering Science and Technology, National Yunlin University of Science and Technology, Taiwan (China)

2008-03-15

The self-assembled fabrication of nanostructure, a dreaming approach in the area of fabrication engineering, is the ultimate goal of this research. A finding was proved through previous research that the size of the self-assembled gold nanoparticles could be controlled with the mole ratio between AuCl{sub 4}{sup -} and thiol. In this study, the moles of Au were fixed, only the moles of thiol were adjusted. Five different mole ratios of Au/S with their effect on size uniformity were investigated. The mole ratios were 1:1/16, 1:1/8, 1:1, 1:8, 1:16, respectively. The size distributions of the gold nanoparticles were analyzed by Mac-View analysis software. HR-TEM was used to derive images of self-assembled gold nanoparticles. The result reached was also the higher the mole ratio between AuCl{sub 4}{sup -} and thiol the bigger the self-assembled gold nanoparticles. Under the condition of moles of Au fixed, the most homogeneous nanoparticles in size distribution derived with the mole ratio of 1:1/8 between AuCl{sub 4}{sup -} and thiol. The obtained nanoparticles could be used, for example, in uniform surface nanofabrication, leading to the fabrication of ordered array of quantum dots.

Synthesis, characterization and self-assembly with gold nanoparticles

Indian Academy of Sciences (India)

Administrator

characterization and self-assembly with gold nanoparticles. JUN-BO LI. 1, ... gold surface lead to the enhancement of device prop- erties. 36,37 ... Reactions were monitored by thin-layer ..... plasmon (SP) absorption band (figure 5) of TOAB-.

Assembling RNA Nanoparticles.

Science.gov (United States)

Xiao, Shou-Jun

2017-01-01

RNA nanoparticles are designed and self-assembled according to noncanonical interactions of naturally conserved RNA motifs and/or canonical Watson-Crick base-pairing interactions, which have potential applications in gene therapy and nanomedicine. These artificially engineered nanoparticles are mainly synthesized from in vitro transcribed RNAs, purified by denaturing and native polyacrylamide gel electrophoresis (PAGE), and characterized with native PAGE, AFM, and TEM technologies. The protocols of in vitro transcription, denaturing and native PAGE, and RNA nanoparticle self-assembly are described in detail.

Self-Assembly of Gold Nanoparticles at the Liquid/Liquid Interface

International Nuclear Information System (INIS)

Lee, Kang Yeol; Han, Sang Woo

2005-01-01

We have shown that the crown ether derivative can mediate the transfer of gold nanoparticles in water solution to water/oil interface, results in directing the self-assembly of nanoparticles in the form of a novel nanocomposite film. The interfacial film of nanoparticles could be transferred to various solid substrates. The experimental results indicate the formation of nanoparticles monolayers at water/oil interfaces. Our work is an important step towards interfacial entrapment and self-assembly of nanoparticles for efficient creation of 2D nanostructures. These types of materials may be used in developing catalysts, sensors, and nanoelectronic devices. Currently, we are attempting to synthesize other composite films by using specific interactions between suitable organic or inorganic ligands and various nanoparticles. The intense research activity in the field of nanoparticles is motivated by the search for new materials in order to further miniaturize electronic devices, as well as by the fundamental question of how molecular electronic properties evolve with increasing size in this intermediate region between molecular and solid-state physics. In this respect, molecularly bridged nanoparticle aggregates have been attracting growing interest. The properties of two-dimensional assemblies of metal nanoparticles are controlled by the composition, geometry, and spatial arrangement of the nanoparticle building blocks. Such structures have been used for a variety of important applications in catalysis, photonics, electronics, and biological sensing. The 2D/3D control over the spatial arrangement of nanoparticles is primarily based on the thiolamphilic nature of metal nanoparticles, hydrogenbonding interactions, the highly specific recognition interaction of antigens/antibodies, and specific base-pairing interactions between DNA and its complementary strand

Self assembly of SiO2-encapsulated carbon microsphere composites

International Nuclear Information System (INIS)

Yang Yongzhen; Song Jingjing; Han Yanxing; Guo Xingmei; Liu Xuguang; Xu Bingshe

2011-01-01

SiO 2 was firstly coated onto the surface of carbon microspheres (CMSs) using tetraethyl orthosilicate (TEOS) as precursor by Stoeber method. Then SiO 2 -encapsulated CMS (CMS-SiO 2 ) composites were self-assembled by vertical deposition, in which the effects of deposition temperature and suspension concentration on the quality of self-assembling film were investigated. Morphologies and structures of the samples were characterized by field emission scanning electron microscopy, Fourier transformation infrared spectrometry, X-ray diffraction and thermogravimetry. The results show that uniform CMS-SiO 2 composites with good mono-dispersion were prepared by Stober method with 0.5 g of CMSs, 2 mL of TEOS, 30 mL of ammonia and 12 h of reaction time, the CMSs-based films with ordered and denser structure were prepared by vertical deposition using CMS-SiO 2 composites as monodipersion spheres under suspension concentration of 1 wt% and deposition temperature of 50 deg. C. The ultraviolet-visible absorption measurement shows that the absorbance of CMS-SiO 2 composite films grew steadily with increasing suspension concentration.

Protein-like Nanoparticles Based on Orthogonal Self-Assembly of Chimeric Peptides.

Science.gov (United States)

Jiang, Linhai; Xu, Dawei; Namitz, Kevin E; Cosgrove, Michael S; Lund, Reidar; Dong, He

2016-10-01

A novel two-component self-assembling chimeric peptide is designed where two orthogonal protein folding motifs are linked side by side with precisely defined position relative to one another. The self-assembly is driven by a combination of symmetry controlled molecular packing, intermolecular interactions, and geometric constraint to limit the assembly into compact dodecameric protein nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-assembly of coiled coil peptides into nanoparticles vs 2-d plates: effects of assembly pathway

Science.gov (United States)

Kim, Kyunghee; Pochan, Darrin

Molecular solution assembly, or self-assembly, is a process by which ordered nanostructures or patterns are formed by non-covalent interactions during assembly. Biomimicry, the use of bioinspired molecules or biologically relevant materials, is an important area of self-assembly research with peptides serving a critical role as molecular tools. The morphology of peptide assemblies can be controlled by adjusting solution conditions such as the concentration of peptides, the temperature, and pH. Herein, spherical nanostructures, which have potential for creating an encapsulation system, are formed by self-assembly when coiled coil peptides are combined in solution. These peptides are homotrimeric and heterodimeric coiled-coil bundles and the homotrimer is connected with each of heterodimer through their external surfaces via disulfide bonds. The resultant covalent constructs could co-assemble into complementary trimeric hubs, respectively. The two peptide constructs are directly mixed and assembled in solution in order to produce either spherical particles or 2-d plates depending on the solution conditions and kinetic pathway of assembly. In particular, structural changes of the self-assembled peptides are explored by control of the thermal history of the assembly solution.

Encapsulation of Curcumin in Self-Assembling Peptide Hydrogels as Injectable Drug Delivery Vehicles

Science.gov (United States)

Altunbas, Aysegul; Lee, Seung Joon; Rajasekaran, Sigrid A.; Schneider, Joel P.; Pochan, Darrin J.

2011-01-01

Curcumin, a hydrophobic polyphenol, is an extract of turmeric root with antioxidant, anti-inflammatory and anti-tumorigenic properties. Its lack of water solubility and relatively low bioavailability set major limitations for its therapeutic use. In this study, a self-assembling peptide hydrogel is demonstrated to be an effective vehicle for the localized delivery of curcumin over sustained periods of time. The curcumin-hydrogel is prepared in-situ where curcumin encapsulation within the hydrogel network is accomplished concurrently with peptide self-assembly. Physical and in vitro biological studies were used to demonstrate the effectiveness of curcumin-loaded β-hairpin hydrogels as injectable agents for localized curcumin delivery. Notably, rheological characterization of the curcumin loaded hydrogel before and after shear flow have indicated solid-like properties even at high curcumin payloads. In vitro experiments with a medulloblastoma cell line confirm that the encapsulation of the curcumin within the hydrogel does not have an adverse effect on its bioactivity. Most importantly, the rate of curcumin release and its consequent therapeutic efficacy can be conveniently modulated as a function of the concentration of the MAX8 peptide. PMID:21601921

Light-enabled reversible self-assembly and tunable optical properties of stable hairy nanoparticles

Science.gov (United States)

Chen, Yihuang; Wang, Zewei; He, Yanjie; Yoon, Young Jun; Jung, Jaehan; Zhang, Guangzhao; Lin, Zhiqun

2018-02-01

The ability to dynamically organize functional nanoparticles (NPs) via the use of environmental triggers (temperature, pH, light, or solvent polarity) opens up important perspectives for rapid and convenient construction of a rich variety of complex assemblies and materials with new structures and functionalities. Here, we report an unconventional strategy for crafting stable hairy NPs with light-enabled reversible and reliable self-assembly and tunable optical properties. Central to our strategy is to judiciously design amphiphilic star-like diblock copolymers comprising inner hydrophilic blocks and outer hydrophobic photoresponsive blocks as nanoreactors to direct the synthesis of monodisperse plasmonic NPs intimately and permanently capped with photoresponsive polymers. The size and shape of hairy NPs can be precisely tailored by modulating the length of inner hydrophilic block of star-like diblock copolymers. The perpetual anchoring of photoresponsive polymers on the NP surface renders the attractive feature of self-assembly and disassembly of NPs on demand using light of different wavelengths, as revealed by tunable surface plasmon resonance absorption of NPs and the reversible transformation of NPs between their dispersed and aggregated states. The dye encapsulation/release studies manifested that such photoresponsive NPs may be exploited as smart guest molecule nanocarriers. By extension, the star-like block copolymer strategy enables the crafting of a family of stable stimuli-responsive NPs (e.g., temperature- or pH-sensitive polymer-capped magnetic, ferroelectric, upconversion, or semiconducting NPs) and their assemblies for fundamental research in self-assembly and crystallization kinetics of NPs as well as potential applications in optics, optoelectronics, magnetic technologies, sensory materials and devices, catalysis, nanotechnology, and biotechnology.

Fabrication of Reductive-Responsive Prodrug Nanoparticles with Superior Structural Stability by Polymerization-Induced Self-Assembly and Functional Nanoscopic Platform for Drug Delivery.

Science.gov (United States)

Zhang, Wen-Jian; Hong, Chun-Yan; Pan, Cai-Yuan

2016-09-12

A highly efficient strategy, polymerization-induced self-assembly (PISA) for fabrication of the polymeric drug delivery systems in cancer chemotherapy is reported. Diblock prodrug copolymer, PEG-b-P(MEO2MA-co-CPTM) was used as the macro-RAFT agent to fabricate prodrug nanoparticles through PISA. The advantages of fabricating intelligent drug delivery system via this approach are as following: (1) Simultaneous fulfillment of polymerization, self-assembly, and drug encapsulation in one-pot at relatively high concentration (100 mg/mL); (2) Almost complete monomer conversion allows direct application of the resultant prodrug nanoparticles without further purification; (3) Robust structures of the resultant prodrug nanoparticles, because the cross-linker was used as the comonomer, resulted in core-cross-linking simultaneously with the formation of the prodrug nanoparticles; (4) The drug content in the resultant prodrug nanoparticles can be accurately modulated just via adjusting the feed molar ratio of MEO2MA/CPTM in the synthesis of PEG-b-P(MEO2MA-co-CPTM). The prodrug nanoparticles with similar diameters but various drug contents were obtained using different prodrug macro-CTA. In consideration of the long-term biological toxicity, the prodrug nanoparticles with higher drug content exhibit more excellent anticancer efficiency due to that lower dosage of them are enough for effectively killing HeLa cells.

Room temperature Coulomb blockade mediated field emission via self-assembled gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wang, Fei [College of Physics and Electronics, Central South University, Changsha, Hunan 410073 (China); College of Science, National University of Defense Technology, Changsha, Hunan 410073 (China); Fang, Jingyue, E-mail: fjynudt@aliyun.com [College of Science, National University of Defense Technology, Changsha, Hunan 410073 (China); Chang, Shengli; Qin, Shiqiao; Zhang, Xueao [College of Science, National University of Defense Technology, Changsha, Hunan 410073 (China); Xu, Hui, E-mail: cmpxhg@csu.edu.cn [College of Physics and Electronics, Central South University, Changsha, Hunan 410073 (China)

2017-02-05

Coulomb blockade mediated field-emission current was observed in single-electron tunneling devices based on self-assembled gold nanoparticles at 300 K. According to Raichev's theoretical model, by fixing a proper geometric distribution of source, island and drain, the transfer characteristics can be well explained through a combination of Coulomb blockade and field emission. Coulomb blockade and field emission alternately happen in our self-assembled devices. The Coulomb island size derived from the experimental data is in good agreement with the average size of the gold nanoparticles used in the device. The integrated tunneling can be adjusted via a gate electrode. - Highlights: • The phenomenon of single-electron field emission in a transistor setting using self-assembled gold nanoparticles was investigated. • The transfer characteristics can be well explained by the model that is a combination of Coulomb blockage and field emission. • This transport mechanism is novel and may be used in many applications in field emission devices.

Liquid-liquid interfacial nanoparticle assemblies

Science.gov (United States)

Emrick, Todd S [South Deerfield, MA; Russell, Thomas P [Amherst, MA; Dinsmore, Anthony [Amherst, MA; Skaff, Habib [Amherst, MA; Lin, Yao [Amherst, MA

2008-12-30

Self-assembly of nanoparticles at the interface between two fluids, and methods to control such self-assembly process, e.g., the surface density of particles assembling at the interface; to utilize the assembled nanoparticles and their ligands in fabrication of capsules, where the elastic properties of the capsules can be varied from soft to tough; to develop capsules with well-defined porosities for ultimate use as delivery systems; and to develop chemistries whereby multiple ligands or ligands with multiple functionalities can be attached to the nanoparticles to promote the interfacial segregation and assembly of the nanoparticles. Certain embodiments use cadmium selenide (CdSe) nanoparticles, since the photoluminescence of the particles provides a convenient means by which the spatial location and organization of the particles can be probed. However, the systems and methodologies presented here are general and can, with suitable modification of the chemistries, be adapted to any type of nanoparticle.

Self-assembling nanoparticles at surfaces and interfaces

NARCIS (Netherlands)

Kinge, S.S.; Crego Calama, Mercedes; Reinhoudt, David

2008-01-01

Nanoparticles are the focus of much attention due to their astonishing properties and numerous possibilities for applications in nanotechnology. For realising versatile functions, assembly of nanoparticles in regular patterns on surfaces and at interfaces is required. Assembling nanoparticles

Self-assembled nanotextures impart broadband transparency to glass windows and solar cell encapsulants

Science.gov (United States)

Liapis, Andreas C.; Rahman, Atikur; Black, Charles T.

2017-10-01

Most optoelectronic components and consumer display devices require glass or plastic covers for protection against the environment. Optical reflections from these encapsulation layers can degrade the device performance or lessen the user experience. Here, we use a highly scalable self-assembly based approach to texture glass surfaces at the nanoscale, reducing reflections by such an extent so as to make the glass essentially invisible. Our nanotextures provide broadband antireflection spanning visible and infrared wavelengths (450-2500 nm) that is effective even at large angles of incidence. This technology can be used to improve the performance of photovoltaic devices by eliminating reflection losses, which can be as much as 8% for glass encapsulated cells. In contrast, solar cells encapsulated with nanotextured glass generate the same photocurrent as when operated without a cover. Ultra-transparent windows having surface nanotextures on both sides can withstand three times more optical fluence than commercial broadband antireflection coatings, making them useful for pulsed laser applications.

Dendrimer-encapsulated nanoparticle-core micelles as a modular strategy for particle-in-a-box-in-a-box nanostructures.

Science.gov (United States)

Ten Hove, J B; Wang, J; van Leeuwen, F W B; Velders, A H

2017-12-07

The hierarchically controlled synthesis and characterization of self-assembling macromolecules and particles are key to explore and exploit new nanomaterials. Here we present a versatile strategy for constructing particle-in-a-box-in-a-box systems by assembling dendrimer-encapsulated gold nanoparticles (DENs) into dendrimicelles. This is realized by combining positively charged PAMAM dendrimers with a negative-neutral block copolymer. The number of particles per dendrimicelle can be controlled by mixing DENs with empty PAMAM dendrimers. The dendrimicelles are stable in solution for months and provide improved resistance for the nanoparticles against degradation. The dendrimicelle strategy provides a flexible platform with a plethora of options for variation in the type of nanoparticles, dendrimers and block copolymers used, and hence is tunable for applications ranging from nanomedicine to catalysis.

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

Science.gov (United States)

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

2014-11-04

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

Predicting Chiral Nanostructures, Lattices and Superlattices in Complex Multicomponent Nanoparticle Self-Assembly

KAUST Repository

Hur, Kahyun; Hennig, Richard G.; Escobedo, Fernando A.; Wiesner, Ulrich

2012-01-01

"Bottom up" type nanoparticle (NP) self-assembly is expected to provide facile routes to nanostructured materials for various, for example, energy related, applications. Despite progress in simulations and theories, structure prediction of self

Magnetic behavior of iron oxide nanoparticle-biomolecule assembly

International Nuclear Information System (INIS)

Kim, Taegyun; Reis, Lynn; Rajan, Krishna; Shima, Mutsuhiro

2005-01-01

Iron oxide nanoparticles of 8-20 nm in size were investigated as an assembly with biomolecules synthesized in an aqueous solution. The magnetic behavior of the biomolecule-nanoparticles assembly depends sensitively on the morphology and hence the distribution of the nanoparticles, where the dipole coupling between the nanoparticles governs the overall magnetic behavior. In assemblies of iron oxide nanoparticles with trypsin, we observe a formation of unusual self-alignment of nanoparticles within trypsin molecules. In such an assembly structure, the magnetic particles tend to exhibit a lower spin-glass transition temperature than as-synthesized bare iron oxide nanoparticles probably due to reduced interparticle couplings within the molecular matrix. The observed self-alignment of nanoparticles in biomolecules may be a useful approach for directed nanoparticles assembly

Self-assembly and flux closure studies of magnetic nanoparticle rings

DEFF Research Database (Denmark)

Wei, Alexander; Kasama, Takeshi; Dunin-Borkowski, Rafal E.

2011-01-01

Thermoremanent magnetic nanoparticles (MNPs) can self-assemble into rings through dipolar interactions, when dispersed under appropriate conditions. Analysis of individual MNP rings and clusters by off-axis electron holography reveals bistable flux closure (FC) states at ambient temperatures...

Self-assembly of core-polyethylene glycol-lipid shell (CPLS) nanoparticles and their potential as drug delivery vehicles

Science.gov (United States)

Shen, Zhiqiang; Loe, David T.; Awino, Joseph K.; Kröger, Martin; Rouge, Jessica L.; Li, Ying

2016-08-01

Herein a new multifunctional formulation, referred to as a core-polyethylene glycol-lipid shell (CPLS) nanoparticle, has been proposed and studied in silico via large scale coarse-grained molecular dynamics simulations. A PEGylated core with surface tethered polyethylene glycol (PEG) chains is used as the starting configuration, where the free ends of the PEG chains are covalently bonded with lipid molecules (lipid heads). A complete lipid bilayer is formed at the surface of the PEGylated particle core upon addition of free lipids, driven by the hydrophobic properties of the lipid tails, leading to the formation of a CPLS nanoparticle. The self-assembly process is found to be sensitive to the grafting density and molecular weight of the tethered PEG chains, as well as the amount of free lipids added. At low grafting densities the assembly of CPLS nanoparticles cannot be accomplished. As demonstrated by simulations, a lipid bud/vesicle can be formed on the surface when an excess amount of free lipids is added at high grafting density. Therefore, the CPLS nanoparticles can only be formed under appropriate conditions of both PEG and free lipids. The CPLS nanoparticle has been recognized to be able to store a large quantity of water molecules, particularly with high molecular weight of PEG chains, indicating its capacity for carrying hydrophilic molecules such as therapeutic biomolecules or imaging agents. Under identical size and surface chemistry conditions of a liposome, it has been observed that the CPLS particle can be more efficiently wrapped by the lipid membrane, indicating its potential for a greater efficiency in delivering its hydrophilic cargo. As a proof-of-concept, the experimental realization of CPLS nanoparticles is explicitly demonstrated in this study. To test the capacity of the CPLS to store small molecule cargo a hydrophilic dye was successfully encapsulated in the particles' water soluble layer. The results of this study show the power and

Self-assembly of gibberellic amide assemblies and their applications in the growth and fabrication of ordered gold nanoparticles

International Nuclear Information System (INIS)

Smoak, Evan M; Carlo, Andrew D; Fowles, Catherine C; Banerjee, Ipsita A

2010-01-01

Gibberellins are a group of naturally occurring diterpenoid based phytohormones that play a vital role in plant growth and development. In this work, we have studied the self-assembly of gibberellic acid, a phytohormone, which belongs to the family of gibberellins, and designed amide derivatives of gibberellic acid (GA 3 ) for the facile, green synthesis of gold nanoparticles. It was found that the derivatives self-assembled into nanofibers and nanoribbons in aqueous solutions at varying pH. Further, upon incubation with tetrachloroaurate, the self-assembled GA 3 -amide derivatives efficiently nucleated and formed gold nanoparticles when heated to 60 deg. C. Energy dispersive x-ray spectroscopy, transmission electron microscopy and scanning electron microscopy analyses revealed that uniform coatings of gold nanoparticles in the 10-20 nm range were obtained at low pH on the nanowire surfaces without the assistance of additional reducing agents. This simple method for the development of morphology controlled gold nanoparticles using a plant hormone derivative opens doors for a new class of plant biomaterials which can efficiently yield gold nanoparticles in an environmentally friendly manner. The gold encrusted nanowires formed using biomimetic methods may lead on to the formation of conductive nanowires, which may be useful for a wide range of applications such as in optoelectronics and sensors. Further, the spontaneous formation of highly organized nanostructures obtained from plant phytohormone derivatives such as gibberellic acid is of particular interest as it might help in further understanding the supramolecular assembly mechanism of more highly organized biological structures.

Nanoparticle assembled microcapsules for application as pH and ammonia sensor

International Nuclear Information System (INIS)

Amali, Arlin Jose; Awwad, Nour H.; Rana, Rohit Kumar; Patra, Digambara

2011-01-01

Graphical abstract: HPTS encapsulated nanoparticle assembled microcapsule is exploited as dual excitations ratiometic pH sensor. This nanoparticle assembled microcapsule based fluorescence sensor can determine ammonia and offers a robust, simple and fast sensing material. Highlights: ► A novel HPTS encapsulated nanoparticle assembled microcapsule is developed. ► Its dual excitation facilitates a ratiometic pH sensor. ► It is successfully applied for the determination of ammonia. ► It provides a robust, simple and fast sensing material. - Abstract: The encapsulation of molecular probes in a suitable nanostructured matrix can be exploited to alter their optical properties and robustness for fabricating efficient chemical sensors. Despite high sensitivity, simplicity, selectivity and cost effectiveness, the photo-destruction and photo-bleaching are the serious concerns while utilizing molecular probes. Herein we demonstrate that hydroxy pyrene trisulfonate (HPTS), a pH sensitive molecular probe, when encapsulated in a microcapsule structure prepared via the assembly of silica nanoparticles mediated by poly-L-lysine and trisodium citrate, provides a robust sensing material for pH sensing under the physiological conditions. The temporal evolution under continuous irradiation indicates that the fluorophore inside the silica microcapsule is extraordinarily photostable. The fluorescence intensity alternation at dual excitation facilitates for a ratiometic sensing of the pH, however, the fluorescence lifetime is insensitive to hydrogen ion concentration. The sensing scheme is found to be robust, fast and simple for the measurement of pH in the range 5.8–8.0, and can be successfully applied for the determination of ammonia in the concentration range 0–1.2 mM, which is important for aquatic life and the environment.

Linear-chain assemblies of iron oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Dhak, Prasanta; Kim, Min-Kwan; Lee, Jae Hyeok; Kim, Miyoung; Kim, Sang-Koog, E-mail: sangkoog@snu.ac.kr

2017-07-01

Highlights: • Hydrothermal synthesis of pure phase 200 nm Fe{sub 3}O{sub 4} nanoparticles. • Studies of linear-chain assemblies of iron oxide nanosphere by FESEM. • Micromagnetic simulations showed the presence of 3D vortex states. • The B.E. for different numbers of particles in linear chain assemblies were calculated. - Abstract: We synthesized iron oxide nanoparticles using a simple hydrothermal approach and found several types of segments of their linear-chain self-assemblies as observed by field emission scanning electron microscopy. X-ray diffraction and transmission electron microscopy measurements confirm a well-defined single-phase FCC structure. Vibrating sample magnetometry measurements exhibit a ferromagnetic behavior. Micromagnetic numerical simulations show magnetic vortex states in the nanosphere model. Also, calculations of binding energies for different numbers of particles in the linear-chain assemblies explain a possible mechanism responsible for the self-assemblies of segments of the linear chains of nanoparticles. This work offers a step towards linear-chain self-assemblies of iron oxide nanoparticles and the effect of magnetic vortex states in individual nanoparticles on their binding energy.

The Self-Assembly of Nanogold for Optical Metamaterials

Science.gov (United States)

Nidetz, Robert A.

2011-12-01

Optical metamaterials are an emerging field that enables manipulation of light like never before. Producing optical metamaterials requires sub-wavelength building blocks. The focus here was to develop methods to produce building blocks for metamaterials from nanogold. Electron-beam lithography was used to define an aminosilane patterned chemical template in order to electrostatically self-assemble citrate-capped gold nanoparticles. Equilibrium self-assembly was achieved in 20 minutes by immersing chemical templates into gold nanoparticle solutions. The number of nanoparticles that self-assembled on an aminosilane dot was controlled by manipulating the diameters of the dots and nanoparticles. Adding salt to the nanoparticle solution enabled the nanoparticles to self-assemble in greater numbers on the same sized dot. However, the preparation of the nanoparticle solution containing salt was sensitive to spikes in the salt concentration which led to aggregation of the nanoparticles and non-specific deposition. Gold nanorods were also electrostatically self-assembled. Polyelectrolyte-coated gold nanorods were patterned with limited success. A polyelectrolyte chemical template also patterned gold nanorods, but the gold nanorods preferred to pattern on the edges of the pattern. Ligand-exchanged gold nanorods displayed the best self-assembly, but suffered from slow kinetics. Self-assembled gold nanoparticles were cross-linked with poly(diallyldimethylammonium chloride). The poly(diallyldimethylammonium chloride) allowed additional nanoparticles to pattern on top of the already patterned nanoparticles. Cross-linked nanoparticles were lifted-off of the substrate by sonication in a sodium hydroxide solution. The presence of van der Waals forces and/or amine bonding prevent the nanogold from lifting-off without sonication. A good-solvent evaporation process was used to self-assemble poly(styrene) coated gold nanoparticles into spherical microbead assemblies. The use of larger

Electrochromic properties of self-assembled nanoparticle multilayer films

International Nuclear Information System (INIS)

Xue Bo; Li Hong; Zhang Lanlan; Peng Jun

2010-01-01

Hexagonal tungsten bronze (HTB) nanocrystal and TiO 2 nanoparticles were assembled into thin films by layer-by-layer self-assembly method. HTB nanocrystals were synthesized by hydrothermal route at 155 o C. UV-Vis spectra showed that the HTB/TiO 2 films exhibit a linear increase in film thickness with assembly exposure steps. The electrochromic property of the film was carefully investigated. Cyclic voltammetry indicated that the redox peak was around -0.5 V. The electrochromic contrast, coloration efficiency, switching speed, stability and optical memory were carefully investigated. The films vary from white to blue and finally dark brown. The electrochromic contrast is 63.9% at 633 nm. The coloration efficiency of the films is relatively high. The response time is less than 3 s.

In Vitro Investigation of Self-Assembled Nanoparticles Based on Hyaluronic Acid-Deoxycholic Acid Conjugates for Controlled Release Doxorubicin: Effect of Degree of Substitution of Deoxycholic Acid

Directory of Open Access Journals (Sweden)

Wen-Hao Wei

2015-03-01

Full Text Available Self-assembled nanoparticles based on a hyaluronic acid-deoxycholic acid (HD chemical conjugate with different degree of substitution (DS of deoxycholic acid (DOCA were prepared. The degree of substitution (DS was determined by titration method. The nanoparticles were loaded with doxorubicin (DOX as the model drug. The human cervical cancer (HeLa cell line was utilized for in vitro studies and cell cytotoxicity of DOX incorporated in the HD nanoparticles was accessed by the 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay. In addition, cellular uptake of fluorescently labeled nanoparticles was also investigated. An increase in the degree of deoxycholic acid substitution reduced the size of the nanoparticles and also enhanced their drug encapsulation efficiency (EE, which increased with the increase of DS. A higher degree of deoxycholic acid substitution also lead to a lower release rate and an initial burst release of doxorubicin from the nanoparticles. In summary, the degree of substitution allows the modulation of the particle size, drug encapsulation efficiency, drug release rate, and cell uptake efficiency of the nanoparticles. The herein developed hyaluronic acid-deoxycholic acid conjugates are a good candidate for drug delivery and could potentiate therapeutic formulations for doxorubicin–mediated cancer therapy.

Review and outlook: from single nanoparticles to self-assembled monolayers and granular GMR sensors

Directory of Open Access Journals (Sweden)

Alexander Weddemann

2010-11-01

Full Text Available This paper highlights recent advances in synthesis, self-assembly and sensing applications of monodisperse magnetic Co and Co-alloyed nanoparticles. A brief introduction to solution phase synthesis techniques as well as the magnetic properties and aspects of the self-assembly process of nanoparticles will be given with the emphasis placed on selected applications, before recent developments of particles in sensor devices are outlined. Here, the paper focuses on the fabrication of granular magnetoresistive sensors by the employment of particles themselves as sensing layers. The role of interparticle interactions is discussed.

Self-assembling process of flash nanoprecipitation in a multi-inlet vortex mixer to produce drug-loaded polymeric nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Shen Hao [University of Illinois at Chicago, Department of Chemical Engineering (United States); Hong, Seungpyo [University of Illinois at Chicago, Department of Biopharmaceutical Sciences (United States); Prud' homme, Robert K. [Princeton University, Department of Chemical Engineering (United States); Liu Ying, E-mail: liuying@uic.edu [University of Illinois at Chicago, Department of Chemical Engineering (United States)

2011-09-15

We present an experimental study of self-assembled polymeric nanoparticles in the process of flash nanoprecipitation using a multi-inlet vortex mixer (MIVM). {beta}-Carotene and polyethyleneimine (PEI) are used as a model drug and a macromolecule, respectively, and encapsulated in diblock copolymers. Flow patterns in the MIVM are microscopically visualized by mixing iron nitrate (Fe(NO{sub 3}){sub 3}) and potassium thiocyanate (KSCN) to precipitate Fe(SCN){sub x}{sup (3-x)+}. Effects of physical parameters, including Reynolds number, supersaturation rate, interaction force, and drug-loading rate, on size distribution of the nanoparticle suspensions are investigated. It is critical for the nanoprecipitation process to have a short mixing time, so that the solvent replacement starts homogeneously in the reactor. The properties of the nanoparticles depend on the competitive kinetics of polymer aggregation and organic solute nucleation and growth. We report the existence of a threshold Reynolds number over which nanoparticle sizes become independent of mixing. A similar value of the threshold Reynolds number is confirmed by independent measurements of particle size, flow-pattern visualization, and our previous numerical simulation along with experimental study of competitive reactions in the MIVM.

Self-assembling chimeric polypeptide-doxorubicin conjugate nanoparticles that abolish tumours after a single injection

Science.gov (United States)

Andrew Mackay, J.; Chen, Mingnan; McDaniel, Jonathan R.; Liu, Wenge; Simnick, Andrew J.; Chilkoti, Ashutosh

2009-12-01

New strategies to self-assemble biocompatible materials into nanoscale, drug-loaded packages with improved therapeutic efficacy are needed for nanomedicine. To address this need, we developed artificial recombinant chimeric polypeptides (CPs) that spontaneously self-assemble into sub-100-nm-sized, near-monodisperse nanoparticles on conjugation of diverse hydrophobic molecules, including chemotherapeutics. These CPs consist of a biodegradable polypeptide that is attached to a short Cys-rich segment. Covalent modification of the Cys residues with a structurally diverse set of hydrophobic small molecules, including chemotherapeutics, leads to spontaneous formation of nanoparticles over a range of CP compositions and molecular weights. When used to deliver chemotherapeutics to a murine cancer model, CP nanoparticles have a fourfold higher maximum tolerated dose than free drug, and induce nearly complete tumour regression after a single dose. This simple strategy can promote co-assembly of drugs, imaging agents and targeting moieties into multifunctional nanomedicines.

Rationally Designed, Multifunctional Self-Assembled Nanoparticles for Covalently Networked, Flexible and Self-Healable Superhydrophobic Composite Films.

Science.gov (United States)

Lee, Yujin; You, Eun-Ah; Ha, Young-Geun

2018-03-21

For constructing bioinspired functional films with various superhydrophobic functions, including self-cleaning, anticorrosion, antibioadhesion, and oil-water separation, hydrophobic nanomaterials have been widely used as crucial structural components. In general, hydrophobic nanomaterials, however, cannot form strong chemical bond networks in organic-inorganic hybrid composite films because of the absence of chemically compatible binding components. Herein, we report the rationally designed, multifunctional self-assembled nanoparticles with tunable functionalities of covalent cross-linking and hydrophobicity for constructing three-dimensionally interconnected superhydrophobic composite films via a facile solution-based fabrication at room temperature. The multifunctional self-assembled nanoparticles allow the systematic control of functionalities of composite films, as well as the stable formation of covalently linked superhydrophobic composite films with excellent flexibility (bending radii of 6.5 and 3.0 mm, 1000 cycles) and self-healing ability (water contact angle > 150°, ≥10 cycles). The presented strategy can be a versatile and effective route to generating other advanced functional films with covalently interconnected composite networks.

Self-assembling nanoparticles encapsulating zoledronic acid inhibit mesenchymal stromal cells differentiation, migration and secretion of proangiogenic factors and their interactions with prostate cancer cells

Czech Academy of Sciences Publication Activity Database

Borghese, C.; Casagrande, N.; Pivetta, E.; Colombatti, A.; Boccellino, M.; Amler, Evžen; Normanno, N.; Caraglia, M.; de Rosa, G.; Aldinucci, D.

2017-01-01

Roč. 8, č. 26 (2017), s. 42926-42938 ISSN 1949-2553 Institutional support: RVO:68378041 Keywords : zoledronic acid * self-assembling nanoparticles * mesenchymal stromal cells * prostate cancer * tumor microenvironment Subject RIV: FP - Other Medical Disciplines OBOR OECD: Technologies involving the manipulation of cells, tissues, organs or the whole organism (assisted reproduction) Impact factor: 5.168, year: 2016

Self-assembly of cyclodextrins

DEFF Research Database (Denmark)

Fülöp, Z.; Kurkov, S.V.; Nielsen, T.T.

2012-01-01

The design of functional cyclodextrin (CD) nanoparticles is a developing area in the field of nanomedicine. CDs can not only help in the formation of drug carriers but also increase the local concentration of drugs at the site of action. CD monomers form aggregates by self-assembly, a tendency...... that increases upon formation of inclusion complexes with lipophilic drugs. However, the stability of such aggregates is not sufficient for parenteral administration. In this review CD polymers and CD containing nanoparticles are categorized, with focus on self-assembled CD nanoparticles. It is described how...

Highly ordered self-assembly of one-dimensional nanoparticles in amphiphilic molecular systems

International Nuclear Information System (INIS)

Kim, Tae Hwan

2009-02-01

Two kinds of one-dimensional (1D) nanoparticles, stable rod-like nanoparticles with highly controlled surface charge density (cROD) and non-covalently functionalized isolated single wall carbon nanotubes (p-SWNT) that were readily redispersible in water, have been developed. Using these 1D nanoparticles, various highly ordered superstructures of 1D nanoparticles by molecular self-assembling based on electrostatic interaction in amphiphilic molecular systems (two different cationic liposome systems) have been investigated. To our knowledge, this is the first demonstration of highly ordered self-assembly of 1D nanoparticles based on electrostatic interaction between 1D nanoparticles and amphiphilic molecules. The cRODs have been developed by free radical polymerization of a mixture of polymerizable cationic surfactant, cetyltrimethylammonium 4-vinylbenzoate (CTVB), and hydrotropic salt sodium 4-styrenesulfonate (NaSS) in aqueous solution. The surface charge of the cROD was controlled by varying the NaSS concentration during the polymerization process and the charge variation was interpreted in terms of the overcharging effect in colloidal systems. The small angle neutron scattering (SANS) measurements showed that the diameter of cROD is constant at 4 nm and the particle length ranges from 20 nm to 85 nm, depending on the NaSS concentration. The cRODs are longest when the NaSS concentration is 5 mol % which corresponds to the charge inversion or neutral point. The SANS and zeta potential measurements showed that the Coulomb interactions between the particles are strongly dependent on the NaSS concentration and the zeta potential of the cRODs changes from positive to negative (+ 12.8 mV ∼ - 44.2 mV) as the concentration of NaSS increases from 0 mol % to 40 mol %. As the NaSS concentration is further increased, the zeta potential is saturated at approximately - 50 mV. The p-SWNTs have been developed by 1) dispersing single wall carbon nanotubes (SWNTs) in water using

Glutamate decarboxylase-derived IDDM autoantigens displayed on self-assembled protein nanoparticles

International Nuclear Information System (INIS)

Choi, Hyoung; Ahn, Ji-Young; Sim, Sang Jun; Lee, Jeewon

2005-01-01

The recombinant ferritin heavy chain (FTN-H) formed self-assembled spherical nanoparticles with the size comparable to native one. We tried to express the GAD65 COOH-terminal fragments, i.e., 448-585 (GAD65 448-585 ), 487-585 (GAD65 487-585 ), and 512-585 (GAD65 512-585 ) amino acid fragments, using FTN-H as N-terminus fusion expression partner in Escherichia coli. All of recombinant fusion proteins (FTN-H::GAD65 448-585 , FTN-H::GAD65 487-585 , and FTN-H::GAD65 512-585 ) also formed spherical nanoparticles due probably to the self-assembly function of the fused ferritin heavy chain. The antigenic epitopes within GAD65 448-585 , GAD65 487-585 , and GAD65 512-585 against insulin-dependent diabetes mellitus (IDDM) marker (autoantibodies against GAD65) were localized at the surface of the spherical protein nanoparticles so that anti-GAD65 Ab could recognize them. Protein nanoparticles like FTN-H seem to provide distinct advantages over other inorganic nanoparticles (e.g., Au, Ag, CdSe, etc.) in that through the bacterial synthesis, the active capture probes can be located at the nanoparticle surface with constant orientation/conformation via covalent cross-linking without complex chemistry. Also it is possible for the protein nanoparticles to have uniform particle size, which is rarely achieved in the chemical synthesis of inorganic nanoparticles. Thus, the recombinant ferritin particles can be used as a three-dimensional (spherical) and nanometer-scale probe structure that is a key component in ultra-sensitive protein chip for detecting protein-small molecule interactions and protein-protein interactions

Self-assembled gemcitabine-gadolinium nanoparticles for magnetic resonance imaging and cancer therapy.

Science.gov (United States)

Li, Lele; Tong, Rong; Li, Mengyuan; Kohane, Daniel S

2016-03-01

Nanoparticles with combined diagnostic and therapeutic functions are promising tools for cancer diagnosis and treatment. Here, we demonstrate a theranostic nanoparticle that integrates an active gemcitabine metabolite and a gadolinium-based magnetic resonance imaging agent via a facile supramolecular self-assembly synthesis, where the anti-cancer drug gemcitabine-5'-monophosphate (a phosphorylated active metabolite of the anti-cancer drug gemcitabine) was used to coordinate with Gd(III) to self-assemble into theranostic nanoparticles. The formulation exhibits a strong T1 contrast signal for magnetic resonance imaging of tumors in vivo, with enhanced retention time. Furthermore, the nanoparticles did not require other inert nanocarriers or excipients and thus had an exceptionally high drug loading (55 wt%), resulting in the inhibition of MDA-MB-231 tumor growth in mice. Recent advances in nanoparticle-based drug delivery systems have spurred the development of "theranostic" multifunctional nanoparticles, which combine therapeutic and diagnostic functionalities in a single formulation. Developing simple and efficient synthetic strategies for the construction of nanotheranostics with high drug loading remains a challenge. Here, we demonstrate a theranostic nanoparticle that integrates high loadings of an active gemcitabine metabolite and a gadolinium-based magnetic resonance imaging agent via a facile synthesis. The nanoparticles were better T1 contrast agents than currently used Gd-DTPA and had prolonged retention in tumor. Moreover they exhibited enhanced in vivo antitumor activity compared to free drug in a breast cancer xenograft mouse model. The strategy provides a scalable way to fabricate nanoparticles that enables enhancement of both therapeutic and diagnostic capabilities. Published by Elsevier Ltd.

Graphene-encapsulated hollow Fe₃O₄ nanoparticle aggregates as a high-performance anode material for lithium ion batteries.

Science.gov (United States)

Chen, Dongyun; Ji, Ge; Ma, Yue; Lee, Jim Yang; Lu, Jianmei

2011-08-01

Graphene-encapsulated ordered aggregates of Fe(3)O(4) nanoparticles with nearly spherical geometry and hollow interior were synthesized by a simple self-assembly process. The open interior structure adapts well to the volume change in repetitive Li(+) insertion and extraction reactions; and the encapsulating graphene connects the Fe(3)O(4) nanoparticles electrically. The structure and morphology of the graphene-Fe(3)O(4) composite were confirmed by X-ray diffraction, scanning electron microscopy, and high-resolution transmission microscopy. The electrochemical performance of the composite for reversible Li(+) storage was evaluated by cyclic voltammetry and constant current charging and discharging. The results showed a high and nearly unvarying specific capacity for 50 cycles. Furthermore, even after 90 cycles of charge and discharge at different current densities, about 92% of the initial capacity at 100 mA g(-1) was still recoverable, indicating excellent cycle stability. The graphene-Fe(3)O(4) composite is therefore a capable Li(+) host with high capacity that can be cycled at high rates with good cycle life. The unique combination of graphene encapsulation and a hollow porous structure definitely contributed to this versatile electrochemical performance.

Multifunctional Nanoparticles Self-Assembled from Small Organic Building Blocks for Biomedicine.

Science.gov (United States)

Xing, Pengyao; Zhao, Yanli

2016-09-01

Supramolecular self-assembly shows significant potential to construct responsive materials. By tailoring the structural parameters of organic building blocks, nanosystems can be fabricated, whose performance in catalysis, energy storage and conversion, and biomedicine has been explored. Since small organic building blocks are structurally simple, easily modified, and reproducible, they are frequently employed in supramolecular self-assembly and materials science. The dynamic and adaptive nature of self-assembled nanoarchitectures affords an enhanced sensitivity to the changes in environmental conditions, favoring their applications in controllable drug release and bioimaging. Here, recent significant research advancements of small-organic-molecule self-assembled nanoarchitectures toward biomedical applications are highlighted. Functionalized assemblies, mainly including vesicles, nanoparticles, and micelles are categorized according to their topological morphologies and functions. These nanoarchitectures with different topologies possess distinguishing advantages in biological applications, well incarnating the structure-property relationship. By presenting some important discoveries, three domains of these nanoarchitectures in biomedical research are covered, including biosensors, bioimaging, and controlled release/therapy. The strategies regarding how to design and characterize organic assemblies to exhibit biomedical applications are also discussed. Up-to-date research developments in the field are provided and research challenges to be overcome in future studies are revealed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-Assembly of Octopus Nanoparticles into Pre-Programmed Finite Clusters

Science.gov (United States)

Halverson, Jonathan; Tkachenko, Alexei

2012-02-01

The precise control of the spatial arrangement of nanoparticles (NP) is often required to take full advantage of their novel optical and electronic properties. NPs have been shown to self-assemble into crystalline structures using either patchy surface regions or complementary DNA strands to direct the assembly. Due to a lack of specificity of the interactions these methods lead to only a limited number of structures. An emerging approach is to bind ssDNA at specific sites on the particle surface making so-called octopus NPs. Using octopus NPs we investigate the inverse problem of the self-assembly of finite clusters. That is, for a given target cluster (e.g., arranging the NPs on the vertices of a dodecahedron) what are the minimum number of complementary DNA strands needed for the robust self-assembly of the cluster from an initially homogeneous NP solution? Based on the results of Brownian dynamics simulations we have compiled a set of design rules for various target clusters including cubes, pyramids, dodecahedrons and truncated icosahedrons. Our approach leads to control over the kinetic pathway and has demonstrated nearly perfect yield of the target.

Encapsulation of dye molecules into mesoporous polymer resin and mesoporous polymer-silica films by an evaporation-induced self-assembly method

Energy Technology Data Exchange (ETDEWEB)

Chi Yue; Li Nan; Tu Jinchun; Zhang Yujie [School of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, Changchun 130012 (China); Li Xiaotian, E-mail: xiaotianli@jlu.edu.c [School of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, Changchun 130012 (China); Shao Changlu, E-mail: clshao@nenu.edu.c [Center for Advanced Optoelectronic Functional Materials Research, Northeast Normal University, Changchun 130024 (China)

2010-03-15

Polymer resin and polymer-silica films with highly ordered mesostructure have been used as host materials to encapsulate DCM (4-(dicyanomethylene) -2-methyl-6-(4-dimethylaminostyryl)-4h-pyran), a kind of fluorescent dye, through evaporation-induced self-assembly method (EISA). After encapsulation, the composites show significant blue-shift in photoluminescence (PL) spectra. Particularly, by changing the excitation wavelength, the samples show different emission bands. These phenomena are related to the mesostructure and the positions of DCM molecules in the host.

Self-assembly of poly(ionic liquid) (PIL)-based amphiphilic homopolymers into vesicles and supramolecular structures with dyes and silver nanoparticles

KAUST Repository

Manojkumar, Kasina

2017-04-27

The incorporation of both hydrophilic and hydrophobic segments in homopolymers leads to their self-assembly into nanostructures in selective solvents, owing to their amphiphilic character. Here we report the RAFT polymerization of N-imidazole-3-propylmethacrylamide and the further quaternization of the resulting polymer with different alkyl bromides of a varying chain length, which afforded well-defined polymeric ionic liquids (PILs) 1-4. These PILs are characterized by the presence of both hydrophobic alkyl chains and hydrophilic ionic moieties, allowing their spontaneous self-assembly in water, forming distinct polymeric vesicles (= polymersomes) the size of which can be varied as a function of alkyl chain length. As demonstrated by the dye-encapsulation study, a particular organic-soluble PIL, 3, consisting of a dodecyl side-chain enabled the transfer of the water-soluble Rose Bengal dye, from an aqueous solution to the organic phase. In addition, polymersomes obtained from a PIL (2) featuring butyl side chains were used as templates and polymeric stabilizers of silver nanoparticles (NPs), i.e. leading to AgNP@PIL hybrids, as observed by transmission electron microscopy (TEM). It was found that the extent of functionalization of polymersomes by the Ag-based NPs varied greatly before and after the end-group removal of the PIL. Altogether, this report emphasizes the facile synthesis of amphiphilic homoPILs and their manipulation in water for dye encapsulation and for stabilization of silver NPs.

Self-assembly of poly(ionic liquid) (PIL)-based amphiphilic homopolymers into vesicles and supramolecular structures with dyes and silver nanoparticles

KAUST Repository

Manojkumar, Kasina; Mecerreyes, David; Taton, Daniel; Gnanou, Yves; Vijayakrishna, Kari

2017-01-01

The incorporation of both hydrophilic and hydrophobic segments in homopolymers leads to their self-assembly into nanostructures in selective solvents, owing to their amphiphilic character. Here we report the RAFT polymerization of N-imidazole-3-propylmethacrylamide and the further quaternization of the resulting polymer with different alkyl bromides of a varying chain length, which afforded well-defined polymeric ionic liquids (PILs) 1-4. These PILs are characterized by the presence of both hydrophobic alkyl chains and hydrophilic ionic moieties, allowing their spontaneous self-assembly in water, forming distinct polymeric vesicles (= polymersomes) the size of which can be varied as a function of alkyl chain length. As demonstrated by the dye-encapsulation study, a particular organic-soluble PIL, 3, consisting of a dodecyl side-chain enabled the transfer of the water-soluble Rose Bengal dye, from an aqueous solution to the organic phase. In addition, polymersomes obtained from a PIL (2) featuring butyl side chains were used as templates and polymeric stabilizers of silver nanoparticles (NPs), i.e. leading to AgNP@PIL hybrids, as observed by transmission electron microscopy (TEM). It was found that the extent of functionalization of polymersomes by the Ag-based NPs varied greatly before and after the end-group removal of the PIL. Altogether, this report emphasizes the facile synthesis of amphiphilic homoPILs and their manipulation in water for dye encapsulation and for stabilization of silver NPs.

Diblock-copolymer-mediated self-assembly of protein-stabilized iron oxide nanoparticle clusters for magnetic resonance imaging.

Science.gov (United States)

Tähkä, Sari; Laiho, Ari; Kostiainen, Mauri A

2014-03-03

Superparamagnetic iron oxide nanoparticles (SPIONs) can be used as efficient transverse relaxivity (T2 ) contrast agents in magnetic resonance imaging (MRI). Organizing small (Doxide) diblock copolymer (P2QVP-b-PEO) to mediate the self-assembly of protein-cage-encapsulated iron oxide (γ-Fe2 O3 ) nanoparticles (magnetoferritin) into stable PEO-coated clusters. This approach relies on electrostatic interactions between the cationic N-methyl-2-vinylpyridinium iodide block and magnetoferritin protein cage surface (pI≈4.5) to form a dense core, whereas the neutral ethylene oxide block provides a stabilizing biocompatible shell. Formation of the complexes was studied in aqueous solvent medium with dynamic light scattering (DLS) and cryogenic transmission electron microcopy (cryo-TEM). DLS results indicated that the hydrodynamic diameter (Dh ) of the clusters is approximately 200 nm, and cryo-TEM showed that the clusters have an anisotropic stringlike morphology. MRI studies showed that in the clusters the longitudinal relaxivity (r1 ) is decreased and the transverse relaxivity (r2 ) is increased relative to free magnetoferritin (MF), thus indicating that clusters can provide considerable contrast enhancement. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of Cu{sub 2}S nanoneedles by self-assembly of nanoparticles via simple wet chemical route

Energy Technology Data Exchange (ETDEWEB)

Kumarakuru, Haridas, E-mail: haridas.kumarakuru@nmmu.ac.za; Coombes, Matthew J.; Neethling, Johannes H.; Westraadt, Johan E.

2014-03-15

Highlights: • An inexpensive wet chemical method was used at room temperature to grow Cu{sub 2}S. • Growth of Cu{sub 2}S nanostructures influences by the Cl{sup −} ion concentration. • Thioglycerol and Cl{sup −} ions are used as a blend capping agents. • Cu{sub 2}S nanoneedles were formed via self-assembly of nanoparticles. • We can propose a growth model for Cu{sub 2}S nanoneedles based on our observations. -- Abstract: Cu{sub 2}S nanoneedles, fabricated by self-assembly of Cu{sub 2}S nanoparticles via wet chemical method are investigated. Crystallinity and surface morphologies of the as-grown needles are examined using X-ray diffraction and scanning and transmission electron microscopy. It is observed that the nanoparticle formation is controlled by the blend concentration of capping agents, thioglycerol, added during the synthesis and the Cl{sup −} ions delivered by the CuCl source. The likely reasons for the elongated structure of the nanoparticle self-assembly are also discussed.

Self-assembled iron oxide nanoparticle multilayer: x-ray and polarized neutron reflectivity

International Nuclear Information System (INIS)

Mishra, D; Benitez, M J; Petracic, O; Badini Confalonieri, G A; Szary, P; Brüssing, F; Devishvili, A; Toperverg, B P; Zabel, H; Theis-Bröhl, K; Vorobiev, A; Konovalov, O; Paulus, M; Sternemann, C

2012-01-01

We have investigated the structure and magnetism of self-assembled, 20 nm diameter iron oxide nanoparticles covered by an oleic acid shell for scrutinizing their structural and magnetic correlations. The nanoparticles were spin-coated on an Si substrate as a single monolayer and as a stack of 5 ML forming a multilayer. X-ray scattering (reflectivity and grazing incidence small-angle scattering) confirms high in-plane hexagonal correlation and a good layering property of the nanoparticles. Using polarized neutron reflectivity we have also determined the long range magnetic correlations parallel and perpendicular to the layers in addition to the structural ones. In a field of 5 kOe we determine a magnetization value of about 80% of the saturation value. At remanence the global magnetization is close to zero. However, polarized neutron reflectivity reveals the existence of regions in which magnetic moments of nanoparticles are well aligned, while losing order over longer distances. These findings confirm that in the nanoparticle assembly the magnetic dipole–dipole interaction is rather strong, dominating the collective magnetic properties at room temperature. (paper)

Self-assembled iron oxide nanoparticle multilayer: x-ray and polarized neutron reflectivity.

Science.gov (United States)

Mishra, D; Benitez, M J; Petracic, O; Badini Confalonieri, G A; Szary, P; Brüssing, F; Theis-Bröhl, K; Devishvili, A; Vorobiev, A; Konovalov, O; Paulus, M; Sternemann, C; Toperverg, B P; Zabel, H

2012-02-10

We have investigated the structure and magnetism of self-assembled, 20 nm diameter iron oxide nanoparticles covered by an oleic acid shell for scrutinizing their structural and magnetic correlations. The nanoparticles were spin-coated on an Si substrate as a single monolayer and as a stack of 5 ML forming a multilayer. X-ray scattering (reflectivity and grazing incidence small-angle scattering) confirms high in-plane hexagonal correlation and a good layering property of the nanoparticles. Using polarized neutron reflectivity we have also determined the long range magnetic correlations parallel and perpendicular to the layers in addition to the structural ones. In a field of 5 kOe we determine a magnetization value of about 80% of the saturation value. At remanence the global magnetization is close to zero. However, polarized neutron reflectivity reveals the existence of regions in which magnetic moments of nanoparticles are well aligned, while losing order over longer distances. These findings confirm that in the nanoparticle assembly the magnetic dipole-dipole interaction is rather strong, dominating the collective magnetic properties at room temperature.

Self-Assembled Complexes of Horseradish Peroxidase with Magnetic Nanoparticles Showing Enhanced Peroxidase Activity

KAUST Repository

Corgié , Sté phane C.; Kahawong, Patarawan; Duan, Xiaonan; Bowser, Daniel; Edward, Joseph B.; Walker, Larry P.; Giannelis, Emmanuel P.

2012-01-01

Bio-nanocatalysts (BNCs) consisting of horseradish peroxidase (HRP) self-assembled with magnetic nanoparticles (MNPs) enhance enzymatic activity due to the faster turnover and lower inhibition of the enzyme. The size and magnetization of the MNPs

Ordered CdSe nanoparticles within self-assembled block copolymer domains on surfaces.

Science.gov (United States)

Zou, Shan; Hong, Rui; Emrick, Todd; Walker, Gilbert C

2007-02-13

Hierarchical, high-density, ordered patterns were fabricated on Si substrates by self-assembly of CdSe nanoparticles within approximately 20-nm-thick diblock copolymer films in a controlled manner. Surface-modified CdSe nanoparticles formed well-defined structures within microphase-separated polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) domains. Trioctylphosphine oxide (TOPO)-coated CdSe nanoparticles were incorporated into PS domains and polyethylene glycol-coated CdSe nanoparticles were located primarily in the P2VP domains. Nearly close-packed CdSe nanoparticles were clearly identified within the highly ordered patterns on Si substrates by scanning electron microscopy (SEM). Contact angle measurements together with SEM results indicate that TOPO-CdSe nanoparticles were partially placed at the air/copolymer interface.

The release characteristics of a model protein from self-assembled succinimide-terminated poly(lactide-co-glycolide ethylene oxide fumarate) nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Mercado, Angel E; He Xuezhong; Xu Weijie; Jabbari, Esmaiel [Biomimetic Materials and Tissue Engineering Laboratories, Department of Chemical Engineering, University of South Carolina, SC 29208, Columbia (United States)], E-mail: jabbari@engr.sc.edu

2008-08-13

Lactide-co-glycolide-based functionalized nanoparticles (NPs), because of their high surface areas for conjugation and biodegradability, are attractive as carriers for stabilization and sustained delivery of therapeutic agents and protein drugs. The objective of this work was to compare the release characteristics of model molecules encapsulated in NPs produced from poly(lactide-co-glycolide fumarate) (PLGF) macromer with those of model molecules conjugated to NPs produced from succinimide (NHS)-terminated PLGF-NHS macromer. Poly(lactide fumarate) (PLAF), PLGF and poly(lactide-co-ethylene oxide fumarate) (PLEOF) macromers were synthesized by condensation polymerization. The hydroxyl end-groups of PLAF and PLGF macromers were reacted with N,N{sup '}-disuccinimidyl carbonate (DSC) to produce succinimide-terminated PLAF-NHS and PLGF-NHS macromers. The macromers were self-assembled by dialysis to form NPs. The amphiphilic PLEOF macromer was used as the surfactant to stabilize the NPs in the process of self-assembly. 1-(2-pyridylazo)-2-naphthol (PAN) was used as a model small molecule for encapsulation in PLAF or PLGF NPs and bovine serum albumin (BSA) was used as a model protein for conjugation to PLAF-NHS and PLGF-NHS NPs. The profile of release of the encapsulated PAN from PLAF and PLGF NPs was non-linear and consisted of a burst release followed by a period of sustained release. The release profile for BSA, conjugated to PLAF-NHS and PLGF-NHS NPs, was linear up to complete degradation of the NPs. PLGF and PLAF NPs degraded in 15 and 28 days, respectively, while PLGF-NHS and PLAF-NHS NPs degraded in 25 and 38 days, which demonstrated that the release was dominated by erosion of the matrix. PLAF-NHS and PLGF-NHS NPs are potentially useful as carriers for sustained in situ release of protein drugs.

Lipid nanoparticle interactions and assemblies

Science.gov (United States)

Preiss, Matthew Ryan

Novel liposome-nanoparticle assemblies (LNAs) provide a biologically inspired route for designing multifunctional bionanotheranostics. LNAs combine the benefits of lipids and liposomes to encapsulate, transport, and protect hydrophilic and hydrophobic therapeutics with functional nanoparticles. Functional nanoparticles endow LNAs with additional capabilities, including the ability to target diseases, triggered drug release, controlled therapeutic output, and diagnostic capabilities to produce a drug delivery system that can effectively and efficiently deliver therapeutics while reducing side effects. Not only could LNAs make existing drugs better, they could also provide an avenue to allow once promising non-approved drugs (rejected due to harmful side effects, inadequate pharmacokinetics, and poor efficacy) to be safely used through targeted and controlled delivery directly to the diseased site. LNAs have the potential to be stimuli responsive, delivering drugs on command by external (ultrasound, RF heating, etc.) or internal (pH, blood sugar, heart rate, etc.) stimuli. Individually, lipids and nanoparticles have been clinically approved for therapy, such as Doxil (a liposomal doxorubicin for cancer treatment), and diagnosis, such as Feridex (an iron oxide nanoparticle an MRI contrast enhancement agent for liver tumors). In order to engineer these multifunctional LNAs for theranostic applications, the interactions between nanoparticles and lipids must be better understood. This research sought to explore the formation, design, structures, characteristics, and functions of LNAs. To achieve this goal, different types of LNAs were formed, specifically magnetoliposomes, bilayer decorated LNAs (DLNAs), and lipid-coated magnetic nanoparticles (LMNPs). A fluorescent probe was embedded in the lipid bilayer of magnetoliposomes allowing the local temperature and membrane fluidity to be observed. When subjected to an electromagnetic field that heated the encapsulated iron

Self-assembled nanogaps for molecular electronics.

Science.gov (United States)

Tang, Qingxin; Tong, Yanhong; Jain, Titoo; Hassenkam, Tue; Wan, Qing; Moth-Poulsen, Kasper; Bjørnholm, Thomas

2009-06-17

A nanogap for molecular devices was realized using solution-based self-assembly. Gold nanorods were assembled to gold nanoparticle-coated conducting SnO2:Sb nanowires via thiol end-capped oligo(phenylenevinylene)s (OPVs). The molecular gap was easily created by the rigid molecule itself during self-assembly and the gap length was determined by the molecule length. The gold nanorods and gold nanoparticles, respectively covalently bonded at the two ends of the molecule, had very small dimensions, e.g. a width of approximately 20 nm, and hence were expected to minimize the screening effect. The ultra-long conducting SnO2:Sb nanowires provided the bridge to connect one of the electrodes of the molecular device (gold nanoparticle) to the external circuit. The tip of the atomic force microscope (AFM) was contacted onto the other electrode (gold nanorod) for the electrical measurement of the OPV device. The conductance measurement confirmed that the self-assembly of the molecules and the subsequent self-assembly of the gold nanorods was a feasible method for the fabrication of the nanogap of the molecular devices.

Self-assembled nanogaps for molecular electronics

International Nuclear Information System (INIS)

Tang Qingxin; Tong Yanhong; Jain, Titoo; Hassenkam, Tue; Moth-Poulsen, Kasper; Bjoernholm, Thomas; Wan Qing

2009-01-01

A nanogap for molecular devices was realized using solution-based self-assembly. Gold nanorods were assembled to gold nanoparticle-coated conducting SnO 2 :Sb nanowires via thiol end-capped oligo(phenylenevinylene)s (OPVs). The molecular gap was easily created by the rigid molecule itself during self-assembly and the gap length was determined by the molecule length. The gold nanorods and gold nanoparticles, respectively covalently bonded at the two ends of the molecule, had very small dimensions, e.g. a width of ∼20 nm, and hence were expected to minimize the screening effect. The ultra-long conducting SnO 2 :Sb nanowires provided the bridge to connect one of the electrodes of the molecular device (gold nanoparticle) to the external circuit. The tip of the atomic force microscope (AFM) was contacted onto the other electrode (gold nanorod) for the electrical measurement of the OPV device. The conductance measurement confirmed that the self-assembly of the molecules and the subsequent self-assembly of the gold nanorods was a feasible method for the fabrication of the nanogap of the molecular devices.

Directing self-assembly of gold nanoparticles in diblock copolymer scaffold

Science.gov (United States)

Li, Qifang; He, Jinbo; Glogowski, Elizabeth; Emrick, Todd; Russell, Thomas

2007-03-01

A versatile hierarchical approach for directing self -assembly of gold nanostructures with size 2-3nm in diblock copolymer scaffolds is found. Diblock copolymer polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) is used to form a regular scaffold of highly anisotropic, stripe-like domains, and controlled differential wetting by dichloromethane and thermal annealing guides gold nanoparticles with half hydrophilic ligand to aggregate selectively along the scaffold, producing highly organized metal nanostructures. In as-cast block-copolymer and gold nanoparticles thin films, micelle structure and gold nanoparticles random distribution on scaffold are typically observed. However, samples annealed in dichloromethane exhibit well-defined short-range ordered nanostructure with gold nanoparticles located at the interface of PS and P2VP nanoscale domain. After annealing at 170 C, the gold nanoparticles at interface migrated into the middle of P2VP phase and exhibited long-range ordered hierarchical structures. Synergistic interactions between the gold nanoparticles and the PS-b-P2VP caused an orientation of the microdomains normal to the film surface.

Inverse Problem in Self-assembly

Science.gov (United States)

Tkachenko, Alexei

2012-02-01

By decorating colloids and nanoparticles with DNA, one can introduce highly selective key-lock interactions between them. This leads to a new class of systems and problems in soft condensed matter physics. In particular, this opens a possibility to solve inverse problem in self-assembly: how to build an arbitrary desired structure with the bottom-up approach? I will present a theoretical and computational analysis of the hierarchical strategy in attacking this problem. It involves self-assembly of particular building blocks (``octopus particles''), that in turn would assemble into the target structure. On a conceptual level, our approach combines elements of three different brands of programmable self assembly: DNA nanotechnology, nanoparticle-DNA assemblies and patchy colloids. I will discuss the general design principles, theoretical and practical limitations of this approach, and illustrate them with our simulation results. Our crucial result is that not only it is possible to design a system that has a given nanostructure as a ground state, but one can also program and optimize the kinetic pathway for its self-assembly.

Antimicrobial activity of silver nanoparticles encapsulated in poly-N-isopropylacrylamide-based polymeric nanoparticles.

Science.gov (United States)

Qasim, Muhammad; Udomluck, Nopphadol; Chang, Jihyun; Park, Hansoo; Kim, Kyobum

2018-01-01

In this study, we analyzed the antimicrobial activities of poly- N -isopropylacrylamide (pNIPAM)-based polymeric nanoparticles encapsulating silver nanoparticles (AgNPs). Three sizes of AgNP-encapsulating pNIPAM- and pNIPAM-NH 2 -based polymeric nanoparticles were fabricated. Highly stable and uniformly distributed AgNPs were encapsulated within polymeric nanoparticles via in situ reduction of AgNO 3 using NaBH 4 as the reducing agent. The formation and distribution of AgNPs was confirmed by UV-visible spectroscopy, transmission electron microscopy, and inductively coupled plasma optical emission spectrometry, respectively. Both polymeric nanoparticles showed significant bacteriostatic activities against Gram-negative ( Escherichia coli ) and Gram-positive ( Staphylococcus aureus ) bacteria depending on the nanoparticle size and amount of AgNO 3 used during fabrication.

Characterization of self-assembled electrodes based on Au-Pt nanoparticles for PEMFC application

Energy Technology Data Exchange (ETDEWEB)

Valenzuela, E. [Univ. Politecnica de Chiapas (Mexico). Energia y Sustentabilidad; Sebastian, P.J.; Gamboa, S.A.; Joseph, S. [Univ. Nacional Autonoma de Mexico, Morelos (Mexico). Centrode Investigacion en Energia; Pal, U. [Univ. Autonoma de Puebla, Pue (Mexico). Inst. de Fisica; Gonzalez, I. [Univ. Autonoma Metropolitana, Mexico City (Mexico). Dept. de Quimica

2010-07-01

This paper described the synthesis and characterization of gold (Au), platinum (Pt) and Au-Pt nanoparticles impregnated on a Nafion membrane in a proton exchange membrane fuel cell (PEMFC). The aim of the study was to fabricate the membrane electrode assembly (MEA) by depositing the nanoparticles on the membrane using an immersion technique. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to study the deposition process. Electrochemical impedance spectroscopy (EIS) was used to study the membrane proton conduction process. An elemental mapping analysis was performed in order to study the location of the Au and Pt in the self-assemblies. Results of the study showed that the particles deposited on the Nafion had good stability and a homogenous distribution along the membrane surface. The particles showed a direct relation in size and location with the hydrophilic and hydrophobic distribution phases of the membrane. The main membrane resistance was located between the membrane and the electrolyte. The self-assembled electrodes demonstrated a good performance at standard conditions. 33 refs., 4 tabs., 11 figs.

Encapsulation of cobalt nanoparticles in cross-linked-polymer cages

Energy Technology Data Exchange (ETDEWEB)

Hatamie, Shadie [Department of Electronic-Science, Fergusson College, Pune 411 004 (India); Dhole, S.D. [Department of Physics, University of Pune, Pune 411 007 (India); Ding, J. [Department of Materials Science and Engineering, National University of Singapore, 7, Engineering Drive 1, Singapore 117574 (Singapore); Kale, S.N. [Department of Electronic-Science, Fergusson College, Pune 411 004 (India)], E-mail: sangeetakale2004@gmail.com

2009-07-15

Nanoparticles embedded in polymeric cages give rise to interesting applications ranging from nanocatalysis to drug-delivery systems. In this context, we report on synthesis of cobalt (Co) nanoparticles trapped in polyvinyl alcohol (PVA) matrix to yield self-supporting magnetic films in PVA slime. A 20 nm, Co formed in FCC geometry encapsulated with a weak citrate coat when caged in PVA matrix exhibited persistence of magnetism and good radio-frequency response. Cross-linking of PVA chains to form cage-like structures to arrest Co nanoparticles therein, is believed to be the reason for oxide-free nature of Co, promising applications in biomedicine as well as in radio-frequency shielding.

Temperature and anion responsive self-assembly of ionic liquid block copolymers coating gold nanoparticles

Science.gov (United States)

Li, Junbo; Zhao, Jianlong; Wu, Wenlan; Liang, Ju; Guo, Jinwu; Zhou, Huiyun; Liang, Lijuan

2016-06-01

In this paper, double hydrophilic ionic liquid block copolymers (ILBCs), poly poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine)]- block-(N-isopropylacrylamide) (PMMPImB- b-PNIPAAm) was first synthesized by reversible additionfragmentation chain transfer (RAFT) and then attached on the surface of gold nanoparticles (Au NPs) via a strong gold-sulfur bonding for preparing hybrid nanoparticles (PMMPImB- b-PNIPAAm-@-Au NPs). The hybrid NPs had a three layers micelle-like structure, including a gold core, thermo-responsive inner shell and anion responsive outer corona. The self-assembling behavior of thermal- and anion-response from shell and corona were respectively investigated by change of temperature and addition of (CF3SO2)2N-. The results showed the hybrid NPs retained a stable dispersion beyond the lower critical solution temperature (LCST) because of the space or electrostatic protecting by outer PMMPImB. However, with increasing concentration of (CF3SO2)2N-, the micellization of self-assembling PMMPImB- b-PNIPAAm-@-Au NPs was induced to form micellar structure containing the core with hydrophobic PMMPImB-(CF3SO2)2N- surrounded by composite shell of Au NPs-PNIPAAm via the anionresponsive properties of ILBCs. These results indicated that the block copolymers protected plasmonic nanoparticles remain self-assembling properties of block copolymers when phase transition from outer corona polymer.

1-D Metal Nanobead Arrays within Encapsulated Nanowires via a Red-Ox-Induced Dewetting: Mechanism Study by Atom-Probe Tomography.

Science.gov (United States)

Sun, Zhiyuan; Tzaguy, Avra; Hazut, Ori; Lauhon, Lincoln J; Yerushalmi, Roie; Seidman, David N

2017-12-13

Metal nanoparticle arrays are excellent candidates for a variety of applications due to the versatility of their morphology and structure at the nanoscale. Bottom-up self-assembly of metal nanoparticles provides an important complementary alternative to the traditional top-down lithography method and makes it possible to assemble structures with higher-order complexity, for example, nanospheres, nanocubes, and core-shell nanostructures. Here we present a mechanism study of the self-assembly process of 1-D noble metal nanoparticles arrays, composed of Au, Ag, and AuAg alloy nanoparticles. These are prepared within an encapsulated germanium nanowire, obtained by the oxidation of a metal-germanium nanowire hybrid structure. The resulting structure is a 1-D array of equidistant metal nanoparticles with the same diameter, the so-called nanobead (NB) array structure. Atom-probe tomography and transmission electron microscopy were utilized to investigate the details of the morphological and chemical evolution during the oxidation of the encapsulated metal-germanium nanowire hybrid-structures. The self-assembly of nanoparticles relies on the formation of a metal-germanium liquid alloy and the migration of the liquid alloy into the nanowire, followed by dewetting of the liquid during shape-confined oxidation where the liquid column breaks-up into nanoparticles due to the Plateau-Rayleigh instability. Our results demonstrate that the encapsulating oxide layer serves as a structural scaffold, retaining the overall shape during the eutectic liquid formation and demonstrates the relationship between the oxide mechanical properties and the final structural characteristics of the 1-D arrays. The mechanistic details revealed here provide a versatile tool-box for the bottom-up fabrication of 1-D arrays nanopatterning that can be modified for multiple applications according to the RedOx properties of the material system components.

Templated Synthesis of Magnetic Nanoparticles through the Self-Assembly of Polymers and Surfactants

Directory of Open Access Journals (Sweden)

Vo Thu An Nguyen

2014-08-01

Full Text Available The synthesis of superparamagnetic nanoparticles (NPs for various technological applications continues to be an interesting research topic. The successful application of superparamagnetic NPs to each specific area typically depends on the achievement of high magnetization for the nanocrystals obtained, which is determined by their average size and size distribution. The size dispersity of magnetic NPs (MNPs is markedly improved when, during the synthesis, the nucleation and growth steps of the reaction are well-separated. Tuning the nucleation process with the assistance of a hosting medium that encapsulates the precursors (such as self-assembled micelles, dispersing them in discrete compartments, improves control over particle formation. These inorganic-organic hybrids inherit properties from both the organic and the inorganic materials, while the organic component can also bring a specific functionality to the particles or prevent their aggregation in water. The general concept of interest in this review is that the shape and size of the synthesized MNPs can be controlled to some extent by the geometry and the size of the organic templates used, which thus can be considered as molds at the nanometer scale, for both porous continuous matrices and suspensions.

Self-assembled nanoparticles of cholesterol-conjugated carboxymethyl curdlan as a novel carrier of epirubicin

International Nuclear Information System (INIS)

Li Lei; Gao Fuping; Tang Hongbo; Ba, Yonggang; Li Ruifeng; Li Xuemin; Liu Lingrong; Wang Yinsong; Zhang Qiqing

2010-01-01

The purpose of this study was to develop nanoparticles made of cholesterol-conjugated carboxymethyl curdlan (CCMC) entrapping epirubicin (EPB) and establish their in vitro and in vivo potential. CCMC was synthesized and characterized by Fourier transform infrared spectra (FT-IR) and proton nuclear magnetic resonance spectra ( 1 H NMR). The degrees of substitution (DS) of the cholesterol moiety were 2.3, 3.5 and 6.4, respectively. EPB-loaded CCMC-3.5 nanoparticles were prepared by the remote loading method. The physicochemical characteristics, drug loading efficiency and drug release kinetics of EPB-loaded CCMC-3.5 nanoparticles were characterized. The in vitro release profiles revealed that EPB release was sensitive to the pH as well as the drug loading contents. The cellular cytotoxicity and cellular uptake were accessed by using human cervical carcinoma (HeLa) cells. The EPB-loaded CCMC-3.5 nanoparticles were found to be more cytotoxic and have a broader distribution within the cells than the free EPB. The in vivo pharmacokinetics and biodistribution were investigated after intravenous injection in rats. Promisingly, a 4.0-fold increase in the mean residence time (MRT), a 4.31-fold increase in the half-life time and a 6.69-fold increase in the area under the curve (AUC 0→∞ ) of EPB were achieved for the EPB-loaded CCMC-3.5 self-assembled nanoparticles compared with the free EPB. The drug level was significantly increased in liver at 24 and 72 h; however, it decreased in heart at 8 and 24 h compared with the free EPB. The in vivo anti-tumor study indicated that the EPB-loaded CCMC-3.5 self-assembled nanoparticles showed greater anti-tumor efficacy than the free EPB. Taken together, the novel CCMC self-assembled nanoparticles might have potential application as anti-cancer drug carriers in a drug delivery system due to good results in vitro and in vivo.

Mesoporous silica-encapsulated gold nanoparticles as artificial enzymes for self-activated cascade catalysis.

Science.gov (United States)

Lin, Youhui; Li, Zhenhua; Chen, Zhaowei; Ren, Jinsong; Qu, Xiaogang

2013-04-01

A significant challenge in chemistry is to create synthetic structures that mimic the complexity and function of natural systems. Here, a self-activated, enzyme-mimetic catalytic cascade has been realized by utilizing expanded mesoporous silica-encapsulated gold nanoparticles (EMSN-AuNPs) as both glucose oxidase- and peroxidase-like artificial enzymes. Specifically, EMSN helps the formation of a high degree of very small and well-dispersed AuNPs, which exhibit an extraordinarily stability and dual enzyme-like activities. Inspired by these unique and attractive properties, we further piece them together into a self-organized artificial cascade reaction, which is usually completed by the oxidase-peroxidase coupled enzyme system. Our finding may pave the way to use matrix as the structural component for the design and development of biomimetic catalysts and to apply enzyme mimics for realizing higher functions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Quantitative self-assembly prediction yields targeted nanomedicines

Science.gov (United States)

Shamay, Yosi; Shah, Janki; Işık, Mehtap; Mizrachi, Aviram; Leibold, Josef; Tschaharganeh, Darjus F.; Roxbury, Daniel; Budhathoki-Uprety, Januka; Nawaly, Karla; Sugarman, James L.; Baut, Emily; Neiman, Michelle R.; Dacek, Megan; Ganesh, Kripa S.; Johnson, Darren C.; Sridharan, Ramya; Chu, Karen L.; Rajasekhar, Vinagolu K.; Lowe, Scott W.; Chodera, John D.; Heller, Daniel A.

2018-02-01

Development of targeted nanoparticle drug carriers often requires complex synthetic schemes involving both supramolecular self-assembly and chemical modification. These processes are generally difficult to predict, execute, and control. We describe herein a targeted drug delivery system that is accurately and quantitatively predicted to self-assemble into nanoparticles based on the molecular structures of precursor molecules, which are the drugs themselves. The drugs assemble with the aid of sulfated indocyanines into particles with ultrahigh drug loadings of up to 90%. We devised quantitative structure-nanoparticle assembly prediction (QSNAP) models to identify and validate electrotopological molecular descriptors as highly predictive indicators of nano-assembly and nanoparticle size. The resulting nanoparticles selectively targeted kinase inhibitors to caveolin-1-expressing human colon cancer and autochthonous liver cancer models to yield striking therapeutic effects while avoiding pERK inhibition in healthy skin. This finding enables the computational design of nanomedicines based on quantitative models for drug payload selection.

Encapsulation and retention of chelated-copper inside hydrophobic nanoparticles

DEFF Research Database (Denmark)

Hervella, Pablo; Ortiz, Elisa Parra; Needham, David

2016-01-01

) Chelate copper into the octaethyl porphyrin; (3) Encapsulate OEP-Cu in nanoparticles: the encapsulation efficiency of copper into liquid nanoparticles (LNP), solid nanoparticles (SNP) and phospholipid liposomes (PL) was evaluated by UV-Vis and atomic absorption spectroscopy; (4) Retain the encapsulated...... OEP-Cu in the liquid or solid cores of the nanoparticles in the presence of a lipid sink. RESULTS: (1) The size of the nanoparticles was found to be strongly dependent on the Reynolds number and the initial concentration of components for the fast injection technique. At high Reynolds number (2181......), a minimum value for the particle diameter of ∼30nm was measured. (2) Copper was chelated by OEP in a 1:1mol ratio with an association constant of 2.57×10(5)M(-1). (3) The diameter of the nanoparticles was not significantly affected by the presence of OEP or OEP-Cu. The percentage of encapsulation of copper...

Nanostructured nanoparticles of self-assembled lipid pro-drugs as a route to improved chemotherapeutic agents

Energy Technology Data Exchange (ETDEWEB)

Sagnella, Sharon M.; Gong, Xiaojuan; Moghaddam, Minoo J.; Conn, Charlotte E.; Kimpton, Kathleen; Waddington, Lynne J.; Krodkiewska, Irena; Drummond, Calum J. (CSIRO/MSE); (CSIRO/LW)

2014-09-24

We demonstrate that oral delivery of self-assembled nanostructured nanoparticles consisting of 5-fluorouracil (5-FU) lipid prodrugs results in a highly effective, target-activated, chemotherapeutic agent, and offers significantly enhanced efficacy over a commercially available alternative that does not self-assemble. The lipid prodrug nanoparticles have been found to significantly slow the growth of a highly aggressive mouse 4T1 breast tumour, and essentially halt the growth of a human MDA-MB-231 breast tumour in mouse xenografts. Systemic toxicity is avoided as prodrug activation requires a three-step, enzymatic conversion to 5-FU, with the third step occurring preferentially at the tumour site. Additionally, differences in the lipid prodrug chemical structure and internal nanostructure of the nanoparticle dictate the enzymatic conversion rate and can be used to control sustained release profiles. Thus, we have developed novel oral nanomedicines that combine sustained release properties with target-selective activation.

Quantum dot-induced viral capsid assembling in dissociation buffer

Directory of Open Access Journals (Sweden)

Gao D

2013-06-01

Full Text Available Ding Gao,1,2 Zhi-Ping Zhang,1 Feng Li,3 Dong Men,1 Jiao-Yu Deng,1 Hong-Ping Wei,1 Xian-En Zhang,1 Zong-Qiang Cui1 1State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 2Graduate University of Chinese Academy of Sciences, Beijing, 3Division of Nanobiomedicine and i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, People's Republic of China Abstract: Viruses encapsulating inorganic nanoparticles are a novel type of nanostructure with applications in biomedicine and biosensors. However, the encapsulation and assembly mechanisms of these hybridized virus-based nanoparticles (VNPs are still unknown. In this article, it was found that quantum dots (QDs can induce simian virus 40 (SV40 capsid assembly in dissociation buffer, where viral capsids should be disassembled. The analysis of the transmission electron microscope, dynamic light scattering, sucrose density gradient centrifugation, and cryo-electron microscopy single particle reconstruction experimental results showed that the SV40 major capsid protein 1 (VP1 can be assembled into ≈25 nm capsids in the dissociation buffer when QDs are present and that the QDs are encapsulated in the SV40 capsids. Moreover, it was determined that there is a strong affinity between QDs and the SV40 VP1 proteins (KD = 2.19E-10 M, which should play an important role in QD encapsulation in the SV40 viral capsids. This study provides a new understanding of the assembly mechanism of SV40 virus-based nanoparticles with QDs, which may help in the design and construction of other similar virus-based nanoparticles. Keywords: quantum dots, simian virus 40, self-assembly, encapsulation, virus-based nanoparticles

Watching Nanoscale Self-Assembly Kinetics of Gold Prisms in Liquids

Science.gov (United States)

Kim, Juyeong; Ou, Zihao; Jones, Matthew R.; Chen, Qian

We use liquid-phase transmission electron microscopy to watch self-assembly of gold triangular prisms into polymer-like structures. The in situ dynamics monitoring enabled by liquid-phase transmission electron microscopy, single nanoparticle tracking, and the marked conceptual similarity between molecular reactions and nanoparticle self-assembly combined elucidate the following mechanistic understanding: a step-growth polymerization based assembly statistics, kinetic pathways sampling particle curvature dependent energy minima and their interconversions, and directed assembly into polymorphs (linear or cyclic chains) through in situ modulation of the prism bonding geometry. Our study bridges the constituent kinetics on the molecular and nanoparticle length scales, which enriches the design rules in directed self-assembly of anisotropic nanoparticles.

Programmable Self-assembly of Hydrocarbon-capped Nanoparticles: Role of Chain Conformations

Science.gov (United States)

Waltmann, Curt; Horst, Nathan; Travesset, Alex

Nanoparticle superlattices (NPS), i.e. crystalline arrangements of nanoparticles, are materials with fascinating structures, which in many cases are not possible to attain from simple atoms or molecules. They also span a wide range of possible applications such as metamaterials, new energy sources, catalysis, and many others. In this talk, we present a theoretical and computational description of the self-assembly of nanoparticles with hydrocarbons as capping ligands. Usually, these systems have been described with hard sphere packing models. In this talk, we show that the conformations of the hydrocarbon chains play a fundamental role in determining the equilibrium phases, including and especially in binary systems. The work of CW was supported by a DOE-SULI internship from May-December 2016, and by NSF, DMR-CMMT 1606336 CDS&E: Design Principles for Ordering Nanoparticles into Super-crystals after January 1st.

Cytotoxicity of Paclitaxel in biodegradable self-assembled core-shell poly(lactide-co-glycolide ethylene oxide fumarate) nanoparticles.

Science.gov (United States)

He, Xuezhong; Ma, Junyu; Mercado, Angel E; Xu, Weijie; Jabbari, Esmaiel

2008-07-01

Biodegradable core-shell polymeric nanoparticles (NPs), with a hydrophobic core and hydrophilic shell, are developed for surfactant-free encapsulation and delivery of Paclitaxel to tumor cells. Poly (lactide-co-glycolide fumarate) (PLGF) and Poly (lactide-fumarate) (PLAF) were synthesized by condensation polymerization of ultra-low molecular weight poly(L: -lactide-co-glycolide) (ULMW PLGA) with fumaryl chloride (FuCl). Similarly, poly(lactide-co-ethylene oxide fumarate) (PLEOF) macromer was synthesized by reacting ultra-low molecular weight poly(L: -lactide) (ULMW PLA) and PEG with FuCl. The blend PLGF/PLEOF and PLAF/PLEOF macromers were self-assembled into NPs by dialysis. The NPs were characterized with respect to particle size distribution, morphology, and loading efficiency. The physical state and miscibility of Paclitaxel in NPs were characterized by differential scanning calorimetry. Tumor cell uptake and cytotoxicity of Paclitaxel loaded NPs were measured by incubation with HCT116 human colon carcinoma cells. The distribution of NPs in vivo was assessed with Apc(Min/+)mouse using infrared imaging. PLEOF macromer, due to its amphiphilic nature, acted as a surface active agent in the process of self-assembly which produced core-shell NPs with PLGF/PLAF and PLEOF macromers as the core and shell, respectively. The encapsulation efficiency ranged from 70 to 56% and it was independent of the macromer but decreased with increasing concentration of Paclitaxel. Most of the PLGF and PLAF NPs degraded in 15 and 28 days, respectively, which demonstrated that the release was dominated by hydrolytic degradation and erosion of the matrix. As the concentration of Paclitaxel was increased from 0 to 10, and 40 mug/ml, the viability of HCT116 cells incubated with free Paclitaxel decreased from 100 to 65 and 40%, respectively, while those encapsulated in PLGF/PLEOF NPs decreased from 93 to 54 and 28%. Groups with Paclitaxel loaded NPs had higher cytotoxicity compared to

Light-assisted, templated self-assembly of gold nanoparticle chains.

Science.gov (United States)

Jaquay, Eric; Martínez, Luis Javier; Huang, Ningfeng; Mejia, Camilo A; Sarkar, Debarghya; Povinelli, Michelle L

2014-09-10

We experimentally demonstrate the technique of light-assisted, templated self-assembly (LATS) to trap and assemble 200 nm diameter gold nanoparticles. We excite a guided-resonance mode of a photonic-crystal slab with 1.55 μm laser light to create an array of optical traps. Unlike our previous demonstration of LATS with polystyrene particles, we find that the interparticle interactions play a significant role in the resulting particle patterns. Despite a two-dimensionally periodic intensity profile in the slab, the particles form one-dimensional chains whose orientations can be controlled by the incident polarization of the light. The formation of chains can be understood in terms of a competition between the gradient force due to the excitation of the mode in the slab and optical binding between particles.

Self-assembly of robotic micro- and nanoswimmers using magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Cheang, U. Kei; Kim, Min Jun, E-mail: mkim@coe.drexel.edu [Drexel University, Department of Mechanical Engineering & Mechanics (United States)

2015-03-15

Micro- and nanoscale robotic swimmers are very promising to significantly enhance the performance of particulate drug delivery by providing high accuracy at extremely small scales. Here, we introduce micro- and nanoswimmers fabricated using self-assembly of nanoparticles and control via magnetic fields. Nanoparticles self-align into parallel chains under magnetization. The swimmers exhibit flexibility under a rotating magnetic field resulting in chiral structures upon deformation, thereby having the prerequisite for non-reciprocal motion to move about at low Reynolds number. The swimmers are actuated wirelessly using an external rotating magnetic field supplied by approximate Helmholtz coils. By controlling the concentration of the suspended magnetic nanoparticles, the swimmers can be modulated into different sizes. Nanoscale swimmers are largely influenced by Brownian motion, as observed from their jerky trajectories. The microswimmers, which are roughly three times larger, are less vulnerable to the effects from Brownian motion. In this paper, we demonstrate responsive directional control of micro- and nanoswimmers and compare their respective diffusivities and trajectories to characterize the implications of Brownian disturbance on the motions of small and large swimmers. We then performed a simulation using a kinematic model for the magnetic swimmers including the stochastic nature of Brownian motion.

Self-assembly of robotic micro- and nanoswimmers using magnetic nanoparticles

Science.gov (United States)

Cheang, U. Kei; Kim, Min Jun

2015-03-01

Micro- and nanoscale robotic swimmers are very promising to significantly enhance the performance of particulate drug delivery by providing high accuracy at extremely small scales. Here, we introduce micro- and nanoswimmers fabricated using self-assembly of nanoparticles and control via magnetic fields. Nanoparticles self-align into parallel chains under magnetization. The swimmers exhibit flexibility under a rotating magnetic field resulting in chiral structures upon deformation, thereby having the prerequisite for non-reciprocal motion to move about at low Reynolds number. The swimmers are actuated wirelessly using an external rotating magnetic field supplied by approximate Helmholtz coils. By controlling the concentration of the suspended magnetic nanoparticles, the swimmers can be modulated into different sizes. Nanoscale swimmers are largely influenced by Brownian motion, as observed from their jerky trajectories. The microswimmers, which are roughly three times larger, are less vulnerable to the effects from Brownian motion. In this paper, we demonstrate responsive directional control of micro- and nanoswimmers and compare their respective diffusivities and trajectories to characterize the implications of Brownian disturbance on the motions of small and large swimmers. We then performed a simulation using a kinematic model for the magnetic swimmers including the stochastic nature of Brownian motion.

Self-assembly of robotic micro- and nanoswimmers using magnetic nanoparticles

International Nuclear Information System (INIS)

Cheang, U. Kei; Kim, Min Jun

2015-01-01

Micro- and nanoscale robotic swimmers are very promising to significantly enhance the performance of particulate drug delivery by providing high accuracy at extremely small scales. Here, we introduce micro- and nanoswimmers fabricated using self-assembly of nanoparticles and control via magnetic fields. Nanoparticles self-align into parallel chains under magnetization. The swimmers exhibit flexibility under a rotating magnetic field resulting in chiral structures upon deformation, thereby having the prerequisite for non-reciprocal motion to move about at low Reynolds number. The swimmers are actuated wirelessly using an external rotating magnetic field supplied by approximate Helmholtz coils. By controlling the concentration of the suspended magnetic nanoparticles, the swimmers can be modulated into different sizes. Nanoscale swimmers are largely influenced by Brownian motion, as observed from their jerky trajectories. The microswimmers, which are roughly three times larger, are less vulnerable to the effects from Brownian motion. In this paper, we demonstrate responsive directional control of micro- and nanoswimmers and compare their respective diffusivities and trajectories to characterize the implications of Brownian disturbance on the motions of small and large swimmers. We then performed a simulation using a kinematic model for the magnetic swimmers including the stochastic nature of Brownian motion

Combretastatin A4/poly(L-glutamic acid-graft-PEG conjugates self-assembled to nanoparticles

Directory of Open Access Journals (Sweden)

Yang Ou

2018-03-01

Full Text Available Combretastatin A4 (CA4 possesses varying ability to cause vascular disruption in tumors, while the short half-life, low water solubility and deactivation of many CA4 analogs during storage limited its antitumor efficacy and drug stability. A novel macromolecular conjugate of CA4 (CA4-PL was synthesized by covalent bonding of CA4 onto poly(L-glutamic acid-graft-polyethylene glycol (PLG-g-PEG via Yamaguchi reaction. The obtained CA4-PL was characterized by 1H NMR, GPC, and UV methods, and the properties of the nanoparticles composed of CA4-PL, including critical aggregation concentration, size and size distribution, and morphology, were investigated. CA4-PL can self-assemble to form micelle-like nanoparticles of 80~120 nm in diameter, which may have potential to improve the blood circulation period as well as the targetability of CA4, and find applications to treat various tumors when combined with traditional chemotherapy or radio therapy. Keywords: Combretastatin A4, Macromolecular conjugate, Poly(L-glutamic acid-graft-polyethylene glycol, Self-assemble, Nanoparticles

Bio-inspired Structural Colors from Deposition of Synthetic Melanin Nanoparticles by Evaporative Self-assembly

Science.gov (United States)

Xiao, Ming; Li, Yiwen; Deheyn, Dimitri; Yue, Xiujun; Gianneschi, Nathan; Shawkey, Matthew; Dhinojwala, Ali

2015-03-01

Melanin, a ubiquitous black or brown pigment in the animal kingdom, is a unique but poorly understood biomaterial. Many bird feathers contain melanosomes (melanin-containing organelles), which pack into ordered nanostructures, like multilayer or two-dimensional photonic crystal structures, to produce structural colors. To understand the optical properties of melanin and how melanosomes assemble into certain structures to produce colors, we prepared synthetic melanin (polydopamine) particles with variable sizes and aspect ratios. We have characterized the absorption and refractive index of the synthetic melanin particles. We have also shown that we can use an evaporative process to self-assemble melanin films with a wide range of colors. The colors obtained using this technique is modeled using a thin-film interference model and the optical properties of the synthetic melanin nanoparticles. Our results on self-assembly of synthetic melanin nanoparticles provide an explanation as why the use of melanosomes to produce colors is prevalent in the animal kingdom. National science foundation, air force office of scientific research, human frontier science program.

DNA-directed self-assembly of gold nanoparticles into binary and ternary nanostructures

International Nuclear Information System (INIS)

Yao Hui; Yi Changqing; Tzang Chihung; Zhu Junjie; Yang Mengsu

2007-01-01

The assembly and characterization of gold nanoparticle-based binary and ternary structures are reported. Two strategies were used to assemble gold nanoparticles into ordered nanoscale architectures: in strategy 1, gold nanoparticles were functionalized with single-strand DNA (ssDNA) first, and then hybridized with complementary ssDNA-labelled nanoparticles to assemble designed architectures. In strategy 2, the designed architectures were constructed through hybridization between complementary ssDNA first, then by assembling gold nanoparticles to the scaffolding through gold-sulfur bonds. Both TEM measurements and agarose gel electrophoresis confirmed that the latter strategy is more efficient in generating the designed nanostructures

Docetaxel-Loaded Nanoparticles Assembled from β-Cyclodextrin/Calixarene Giant Surfactants: Physicochemical Properties and Cytotoxic Effect in Prostate Cancer and Glioblastoma Cells

Directory of Open Access Journals (Sweden)

Laura Gallego-Yerga

2017-05-01

Full Text Available Giant amphiphiles encompassing a hydrophilic β-cyclodextrin (βCD component and a hydrophobic calix[4]arene (CA4 module undergo self-assembly in aqueous media to afford core-shell nanospheres or nanocapsules, depending on the nanoprecipitation protocol, with high docetaxel (DTX loading capacity. The blank and loaded nanoparticles have been fully characterized by dynamic light scattering (DLS, ζ-potential measurements and cryo-transmission electron microscopy (cryo-TEM. The data are compatible with the distribution of the drug between the nanoparticle core and the shell, where it is probably anchored by inclusion of the DTX aromatic moieties in βCD cavities. Indeed, the release kinetics profiles evidenced an initial fast release of the drug, which likely accounts for the fraction hosted on the surface, followed by a slow and sustained release rate, corresponding to diffusion of DTX in the core, which can be finely tuned by modification of the giant amphiphile chemical structure. The ability of the docetaxel-loaded nanoparticles to induce cellular death in different prostate (human LnCap and PC3 and glioblastoma (human U87 and rat C6 cells was also explored. Giant amphiphile-based DTX formulations surpassing or matching the antitumoral activity of the free DTX formulation were identified in all cases with no need to employ any organic co-solvent, thus overcoming the DTX water solubility problems. Moreover, the presence of the βCD shell at the surface of the assemblies is intended to impart stealth properties against serum proteins while permitting nanoparticle surface decoration by supramolecular approaches, paving the way for a new generation of molecularly well-defined antitumoral drug delivery systems with improved specificity and efficiency. Altogether, the results provide a proof of concept of the suitability of the approach based on βCD-CA4 giant amphiphiles to access DTX carriers with tunable properties.

Encapsulation of Antifouling Organic Biocides in Poly(lactic acid) Nanoparticles.

Science.gov (United States)

Kamtsikakis, Aristotelis; Kavetsou, Eleni; Chronaki, Konstantina; Kiosidou, Evangelia; Pavlatou, Evangelia; Karana, Alexandra; Papaspyrides, Constantine; Detsi, Anastasia; Karantonis, Antonis; Vouyiouka, Stamatina

2017-09-26

The scope of the current research was to assess the feasibility of encapsulating three commercial antifouling compounds, Irgarol 1051, Econea and Zinc pyrithione, in biodegradable poly(lactic acid) (PLA) nanoparticles. The emulsification-solvent evaporation technique was herein utilized to manufacture nanoparticles with a biocide:polymer ratio of 40%. The loaded nanoparticles were analyzed for their size and size distribution, zeta potential, encapsulation efficiency and thermal properties, while the relevant physicochemical characteristics were correlated to biocide-polymer system. In addition, the encapsulation process was scaled up and the prepared nanoparticles were dispersed in a water-based antifouling paint in order to examine the viability of incorporating nanoparticles in such coatings. Metallic specimens were coated with the nanoparticles-containing paint and examined regarding surface morphology.

Encapsulation of Antifouling Organic Biocides in Poly(lactic acid) Nanoparticles

Science.gov (United States)

Kamtsikakis, Aristotelis; Kavetsou, Eleni; Chronaki, Konstantina; Kiosidou, Evangelia; Pavlatou, Evangelia; Karana, Alexandra; Papaspyrides, Constantine; Detsi, Anastasia; Karantonis, Antonis; Vouyiouka, Stamatina

2017-01-01

The scope of the current research was to assess the feasibility of encapsulating three commercial antifouling compounds, Irgarol 1051, Econea and Zinc pyrithione, in biodegradable poly(lactic acid) (PLA) nanoparticles. The emulsification–solvent evaporation technique was herein utilized to manufacture nanoparticles with a biocide:polymer ratio of 40%. The loaded nanoparticles were analyzed for their size and size distribution, zeta potential, encapsulation efficiency and thermal properties, while the relevant physicochemical characteristics were correlated to biocide–polymer system. In addition, the encapsulation process was scaled up and the prepared nanoparticles were dispersed in a water-based antifouling paint in order to examine the viability of incorporating nanoparticles in such coatings. Metallic specimens were coated with the nanoparticles-containing paint and examined regarding surface morphology. PMID:28952560

Synthesis of Photocrosslinkable and Amine Containing Multifunctional Nanoparticles via Polymerization-Induced Self-Assembly.

Science.gov (United States)

Huang, Jianbing; Li, Decai; Liang, Hui; Lu, Jiang

2017-08-01

Photo-crosslinkable and amine-containing block copolymer nanoparticles are synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization-induced self-assembly of a multifunctional core-forming monomer, 2-((3-(4-(diethylamino)phenyl)acryloyl)oxy)ethyl methacrylate (DEMA), using poly(2-hydroxypropyl methacrylate) macromolecular chain transfer agent as a steric stabilizer in methanol at 65 °C. By tuning the chain length of PDEMA, a range of nanoparticle morphologies (sphere, worm, and vesicle) can be obtained. Since cinnamate groups can easily undergo a [2 + 2] cycloaddition of the carbon-carbon double bonds upon UV irradiation, the as-prepared block copolymer nanoparticles are readily stabilized by photo-crosslinking to produce anisotropic nanoparticles. The crosslinked block copolymer nanoparticles can be used as templates for in situ formation polymer/gold hybrid nanoparticles. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-assembled nanoparticles of glycol chitosan – Ergocalciferol succinate conjugate, for controlled release

DEFF Research Database (Denmark)

Quinones, Javier Perez; Gothelf, Kurt Vesterager; Kjems, Jørgen

2012-01-01

Glycol chitosan was linked to vitamin D2 hemisuccinate (ergocalciferol hemisuccinate) for controlled release through water-soluble carbodiimide activation. The resulting conjugate formed self-assembled nanoparticles in aqueous solution with particle size of 279 nm and ergocalciferol hemisuccinate...... content of 8.4% (w/w). Almost spherical 50–90 nm nanoparticles were observed by scanning and transmission electron microscopy upon drying. Drug linking to glycol chitosan was confirmed by FTIR spectroscopy and proton NMR. Particles were also characterized by differential scanning calorimetry and wide...

Self-folding polymeric containers for encapsulation and delivery of drugs.

Science.gov (United States)

Fernandes, Rohan; Gracias, David H

2012-11-01

Self-folding broadly refers to self-assembly processes wherein thin films or interconnected planar templates curve, roll-up or fold into three dimensional (3D) structures such as cylindrical tubes, spirals, corrugated sheets or polyhedra. The process has been demonstrated with metallic, semiconducting and polymeric films and has been used to curve tubes with diameters as small as 2nm and fold polyhedra as small as 100nm, with a surface patterning resolution of 15nm. Self-folding methods are important for drug delivery applications since they provide a means to realize 3D, biocompatible, all-polymeric containers with well-tailored composition, size, shape, wall thickness, porosity, surface patterns and chemistry. Self-folding is also a highly parallel process, and it is possible to encapsulate or self-load therapeutic cargo during assembly. A variety of therapeutic cargos such as small molecules, peptides, proteins, bacteria, fungi and mammalian cells have been encapsulated in self-folded polymeric containers. In this review, we focus on self-folding of all-polymeric containers. We discuss the mechanistic aspects of self-folding of polymeric containers driven by differential stresses or surface tension forces, the applications of self-folding polymers in drug delivery and we outline future challenges. Copyright © 2012 Elsevier B.V. All rights reserved.

Predicting Chiral Nanostructures, Lattices and Superlattices in Complex Multicomponent Nanoparticle Self-Assembly

KAUST Repository

Hur, Kahyun

2012-06-13

"Bottom up" type nanoparticle (NP) self-assembly is expected to provide facile routes to nanostructured materials for various, for example, energy related, applications. Despite progress in simulations and theories, structure prediction of self-assembled materials beyond simple model systems remains challenging. Here we utilize a field theory approach for predicting nanostructure of complex and multicomponent hybrid systems with multiple types of short- and long-range interactions. We propose design criteria for controlling a range of NP based nanomaterial structures. In good agreement with recent experiments, the theory predicts that ABC triblock terpolymer directed assemblies with ligand-stabilized NPs can lead to chiral NP network structures. Furthermore, we predict that long-range Coulomb interactions between NPs leading to simple NP lattices, when applied to NP/block copolymer (BCP) assemblies, induce NP superlattice formation within the phase separated BCP nanostructure, a strategy not yet realized experimentally. We expect such superlattices to be of increasing interest to communities involved in research on, for example, energy generation and storage, metamaterials, as well as microelectronics and information storage. © 2012 American Chemical Society.

Improved insulin loading in poly (lactic-co-glycolic) acid (PLGA) nanoparticles upon self-assembly with lipids

DEFF Research Database (Denmark)

Garcia Diaz, Maria; Foged, Camilla; Nielsen, Hanne Mørck

2015-01-01

Polymeric nanoparticles are widely investigated as drug delivery systems for oral administration. However, the hydrophobic nature of many polymers hampers effective loading of the particles with hydrophilic macromolecules such as insulin. Thus, the aim of this work was to improve the loading...... of insulin into poly(lactic-co-glycolic) acid (PLGA) nanoparticles by pre-assembly with amphiphilic lipids. Insulin was complexed with soybean phosphatidylcholine or sodium caprate by self-assembly and subsequently loaded into PLGA nanoparticles by using the double emulsion-solvent evaporation technique...... efficiencies (90% as compared to 24% in the absence of lipids). Importantly, the insulin loading capacity was increased up to 20% by using the lipid–insulin complexes. The results further showed that a main fraction of the lipid was incorporated into the nanoparticles and remained associated to the polymer...

Antioxidant Effects of Quercetin and Catechin Encapsulated into PLGA Nanoparticles

Directory of Open Access Journals (Sweden)

Hector Pool

2012-01-01

Full Text Available Polymeric nanoparticles (PLGA have been developed for the encapsulation and controlled release of quercetin and catechin. Nanoparticles were fabricated using a solvent displacement method. Physicochemical properties were measured by light scattering, scanning electron microscopy and ζ-potential, X-ray diffraction, infrared spectroscopy and differential scanning calorimetry. Encapsulation efficiency and in vitro release profiles were obtained from differential pulse voltammetry experiments. Antioxidant properties of free and encapsulated flavonoids were determined by TBARS, fluorescence spectroscopy and standard chelating activity methods. Relatively small (d≈ 400 nm polymeric nanoparticles were obtained containing quercetin or catechin in a non-crystalline form (EE ≈ 79% and the main interactions between the polymer and each flavonoid were found to consist of hydrogen bonds. In vitro release profiles were pH-dependant, the more acidic pH, the faster release of each flavonoid from the polymeric nanoparticles. The inhibition of the action of free radicals and chelating properties, were also enhanced when quercetin and catechin were encapsulated within PLGA nanoparticles. The information obtained from this study will facilitate the design and fabrication of polymeric nanoparticles as possible oral delivery systems for encapsulation, protection and controlled release of flavonoids aimed to prevent oxidative stress in human body or food products.

Controlled synthesis of pompon-like self-assemblies of Pd nanoparticles under microwave irradiation

International Nuclear Information System (INIS)

Tong Xia; Zhao Yanxi; Huang Tao; Liu Hanfan; Liew, Kong Yong

2009-01-01

Pd nanoparticles with uniform, self-assembled pompon-like nanostructure were synthesized by thermal decomposition of palladium acetate under microwave irradiation with methyl isobutyl ketone (MIBK) as a solvent in the presence of a little amount of ethylene glycol (EG) and KOH without using any special stabilizers. The as-synthesized Pd nano-pompons were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray powder diffraction. The results show that the as-prepared Pd nano-pompons with the average diameters in the range of 28-81 nm were self-assemblies organized by hundreds of smaller primary nanoparticles with an average dimension of about 2.4 nm. The sizes of Pd nano-pompons can be well controlled by adjusting the concentration of palladium acetate. A little amount of EG and KOH also plays an important role in controlling the size, uniformity and dispersion of Pd nano-pompons. The Pd nano-pompons can be easily supported on γ-Al 2 O 3 and their catalytic activity was examined preliminarily.

Scalable and uniform 1D nanoparticles by synchronous polymerization, crystallization and self-assembly

Science.gov (United States)

Boott, Charlotte E.; Gwyther, Jessica; Harniman, Robert L.; Hayward, Dominic W.; Manners, Ian

2017-08-01

The preparation of well-defined nanoparticles based on soft matter, using solution-processing techniques on a commercially viable scale, is a major challenge of widespread importance. Self-assembly of block copolymers in solvents that selectively solvate one of the segments provides a promising route to core-corona nanoparticles (micelles) with a wide range of potential uses. Nevertheless, significant limitations to this approach also exist. For example, the solution processing of block copolymers generally follows a separate synthesis step and is normally performed at high dilution. Moreover, non-spherical micelles—which are promising for many applications—are generally difficult to access, samples are polydisperse and precise dimensional control is not possible. Here we demonstrate the formation of platelet and cylindrical micelles at concentrations up to 25% solids via a one-pot approach—starting from monomers—that combines polymerization-induced and crystallization-driven self-assembly. We also show that performing the procedure in the presence of small seed micelles allows the scalable formation of low dispersity samples of cylindrical micelles of controlled length up to three micrometres.

Intracellular Peptide Self-Assembly: A Biomimetic Approach for in Situ Nanodrug Preparation.

Science.gov (United States)

Du, Wei; Hu, Xiaomu; Wei, Weichen; Liang, Gaolin

2018-04-18

Most nanodrugs are preprepared by encapsulating or loading the drugs with nanocarriers (e.g., dendrimers, liposomes, micelles, and polymeric nanoparticles). However, besides the low bioavailability and fast excretion of the nanodrugs in vivo, nanocarriers often exhibit in vitro and in vivo cytotoxicity, oxidative stress, and inflammation. Self-assembly is a ubiquitous process in biology where it plays important roles and underlies the formation of a wide variety of complex biological structures. Inspired by some cellular nanostructures (e.g., actin filaments, microtubules, vesicles, and micelles) in biological systems which are formed via molecular self-assembly, in recent decades, scientists have utilized self-assembly of oligomeric peptide under specific physiological or pathological environments to in situ construct nanodrugs for lesion-targeted therapies. On one hand, peptide-based nanodrugs always have some excellent intrinsic chemical (specificity, intrinsic bioactivity, biodegradability) and physical (small size, conformation) properties. On the other hand, stimuli-regulated intracellular self-assembly of nanodrugs is quite an efficient way to accumulate the drugs in lesion location and can realize an in situ slow release of the drugs. In this review article, we provided an overview on recent design principles for intracellular peptide self-assembly and illustrate how these principles have been applied for the in situ preparation of nanodrugs at the lesion location. In the last part, we list some challenges underlying this strategy and their possible solutions. Moreover, we envision the future possible theranostic applications of this strategy.

Oxidation of Bioethanol using Zeolite-Encapsulated Gold Nanoparticles

DEFF Research Database (Denmark)

Mielby, Jerrik Jørgen; Abildstrøm, Jacob Oskar; Wang, Feng

2014-01-01

With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite-1 is reported and their high...... zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2-3nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50% conversion of ethanol with 98...

Oxidation of Bioethanol using Zeolite-Encapsulated Gold Nanoparticles

DEFF Research Database (Denmark)

Mielby, Jerrik Jørgen; Abildstrøm, Jacob Oskar; Wang, Feng

2014-01-01

With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite‐1 is reported and their high...... zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2–3 nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50 % conversion of ethanol with 98...

Dewetting-mediated pattern formation in nanoparticle assemblies

International Nuclear Information System (INIS)

Stannard, Andrew

2011-01-01

The deposition of nanoparticles from solution onto solid substrates is a diverse subfield of current nanoscience research. Complex physical and chemical processes underpin the self-assembly and self-organization of colloidal nanoparticles at two-phase (solid-liquid, liquid-air) interfaces and three-phase (solid-liquid-air) contact lines. This review discusses key recent advances made in the understanding of nonequilibrium dewetting processes of nanoparticle-containing solutions, detailing how such an apparently simple experimental system can give rise to such a strikingly varied palette of two-dimensional self-organized nanoparticle array morphologies. Patterns discussed include worm-like domains, cellular networks, microscale rings, and fractal-like fingering structures. There remain many unresolved issues regarding the role of the solvent dewetting dynamics in assembly processes of this type, with a significant focus on how dewetting can be coerced to produce nanoparticle arrays with desirable characteristics such as long-range order. In addition to these topics, methods developed to control nanofluid dewetting through routes such as confining the geometries of drying solutions, depositing onto pre-patterned heterogeneous substrates, and post-dewetting pattern evolution via local or global manipulation are covered. (topical review)

Dewetting-mediated pattern formation in nanoparticle assemblies.

Science.gov (United States)

Stannard, Andrew

2011-03-02

The deposition of nanoparticles from solution onto solid substrates is a diverse subfield of current nanoscience research. Complex physical and chemical processes underpin the self-assembly and self-organization of colloidal nanoparticles at two-phase (solid-liquid, liquid-air) interfaces and three-phase (solid-liquid-air) contact lines. This review discusses key recent advances made in the understanding of nonequilibrium dewetting processes of nanoparticle-containing solutions, detailing how such an apparently simple experimental system can give rise to such a strikingly varied palette of two-dimensional self-organized nanoparticle array morphologies. Patterns discussed include worm-like domains, cellular networks, microscale rings, and fractal-like fingering structures. There remain many unresolved issues regarding the role of the solvent dewetting dynamics in assembly processes of this type, with a significant focus on how dewetting can be coerced to produce nanoparticle arrays with desirable characteristics such as long-range order. In addition to these topics, methods developed to control nanofluid dewetting through routes such as confining the geometries of drying solutions, depositing onto pre-patterned heterogeneous substrates, and post-dewetting pattern evolution via local or global manipulation are covered.

Self-aggregation behavior of hydrophobic sodium alginate derivatives in aqueous solution and their application in the nanoencapsulation of acetamiprid.

Science.gov (United States)

Zhao, Xinyu; Li, Jiacheng; Feng, Yuhong; Yu, Gaobo; Zhou, Qingfeng; He, Furui; Xiao, Dunchao; Chen, Kai; Zhang, Lei

2018-01-01

In this study, cholesteryl-grafted sodium alginate derivatives (CSAD) with different molecular weights were synthesized by esterification. The structure of CSAD was confirmed by FT-IR and 1 H NMR spectrometers. The effects of pH and CSAD polymer concentration on the self-assembled behavior and particle size of CSAD were investigated by fluorescence measurement (FM) and dynamic light scattering (DLS). In the presence of Ca 2+ , the cholesteryl-grafted sodium alginate derivative was used for fabricating self-assembled nanoparticles that can effectively encapsulate the drug acetamiprid. The drug-loaded nanoparticles were characterized by transmission electron microscopy (TEM). The encapsulation efficiency (EE) and acetamiprid drug release behavior from the nanoparticles were also studied. The results reveal that CSAD self-assembled nanoparticles had a diameter of 100nm and were nonaggregated in aqueous media; Moreover, the encapsulation efficiency and the release behavior of nanoparticles were influenced by the MW of CSAD. The mechanism of acetamiprid release was found to vary from non-Fickian (anomalous) to Fickian transport with a decrease in the molecular weight of CSAD. Copyright © 2017 Elsevier B.V. All rights reserved.

Chain-like nanostructures from anisotropic self-assembly of semiconducting metal oxide nanoparticles with a block copolymer.

Science.gov (United States)

Wang, Junzheng; Winardi, Suminto; Sugawara-Narutaki, Ayae; Kumamoto, Akihito; Tohei, Tetsuya; Shimojima, Atsushi; Okubo, Tatsuya

2012-11-21

A facile method is reported for the preparation of chain-like nanostructures by anisotropic self-assembly of TiO(2) and SnO(2) nanoparticles with the aid of a block copolymer in an aqueous medium. Well-defined crystallographic orientations between neighbouring nanoparticles are observed in TiO(2) nanochains, which is important for tailoring the grain boundaries and thus enhancing charge transport.

Nanobiotechnology today: focus on nanoparticles

Directory of Open Access Journals (Sweden)

Soloviev Mikhail

2007-12-01

Full Text Available Abstract In the recent years the nanobiotechnology field and the Journal of Nanobiotechnology readership have witnessed an increase in interest towards the nanoparticles and their biological effects and applications. These include bottom-up and molecular self-assembly, biological effects of naked nanoparticles and nano-safety, drug encapsulation and nanotherapeutics, and novel nanoparticles for use in microscopy, imaging and diagnostics. This review highlights recent Journal of Nanobiotechnology publications in some of these areas http://www.jnanobiotechnology.com.

Applications of calixarenes in cancer chemotherapy: facts and perspectives

Directory of Open Access Journals (Sweden)

Yousaf A

2015-06-01

Full Text Available Ali Yousaf,1 Shafida Abd Hamid,1 Noraslinda M Bunnori,1 AA Ishola2 1Kulliyyah of Science, 2Kulliyyah of Medicine, International Islamic University Malaysia, Bandar Indera Mahkota, Malaysia Abstract: Research on the therapeutic applications of calixarene derivatives is an emerging area of interest. The anticancer activity of various functionalized calixarenes has been reported by several research groups. Due to their superior geometric shape, calixarenes can accommodate drug molecules by forming inclusion complexes. Controlled release of anticancer drugs by calixarenes might help in targeted chemotherapy. This review summarizes the anticancer potential of the calixarenes and their drug loading properties. The potential use of calixarenes in chemoradiotherapy is also highlighted in brief. Keywords: cancer, chemotherapy, calixarenes

Vertically aligned ZnO nanorods via self-assembled spray pyrolyzed nanoparticles for dye-sensitized solar cells

International Nuclear Information System (INIS)

Dwivedi, Charu; Dutta, V

2012-01-01

Well-aligned zinc oxide (ZnO) nanorods are fabricated on indium-tin-oxide (ITO) coated glass substrates via self-assembly of ZnO nanoparticles created using continuous spray pyrolysis (CoSP) technique. The method involves pre-treatment by dip-coating the substrate with a solution comprising of zinc salt for creating a seed layer, and then spray-pyrolyzed ZnO nanoparticles self-assemble on the pre-treated substrate. The effect of the substrate pre-treatment and the deposition time (t dep ) of nanoparticles is investigated. The results show that the substrate pre-treatment influences the growth of ZnO nanorods which are absent without the pre-treatment. Nanoparticle collection and nanorod growth on different substrates are done simultaneously. The thin films of as-grown nanorods are used as photoelectrode materials to fabricate dye-sensitized solar cells (DSSCs) and the effect of nanorods grown for different times has been studied. The best performance with this cell structure is found for the layer with t dep =15 min, which showed a conversion efficiency of 1.77% for the cell area of 0.25 cm 2

Amperometric biosensor based on carbon nanotubes coated with polyaniline/dendrimer-encapsulated Pt nanoparticles for glucose detection

International Nuclear Information System (INIS)

Xu Lihuan; Zhu Yihua; Yang Xiaoling; Li Chunzhong

2009-01-01

A novel amperometric glucose biosensor based on the nanocomposites of multi-wall carbon nanotubes (CNT) coated with polyaniline (PANI) and dendrimer-encapsulated Pt nanoparticles (Pt-DENs) is prepared. CNT coated with protonated PANI is in situ synthesized and Pt-DENs is absorbed on PANI/CNT composite surface by self-assembly method. Then Glucose oxidase (GOx) is crosslink-immobilizated onto Pt-DENs/PANI/CNT composite film. The results show that the fabricated GOx/Pt-DENs/PANI/CNT electrode exhibits excellent response performance to glucose, such as low detection limit (0.5 μM), wide linear range (1 μM-12 mM), short response time (about 5 s), high sensitivity (42.0 μA mM -1 cm -2 ) and stability (83% remains after 3 weeks).

Thickness-Dependent Strain Effect on the Deformation of the Graphene-Encapsulated Au Nanoparticles

Directory of Open Access Journals (Sweden)

Shuangli Ye

2014-01-01

Full Text Available The strain effect on graphene-encapsulated Au nanoparticles is investigated. A finite-element calculation is performed to simulate the strain distribution and morphology of the monolayer and multilayer graphene-encapsulated Au nanoparticles, respectively. It can be found that the inhomogeneous strain and deformation are enhanced with the increasing shrinkage of the graphene shell. Moreover, the strain distribution and deformation are very sensitive to the layer number of the graphene shell. Especially, the inhomogeneous strain at the interface between the graphene shell and encapsulated Au nanoparticles is strongly tuned by the graphene thickness. For the mono- and bilayer graphene-encapsulated Au nanoparticles, the dramatic shape transformation can be observed. However, with increasing the graphene thickness further, there is hardly deformation for the encapsulated Au nanoparticles. These simulated results indicate that the strain and deformation can be designed by the graphene layer thickness, which provides an opportunity to engineer the structure and morphology of the graphene-encapsulated nanoparticles.

Self-assembled peptides for coating of active sulfur nanoparticles in lithium–sulfur battery

International Nuclear Information System (INIS)

Jewel, Yead; Yoo, Kisoo; Liu, Jin; Dutta, Prashanta

2016-01-01

Development of lithium–sulfur (Li–S) battery is hindered by poor cyclability due to the loss of sulfur, although Li–S battery can provide high energy density. Coating of sulfur nanoparticles can help maintain active sulfur in the cathode of Li–S battery, and hence increase the cyclability. Among myriad of coating materials, synthetic peptides are very attractive because of their spontaneous self-assembly as well as electrical conductive characteristics. In this study, we explored the use of various synthetic peptides as a coating material for sulfur nanoparticles. Atomistic simulations were carried out to identify optimal peptide structure and density for coating sulfur nanoparticles. Three different peptide models, poly-proline, poly(leucine–lysine) and poly-histidine, are selected for this study based on their peptide–peptide and peptide-sulfur interactions. Simulation results show that both poly-proline and poly(leucine–lysine) can form self-assembled coating on sulfur nanoparticles (2–20 nm) in pyrrolidinone, a commonly used solvent for cathode slurry. We also studied the structural integrity of these synthetic peptides in organic [dioxolane (DOL) and dimethoxyethane (DME)] electrolyte used in Li–S battery. Both peptides show stable structures in organic electrolyte (DOL/DME) used in Li–S battery. Furthermore, the dissolution of sulfur molecules in organic electrolyte is investigated in the absence and presence of these peptide coatings. It was found that only poly(leucine–lysine)-based peptide can most effectively suppress the sulfur loss in electrolyte, suggesting its potential applications in Li–S battery as a coating material.Graphical abstract

Towards Crystals of Crystals of NanoCrystals : a Self-Assembly Study

NARCIS (Netherlands)

de Nijs, B.

2014-01-01

In this thesis several methods to synthesise monodisperse nanoparticles and how to self-assembled them within emulsion droplets are presented. The self-assembly behaviour of nanoparticles within the spherical confinement of emulsion droplets resulted in highly ordered crystalline supraparticles that

Electrostatically self-assembled films containing II-VI semiconductor nanoparticles: Optical and electrical properties

International Nuclear Information System (INIS)

Suryajaya; Nabok, A.V.; Tsargorodskaya, A.; Hassan, A.K.; Davis, F.

2008-01-01

CdS and ZnS semiconducting colloid nanoparticles were deposited as thin films using the technique of electrostatic self-assembly. The process of alternative deposition of Poly-allylamine Hydrochloride (PAH) and CdS (or ZnS) layers were monitored with a novel optical method of total internal reflection ellipsometry (TIRE). The fitting of TIRE spectra allowed the evaluation of the parameter (thickness, refractive index and extinction coefficients) of all consecutively deposited layers. I-V characteristics of the films obtained were studied in sandwich structures on Indium Tin Oxide (ITO) conductive electrodes using the mercury probe technique. The presence of CdS (or ZnS) nanoparticles in the polyelectrolyte films leads to a switching behaviour, which may be attributed to the resonance electron tunneling via semiconducting nanoparticles

Self-assembling nanoparticles containing dexamethasone as a novel therapy in allergic airways inflammation.

Directory of Open Access Journals (Sweden)

Nicholas J Kenyon

Full Text Available Nanocarriers can deliver a wide variety of drugs, target them to sites of interest, and protect them from degradation and inactivation by the body. They have the capacity to improve drug action and decrease undesirable systemic effects. We have previously developed a well-defined non-toxic PEG-dendritic block telodendrimer for successful delivery of chemotherapeutics agents and, in these studies, we apply this technology for therapeutic development in asthma. In these proof-of-concept experiments, we hypothesized that dexamethasone contained in self-assembling nanoparticles (Dex-NP and delivered systemically would target the lung and decrease allergic lung inflammation and airways hyper-responsiveness to a greater degree than equivalent doses of dexamethasone (Dex alone. We found that ovalbumin (Ova-exposed mice treated with Dex-NP had significantly fewer total cells (2.78 ± 0.44 × 10(5 (n = 18 vs. 5.98 ± 1.3 × 10(5 (n = 13, P<0.05 and eosinophils (1.09 ± 0.28 × 10(5 (n = 18 vs. 2.94 ± 0.6 × 10(5 (n = 12, p<0.05 in the lung lavage than Ova-exposed mice alone. Also, lower levels of the inflammatory cytokines IL-4 (3.43 ± 1.2 (n = 11 vs. 8.56 ± 2.1 (n = 8 pg/ml, p<0.05 and MCP-1 (13.1 ± 3.6 (n = 8 vs. 28.8 ± 8.7 (n = 10 pg/ml, p<0.05 were found in lungs of the Dex-NP compared to control, and they were not lower in the Dex alone group. In addition, respiratory system resistance was lower in the Dex-NP compared to the other Ova-exposed groups suggesting a better therapeutic effect on airways hyperresponsiveness. Taken together, these findings from early-stage drug development studies suggest that the encapsulation and protection of anti-inflammatory agents such as corticosteroids in nanoparticle formulations can improve efficacy. Further development of novel drugs in nanoparticles is warranted to explore potential treatments for chronic inflammatory diseases such as asthma.

Self-assembled hyaluronic acid nanoparticles for controlled release of agrochemicals and diosgenin.

Science.gov (United States)

Quiñones, Javier Pérez; Brüggemann, Oliver; Covas, Carlos Peniche; Ossipov, Dmitri A

2017-10-01

Commercial sodium hyaluronate (HA) and synthetic hydrazide-modified HA were functionalized with diosgenin and two agrochemicals (brassinosteroids DI31 and S7) with degree of substitution ranging from 5.6 to 13.1%. The HA-steroid conjugates were studied with FTIR, 1 H NMR and differential scanning calorimetry. Dynamic light scattering revealed self-assembly of the HA-steroid conjugates into stable negatively charged nanoparticles of around 159nm-441nm in water, which after drying appeared as 140nm-370nm spherically shaped nanoparticles according to transmission electron microscopy. These nanoparticles exhibited almost constant release rates of steroids for the first 8h, demonstrating sustained steroids delivery for 72h in acidic medium. The nanoparticles formed from HA-steroid conjugates were not cytotoxic to human microvascular endothelial cells (HMVEC), while the HA- brassinosteroid nanoparticles showed in vitro agrochemical activity that was superior to the activity observed for the parent brassinosteroids DI31 and S7 at 10 -5 to 10 -7 mgmL -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Encapsulation of nanoparticles into single-crystal ZnO nanorods and microrods.

Science.gov (United States)

Liu, Jinzhang; Notarianni, Marco; Rintoul, Llew; Motta, Nunzio

2014-01-01

One-dimensional single crystal incorporating functional nanoparticles of other materials could be an interesting platform for various applications. We studied the encapsulation of nanoparticles into single-crystal ZnO nanorods by exploiting the crystal growth of ZnO in aqueous solution. Two types of nanodiamonds with mean diameters of 10 nm and 40 nm, respectively, and polymer nanobeads with size of 200 nm have been used to study the encapsulation process. It was found that by regrowing these ZnO nanorods with nanoparticles attached to their surfaces, a full encapsulation of nanoparticles into nanorods can be achieved. We demonstrate that our low-temperature aqueous solution growth of ZnO nanorods do not affect or cause degradation of the nanoparticles of either inorganic or organic materials. This new growth method opens the way to a plethora of applications combining the properties of single crystal host and encapsulated nanoparticles. We perform micro-photoluminescence measurement on a single ZnO nanorod containing luminescent nanodiamonds and the spectrum has a different shape from that of naked nanodiamonds, revealing the cavity effect of ZnO nanorod.

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

Science.gov (United States)

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

2018-01-01

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

The effect of colloidal silica nanoparticles encapsulated fluorescein dye using micelle entrapment method

Science.gov (United States)

Ahmad, Atiqah; Zakaria, Nor Dyana; Lockman, Zainovia; Razak, Khairunisak Abdul

2018-05-01

The advancement of nanoparticle-based approaches such as quantum dots (QDs), metallic (Au and Ag) NPs, silica NPs and other types of nanomaterial have led to a large variety of biomolecular imaging and labelling reagents with controlled size and shaped to overcome the limitation of conventional organic dye. In this study, the yellowish green color of fluorescein dye was encapsulated into colloidal silica nanoparticles by using micelle entrapment approach. Two different size of silica nanoparticles encapsulated fluorescein dye (27.7 ± 5.6 and 46.73 ± 4.3 nm) with spherical and monodispered of nanoparticles were synthesised by varying the volume of co-solvent during the synthesis process. The particles size, particles morphology, absorption spectrum and the photostability of fluorescein dye was measured by using dynamic light scaterring (DLS), Transmission Electron Microscope (TEM) and UV-Vis spectrometer. Furthermore, the effect of photostability of of silica nanoparticles encapsulated fluorescein dye was measured under radiation of 200 W of Halogen lamp for 60 minutes. The silica nanoparticles encapsulated fluorescein dye was more stable compared to bare fluorescein dye after the exposure. In conclusion, the photostability of silica nanoparticles encapsulated fluorescein dye was improved compared to bare fluorescein dye, thus silica nanoparticles encapsulation successfully provides protection from the photobleaching and photodegradation of fluorescein dye.

Nanoparticle Encapsulation in Diblock Copolymer/Homopolymer Blend Thin Film Mixtures

Science.gov (United States)

Zhao, Junnan; Chen, Xi; Green, Peter

2014-03-01

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

Proton Mediated Chemistry and Catalysis in a Self-Assembled Supramolecular Host

Energy Technology Data Exchange (ETDEWEB)

Pluth, Michael; Bergman, Robert; Raymond, Kenneth

2009-04-10

Synthetic supramolecular host assemblies can impart unique reactivity to encapsulated guest molecules. Synthetic host molecules have been developed to carry out complex reactions within their cavities, despite the fact that they lack the type of specifically tailored functional groups normally located in the analogous active sites of enzymes. Over the past decade, the Raymond group has developed a series of self-assembled supramolecules and the Bergman group has developed and studied a number of catalytic transformations. In this Account, we detail recent collaborative work between these two groups, focusing on chemical catalysis stemming from the encapsulation of protonated guests and expanding to acid catalysis in basic solution. We initially investigated the ability of a water-soluble, self-assembled supramolecular host molecule to encapsulate protonated guests in its hydrophobic core. Our study of encapsulated protonated amines revealed rich host-guest chemistry. We established that self-exchange (that is, in-out guest movement) rates of protonated amines were dependent on the steric bulk of the amine rather than its basicity. The host molecule has purely rotational tetrahedral (T) symmetry, so guests with geminal N-methyl groups (and their attendant mirror plane) were effectively desymmetrized; this allowed for the observation and quantification of the barriers for nitrogen inversion followed by bond rotation. Furthermore, small nitrogen heterocycles, such as N-alkylaziridines, N-alkylazetidines, and N-alkylpyrrolidines, were found to be encapsulated as proton-bound homodimers or homotrimers. We further investigated the thermodynamic stabilization of protonated amines, showing that encapsulation makes the amines more basic in the cavity. Encapsulation raises the effective basicity of protonated amines by up to 4.5 pK{sub a} units, a difference almost as large as that between the moderate and strong bases carbonate and hydroxide. The thermodynamic stabilization

Proton-Mediated Chemistry and Catalysis in a Self-Assembled Supramolecular Host

International Nuclear Information System (INIS)

Pluth, Michael; Bergman, Robert; Raymond, Kenneth

2009-01-01

Synthetic supramolecular host assemblies can impart unique reactivity to encapsulated guest molecules. Synthetic host molecules have been developed to carry out complex reactions within their cavities, despite the fact that they lack the type of specifically tailored functional groups normally located in the analogous active sites of enzymes. Over the past decade, the Raymond group has developed a series of self-assembled supramolecules and the Bergman group has developed and studied a number of catalytic transformations. In this Account, we detail recent collaborative work between these two groups, focusing on chemical catalysis stemming from the encapsulation of protonated guests and expanding to acid catalysis in basic solution. We initially investigated the ability of a water-soluble, self-assembled supramolecular host molecule to encapsulate protonated guests in its hydrophobic core. Our study of encapsulated protonated amines revealed rich host-guest chemistry. We established that self-exchange (that is, in-out guest movement) rates of protonated amines were dependent on the steric bulk of the amine rather than its basicity. The host molecule has purely rotational tetrahedral (T) symmetry, so guests with geminal N-methyl groups (and their attendant mirror plane) were effectively desymmetrized; this allowed for the observation and quantification of the barriers for nitrogen inversion followed by bond rotation. Furthermore, small nitrogen heterocycles, such as N-alkylaziridines, N-alkylazetidines, and N-alkylpyrrolidines, were found to be encapsulated as proton-bound homodimers or homotrimers. We further investigated the thermodynamic stabilization of protonated amines, showing that encapsulation makes the amines more basic in the cavity. Encapsulation raises the effective basicity of protonated amines by up to 4.5 pK a units, a difference almost as large as that between the moderate and strong bases carbonate and hydroxide. The thermodynamic stabilization of

Understanding the self-assembly of proteins onto gold nanoparticles and quantum dots driven by metal-histidine coordination.

Science.gov (United States)

Aldeek, Fadi; Safi, Malak; Zhan, Naiqian; Palui, Goutam; Mattoussi, Hedi

2013-11-26

Coupling of polyhistidine-appended biomolecules to inorganic nanocrystals driven by metal-affinity interactions is a greatly promising strategy to form hybrid bioconjugates. It is simple to implement and can take advantage of the fact that polyhistidine-appended proteins and peptides are routinely prepared using well established molecular engineering techniques. A few groups have shown its effectiveness for coupling proteins onto Zn- or Cd-rich semiconductor quantum dots (QDs). Expanding this conjugation scheme to other metal-rich nanoparticles (NPs) such as AuNPs would be of great interest to researchers actively seeking effective means for interfacing nanostructured materials with biology. In this report, we investigated the metal-affinity driven self-assembly between AuNPs and two engineered proteins, a His7-appended maltose binding protein (MBP-His) and a fluorescent His6-terminated mCherry protein. In particular, we investigated the influence of the capping ligand affinity to the nanoparticle surface, its density, and its lateral extension on the AuNP-protein self-assembly. Affinity gel chromatography was used to test the AuNP-MPB-His7 self-assembly, while NP-to-mCherry-His6 binding was evaluated using fluorescence measurements. We also assessed the kinetics of the self-assembly between AuNPs and proteins in solution, using time-dependent changes in the energy transfer quenching of mCherry fluorescent proteins as they immobilize onto the AuNP surface. This allowed determination of the dissociation rate constant, Kd(-1) ∼ 1-5 nM. Furthermore, a close comparison of the protein self-assembly onto AuNPs or QDs provided additional insights into which parameters control the interactions between imidazoles and metal ions in these systems.

Template assisted self-assembly of iron oxide nanoparticles: An x-ray structural analysis

International Nuclear Information System (INIS)

Mishra, D.; Zabel, H.; Ulyanov, S. V.; Romanov, V. P.; Uzdin, V. M.

2014-01-01

We have fabricated by e-beam lithography periodic arrays of rectangular shaped trenches of different widths into Si substrates. The trenches were filled with iron oxide nanoparticles, 20 nm in diameter, by spin-coating them onto the Si substrate. The trenches have the purpose to assist the self-assembly of the iron oxide nanoparticles. Using x-ray scattering techniques, we have analyzed the structure factor of the trenches before and after filling in order to determine the filling factor. We present a theoretical analysis of the x-ray scattering function within the distorted-wave Born approximation and we present a quantitative comparison between theory and experiment

Template assisted self-assembly of iron oxide nanoparticles: An x-ray structural analysis

Energy Technology Data Exchange (ETDEWEB)

Mishra, D. [Department of Physics, Ruhr-University Bochum, 44780 Bochum (Germany); Institut fuer Optik und Atomare Physik, Technische Universitaet Berlin, Strasse des 17. Juni 135, 10623 Berlin (Germany); Zabel, H. [Department of Physics, Ruhr-University Bochum, 44780 Bochum (Germany); Ulyanov, S. V. [St.-Petersburg State University, Ul' yanovskaya ul.1, Petrodvorets, St.-Petersburg 198904 (Russian Federation); St.-Petersburg University of Commerce and Economics, St.-Petersburg 194018 (Russian Federation); Romanov, V. P. [St.-Petersburg State University, Ul' yanovskaya ul.1, Petrodvorets, St.-Petersburg 198904 (Russian Federation); Uzdin, V. M. [St.-Petersburg State University, Ul' yanovskaya ul.1, Petrodvorets, St.-Petersburg 198904 (Russian Federation); St.-Petersburg National Research University of Information Technologies, Mechanics and Optics, 49, Kronverkskij, St.-Petersburg 197101 (Russian Federation)

2014-02-07

We have fabricated by e-beam lithography periodic arrays of rectangular shaped trenches of different widths into Si substrates. The trenches were filled with iron oxide nanoparticles, 20 nm in diameter, by spin-coating them onto the Si substrate. The trenches have the purpose to assist the self-assembly of the iron oxide nanoparticles. Using x-ray scattering techniques, we have analyzed the structure factor of the trenches before and after filling in order to determine the filling factor. We present a theoretical analysis of the x-ray scattering function within the distorted-wave Born approximation and we present a quantitative comparison between theory and experiment.

Encapsulation method for atom probe tomography analysis of nanoparticles

International Nuclear Information System (INIS)

Larson, D.J.; Giddings, A.D.; Wu, Y.; Verheijen, M.A.; Prosa, T.J.; Roozeboom, F.; Rice, K.P.; Kessels, W.M.M.; Geiser, B.P.; Kelly, T.F.

2015-01-01

Open-space nanomaterials are a widespread class of technologically important materials that are generally incompatible with analysis by atom probe tomography (APT) due to issues with specimen preparation, field evaporation and data reconstruction. The feasibility of encapsulating such non-compact matter in a matrix to enable APT measurements is investigated using nanoparticles as an example. Simulations of field evaporation of a void, and the resulting artifacts in ion trajectory, underpin the requirement that no voids remain after encapsulation. The approach is demonstrated by encapsulating Pt nanoparticles in an ZnO:Al matrix created by atomic layer deposition, a growth technique which offers very high surface coverage and conformality. APT measurements of the Pt nanoparticles are correlated with transmission electron microscopy images and numerical simulations in order to evaluate the accuracy of the APT reconstruction. - Highlights: • Pt nanoparticles were analyzed using atom probe tomography and TEM. • The particles were prepared by encapsulation using atomic layer deposition. • Simulation of field evaporation near a void results in aberrations in ion trajectories. • Apparent differences between TEM and APT analyses are reconciled through simulation of field evaporation from a low-field matrix containing high-field NPs; ion trajectory aberrations are shown to lead to an apparent mixing of the matrix into the NPs.

Encapsulation of nanoparticles into single-crystal ZnO nanorods and microrods

Directory of Open Access Journals (Sweden)

Jinzhang Liu

2014-04-01

Full Text Available One-dimensional single crystal incorporating functional nanoparticles of other materials could be an interesting platform for various applications. We studied the encapsulation of nanoparticles into single-crystal ZnO nanorods by exploiting the crystal growth of ZnO in aqueous solution. Two types of nanodiamonds with mean diameters of 10 nm and 40 nm, respectively, and polymer nanobeads with size of 200 nm have been used to study the encapsulation process. It was found that by regrowing these ZnO nanorods with nanoparticles attached to their surfaces, a full encapsulation of nanoparticles into nanorods can be achieved. We demonstrate that our low-temperature aqueous solution growth of ZnO nanorods do not affect or cause degradation of the nanoparticles of either inorganic or organic materials. This new growth method opens the way to a plethora of applications combining the properties of single crystal host and encapsulated nanoparticles. We perform micro-photoluminescence measurement on a single ZnO nanorod containing luminescent nanodiamonds and the spectrum has a different shape from that of naked nanodiamonds, revealing the cavity effect of ZnO nanorod.

Fluorescence enhancement in large-scale self-assembled gold nanoparticle double arrays

International Nuclear Information System (INIS)

Chekini, M.; Bierwagen, J.; Cunningham, A.; Bürgi, T.; Filter, R.; Rockstuhl, C.

2015-01-01

Localized surface plasmon resonances excited in metallic nanoparticles confine and enhance electromagnetic fields at the nanoscale. This is particularly pronounced in dimers made from two closely spaced nanoparticles. When quantum emitters, such as dyes, are placed in the gap of those dimers, their absorption and emission characteristics can be modified. Both processes have to be considered when aiming to enhance the fluorescence from the quantum emitters. This is particularly challenging for dimers, since the electromagnetic properties and the enhanced fluorescence sensitively depend on the distance between the nanoparticles. Here, we use a layer-by-layer method to precisely control the distances in such systems. We consider a dye layer deposited on top of an array of gold nanoparticles or integrated into a central position of a double array of gold nanoparticles. We study the effect of the spatial arrangement and the average distance on the plasmon-enhanced fluorescence. We found a maximum of a 99-fold increase in the fluorescence intensity of the dye layer sandwiched between two gold nanoparticle arrays. The interaction of the dye layer with the plasmonic system also causes a spectral shift in the emission wavelengths and a shortening of the fluorescence life times. Our work paves the way for large-scale, high throughput, and low-cost self-assembled functionalized plasmonic systems that can be used as efficient light sources

Self-assembled superparamagnetic nanoparticles as MRI contrast agents— A review

International Nuclear Information System (INIS)

Su Hong-Ying; Wu Chang-Qiang; Ai Hua; Li Dan-Yang

2015-01-01

Recent progress of the preparation and applications of superparamagnetic iron oxide (SPIO) clusters as magnetic resonance imaging (MRI) probes is reviewed with regard to their applications in labeling and tracking cells in vivo, in diagnosis of cardiovascular diseases and tumors, and in drug delivery systems. Magnetic nanoparticles (NPs), especially SPIO nanoparticles, have long been used as MRI contrast agents and as an advantageous nanoplatform for drug delivery, taking advantage of their unique magnetic properties and ability to function at the molecular and cellular levels. Due to advances in nanotechnology, various means to control SPIO NPs’ size, composition, magnetization and relaxivity have been developed, as well as ways to usefully modify their surface. Recently, self-assembly of SPIO NP clusters in particulate carriers—such as polymeric micelles, vesicles, liposomes, and layer-by-layer (LbL) capsules—have been widely studied for application as ultrasensitive MRI probes, owing to their remarkably high spin–spin (T 2 ) relaxivity and convenience for further functionalization. (topical review)

Insitu synthesis of self-assembled gold nanoparticles on glass or silicon substrates through reactive inkjet printing

KAUST Repository

Abulikemu, Mutalifu; Da'As, Eman Husni; Haverinen, Hanna M.; Cha, Dong Kyu; Malik, Mohammad A.; Jabbour, Ghassan Elie

2013-01-01

A facile and low cost method for the synthesis of self-assembled nanoparticles (NPs) with minimal size variation and chemical waste by using reactive inkjet printing was developed. Gold NPs with diameters as small as (8±2)nm can be made at low

Kinetic control of block copolymer self-assembly into multicompartment and novel geometry nanoparticles

Science.gov (United States)

Chen, Yingchao; Wang, Xiaojun; Zhang, Ke; Wooley, Karen; Mays, Jimmy; Percec, Virgil; Pochan, Darrin

2012-02-01

Micelles with the segregation of hydrophobic blocks trapped in the same nanoparticle core have been produced through co-self-assembly of two block copolymers in THF/water dilute solution. The dissolution of two block copolymer sharing the same polyacrylic acid PAA blocks in THF undergoes consequent aggregation and phase separation through either slow water titration or quick water addition that triggers the micellar formation. The combination and comparison of the two water addition kinetic pathways are the keys of forming multicompartment structures at high water content. Importantly, the addition of organic diamine provides for acid-base complexation with the PAA side chains which, in turn, plays the key role of trapping unlike hydrophobic blocks from different block copolymers into one nanoparticle core. The kinetic control of solution assembly can be applied to other molecular systems such as dendrimers as well as other block copolymer molecules. Transmission electron microscopy, cryogenic transmission electron microscopy, light scattering have been applied to characterize the micelle structures.

Dipolar magnetism in ordered and disordered low-dimensional nanoparticle assemblies

DEFF Research Database (Denmark)

Varón, M.; Beleggia, M; Kasama, T

2013-01-01

order at ambient temperature in assemblies of closely-spaced nanoparticles with magnetic moments of ≥ 100 μ(B). Here we use electron holography with sub-particle resolution to reveal the correlation between particle arrangement and magnetic order in self-assembled 1D and quasi-2D arrangements of 15 nm...... cobalt nanoparticles. In the initial states, we observe dipolar ferromagnetism, antiferromagnetism and local flux closure, depending on the particle arrangement. Surprisingly, after magnetic saturation, measurements and numerical simulations show that overall ferromagnetic order exists in the present...... nanoparticle assemblies even when their arrangement is completely disordered. Such direct quantification of the correlation between topological and magnetic order is essential for the technological exploitation of magnetic quasi-2D nanoparticle assemblies....

Encapsulation of albumin in self-assembled layer-by-layer microcapsules: comparison of co-precipitation and adsorption techniques.

Science.gov (United States)

Labala, Suman; Mandapalli, Praveen Kumar; Bhatnagar, Shubhmita; Venuganti, Venkata Vamsi Krishna

2015-01-01

The objective of this study is to prepare and characterize polymeric self-assembled layer-by-layer microcapsules (LbL-MC) to deliver a model protein, bovine serum albumin (BSA). The aim is to compare the BSA encapsulation in LbL-MC using co-precipitation and adsorption methods. In co-precipitation method, BSA was co-precipitated with growing calcium carbonate particles to form a core template. Later, poly(styrene sulfonate) and poly(allylamine hydrochloride) were sequentially adsorbed onto the CaCO3 templates. In adsorption method, preformed LbL-MC were incubated with BSA and encapsulation efficiency is optimized for pH and salt concentration. Free and BSA-encapsulated LbL-MC were characterized using Zetasizer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and differential scanning calorimeter. Later, in vitro release studies were performed using dialysis membrane method at pH 4, 7.4 and 9. Results from Zetasizer and SEM showed free LbL-MC with an average size and zeta-potential of 2.0 ± 0.6 μm and 8.1 ± 1.9 mV, respectively. Zeta-potential of BSA-loaded LbL-MC was (-)7.4 ± 0.7 mV and (-)5.7 ± 1.0 mV for co-precipitation and adsorption methods, respectively. In adsorption method, BSA encapsulation in LbL-MC was found to be greater at pH 6.0 and 0.2 M NaCl. Co-precipitation method provided four-fold greater encapsulation efficiency (%) of BSA in LbL-MC compared with adsorption method. At pH 4, the BSA release from LbL-MC was extended up to 120 h. Polyacrylamide gel electrophoresis showed that BSA encapsulated in LBL-MC through co-precipitation is stable toward trypsin treatment. In conclusion, co-precipitation method provided greater encapsulation of BSA in LbL-MC. Furthermore, LbL-MC can be developed as carriers for pH-controlled protein delivery.

Preparation and structure of carbon encapsulated copper nanoparticles

International Nuclear Information System (INIS)

Hao Chuncheng; Xiao Feng; Cui Zuolin

2008-01-01

Carbon-encapsulated copper nanoparticles were synthesized by a modified arc plasma method using methane as carbon source. The particles were characterized in detail by transmission electron microscope, high-resolution transmission electron microscopy, selected-area electron diffraction, X-ray diffraction, thermogravimetric and differential scanning calorimetry. The encapsulated copper nanoparticles were about 30 nm in diameter with 3-5 nm graphitic carbon shells. The outside graphitic carbon layers effectively prevented unwanted oxidation of the copper inside. The effect of the ratio of He/CH 4 on the morphologies and the formation of the carbon shell were investigated

Self-assembly synthesis of 3D graphene-encapsulated hierarchical Fe3O4 nano-flower architecture with high lithium storage capacity and excellent rate capability

Science.gov (United States)

Ma, Yating; Huang, Jian; Lin, Liang; Xie, Qingshui; Yan, Mengyu; Qu, Baihua; Wang, Laisen; Mai, Liqiang; Peng, Dong-Liang

2017-10-01

Graphene-encapsulated hierarchical metal oxides architectures can efficiently combine the merits of graphene and hierarchical metal oxides, which are deemed as the potential anode material candidates for the next-generation lithium-ion batteries due to the synergistic effect between them. Herein, a cationic surfactant induced self-assembly method is developed to construct 3D Fe3O4@reduction graphene oxide (H-Fe3O4@RGO) hybrid architecture in which hierarchical Fe3O4 nano-flowers (H-Fe3O4) are intimately encapsulated by 3D graphene network. Each H-Fe3O4 particle is constituted of rod-shaped skeletons surrounded by petal-like nano-flakes that are made up of enormous nanoparticles. When tested as the anode material in lithium-ion batteries, a high reversible capacity of 2270 mA h g-1 after 460 cycles is achieved under a current density of 0.5 A g-1. More impressively, even tested at a large current density of 10 A g-1, a decent reversible capacity of 490 mA h g-1 can be retained, which is still higher than the theoretical capacity of traditional graphite anode, demonstrating the remarkable lithium storage properties. The reasons for the excellent electrochemical performance of H-Fe3O4@RGO electrode have been discussed in detail.

Spontaneous phase separation during self-assembly in bi-dispersed spherical iron oxide nanoparticle monolayers

International Nuclear Information System (INIS)

Stanley, Jacob; Boucheron, Leandra; Shpyrko, Oleg; Lin, Binhua; Meron, Mati

2015-01-01

Recent developments in the synthesis of iron oxide nanoparticles have resulted in the ability to fabricate roughly spherical particles with extremely high size uniformity (low polydispersity). These particles can form self-assembled monolayer films at an air-water interface. When the polydispersity of the particles is low, these monolayers can be well-ordered over a length scale dozens of times the particle size. The van der Waals force between the particles is what drives this self-assembly. Through the use of Grazing Incidence X-Ray Diffraction we demonstrate that, when these films are formed at the liquid surface from bi-dispersed solutions containing 10 and 20 nm spherical particles suspended in chloroform, the particles phase separate into well-ordered patches during the self-assembly process. Furthermore, the domain sizes of these phase separated regions are at most 2–3 times smaller than that of a film comprising only mono-dispersed particles and their degree of disorder is comparable. This is shown for multiple solutions with differing ratios of 10 and 20 nm particles

Spontaneous phase separation during self-assembly in bi-dispersed spherical iron oxide nanoparticle monolayers

Energy Technology Data Exchange (ETDEWEB)

Stanley, Jacob; Boucheron, Leandra; Shpyrko, Oleg, E-mail: lin@cars.uchicago.edu, E-mail: oshpyrko@physics.ucsd.edu [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Lin, Binhua, E-mail: lin@cars.uchicago.edu, E-mail: oshpyrko@physics.ucsd.edu; Meron, Mati [Center for Advanced Radiation Sources (CARS), University of Chicago, Chicago, Illinois 60637 (United States)

2015-04-20

Recent developments in the synthesis of iron oxide nanoparticles have resulted in the ability to fabricate roughly spherical particles with extremely high size uniformity (low polydispersity). These particles can form self-assembled monolayer films at an air-water interface. When the polydispersity of the particles is low, these monolayers can be well-ordered over a length scale dozens of times the particle size. The van der Waals force between the particles is what drives this self-assembly. Through the use of Grazing Incidence X-Ray Diffraction we demonstrate that, when these films are formed at the liquid surface from bi-dispersed solutions containing 10 and 20 nm spherical particles suspended in chloroform, the particles phase separate into well-ordered patches during the self-assembly process. Furthermore, the domain sizes of these phase separated regions are at most 2–3 times smaller than that of a film comprising only mono-dispersed particles and their degree of disorder is comparable. This is shown for multiple solutions with differing ratios of 10 and 20 nm particles.

Human serum albumin mediated self-assembly of gold nanoparticles into hollow spheres

Energy Technology Data Exchange (ETDEWEB)

Nayak, Nimai C [Singapore-MIT Alliance, Manufacturing Systems and Technology Programme, Nanyang Technological University, 65 Nanyang Drive, 637460 (Singapore); Shin, Kwanwoo [Interdisciplinary Program of Integrated Biotechnology, Sogang University, Shinsoo-dong, Mapo-gu, Seoul 121-742 (Korea, Republic of)], E-mail: ncnayak@gmail.com

2008-07-02

The assembly of nanoparticles in topologically predefined superstructures is an important area in nanoscale architecture. In this paper, we report an unusual aggregation phenomenon involving L-lysine capped gold nanoparticles and human serum albumin into hollow nanospheres. The electrostatic interaction between positively charged L-lysine capped gold nanoparticles and negatively charged human serum albumin at physiological pH led to the assembly of the gold nanoparticles into hollow spheres. The phenomenon can be explained by the dry hole opening mechanism.

Human serum albumin mediated self-assembly of gold nanoparticles into hollow spheres

International Nuclear Information System (INIS)

Nayak, Nimai C; Shin, Kwanwoo

2008-01-01

The assembly of nanoparticles in topologically predefined superstructures is an important area in nanoscale architecture. In this paper, we report an unusual aggregation phenomenon involving L-lysine capped gold nanoparticles and human serum albumin into hollow nanospheres. The electrostatic interaction between positively charged L-lysine capped gold nanoparticles and negatively charged human serum albumin at physiological pH led to the assembly of the gold nanoparticles into hollow spheres. The phenomenon can be explained by the dry hole opening mechanism

Plasmon-enhanced photocurrent generation from self-assembled monolayers of phthalocyanine by using gold nanoparticle films.

Science.gov (United States)

Sugawa, Kosuke; Akiyama, Tsuyoshi; Kawazumi, Hirofumi; Yamada, Sunao

2009-04-09

The effect of localized electric fields on the photocurrent responses of phthalocyanine that was self-assembled on a gold nanoparticle film was investigated by comparing the conventional and the total internal reflection (TIR) experimental systems. In the case of photocurrent measurements, self-assembled monolayers (SAMs) of a thiol derivative of palladium phthalocyanine (PdPc) were prepared on the surface of gold-nanoparticle film that was fixed on the surface of indium-tin-oxide (ITO) substrate via a polyion (PdPc/AuP/polyion/ITO) or on the ITO surface (PdPc/ITO). Photocurrent action spectra from the two samples were compared by using the conventional spectrometer, and were found that PdPc/AuP/polyion/ITO gave considerably larger photocurrent signals than PdPc/ITO under the identical concentration of PdPc. In the case of the TIR experiments for the PdPc/AuP/polyion/ITO and the PdPc/AuP/Glass systems, incident-angle profiles of photocurrent and emission signals were correlated with each other, and they were different from that of the PdPc/ITO system. Accordingly, it was demonstrated that the photocurrent signals were certainly enhanced by the localized electric fields of the gold-nanoparticle film.

Random lasing actions in self-assembled perovskite nanoparticles

Science.gov (United States)

Liu, Shuai; Sun, Wenzhao; Li, Jiankai; Gu, Zhiyuan; Wang, Kaiyang; Xiao, Shumin; Song, Qinghai

2016-05-01

Solution-based perovskite nanoparticles have been intensively studied in the past few years due to their applications in both photovoltaic and optoelectronic devices. Here, based on the common ground between solution-based perovskite and random lasers, we have studied the mirrorless lasing actions in self-assembled perovskite nanoparticles. After synthesis from a solution, discrete lasing peaks have been observed from optically pumped perovskites without any well-defined cavity boundaries. We have demonstrated that the origin of the random lasing emissions is the scattering between the nanostructures in the perovskite microplates. The obtained quality (Q) factors and thresholds of random lasers are around 500 and 60 μJ/cm2, respectively. Both values are comparable to the conventional perovskite microdisk lasers with polygon-shaped cavity boundaries. From the corresponding studies on laser spectra and fluorescence microscope images, the lasing actions are considered random lasers that are generated by strong multiple scattering in random gain media. In additional to conventional single-photon excitation, due to the strong nonlinear effects of perovskites, two-photon pumped random lasers have also been demonstrated for the first time. We believe this research will find its potential applications in low-cost coherent light sources and biomedical detection.

Self-assembled nanogaps for molecular electronics

DEFF Research Database (Denmark)

Tang, Qingxin; Tong, Yanhong; Jain, Titoo

2009-01-01

A nanogap for molecular devices was realized using solution-based self-assembly. Gold nanorods were assembled to gold nanoparticle-coated conducting SnO2:Sb nanowires via thiol end-capped oligo(phenylenevinylene)s (OPVs). The molecular gap was easily created by the rigid molecule itself during se...

Effect of cationic grafted copolymer structure on the encapsulation of bovine serum albumin

International Nuclear Information System (INIS)

Flynn, Nicholas; Topal, Ç. Özge; Hikkaduwa Koralege, Rangika S.; Hartson, Steve; Ranjan, Ashish; Liu, Jing; Pope, Carey; Ramsey, Joshua D.

2016-01-01

The aim of the present study was to evaluate a library of poly-L-lysine (PLL)-graft (g)-polyethylene glycol (PEG) copolymers for the ability to encapsulate effectively a model protein, bovine serum albumin (BSA), and to characterize the stability and protein function of the resulting nanoparticle. A library of nine grafted copolymers was produced by varying PLL molecular weight and PEG grafting ratio. Electrostatic self-assembly of the protein and the grafted copolymer drove encapsulation. The formation of protein/polymer nanoparticles with a core/shell structure was confirmed using PAGE, dynamic light scattering, and electron microscopy. Encapsulation of the BSA into nanoparticles was strongly dependent on the copolymer-to-protein mass ratio, PEG grafting ratio, and PLL molecular weight. A copolymer-to-protein mass ratio of 7:1 and higher was generally required for high levels of encapsulation, and under these conditions, no loss of protein activity was observed. Copolymer characteristics also influenced nanoparticle resistance to polyanions and protease degradation. The results indicate that a copolymer of 15–30 kDa PLL, with a PEG grafting ratio of 10:1, is most promising for protein delivery. - Highlights: • A 4–70 kDa range of PLL-g-PEG copolymers was able to encapsulate BSA into NPs. • Encapsulation of BSA by PLL-g-PEG not only retained but increased esterolytic activity. • NPs were stable against protease degradation and polyanion dissociation.

Effect of cationic grafted copolymer structure on the encapsulation of bovine serum albumin

Energy Technology Data Exchange (ETDEWEB)

Flynn, Nicholas [School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States); Topal, Ç. Özge [School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK 74078 (United States); Hikkaduwa Koralege, Rangika S. [School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States); Hartson, Steve [Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078 (United States); Ranjan, Ashish; Liu, Jing; Pope, Carey [Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078 (United States); Ramsey, Joshua D., E-mail: josh.ramsey@okstate.edu [School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States)

2016-05-01

The aim of the present study was to evaluate a library of poly-L-lysine (PLL)-graft (g)-polyethylene glycol (PEG) copolymers for the ability to encapsulate effectively a model protein, bovine serum albumin (BSA), and to characterize the stability and protein function of the resulting nanoparticle. A library of nine grafted copolymers was produced by varying PLL molecular weight and PEG grafting ratio. Electrostatic self-assembly of the protein and the grafted copolymer drove encapsulation. The formation of protein/polymer nanoparticles with a core/shell structure was confirmed using PAGE, dynamic light scattering, and electron microscopy. Encapsulation of the BSA into nanoparticles was strongly dependent on the copolymer-to-protein mass ratio, PEG grafting ratio, and PLL molecular weight. A copolymer-to-protein mass ratio of 7:1 and higher was generally required for high levels of encapsulation, and under these conditions, no loss of protein activity was observed. Copolymer characteristics also influenced nanoparticle resistance to polyanions and protease degradation. The results indicate that a copolymer of 15–30 kDa PLL, with a PEG grafting ratio of 10:1, is most promising for protein delivery. - Highlights: • A 4–70 kDa range of PLL-g-PEG copolymers was able to encapsulate BSA into NPs. • Encapsulation of BSA by PLL-g-PEG not only retained but increased esterolytic activity. • NPs were stable against protease degradation and polyanion dissociation.

Molecular dynamics simulations of surfactant and nanoparticle self-assembly at liquid-liquid interfaces

Energy Technology Data Exchange (ETDEWEB)

Luo Mingxiang; Dai, Lenore L [Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409 (United States)

2007-09-19

We have performed molecular dynamics (MD) simulations to investigate self-assembly at water-trichloroethylene (TCE) interfaces with the emphasis on systems containing modified hydrocarbon nanoparticles (1.2 nm in diameter) and sodium dodecyl sulfate (SDS) surfactants. The nanoparticles and surfactants were first distributed randomly in the water phase. The MD simulations have clearly shown the progress of migration and final equilibrium of the SDS molecules at the water-TCE interfaces with the nanoparticles either at or in the vicinity of the interfaces. One unique feature is the 'attachment' of surfactant molecules to the nanoparticle clusters in the water phase followed by the 'detachment' at the water-TCE interfaces. At low concentrations of surfactants, the surfactants and nanoparticles co-equilibrate at the interfaces. However, the surfactants, at high concentrations, competitively dominate the interfaces and deplete nanoparticles away from the interfaces. The interfacial properties, such as interfacial thickness and interfacial tension, are significantly influenced by the presence of the surfactants, but not the nanoparticles. The order of the surfactants at the interfaces increases with increasing surfactant concentration, but is independent of nanoparticle concentration. Finally, the simulation has shown that surfactants can aggregate along the water-TCE interfaces, with and without the presence of nanoparticles.

Precipitation synthesis and magnetic properties of self-assembled magnetite-chitosan nanostructures

Energy Technology Data Exchange (ETDEWEB)

Bezdorozhev, Oleksii; Kolodiazhnyi, Taras; Vasylkiv, Oleg, E-mail: oleg.vasylkiv@nims.go.jp

2017-04-15

This paper reports the synthesis and magnetic properties of unique magnetite-chitosan nanostructures synthesized by the chemical precipitation of magnetite nanoparticles in the presence of chitosan. The influence of varying synthesis parameters on the morphology of the magnetic composites is determined. Depending on the synthesis parameters, magnetite-chitosan nanostructures of spherical (9–18 nm), rice-seed-like (75–290 nm) and lumpy (75–150 nm) shapes were obtained via self-assembly. Spherical nanostructures encapsulated by a 9–15 nm chitosan layer were assembled as well. The prospective morphology of the nanostructures is combined with their excellent magnetic characteristics. It was found that magnetite-chitosan nanostructures are ferromagnetic and pseudo-single domain. Rice-seed-like nanostructures exhibited a coercivity of 140 Oe and saturation magnetization of 56.7 emu/g at 300 K. However, a drop in the magnetic properties was observed for chitosan-coated spherical nanostructures due to the higher volume fraction of chitosan. - Highlights: • Magnetite-chitosan nanostructures are synthesized via self-assembly. • Different morphology can be obtained by adjusting the synthesis parameters. • An attractive combination of magnetic properties and morphology is obtained. • Magnetite-chitosan nanostructures are ferrimagnetic and pseudo-single domain.

Precipitation synthesis and magnetic properties of self-assembled magnetite-chitosan nanostructures

International Nuclear Information System (INIS)

Bezdorozhev, Oleksii; Kolodiazhnyi, Taras; Vasylkiv, Oleg

2017-01-01

This paper reports the synthesis and magnetic properties of unique magnetite-chitosan nanostructures synthesized by the chemical precipitation of magnetite nanoparticles in the presence of chitosan. The influence of varying synthesis parameters on the morphology of the magnetic composites is determined. Depending on the synthesis parameters, magnetite-chitosan nanostructures of spherical (9–18 nm), rice-seed-like (75–290 nm) and lumpy (75–150 nm) shapes were obtained via self-assembly. Spherical nanostructures encapsulated by a 9–15 nm chitosan layer were assembled as well. The prospective morphology of the nanostructures is combined with their excellent magnetic characteristics. It was found that magnetite-chitosan nanostructures are ferromagnetic and pseudo-single domain. Rice-seed-like nanostructures exhibited a coercivity of 140 Oe and saturation magnetization of 56.7 emu/g at 300 K. However, a drop in the magnetic properties was observed for chitosan-coated spherical nanostructures due to the higher volume fraction of chitosan. - Highlights: • Magnetite-chitosan nanostructures are synthesized via self-assembly. • Different morphology can be obtained by adjusting the synthesis parameters. • An attractive combination of magnetic properties and morphology is obtained. • Magnetite-chitosan nanostructures are ferrimagnetic and pseudo-single domain.

Factors affecting drug encapsulation and stability of lipid-polymer hybrid nanoparticles.

Science.gov (United States)

Cheow, Wean Sin; Hadinoto, Kunn

2011-07-01

Lipid-polymer hybrid nanoparticles are polymeric nanoparticles enveloped by lipid layers that combine the highly biocompatible nature of lipids with the structural integrity afforded by polymeric nanoparticles. Recognizing them as attractive drug delivery vehicles, antibiotics are encapsulated in the present work into hybrid nanoparticles intended for lung biofilm infection therapy. Modified emulsification-solvent-evaporation methods using lipid as surfactant are employed to prepare the hybrid nanoparticles. Biodegradable poly (lactic-co-glycolic acid) and phosphatidylcholine are used as the polymer and lipid models, respectively. Three fluoroquinolone antibiotics (i.e. levofloxacin, ciprofloxacin, and ofloxacin), which vary in their ionicity, lipophilicity, and aqueous solubility, are used. The hybrid nanoparticles are examined in terms of their drug encapsulation efficiency, drug loading, stability, and in vitro drug release profile. Compared to polymeric nanoparticles prepared using non-lipid surfactants, hybrid nanoparticles in general are larger and exhibit higher drug loading, except for the ciprofloxacin-encapsulated nanoparticles. Hybrid nanoparticles, however, are unstable in salt solutions, but the stability can be conferred by adding TPGS into the formulation. Drug-lipid ionic interactions and drug lipophilicity play important roles in the hybrid nanoparticle preparation. First, interactions between oppositely charged lipid and antibiotic (i.e. ciprofloxacin) during preparation cause failed nanoparticle formation. Charge reversal of the lipid facilitated by adding counterionic surfactants (e.g. stearylamine) must be performed before drug encapsulation can take place. Second, drug loading and the release profile are strongly influenced by drug lipophilicity, where more lipophilic drug (i.e. levofloxacin) exhibit a higher drug loading and a sustained release profile attributed to the interaction with the lipid coat. Copyright © 2011 Elsevier B.V. All

Hierarchical self-assembly of PDMA-b-PS chains into granular nanoparticles: genesis and fate.

Science.gov (United States)

Bianchi, Alberto; Mauri, Michele; Bonetti, Simone; Koynov, Kaloian; Kappl, Michael; Lieberwirth, Ingo; Butt, Hans-Jürgen; Simonutti, Roberto

2014-12-01

The hierarchical self-assembly of an amphiphilic block copolymer, poly(N,N-dimethylacrylamide)-block-polystyrene with a very short hydrophilic block (PDMA10 -b-PS62 ), in large granular nanoparticles is reported. While these nanoparticles are stable in water, their disaggregation can be induced either mechanically (i.e., by applying a force via the tip of the cantilever of an atomic force microscope (AFM)) or by partial hydrolysis of the acrylamide groups. AFM force spectroscopy images show the rupture of the particle as a combination of collapse and flow, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of partly hydrolyzed nanoparticles provide a clear picture of the granular structure. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Plasma-Induced Wafer-Scale Self-Assembly of Silver Nanoparticles and Application to Biochemical Sensing

Directory of Open Access Journals (Sweden)

Yunbo Shi

2015-06-01

Full Text Available In this work, the wafer-scale silver nanoparticles fabricated by a self-assembly method was demonstrated based on a magnetron sputtering and plasma treatment process. Silver nanoparticles of different sizes and shapes were prepared, and the effects of the plasma treatment time, plasma gas composition, and power were systematically investigated to develop a method for low-cost and large-scale fabrication of silver nanoparticles. Furthermore, the surface-enhanced Raman scattering experiments: crystal violet, as the probe, was absorbed on the silver nanoparticles film of different size and density, and get the phenomena of surface-enhanced Raman scattering and surface-enhanced fluorescence. The results show that the proposed technique provides a rapid method for the fabrication of silver nanomaterial; the method is adaptable to large-scale production and is compatible with the fabrication of other materials and biosensors.

Realization of thermally durable close-packed 2D gold nanoparticle arrays using self-assembly and plasma etching

International Nuclear Information System (INIS)

Sivaraman, Sankar K; Santhanam, Venugopal

2012-01-01

Realization of thermally and chemically durable, ordered gold nanostructures using bottom-up self-assembly techniques are essential for applications in a wide range of areas including catalysis, energy generation, and sensing. Herein, we describe a modular process for realizing uniform arrays of gold nanoparticles, with interparticle spacings of 2 nm and above, by using RF plasma etching to remove ligands from self-assembled arrays of ligand-coated gold nanoparticles. Both nanoscale imaging and macroscale spectroscopic characterization techniques were used to determine the optimal conditions for plasma etching, namely RF power, operating pressure, duration of treatment, and type of gas. We then studied the effect of nanoparticle size, interparticle spacing, and type of substrate on the thermal durability of plasma-treated and untreated nanoparticle arrays. Plasma-treated arrays showed enhanced chemical and thermal durability, on account of the removal of ligands. To illustrate the application potential of the developed process, robust SERS (surface-enhanced Raman scattering) substrates were formed using plasma-treated arrays of silver-coated gold nanoparticles that had a silicon wafer or photopaper as the underlying support. The measured value of the average SERS enhancement factor (2 × 10 5 ) was quantitatively reproducible on both silicon and paper substrates. The silicon substrates gave quantitatively reproducible results even after thermal annealing. The paper-based SERS substrate was also used to swab and detect probe molecules deposited on a solid surface. (paper)

Formation of linear and crosslinked polyurethane nanoparticles that self-assemble differently in acetone and in water

Czech Academy of Sciences Publication Activity Database

Serkis-Rodzen, Magdalena; Špírková, Milena; Matějíček, P.; Štěpánek, M.

2017-01-01

Roč. 106, May (2017), s. 119-127 ISSN 0300-9440 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane water dispersion * nanoparticles * self-assembly Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 2.858, year: 2016

Controlled in situ growth of tunable plasmonic self-assembled nanoparticle arrays

International Nuclear Information System (INIS)

Verre, R; Fleischer, K; McGilp, J F; Fox, D; Behan, G; Zhang, H; Shvets, I V

2012-01-01

Self-assembled silver nanoparticle (NP) arrays were produced by deposition at glancing angles on transparent stepped Al 2 O 3 templates. The evolution of the plasmonic resonances has been monitored using reflection anisotropy spectroscopy (RAS) during growth. It is demonstrated that the morphology of the array can be tailored by changing the template structure, resulting in a large tunability of the optical resonances. In order to extract detailed information on the origin of the measured dichroic response of the system, a model based on dipolar interactions has been developed and the effect of tarnishing and morphological dispersion addressed. (paper)

Synthesis and Self-Assembly of the "Tennis Ball" Dimer and Subsequent Encapsulation of Methane. An Advanced Organic Chemistry Laboratory Experiment

Science.gov (United States)

Hof, Fraser; Palmer, Liam C.; Rebek, Julius, Jr.

2001-11-01

While important to the biological and materials sciences, noncovalent interactions, self-folding, and self-assembly often receive little discussion in the undergraduate chemistry curriculum. The synthesis and NMR characterization of a molecular "tennis ball" in an advanced undergraduate organic chemistry laboratory is a simple and effective way to introduce the relevance of these concepts. In appropriate solvents, the monomer dimerizes through a seam of eight hydrogen bonds with encapsulation of a guest molecule and symmetry reminiscent of a tennis ball. The entire experiment can be completed in three lab periods, however large-scale synthetic preparation of the starting monomer by a teaching assistant would reduce the laboratory to a single lab period for NMR studies.

Dendrimer-encapsulated nanoparticle-core micelles as a modular strategy for particle-in-a-box-in-a-box nanostructures

NARCIS (Netherlands)

Hove, ten J.B.; Wang, J.; Leeuwen, van F.W.B.; Velders, A.H.

2017-01-01

The hierarchically controlled synthesis and characterization of self-assembling macromolecules and particles are key to explore and exploit new nanomaterials. Here we present a versatile strategy for constructing particle-in-a-box-in-a-box systems by assembling dendrimer-encapsulated gold

Cyclodextrin-insulin complex encapsulated polymethacrylic acid based nanoparticles for oral insulin delivery.

Science.gov (United States)

Sajeesh, S; Sharma, Chandra P

2006-11-15

Present investigation was aimed at developing an oral insulin delivery system based on hydroxypropyl beta cyclodextrin-insulin (HPbetaCD-I) complex encapsulated polymethacrylic acid-chitosan-polyether (polyethylene glycol-polypropylene glycol copolymer) (PMCP) nanoparticles. Nanoparticles were prepared by the free radical polymerization of methacrylic acid in presence of chitosan and polyether in a solvent/surfactant free medium. Dynamic light scattering (DLS) experiment was conducted with particles dispersed in phosphate buffer (pH 7.4) and size distribution curve was observed in the range of 500-800 nm. HPbetaCD was used to prepare non-covalent inclusion complex with insulin and complex was analyzed by Fourier transform infrared (FTIR) and fluorescence spectroscopic studies. HPbetaCD complexed insulin was encapsulated into PMCP nanoparticles by diffusion filling method and their in vitro release profile was evaluated at acidic/alkaline pH. PMCP nanoparticles displayed good insulin encapsulation efficiency and release profile was largely dependent on the pH of the medium. Enzyme linked immunosorbent assay (ELISA) study demonstrated that insulin encapsulated inside the particles was biologically active. Trypsin inhibitory effect of PMCP nanoparticles was evaluated using N-alpha-benzoyl-L-arginine ethyl ester (BAEE) and casein as substrates. Mucoadhesive studies of PMCP nanoparticles were conducted using freshly excised rat intestinal mucosa and the particles were found fairly adhesive. From the preliminary studies, cyclodextrin complexed insulin encapsulated mucoadhesive nanoparticles appear to be a good candidate for oral insulin delivery.

Effective interactions between nanoparticles: Creating temperature-independent solvation environments for self-assembly

Energy Technology Data Exchange (ETDEWEB)

Yadav, Hari O. S., E-mail: cyz108802@chemistry.iitd.ac.in, E-mail: hariyadav.iitd@gmail.com; Shrivastav, Gourav; Agarwal, Manish; Chakravarty, Charusita [Department of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016 (India)

2016-06-28

emergent anisotropy due to correlation of mass dipoles on the two nanoparticles. One expects therefore that during self-assembly using solvent evaporation, temperature can be used as a structure-directing factor as long as good solvent conditions are maintained. It also suggests that disordered configurations may emerge as solvent quality decreases due to increasing role of short-range attractions and ligand fluctuation-driven anisotropy. The possibilities of using structural estimators of various thermodynamic quantities to analyse the interplay of ligand fluctuations and solvent quality in self-assembly as well as to design solvation environments are discussed.

Single-step generation of fluorophore-encapsulated gold nanoparticle core-shell materials

International Nuclear Information System (INIS)

Sardar, R; Shem, P M; Pecchia-Bekkum, C; Bjorge, N S; Shumaker-Parry, J S

2010-01-01

We report a simple route to produce fluorophore-encapsulated gold nanoparticles (AuNPs) in a single step under aqueous conditions using the fluorophore 1-pyrenemethylamine (PMA). Different amounts of PMA were used and the resulting core-shell gold nanoparticles were analyzed using UV-visible absorption spectroscopy, fluorescence spectroscopy, and transmission and scanning electron microscopy. Electron microscopy analysis shows nanoparticles consisting of a gold nanoparticle core which is encapsulated with a lower contrast shell. In the UV-visible spectra, we observed a significant red shift (37 nm) of the localized surface plasmon resonance (LSPR) absorption maximum (λ max ) compared to citrate-stabilized AuNPs of a similar size. We attribute the prominent LSPR wavelength shift for PMA-AuNP conjugates to the increase in the local dielectric environment near the gold nanoparticles due to the shell formation. This simple, aqueous-based synthesis is a new approach to the production of fluorophore-encapsulated AuNPs that could be applicable in biological sensing systems and photonic device fabrication.

A one-pot strategy for biomimetic synthesis and self-assembly of gold nanoparticles

International Nuclear Information System (INIS)

Wang Yi; Li Yuanfang; Zhao Xijuan; Huang Chengzhi; Chen Liqiang; Peng Li

2010-01-01

A simple, one-pot and controllable strategy is reported in this contribution for biomimetic synthesis and self-assembly of gold nanoparticles (Au-NPs). It involves our synthesized polyaldehyde dextran (PAD), which has been proved to be a biomacromolecule with excellent biocompatibility and biodegradability, acting as both a reducing agent and a stabilizer. The morphology of the as-prepared Au-NP assemblies can be controlled by adjusting the reaction conditions, such as the concentration of aldehyde in PAD, the reaction time and the temperature. Investigations of the mechanism suggest that stabilizers may distribute on different crystal facets of NPs non-uniformly owing to the different binding forces, and dipole-dipole interaction of NPs could be the main driving force for the assembly of Au-NPs. In addition, intermolecular hydrogen bonding interaction of stabilizers could also act as a possible driving force. The excellent biocompatibility of the Au-NP assemblies makes them promising candidates for fabricating future optical nanodevices and application in biological systems.

A one-pot strategy for biomimetic synthesis and self-assembly of gold nanoparticles

Science.gov (United States)

Wang, Yi; Chen, Li Qiang; Li, Yuan Fang; Zhao, Xi Juan; Peng, Li; Zhi Huang, Cheng

2010-07-01

A simple, one-pot and controllable strategy is reported in this contribution for biomimetic synthesis and self-assembly of gold nanoparticles (Au-NPs). It involves our synthesized polyaldehyde dextran (PAD), which has been proved to be a biomacromolecule with excellent biocompatibility and biodegradability, acting as both a reducing agent and a stabilizer. The morphology of the as-prepared Au-NP assemblies can be controlled by adjusting the reaction conditions, such as the concentration of aldehyde in PAD, the reaction time and the temperature. Investigations of the mechanism suggest that stabilizers may distribute on different crystal facets of NPs non-uniformly owing to the different binding forces, and dipole-dipole interaction of NPs could be the main driving force for the assembly of Au-NPs. In addition, intermolecular hydrogen bonding interaction of stabilizers could also act as a possible driving force. The excellent biocompatibility of the Au-NP assemblies makes them promising candidates for fabricating future optical nanodevices and application in biological systems.

Photoswitching in azobenzene self-assembled monolayers capped on zinc oxide: nanodots vs nanorods.

Science.gov (United States)

Shah, Syed Mujtaba; Martini, Cyril; Ackermann, Jörg; Fages, Frédéric

2012-02-01

We report the synthesis and spectroscopic characterization of nanohybrid structures consisting of an azobenzene compound grafted on the surface of zinc oxide nanoparticles. Characteristic bathochromic shifts indicate that the azobenzene photochromic molecules self-assemble onto the surface of the nanocrystals. The extent of packing is dependent on the shape of the nanoparticle. ZnO nanorods, with flat facets, enable a tighter organization of the molecules in the self-assembled monolayer than in the case of nanodots that display a more curvated shape. Consistently, the efficiency of photochromic switching of the self-assembled monolayer on ZnO nanoparticles is also shown to be strongly affected by nanoparticle shape. Copyright © 2011 Elsevier Inc. All rights reserved.

All-nanoparticle self-assembly ZnO/TiO₂ heterojunction thin films with remarkably enhanced photoelectrochemical activity.

Science.gov (United States)

Yuan, Sujun; Mu, Jiuke; Mao, Ruiyi; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

2014-04-23

The multilaminated ZnO/TiO2 heterojunction films were successfully deposited on conductive substrates including fluorine-doped tin oxide (FTO) glass and flexible indium tin oxide coated poly(ethylene terephthalate) via the layer-by-layer (LBL) self assembly method from the oxide colloids without using any polyelectrolytes. The positively charged ZnO nanoparticles and the negatively charged TiO2 nanoparticles were directly used as the components in the consecutive deposition process to prepare the heterojunction thin films by varying the thicknesses. Moreover, the crystal growth of both oxides could be efficiently inhibited by the good connection between ZnO and TiO2 nanoparticles even after calcination at 500 °C, especially for ZnO which was able to keep the crystallite size under 25 nm. The as-prepared films were used as the working electrodes in the three-electrode photoelectrochemical cells. Because the well-contacted nanoscale heterojunctions were formed during the LBL self-assembling process, the ZnO/TiO2 all-nanoparticle films deposited on both substrates showed remarkably enhanced photoelectrochemical properties compared to that of the well-established TiO2 LBL thin films with similar thicknesses. The photocurrent response collected from the ZnO/TiO2 electrode on the FTO glass substrate was about five times higher than that collected from the TiO2 electrode. Owing to the absence of the insulating layer of dried polyelectrolytes, the ZnO/TiO2 all-nanoparticle heterojunction films were expected to be used in the photoelectrochemical device before calcination.

Opto-electronic devices with nanoparticles and their assemblies

Science.gov (United States)

Nguyen, Chieu Van

Nanotechnology is a fast growing field; engineering matters at the nano-meter scale. A key nanomaterial is nanoparticles (NPs). These sub-wavelength (background noise. The second device is based on a one-dimensional (1-D) self-directed self-assembly of Au NPs mediated by dielectric materials. Depending on the coverage density of the Au NPs assembly deposited on the device, electronic emission was observed at ultra-low bias of 40V, leading to low-power plasma generation in air at atmospheric pressure. Light emitted from the plasma is apparent to the naked eyes. Similarly, 1-D self-assembly of Au NPs mediated by iron oxide was fabricated and exhibits ferro-magnetic behavior. The multi-functional 1-D self-assembly of Au NPs has great potential in modern electronics such as solid state lighting, plasma-based nanoelectronics, and memory devices.

Giant surfactants of poly(ethylene oxide)- b-polystyrene-(molecular nanoparticle): nanoparticle-driven self-assembly with sub-10-nm nanostructures in thin films

Science.gov (United States)

Hsu, Chih-Hao; Lin, Zhiwei; Dong, Xue-Hui; Hsieh, I.-Fan; Cheng, Stephen Z. D.

2014-03-01

Giant surfactants are built upon precisely attaching shape- and volume-persistent molecular nanoparticles (MNP) to polymeric flexible tails. The unique class of self-assembling materials, giant surfactants, has been demonstrated to form self-assembled ordered nanostructures, and their self-assembly behaviors are remarkably sensitive to primary chemical structures. In this work, two sets of giant surfactants with functionalized MNP attached to diblock copolymer tails were studied in thin films. Carboxylic acid-functionalized [60]fullerene (AC60) tethered with PEO- b-PS (PEO-PS-AC60) represents an ABA' (hydrophilic-hydrophobic-hydrophilic) giant surfactant, and fluoro-functionalized polyhedral oligomeric silsesquioxane (FPOSS) tethered with PEO- b-PS (PEO-PS-FPOSS) represents an ABC (hydrophilic-hydrophobic-omniphobic) one. The dissimilar chemical natures of the MNPs result in different arrangement of MNPs in self-assembled structures, the dispersion of AC60 in PEO domain and the single domain of FPOSS. Moreover, the chemically bonded MNPs could induce the originally disordered small molecular PEO- b-PS to form ordered cylindrical and lamellar structure, as evidenced by TEM and GISAXS, leading to sub-10-nm nanostructures of copolymer in the thin film state.

Cellulase immobilization on magnetic nanoparticles encapsulated in polymer nanospheres.

Science.gov (United States)

Lima, Janaina S; Araújo, Pedro H H; Sayer, Claudia; Souza, Antonio A U; Viegas, Alexandre C; de Oliveira, Débora

2017-04-01

Immobilization of cellulases on magnetic nanoparticles, especially magnetite nanoparticles, has been the main approach studied to make this enzyme, economically and industrially, more attractive. However, magnetite nanoparticles tend to agglomerate, are very reactive and easily oxidized in air, which has strong impact on their useful life. Thus, it is very important to provide proper surface coating to avoid the mentioned problems. This study aimed to investigate the immobilization of cellulase on magnetic nanoparticles encapsulated in polymeric nanospheres. The support was characterized in terms of morphology, average diameter, magnetic behavior and thermal decomposition analyses. The polymer nanospheres containing encapsulated magnetic nanoparticles showed superparamagnetic behavior and intensity average diameter about 150 nm. Immobilized cellulase exhibited broader temperature stability than in the free form and great reusability capacity, 69% of the initial enzyme activity was maintained after eight cycles of use. The magnetic support showed potential for cellulase immobilization and allowed fast and easy biocatalyst recovery through a single magnet.

Ultrasensitive colorimetric detection of heparin based on self-assembly of gold nanoparticles on graphene oxide.

Science.gov (United States)

Fu, Xiuli; Chen, Lingxin; Li, Jinhua

2012-08-21

A novel colorimetric method was developed for ultrasensitive detection of heparin based on self-assembly of gold nanoparticles (AuNPs) onto the surface of graphene oxide (GO). Polycationic protamine was used as a medium for inducing the self-assembly of citrate-capped AuNPs on GO through electrostatic interaction, resulting in a shift in the surface plasmon resonance (SPR) absorption of AuNPs and exhibiting a blue color. Addition of polyanionic heparin disturbed the self-assemble of AuNPs due to its strong affinity to protamine. With the increase of heparin concentration, the amounts of self-assembly AuNPs decreased and the color changed from blue to red in solution. Therefore, a "blue-to-red" colorimetric sensing strategy based on self-assembly of AuNPs could be established for heparin detection. Compared with the commonly reported aggregation-based methods ("red-to-blue"), the color change from blue to red was more eye-sensitive, especially in low concentration of target. Moreover, stronger interaction between protamine and heparin led to distinguish heparin from its analogues as well as various potentially coexistent physiological species. The strategy was simply achieved by the self-assembly nature of AuNPs and the application of two types of polyionic media, showing it to be label-free, simple, rapid and visual. This method could selectively detect heparin with a detection limit of 3.0 ng mL(-1) in standard aqueous solution and good linearity was obtained over the range 0.06-0.36 μg mL(-1) (R = 0.9936). It was successfully applied to determination of heparin in fetal bovine serum samples as low as 1.7 ng mL(-1) with a linear range of 0-0.8 μg mL(-1).

Pectin-lipid self-assembly: influence on the formation of polyhydroxy fatty acids nanoparticles.

Directory of Open Access Journals (Sweden)

Susana Guzman-Puyol

Full Text Available Nanoparticles, named cutinsomes, have been prepared from aleuritic (9,10,16-trihidroxipalmitic acid and tomato fruit cutin monomers (a mixture of mainly 9(10,16-dihydroxypalmitic acid (85%, w/w and 16-hydroxyhexadecanoic acid (7.5%, w/w with pectin in aqueous solution. The process of formation of the nanoparticles of aleuritic acid plus pectin has been monitored by UV-Vis spectrophotometry, while their chemical and morphological characterization was analyzed by ATR-FTIR, TEM, and non-contact AFM. The structure of these nanoparticles can be described as a lipid core with a pectin shell. Pectin facilitated the formation of nanoparticles, by inducing their aggregation in branched chains and favoring the condensation between lipid monomers. Also, pectin determined the self-assembly of cutinsomes on highly ordered pyrolytic graphite (HOPG surfaces, causing their opening and forming interconnected structures. In the case of cutin monomers, the nanoparticles are fused, and the condensation of the hydroxy fatty acids is strongly affected by the presence of the polysaccharide. The interaction of pectin with polyhydroxylated fatty acids could be related to an initial step in the formation of the plant biopolyester cutin.

Pectin-lipid self-assembly: influence on the formation of polyhydroxy fatty acids nanoparticles.

Science.gov (United States)

Guzman-Puyol, Susana; Benítez, José Jesús; Domínguez, Eva; Bayer, Ilker Sefik; Cingolani, Roberto; Athanassiou, Athanassia; Heredia, Antonio; Heredia-Guerrero, José Alejandro

2015-01-01

Nanoparticles, named cutinsomes, have been prepared from aleuritic (9,10,16-trihidroxipalmitic) acid and tomato fruit cutin monomers (a mixture of mainly 9(10),16-dihydroxypalmitic acid (85%, w/w) and 16-hydroxyhexadecanoic acid (7.5%, w/w)) with pectin in aqueous solution. The process of formation of the nanoparticles of aleuritic acid plus pectin has been monitored by UV-Vis spectrophotometry, while their chemical and morphological characterization was analyzed by ATR-FTIR, TEM, and non-contact AFM. The structure of these nanoparticles can be described as a lipid core with a pectin shell. Pectin facilitated the formation of nanoparticles, by inducing their aggregation in branched chains and favoring the condensation between lipid monomers. Also, pectin determined the self-assembly of cutinsomes on highly ordered pyrolytic graphite (HOPG) surfaces, causing their opening and forming interconnected structures. In the case of cutin monomers, the nanoparticles are fused, and the condensation of the hydroxy fatty acids is strongly affected by the presence of the polysaccharide. The interaction of pectin with polyhydroxylated fatty acids could be related to an initial step in the formation of the plant biopolyester cutin.

A comparison of self-assembly and hydrogel encapsulation as a means to engineer functional cartilaginous grafts using culture expanded chondrocytes.

Science.gov (United States)

Mesallati, Tariq; Buckley, Conor T; Kelly, Daniel J

2014-01-01

Despite an increased interest in the use of hydrogel encapsulation and cellular self-assembly (often termed "self-aggregating" or "scaffold-free" approaches) for tissue-engineering applications, to the best of our knowledge, no study to date has been undertaken to directly compare both approaches for generating functional cartilaginous grafts. The objective of this study was to directly compare self-assembly (SA) and agarose hydrogel encapsulation (AE) as a means to engineer such grafts using passaged chondrocytes. Agarose hydrogels (5 mm diameter × 1.5 mm thick) were seeded with chondrocytes at two cell seeding densities (900,000 cells or 4 million cells in total per hydrogel), while SA constructs were generated by adding the same number of cells to custom-made molds. Constructs were either supplemented with transforming growth factor (TGF)-β3 for 6 weeks, or only supplemented with TGF-β3 for the first 2 weeks of the 6 week culture period. The SA method was only capable of generating geometrically uniform cartilaginous tissues at high seeding densities (4 million cells). At these high seeding densities, we observed that total sulphated glycosaminoglycan (sGAG) and collagen synthesis was greater with AE than SA, with higher sGAG retention also observed in AE constructs. When normalized to wet weight, however, SA constructs exhibited significantly higher levels of collagen accumulation compared with agarose hydrogels. Furthermore, it was possible to engineer such functionality into these tissues in a shorter timeframe using the SA approach compared with AE. Therefore, while large numbers of chondrocytes are required to engineer cartilaginous grafts using the SA approach, it would appear to lead to the faster generation of a more hyaline-like tissue, with a tissue architecture and a ratio of collagen to sGAG content more closely resembling native articular cartilage.

Elucidating dominant pathways of the nano-particle self-assembly process.

Science.gov (United States)

Zeng, Xiangze; Li, Bin; Qiao, Qin; Zhu, Lizhe; Lu, Zhong-Yuan; Huang, Xuhui

2016-09-14

Self-assembly processes play a key role in the fabrication of functional nano-structures with widespread application in drug delivery and micro-reactors. In addition to the thermodynamics, the kinetics of the self-assembled nano-structures also play an important role in determining the formed structures. However, as the self-assembly process is often highly heterogeneous, systematic elucidation of the dominant kinetic pathways of self-assembly is challenging. Here, based on mass flow, we developed a new method for the construction of kinetic network models and applied it to identify the dominant kinetic pathways for the self-assembly of star-like block copolymers. We found that the dominant pathways are controlled by two competing kinetic parameters: the encounter time Te, characterizing the frequency of collision and the transition time Tt for the aggregate morphology change from rod to sphere. Interestingly, two distinct self-assembly mechanisms, diffusion of an individual copolymer into the aggregate core and membrane closure, both appear at different stages (with different values of Tt) of a single self-assembly process. In particular, the diffusion mechanism dominates the middle-sized semi-vesicle formation stage (with large Tt), while the membrane closure mechanism dominates the large-sized vesicle formation stage (with small Tt). Through the rational design of the hydrophibicity of the copolymer, we successfully tuned the transition time Tt and altered the dominant self-assembly pathways.

Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses

Science.gov (United States)

Mudanyali, Onur; McLeod, Euan; Luo, Wei; Greenbaum, Alon; Coskun, Ahmet F.; Hennequin, Yves; Allier, Cédric P.; Ozcan, Aydogan

2013-03-01

The direct observation of nanoscale objects is a challenging task for optical microscopy because the scattering from an individual nanoparticle is typically weak at optical wavelengths. Electron microscopy therefore remains one of the gold standard visualization methods for nanoparticles, despite its high cost, limited throughput and restricted field-of-view. Here, we describe a high-throughput, on-chip detection scheme that uses biocompatible wetting films to self-assemble aspheric liquid nanolenses around individual nanoparticles to enhance the contrast between the scattered and background light. We model the effect of the nanolens as a spatial phase mask centred on the particle and show that the holographic diffraction pattern of this effective phase mask allows detection of sub-100 nm particles across a large field-of-view of >20 mm2. As a proof-of-concept demonstration, we report on-chip detection of individual polystyrene nanoparticles, adenoviruses and influenza A (H1N1) viral particles.

Large branched self-assembled DNA complexes

International Nuclear Information System (INIS)

Tosch, Paul; Waelti, Christoph; Middelberg, Anton P J; Davies, A Giles

2007-01-01

Many biological molecules have been demonstrated to self-assemble into complex structures and networks by using their very efficient and selective molecular recognition processes. The use of biological molecules as scaffolds for the construction of functional devices by self-assembling nanoscale complexes onto the scaffolds has recently attracted significant attention and many different applications in this field have emerged. In particular DNA, owing to its inherent sophisticated self-organization and molecular recognition properties, has served widely as a scaffold for various nanotechnological self-assembly applications, with metallic and semiconducting nanoparticles, proteins, macromolecular complexes, inter alia, being assembled onto designed DNA scaffolds. Such scaffolds may typically contain multiple branch-points and comprise a number of DNA molecules selfassembled into the desired configuration. Previously, several studies have used synthetic methods to produce the constituent DNA of the scaffolds, but this typically constrains the size of the complexes. For applications that require larger self-assembling DNA complexes, several tens of nanometers or more, other techniques need to be employed. In this article, we discuss a generic technique to generate large branched DNA macromolecular complexes

pH-Sensitive Reversible Programmed Targeting Strategy by the Self-Assembly/Disassembly of Gold Nanoparticles.

Science.gov (United States)

Ma, Jinlong; Hu, Zhenpeng; Wang, Wei; Wang, Xinyu; Wu, Qiang; Yuan, Zhi

2017-05-24

A reversible programmed targeting strategy could achieve high tumor accumulation due to its long blood circulation time and high cellular internalization. Here, targeting ligand-modified poly(ethylene glycol) (PEG-ligand), dibutylamines (Bu), and pyrrolidinamines (Py) were introduced on the surface of gold nanoparticles (Au NPs) for reversible shielding/deshielding of the targeting ligands by pH-responsive self-assembly. Hydrophobic interaction and steric repulsion are the main driving forces for the self-assembly/disassembly of Au NPs. The precise self-assembly (pH ≥ 7.2) and disassembly (pH ≤ 6.8) of Au NPs with different ligands could be achieved by fine-tuning the modifying molar ratio of Bu and Py (R m ), which followed the formula R m = 1/(-0.0013X 2 + 0.0323X + 1), in which X is the logarithm of the partition coefficient of the targeting ligand. The assembled/disassembled behavior of Au NPs at pH 7.2 and 6.8 was confirmed by transmission electron microscopy and dynamic light scattering. Enzyme-linked immunosorbent assays and cellular uptake studies showed that the ligands could be buried inside the assembly and exposed when disassembled. More importantly, this process was reversible, which provides the possibility of prolonging blood circulation by shielding ligands associated with the NPs that were effused from tumor tissue.

Synthesis and Self-Assembly of Chiral Cylindrical Molecular Complexes: Functional Heterogeneous Liquid-Solid Materials Formed by Helicene Oligomers

Directory of Open Access Journals (Sweden)

Nozomi Saito

2018-01-01

Full Text Available Chiral cylindrical molecular complexes of homo- and hetero-double-helices derived from helicene oligomers self-assemble in solution, providing functional heterogeneous liquid-solid materials. Gels and liotropic liquid crystals are formed by fibril self-assembly in solution; molecular monolayers and fibril films are formed by self-assembly on solid surfaces; gels containing gold nanoparticles emit light; silica nanoparticles aggregate and adsorb double-helices. Notable dynamics appears during self-assembly, including multistep self-assembly, solid surface catalyzed double-helix formation, sigmoidal and stairwise kinetics, molecular recognition of nanoparticles, discontinuous self-assembly, materials clocking, chiral symmetry breaking and homogeneous-heterogeneous transitions. These phenomena are derived from strong intercomplex interactions of chiral cylindrical molecular complexes.

Magnetic nanoparticle assemblies

CERN Document Server

Trohidou, Kalliopi N

2014-01-01

Magnetic nanoparticles with diameters in the range of a few nanometers are today at the cutting edge of modern technology and innovation because of their use in numerous applications ranging from engineering to biomedicine. A great deal of scientific interest has been focused on the functionalization of magnetic nanoparticle assemblies. The understanding of interparticle interactions is necessary to clarify the physics of these assemblies and their use in the development of high-performance magnetic materials. This book reviews prominent research studies on the static and dynamic magnetic properties of nanoparticle assemblies, gathering together experimental and computational techniques in an effort to reveal their optimized magnetic properties for biomedical use and as ultra-high magnetic recording media.

Novel multi-biotin grafted poly(lactic acid) and its self-assembling nanoparticles capable of binding to streptavidin

Science.gov (United States)

Yan, Hao; Jiang, Weimin; Zhang, Yinxing; Liu, Ying; Wang, Bin; Yang, Li; Deng, Lihong; Singh, Gurinder K; Pan, Jun

2012-01-01

Targeted drug delivery requires novel biodegradable, specific binding systems with longer circulation time. The aim of this study was to prepare biotinylated poly(lactic acid) (PLA) nanoparticles (NPs) which can meet regular requirements as well conjugate more biotins in the polymer to provide better binding with streptavidin. A biotin-graft-PLA was synthesized based on previously published biodegradable poly(ethylene glycol) (PEG)-graft-PLA, with one polymer molecule containing three PEG molecules. Newly synthesized biotin-graft-PLA had three biotins per polymer molecule, higher than the previous biotinylated PLA (≤1 biotin per polymer molecule). A PEG with a much lower molecular weight (MW ~1900) than the previous biotinylated PLA (PEG MW ≥ 3800), and thus more biocompatible, was used which supplied good nonspecific protein-resistant property compatible to PEG-graft-PLA, suggesting its possible longer stay in the bloodstream. Biotin-graft-PLA specifically bound to streptavidin and self-assembled into NPs, during which naproxen, a model small molecule (MW 230 Da) and hydrophobic drug, was encapsulated (encapsulation efficiency 51.88%). The naproxen-loaded NPs with particle size and zeta potential of 175 nm and −27.35 mV realized controlled release within 170 hours, comparable to previous studies. The biotin-graft-PLA NPs adhered approximately two-fold more on streptavidin film and on biotin film via a streptavidin arm both in static and dynamic conditions compared with PEG-graft-PLA NPs, the proven nonspecific protein-resistant NPs. The specific binding of biotin-graft-PLA NPs with streptavidin and with biotin using streptavidin arm, as well as its entrapment and controlled release for naproxen, suggest potential applications in targeted drug delivery. PMID:22334778

Self-assembled DNA Structures for Nanoconstruction

Science.gov (United States)

Yan, Hao; Yin, Peng; Park, Sung Ha; Li, Hanying; Feng, Liping; Guan, Xiaoju; Liu, Dage; Reif, John H.; LaBean, Thomas H.

2004-09-01

In recent years, a number of research groups have begun developing nanofabrication methods based on DNA self-assembly. Here we review our recent experimental progress to utilize novel DNA nanostructures for self-assembly as well as for templates in the fabrication of functional nano-patterned materials. We have prototyped a new DNA nanostructure known as a cross structure. This nanostructure has a 4-fold symmetry which promotes its self-assembly into tetragonal 2D lattices. We have utilized the tetragonal 2D lattices as templates for highly conductive metallic nanowires and periodic 2D protein nano-arrays. We have constructed and characterized a DNA nanotube, a new self-assembling superstructure composed of DNA tiles. We have also demonstrated an aperiodic DNA lattice composed of DNA tiles assembled around a long scaffold strand; the system translates information encoded in the scaffold strand into a specific and reprogrammable barcode pattern. We have achieved metallic nanoparticle linear arrays templated on self-assembled 1D DNA arrays. We have designed and demonstrated a 2-state DNA lattice, which displays expand/contract motion switched by DNA nanoactuators. We have also achieved an autonomous DNA motor executing unidirectional motion along a linear DNA track.

On the solution self-assembly of nanocolloidal brushes: insights from simulations

International Nuclear Information System (INIS)

Striolo, Alberto

2008-01-01

The synthesis of novel nanoparticles with exceptional properties continues to stimulate the search for advanced applications in fields as diverse as solar energy harvesting and polymer reinforcement. It is widely recognized that to practically exploit the promised benefits it is necessary to guide the assembly of the various nanoparticles into well-defined supra-molecular structures. Towards this goal, we report Monte Carlo simulation results for the self-assembly of spherical nanoparticles in implicit solvent. The nanoparticles interact solely via dispersive interactions, modeled as square-well potentials. To control the morphology of the self-assembled aggregates, side chains are grafted on specific locations on the nanoparticle surface (i.e., on the equator, on the tropics, on the entire tropical region, or uniformly on the nanoparticle surface). The results are discussed in terms of average cluster size, probability of observing aggregates of given size, and aggregate radius of gyration and asphericity as a function of the aggregate size. The parameters of interest are the solution conditions and the nanoparticle volume fraction (always in the dilute regime). As shown in previous reports (e.g., Striolo 2007 Small 3 628), the nanoparticles form insoluble agglomerates in the absence of the side chains. When the side chains are long and uniformly distributed on the nanoparticles, these remain individually dispersed in solution. More importantly, when the side chains are grafted on selected locations on the nanoparticles, these self-assemble, yielding structures composed of up to 7-10 nanoparticles. The number of grafted side chains is the parameter that predominantly determines the average aggregate size, while the aggregate morphology can be tuned by appropriately controlling the distribution and length of the grafted side chains.

Tunable porous nanoallotropes prepared by post-assembly etching of binary nanoparticle superlattices

Science.gov (United States)

Udayabhaskararao, Thumu; Altantzis, Thomas; Houben, Lothar; Coronado-Puchau, Marc; Langer, Judith; Popovitz-Biro, Ronit; Liz-Marzán, Luis M.; Vuković, Lela; Král, Petr; Bals, Sara; Klajn, Rafal

2017-10-01

Self-assembly of inorganic nanoparticles has been used to prepare hundreds of different colloidal crystals, but almost invariably with the restriction that the particles must be densely packed. Here, we show that non-close-packed nanoparticle arrays can be fabricated through the selective removal of one of two components comprising binary nanoparticle superlattices. First, a variety of binary nanoparticle superlattices were prepared at the liquid-air interface, including several arrangements that were previously unknown. Molecular dynamics simulations revealed the particular role of the liquid in templating the formation of superlattices not achievable through self-assembly in bulk solution. Second, upon stabilization, all of these binary superlattices could be transformed into distinct “nanoallotropes”—nanoporous materials having the same chemical composition but differing in their nanoscale architectures.

Directed Self-Assembly of Nanodispersions

Energy Technology Data Exchange (ETDEWEB)

Furst, Eric M [University of Delaware

2013-11-15

directed self-assembly of anisotropic nanoparticles and their unique physical properties.

Self-assembly of gold nanoparticles as colloidal crystals induced by polymerization of amphiphilic monomers

Czech Academy of Sciences Publication Activity Database

Zucchi, I. A.; Hoppe, C. E.; Galante, M. J.; Williams, R. J. J.; López-Quintela, M. A.; Matějka, Libor; Šlouf, Miroslav; Pleštil, Josef

2008-01-01

Roč. 41, č. 13 (2008), s. 4895-4903 ISSN 0024-9297 R&D Projects: GA AV ČR IAA400500701 Grant - others:National Agency for the Promotion of Science and Technology(AR) PICT03-14738; Ministry of Science and Technology(ES) MAT2005-07554-C02-01 Institutional research plan: CEZ:AV0Z40500505 Keywords : self -assembly * gold nanoparticles * hierarchical structure * colloidal crystals Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.407, year: 2008

Intracellular targeting of CD44+ cells with self-assembling, protein only nanoparticles.

Science.gov (United States)

Pesarrodona, Mireia; Ferrer-Miralles, Neus; Unzueta, Ugutz; Gener, Petra; Tatkiewicz, Witold; Abasolo, Ibane; Ratera, Imma; Veciana, Jaume; Schwartz, Simó; Villaverde, Antonio; Vazquez, Esther

2014-10-01

CD44 is a multifunctional cell surface protein involved in proliferation and differentiation, angiogenesis and signaling. The expression of CD44 is up-regulated in several types of human tumors and particularly in cancer stem cells, representing an appealing target for drug delivery in the treatment of cancer. We have explored here several protein ligands of CD44 for the construction of self-assembling modular proteins designed to bind and internalize target cells. Among five tested ligands, two of them (A5G27 and FNI/II/V) drive the formation of protein-only, ring-shaped nanoparticles of about 14 nm that efficiently bind and penetrate CD44(+) cells by an endosomal route. The potential of these newly designed nanoparticles is evaluated regarding the need of biocompatible nanostructured materials for drug delivery in CD44-linked conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

A review of calixarene applications in nuclear industries

International Nuclear Information System (INIS)

Bahram Mokhtari; Iranian Offshore Oil Company, Lavan Island; Kobra Pourabdollah; Naser Dallali

2011-01-01

Calixarenes has been subject to extensive research in development of many extractants, transporters, stationary phases, electrode ionophores and optical and electrochemical sensors over the past four decades. In this paper, the nuclear applications of calixarenes are summarized in six fields including complexation studies, solvent extraction, membrane transport, chromatography, luminescent and colorimetric applications, and electroanalytical applications. In the first to fourth sections, the extractability, extraction equilibria and extraction constants of lanthanide, actinide and other nuclear waste cations ions, which were subjected to solvent extraction by the macrocyclic ligands, are reviewed. In two last sections, the analytical applications of calixarene complexes towards nuclear waste cations, including spectroscopic and electroanalytic sensors, are discussed. The examples described in this review illustrate the potential of calixarene derivatives in the rapidly growing field of cations recognition in nuclear wastes. (author)

Encapsulation of testosterone by chitosan nanoparticles.

Science.gov (United States)

Chanphai, P; Tajmir-Riahi, H A

2017-05-01

The loading of testosterone by chitosan nanoparticles was investigated, using multiple spectroscopic methods, thermodynamic analysis, TEM images and modeling. Thermodynamic parameters showed testosterone-chitosan bindings occur mainly via H-bonding and van der Waals contacts. As polymer size increased more stable steroid-chitosan conjugates formed and hydrophobic contact was also observed. The loading efficacy of testosterone-nanocarrier was 40-55% and increased as chitosan size increased. Testosterone encapsulation markedly alters chitosan morphology. Chitosan nanoparticles are capable of transporting testosterone in vitro. Copyright © 2017 Elsevier B.V. All rights reserved.

Sample preconcentration utilizing nanofractures generated by junction gap breakdown assisted by self-assembled monolayer of gold nanoparticles.

Directory of Open Access Journals (Sweden)

Chun-Ping Jen

Full Text Available The preconcentration of proteins with low concentrations can be used to increase the sensitivity and accuracy of detection. A nonlinear electrokinetic flow is induced in a nanofluidic channel due to the overlap of electrical double layers, resulting in the fast accumulation of proteins, referred to as the exclusion-enrichment effect. The proposed chip for protein preconcentration was fabricated using simple standard soft lithography with a polydimethylsiloxane replica. This study extends our previous paper, in which gold nanoparticles were manually deposited onto the surface of a protein preconcentrator. In the present work, nanofractures were formed by utilizing the self-assembly of gold-nanoparticle-assisted electric breakdown. This reliable method for nanofracture formation, involving self-assembled monolayers of nanoparticles at the junction gap between microchannels, also decreases the required electric breakdown voltage. The experimental results reveal that a high concentration factor of 1.5×10(4 for a protein sample with an extremely low concentration of 1 nM was achieved in 30 min by using the proposed chip, which is faster than our previously proposed chip at the same conditions. Moreover, an immunoassay of bovine serum albumin (BSA and anti-BSA was carried out to demonstrate the applicability of the proposed chip.

Nanoparticles with high payloads of pipemidic acid, a poorly soluble crystalline drug: drug-initiated polymerization and self-assembly approach

Directory of Open Access Journals (Sweden)

Elisabetta Pancani

2018-05-01

Full Text Available Nowadays, biodegradable polymers such as poly(lactic acid (PLA, poly(D,L-lactic-co-glycolic acid (PLGA and poly(ε-caprolactone (PCL remain the most common biomaterials to produce drug-loaded nanoparticles (NPs. Pipemidic acid (PIP is a poorly soluble antibiotic with a strong tendency to crystallize. PIP incorporation in PLA/PLGA NPs was challenging because of PIP crystals formation and burst release. As PIP had a poor affinity for the NPs, an alternative approach to encapsulation was used, consisting in coupling PIP to PCL. Thus, a PCL–PIP conjugate was successfully synthesized by an original drug-initiated polymerization in a single step without the need of catalyst. PCL–PIP was characterized by NMR, IR, SEC and mass spectrometry. PCL–PIP was used to prepare self-assembled NPs with PIP contents as high as 27% (w/w. The NPs were characterized by microscopy, DLS, NTA and TRPS. This study paves the way towards the production of NPs with high antibiotic payloads by drug-initiated polymerization. Further studies will deal with the synthesis of novel polymer–PIP conjugates with ester bonds between the drug and PCL. PIP can be considered as a model drug and the strategy developed here could be extended to other challenging antibiotics or anticancer drugs and employed to efficiently incorporate them in NPs. KEY WORDS: Pipemidic acid, Nanoparticle, Antibiotic, Nanoprecipitation, Crystalline drug, Drug-initiated   polymerization

Protein nanoparticles for therapeutic protein delivery.

Science.gov (United States)

Herrera Estrada, L P; Champion, J A

2015-06-01

Therapeutic proteins can face substantial challenges to their activity, requiring protein modification or use of a delivery vehicle. Nanoparticles can significantly enhance delivery of encapsulated cargo, but traditional small molecule carriers have some limitations in their use for protein delivery. Nanoparticles made from protein have been proposed as alternative carriers and have benefits specific to therapeutic protein delivery. This review describes protein nanoparticles made by self-assembly, including protein cages, protein polymers, and charged or amphipathic peptides, and by desolvation. It presents particle fabrication and delivery characterization for a variety of therapeutic and model proteins, as well as comparison of the features of different protein nanoparticles.

UV-screening chitosan nanocontainers: increasing the photostability of encapsulated materials and controlled release

International Nuclear Information System (INIS)

Anumansirikul, Nattaporm; Wittayasuporn, Mayura; Klinubol, Patcharawalai; Tachaprutinun, A; Wanichwecharungruang, Supason P

2008-01-01

Methyl ether terminated poly(ethylene glycol)-4-methoxycinnamoylphthaloylchitosan (PCPLC), a UV absorptive polymer, and methyl ether terminated poly(ethylene glycol)-phthaloylchitosan (PPLC) were synthesized, characterized and self-assembled into stable water-dispersible spherical nanoparticles. The encapsulation of a model compound, 2-ethylhexyl-4-methoxycinnamate (EHMC), was carried out to give particles with 67% (w/w) EHMC loading. The E to Z photoisomerization of EHMC encapsulated inside both particles was monitored and compared to non-encapsulated EHMC. Minimal E to Z photoisomerization was observed when EHMC was encapsulated in PCPLC particles prepared from a polymer with a maximum degree of 4-methoxycinnamoyl substitution. The results indicated that the grafted UVB absorptive chromophore, 4-methoxycinnamoyl moieties, situated at the shell of PCPLC nanoparticles acted as a UV-filtering barrier, protecting the encapsulated EHMC from the UVB radiation, thus minimizing its photoisomerization. In vitro experiments revealed the pH-dependent controlled release of EHMC from PCPLC and PPLC particles. Ex vivo experiments, using a Franz diffusion cell with baby mouse skin, indicated that neither PPLC nor PCPLC particles could penetrate the skin into the receptor medium after a 24 h topical application. When applied on the baby mouse skin, both EHMC-encapsulated PPLC and EHMC-encapsulated PCPLC showed comparable controlled releases of the EHMC. The released EHMC could transdermally penetrate the baby mouse skin

UV-screening chitosan nanocontainers: increasing the photostability of encapsulated materials and controlled release

Science.gov (United States)

Anumansirikul, Nattaporm; Wittayasuporn, Mayura; Klinubol, Patcharawalai; Tachaprutinun, A.; Wanichwecharungruang, Supason P.

2008-05-01

Methyl ether terminated poly(ethylene glycol)-4-methoxycinnamoylphthaloylchitosan (PCPLC), a UV absorptive polymer, and methyl ether terminated poly(ethylene glycol)-phthaloylchitosan (PPLC) were synthesized, characterized and self-assembled into stable water-dispersible spherical nanoparticles. The encapsulation of a model compound, 2-ethylhexyl-4-methoxycinnamate (EHMC), was carried out to give particles with 67% (w/w) EHMC loading. The E to Z photoisomerization of EHMC encapsulated inside both particles was monitored and compared to non-encapsulated EHMC. Minimal E to Z photoisomerization was observed when EHMC was encapsulated in PCPLC particles prepared from a polymer with a maximum degree of 4-methoxycinnamoyl substitution. The results indicated that the grafted UVB absorptive chromophore, 4-methoxycinnamoyl moieties, situated at the shell of PCPLC nanoparticles acted as a UV-filtering barrier, protecting the encapsulated EHMC from the UVB radiation, thus minimizing its photoisomerization. In vitro experiments revealed the pH-dependent controlled release of EHMC from PCPLC and PPLC particles. Ex vivo experiments, using a Franz diffusion cell with baby mouse skin, indicated that neither PPLC nor PCPLC particles could penetrate the skin into the receptor medium after a 24 h topical application. When applied on the baby mouse skin, both EHMC-encapsulated PPLC and EHMC-encapsulated PCPLC showed comparable controlled releases of the EHMC. The released EHMC could transdermally penetrate the baby mouse skin.

Stabilization of 2D assemblies of silver nanoparticles by spin-coating polymers

Energy Technology Data Exchange (ETDEWEB)

Hu, Longyu; Pfirman, Aubrie; Chumanov, George, E-mail: gchumak@clemson.edu

2015-12-01

Graphical abstract: - Highlights: • Spin-coating of polymers onto 2D assemblies of Ag NPs was used to stabilize the assemblies against aggregation. • The polymer filled the space between the particles leaving the metal surface uncoated and accessible to various chemical reactions. • Etching nanoparticles produced crater-like structures. - Abstract: Silver nanoparticles self-assembled on poly(4-vinylpyridine) modified surfaces were spin-coated with poly(methyl methacrylate), poly(butyl methacrylate) and polystyrene from anisole and toluene solutions. The polymers filled the space between the particles thereby providing stabilization of the assemblies against particle aggregation when dried or chemically modified. The polymers did not coat the top surface of the nanoparticles offering the chemical accessibility to the metal surface. This was confirmed by converting the stabilized nanoparticles into silver sulfide and gold clusters. Etching the nanoparticles resulted in crater-like polymeric structures with the cavities extending down to the underlying substrate. Electrochemical reduction of silver inside the craters was performed. The approach can be extended to other nanoparticle assemblies and polymers.

Radiosensitizing Silica Nanoparticles Encapsulating Docetaxel for Treatment of Prostate Cancer.

Science.gov (United States)

Belz, Jodi; Castilla-Ojo, Noelle; Sridhar, Srinivas; Kumar, Rajiv

2017-01-01

The applications of nanoparticles in oncology include enhanced drug delivery, efficient tumor targeting, treatment monitoring, and diagnostics. The "theranostic properties" associated with nanoparticles have shown enhanced delivery of chemotherapeutic drugs with superior imaging capabilities and minimal toxicities. In conventional chemotherapy, only a fraction of the administered drug reaches the tumor site or cancer cells. For successful translation of these formulations, it is imperative to evaluate the design and properties of these nanoparticles. Here, we describe the design of ultra-small silica nanoparticles to encapsulate a radiosensitizing drug for combined chemoradiation therapy. The small size of nanoparticles allows for better dispersion and uptake of the drug within the highly vascularized tumor tissue. Silica nanoparticles are synthesized using an oil-in-water microemulsion method. The microemulsion method provides a robust synthetic route in which the inner hydrophobic core is used to encapsulate chemotherapy drug, docetaxel while the outer hydrophilic region provides dispersibility of the synthesized nanoparticles in an aqueous environment. Docetaxel is commonly used for treatment of resistant or metastatic prostate cancer, and is known to have radiosensitizing properties. Here, we describe a systematic approach for synthesizing these theranostic nanoparticles for application in prostate cancer.

Methanation of CO2 over Zeolite-Encapsulated Nickel Nanoparticles

DEFF Research Database (Denmark)

Goodarzi, Farnoosh; Kang, Liqun; Wang, Feng Ryan

2018-01-01

in an increased metal dispersion and, consequently, a high catalytic activity for CO2 methanation. With a gas hourly space velocity of 60000 ml/g catalyst h-1 and H2/CO2=4, the zeolite-encapsulated Ni nanoparticles result in 60% conversion at 450°C, which corresponds to a site-time yield of around 304 mol CH4/mol......Efficient methanation of CO2 relies on the development of more selective and stable heterogeneous catalysts. Here we present a simple and effective method to encapsulate Ni nanoparticles in zeolite silicalite-1. In this method, the zeolite is modified by selective desilication, which creates intra...

Physicochemical and biological properties of self-assembled antisense/poly(amidoamine) dendrimer nanoparticles: the effect of dendrimer generation and charge ratio

OpenAIRE

Nomani, Alireza; Haririan, Ismaeil; Rahimnia, Ramin; Fouladdel, Shamileh; Gazori, Tarane; Dinarvand, Rassoul; Omidi, Yadollah; Azizi, Ebrahim

2010-01-01

To gain a deeper understanding of the physicochemical phenomenon of self-assembled nanoparticles of different generations and ratios of poly (amidoamine) dendrimer (PAMAM) dendrimer and a short-stranded DNA (antisense oligonucleotide), multiple methods were used to characterize these nanoparticles including photon correlation spectroscopy (PCS); zeta potential measurement; and atomic force microscopy (AFM). PCS and AFM results revealed that, in contrast to larger molecules of DNA, smaller mol...

Monolayer assembly and striped architecture of Co nanoparticles on organic functionalized Si surfaces

Energy Technology Data Exchange (ETDEWEB)

Bae, S.-S.; Lim, D.K.; Park, J.-I.; Kim, S. [Korea Advanced Institute of Science and Technology, Department of Chemistry and School of Molecular Science (BK 21), Daejeon (Korea); Cheon, J. [Yonsei University, Department of Chemistry, College of Sciences, Seoul (Korea); Jeon, I.C. [Chonbuk National University, Department of Chemistry, College of Natural Sciences, Chonbuk (Korea)

2005-03-01

We present a new strategy to fabricate a monolayer assembly of Br-terminated Co nanoparticles on functionalized Si surfaces by using chemical covalent bonding and microcontact printing method. Self-assembled monolayers (SAMs) of the Co nanoparticles formed on the hydroxyl-terminated Si surface exhibit two-dimensional island networks with locally ordered arrays via covalent linkage between nanoparticles and surface. On the other hand, SAMs of the nanoparticles on the aminopropyl-terminated Si surface show an individual and random distribution over an entire surface. Furthermore, we have fabricated striped architectures of Co nanoparticles using a combination of microcontact printing and covalent linkage. Microcontact printing of octadecyltrichlorosilane and selective covalent linkage between nanoparticles and functionalized Si surfaces lead to a hybrid nanostructure with selectively assembled nanoparticles stripes on the patterned functionalized Si surfaces. (orig.)

A unique highly hydrophobic anticancer prodrug self-assembled nanomedicine for cancer therapy.

Science.gov (United States)

Ren, Guolian; Jiang, Mengjuan; Xue, Peng; Wang, Jing; Wang, Yongjun; Chen, Bo; He, Zhonggui

2016-11-01

In contrast with common thought, we generated highly hydrophobic anticancer prodrug self-assembled nanoparticles without the aid of surface active substances, based on the conjugation of docetaxel to d-α-tocopherol succinate. The reduction-sensitive prodrug was synthesized with a disulfide bond inserted into the linker and was compared with a control reduction-insensitive prodrug. The morphology and stability of self-assembled nanoparticles were investigated. Cytotoxicity and apoptosis assays showed that the reduction-sensitive nanoparticles had higher anticancer activity than the reduction-insensitive nanoparticles. The reduction-sensitive nanoparticles exhibited favorable in vivo antitumor activity and tolerance compared with docetaxel Tween80-containing formulation and the reduction-insensitive nanoparticles. Taken together, the unique nanomedicine demonstrated a number of advantages: (i) ease and reproducibility of preparation, (ii) high drug payload, (iii) superior stability, (iv) prolonged circulation, and (v) improved therapeutic effect. This highly reproducible molecular assembly strategy should motivate the development of new nanomedicines. Copyright © 2016 Elsevier Inc. All rights reserved.

Guided assembly of nanoparticles on electrostatically charged nanocrystalline diamond thin films

Directory of Open Access Journals (Sweden)

Verveniotis Elisseos

2011-01-01

Full Text Available Abstract We apply atomic force microscope for local electrostatic charging of oxygen-terminated nanocrystalline diamond (NCD thin films deposited on silicon, to induce electrostatically driven self-assembly of colloidal alumina nanoparticles into micro-patterns. Considering possible capacitive, sp2 phase and spatial uniformity factors to charging, we employ films with sub-100 nm thickness and about 60% relative sp2 phase content, probe the spatial material uniformity by Raman and electron microscopy, and repeat experiments at various positions. We demonstrate that electrostatic potential contrast on the NCD films varies between 0.1 and 1.2 V and that the contrast of more than ±1 V (as detected by Kelvin force microscopy is able to induce self-assembly of the nanoparticles via coulombic and polarization forces. This opens prospects for applications of diamond and its unique set of properties in self-assembly of nano-devices and nano-systems.

Self-assembled nanoparticles of modified-chitosan conjugates for the sustained release of dl-α-tocopherol

DEFF Research Database (Denmark)

Quinones, Javier Perez; Gothelf, Kurt Vesterager; Kjems, Jørgen

2013-01-01

Synthetic O6-succinylated chitosan and commercial glycol chitosan were covalently linked to dl-α-tocopheryl monoesters for controlled release of vitamin E. These conjugates formed self-assembled nanoparticles in aqueous solution with 254–496 nm mean diameters and dl-α-tocopherol contents between 27...... and 39% (w/w). The particles appeared as 40–75 nm almost spherical nanoparticles when studied by scanning and transmission electron microscopy upon drying. Drug linking to chitosan matrix was confirmed by FTIR spectroscopy and proton NMR. Conjugates were also characterized by differential scanning...... calorimetry and wide-angle X-ray diffraction. In vitro tocopherol release studies performed in water at acid pH indicated a drug release dependence on drug content, hydrated particle sizes and employed chitosan derivative. Almost constant release rates were observed the first 7 h. The obtained nanoparticles...

Inorganic Nanoparticle Induced Morphological Transition for Confined Self-Assembly of Block Copolymers within Emulsion Droplets.

Science.gov (United States)

Zhang, Yan; He, Yun; Yan, Nan; Zhu, Yutian; Hu, Yuexin

2017-09-07

Recently, it has been reported that the incorporation of functional inorganic nanoparticles (NPs) into the three-dimensional (3D) confined self-assembly of block copolymers (BCPs) creates the unique nanostructured hybrid composites, which can not only introduce new functions to BCPs but also induce some interesting morphological transitions of BCPs. In the current study, we systematically investigate the cooperative self-assembly of a series of size-controlled and surface chemistry-tunable gold nanoparticles (AuNPs) and polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymer within the emulsion droplets. The influences of the size, content, and surface chemistry of the AuNPs on the coassembled nanostructures as well as the spatial distribution of AuNPs in the hybrid particles are examined. It is found that the size and content of the AuNPs are related to the entropic interaction, while the surface chemistry of AuNPs is related to the enthalpic interaction, which can be utilized to tailor the self-assembled morphologies of block copolymer confined in the emulsion droplets. As the content of PS-coated AuNPs increases, the morphology of the resulting AuNPs/PS-b-P2VP hybrid particles changes from the pupa-like particles to the bud-like particles and then to the onion-like particles. However, a unique morphological transition from the pupa-like particles to the mushroom-like particles is observed as the content of P4VP-coated AuNPs increases. More interestingly, it is observed that the large AuNPs are expelled to the surface of the BCP particles to reduce the loss in the conformational entropy of the block segment, which can arrange into the strings of necklaces on the surfaces of the hybrid particles.

One-dimensional self-assembly of gold nanoparticles for tunable surface plasmon resonance properties

International Nuclear Information System (INIS)

Yang Yong; Matsubara, Shigemasha; Nogami, Masayuki; Shi Jianlin; Huang Weiming

2006-01-01

The localized surface plasmon resonance (LSPR) is a collective oscillation of the nanoparticle conduction electrons. LSPR excitation in silver and gold nanoparticles produces strong extinction and scattering spectra that in recent years have been used for important sensing and spectroscopy applications. Tuning the optoelectronic properties by controlling coupled SP modes in metals is one of the major challenges in the area of metal nanomaterials. Here we develop a simple method to fabricate linear-chainlike aggregates of gold nanoparticles (so-called nanochains), tuning the linear optical properties in a wide wavelength range from visible to the near infrared. The aggregation behaviour and linear self-assembly mechanism of citrate-stabilized gold colloids as provoked by the addition of cetyltrimethylammonium bromide (CTAB) are also analysed. The CTAB with appropriate concentration serves as the 'glue' that can link the {100} facets of two neighbour Au NPs, which leads to an anisotropic distribution of the residual surface charge, and this extrinsic electric dipole formation is responsible for the linear organization of the gold NPs into short chains

Synthesis of nanocrystals and nanocrystal self-assembly

Science.gov (United States)

Chen, Zhuoying

Chapter 1. A general introduction is presented on nanomaterials and nanoscience. Nanoparticles are discussed with respect to their structure and properties. Ferroelectric materials and nanoparticles in particular are highlighted, especially in the case of the barium titanate, and their potential applications are discussed. Different nanocrystal synthetic techniques are discussed. Nanoparticle superlattices, the novel "meta-materials" built from self-assembly at the nanoscale, are introduced. The formation of nanoparticle superlattices and the importance and interest of synthesizing these nanostructures is discussed. Chapter 2. Advanced applications for high k dielectric and ferroelectric materials in the electronics industry continues to demand an understanding of the underlying physics in decreasing dimensions into the nanoscale. The first part of this chapter presents the synthesis, processing, and electrical characterization of nanostructured thin films (thickness ˜100 nm) of barium titanate BaTiO3 built from uniform nanoparticles (alcohols were used to study the effect of size and morphological control over the nanocrystals. Techniques including X-ray diffraction, transmission electron microscopy, selected area electron diffraction, and high-resolution electron microscopy are used to examine crystallinity and morphology. Chapter 3. By investigating the self-assembly of cadmium selenide-gold (CdSe-Au) nanoparticle mixtures by transmission electron microscopy after solvent evaporation, the effect of solvents in the formation process of CdSe-Au binary nanoparticle superlattices (BNSLs) was studied. 1-dodecanethiol was found to be critical in generating conditions necessary for superlattice formation, prior to the other factors that likely determine structure, highlighting the dual role of this organic polar molecule as both ligand and high boiling point/crystallization solvent. The influence of thiol was investigated under various concentrations (and also

Encapsulation by Janus spheroids

OpenAIRE

Li, Wei; Liu, Ya; Brett, Genevieve; Gunton, James D.

2011-01-01

The micro/nano encapsulation technology has acquired considerable attention in the fields of drug delivery, biomaterial engineering, and materials science. Based on recent advances in chemical particle synthesis, we propose a primitive model of an encapsulation system produced by the self-assembly of Janus oblate spheroids, particles with oblate spheroidal bodies and two hemi-surfaces coded with dissimilar chemical properties. Using Monte Carlo simulation, we investigate the encapsulation sys...

Directed Self-Assembly of Diblock Copolymer Thin Films on Prepatterned Metal Nanoarrays.

Science.gov (United States)

Chang, Tongxin; Huang, Haiying; He, Tianbai

2016-01-01

The sequential layer by layer self-assembly of block copolymer (BCP) nanopatterns is an effective approach to construct 3D nanostructures. Here large-scale highly ordered metal nano-arrays prepared from solvent annealed thin films of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymer are used to direct the assembly of the same BCP. The influence of initial loading concentration of metal precursor, the type of metal nanoparticle (gold, platinum, and silver), and the nanoparticle-substrate interaction on the directed assembly behavior of the upper BCP layer have been focused. It is found that the upper BCP film can be completely directed by the gold nanoarray with P2VP domain exclusively located between two adjacent gold nanowires or nanodots, which behaves the same way as on the platinum nanoarray. While the silver nanoarray can be destroyed during the upper BCP self-assembly with the silver nanoparticles assembled into the P2VP domain. Based on the discussions of the surface energy of nanoparticles and the interplay between nanoparticle-substrate interaction and nanoparticle-polymer interaction, it is concluded that the effect of immobilization of nanoparticles on the substrate, together with entropy effect to minimize the energetically unfavorable chain stretching contributes to the most effective alignment between each layer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heterogeneous local order in self-assembled nanoparticle films revealed by X-ray cross-correlations

Directory of Open Access Journals (Sweden)

Felix Lehmkühler

2018-05-01

Full Text Available We report on the self-assembly of gold nanoparticles coated with a soft poly(ethylene glycol shell studied by X-ray cross-correlation analysis. Depending on the initial concentration of gold nanoparticles used, structurally heterogeneous films were formed. The films feature hot spots of dominating four- and sixfold local order with patch sizes of a few micrometres, containing 104–105 particles. The amplitude of the order parameters suggested that a minimum sample amount was necessary to form well ordered local structures. Furthermore, the increasing variation in order parameters with sample thickness demonstrated a high degree of structural heterogeneity. This wealth of information cannot be obtained by the conventional microscopy techniques that are commonly used to study nanocrystal superstructures, as illustrated by complementary scanning electron microscopy measurements.

Self-Assembled Hydrogel Nanoparticles for Drug Delivery Applications

Directory of Open Access Journals (Sweden)

Miguel Gama

2010-02-01

Full Text Available Hydrogel nanoparticles—also referred to as polymeric nanogels or macromolecular micelles—are emerging as promising drug carriers for therapeutic applications. These nanostructures hold versatility and properties suitable for the delivery of bioactive molecules, namely of biopharmaceuticals. This article reviews the latest developments in the use of self-assembled polymeric nanogels for drug delivery applications, including small molecular weight drugs, proteins, peptides, oligosaccharides, vaccines and nucleic acids. The materials and techniques used in the development of self-assembling nanogels are also described.

Ultrathin self-assembled anionic polymer membranes for superfast size-selective separation

Science.gov (United States)

Deng, Chao; Zhang, Qiu Gen; Han, Guang Lu; Gong, Yi; Zhu, Ai Mei; Liu, Qing Lin

2013-10-01

Nanoporous membranes with superior separation performance have become more crucial with increasing concerns in functional nanomaterials. Here novel ultrahigh permeable nanoporous membranes have been fabricated on macroporous supports by self-assembly of anionic polymer on copper hydroxide nanostrand templates in organic solution. This facile approach has a great potential for the fabrication of ultrathin anionic polymer membranes as a general method. The as-fabricated self-assembled membranes have a mean pore size of 5-12 nm and an adjustable thickness as low as 85 nm. They allow superfast permeation of water, and exhibit excellent size-selective separation properties and good fouling resistance for negatively-charged solutes during filtration. The 85 nm thick membrane has an ultrahigh water flux (3306 l m-2 h-1 bar-1) that is an order of magnitude larger than commercial membranes, and can highly efficiently separate 5 and 15 nm gold nanoparticles from their mixtures. The newly developed nanoporous membranes have a wide application in separation and purification of biomacromolecules and nanoparticles.Nanoporous membranes with superior separation performance have become more crucial with increasing concerns in functional nanomaterials. Here novel ultrahigh permeable nanoporous membranes have been fabricated on macroporous supports by self-assembly of anionic polymer on copper hydroxide nanostrand templates in organic solution. This facile approach has a great potential for the fabrication of ultrathin anionic polymer membranes as a general method. The as-fabricated self-assembled membranes have a mean pore size of 5-12 nm and an adjustable thickness as low as 85 nm. They allow superfast permeation of water, and exhibit excellent size-selective separation properties and good fouling resistance for negatively-charged solutes during filtration. The 85 nm thick membrane has an ultrahigh water flux (3306 l m-2 h-1 bar-1) that is an order of magnitude larger than

GOLD NANOPARTICLES ENCAPSULATED IN A POLYMERIC MATRIX OF SODIUM ALGINATE

Directory of Open Access Journals (Sweden)

Oana Lelia POP

2016-11-01

Full Text Available Plasmonic nanoparticles can be used as building blocks for the design of multifunctional systems based on polymeric capsules. The use of functionalised particles in therapeutics and imaging and understanding their effect on the cell functions are among the current challenges in nanobiotechnology and nanomedicine. The aim of the study was to manufacture and characterize polymeric microstructures by encapsulating plasmonic gold nanoparticles in biocompatible matrix of sodium alginate. The gold nanoparticles were obtained by reduction of tetracluoroauric acid with sodium citrate. To characterize the microcapsules, UV-Vis and FTIR spectroscopy, optical and confocal microscopy experiments were performed. In vitro cytotoxicity tests on HFL-1 cells were also performed. The capsules have spherical shape and 120 μm diameter. The presence of encapsulated gold nanoparticles is also shown by confocal microscopy. In vitro tests show that the microcapsules are not cytotoxic upon 24 h of cells exposure to microcapsules concentrations ranging from 2.5 to 25 capsules per cell. The obtained microcapsules of sodium alginate loaded with plasmonic gold nanoparticles could potentially be considered as release systems for biologically relevant molecules.

Deterministic nanoparticle assemblies: from substrate to solution

International Nuclear Information System (INIS)

Barcelo, Steven J; Gibson, Gary A; Yamakawa, Mineo; Li, Zhiyong; Kim, Ansoon; Norris, Kate J

2014-01-01

The deterministic assembly of metallic nanoparticles is an exciting field with many potential benefits. Many promising techniques have been developed, but challenges remain, particularly for the assembly of larger nanoparticles which often have more interesting plasmonic properties. Here we present a scalable process combining the strengths of top down and bottom up fabrication to generate deterministic 2D assemblies of metallic nanoparticles and demonstrate their stable transfer to solution. Scanning electron and high-resolution transmission electron microscopy studies of these assemblies suggested the formation of nanobridges between touching nanoparticles that hold them together so as to maintain the integrity of the assembly throughout the transfer process. The application of these nanoparticle assemblies as solution-based surface-enhanced Raman scattering (SERS) materials is demonstrated by trapping analyte molecules in the nanoparticle gaps during assembly, yielding uniformly high enhancement factors at all stages of the fabrication process. (paper)

Dynamic transformation of self-assembled structures using anisotropic magnetized hydrogel microparticles

Science.gov (United States)

Yoshida, Satoru; Takinoue, Masahiro; Iwase, Eiji; Onoe, Hiroaki

2016-08-01

This paper describes a system through which the self-assembly of anisotropic hydrogel microparticles is achieved, which also enables dynamic transformation of the assembled structures. Using a centrifuge-based microfluidic device, anisotropic hydrogel microparticles encapsulating superparamagnetic materials on one side are fabricated, which respond to a magnetic field. We successfully achieve dynamic assembly using these hydrogel microparticles and realize three different self-assembled structures (single and double pearl chain structures, and close-packed structures), which can be transformed to other structures dynamically via tuning of the precessional magnetic field. We believe that the developed system has potential application as an effective platform for a dynamic cell manipulation and cultivation system, in biomimetic autonomous microrobot organization, and that it can facilitate further understanding of the self-organization and complex systems observed in nature.

Photo-reduction on the rupture of disulfide bonds and the related protein assembling

Science.gov (United States)

Wang, Wei

It has been found that many proteins can self-assemble into nanoscale assemblies when they unfold or partially unfold under harsh conditions, such as low pH, high temperature, or the presence of denaturants, and so on. These nanoscale assemblies can have some applications such as the drug-delivery systems (DDSs). Here we report a study that a very physical way, the UV illumination, can be used to facilitate the formation of protein fibrils and nanoparticles under native conditions by breaking disulfide bonds in some disulfide-containing proteins. By controlling the intensity of UV light and the illumination time, we realized the preparation of self-assembly nanoparticles which encapsulate the anticancer drug doxorubicin (DOX) and can be used as the DDS for inhibiting the growth of tumor. The formation of fibrillary assemblies was also observed. The rupture of disulfide bonds through photo-reduction process due to the effect of tryptophan and tyrosine was studied, and the physical mechanism of the assembling of the related disulfide-containing proteins was also discussed. We thank the financial support from NSF of China and the 973 project.

Co-Pt nanoparticles encapsulated in carbon cages prepared by sonoelectrodeposition

Energy Technology Data Exchange (ETDEWEB)

Luong, Nguyen Hoang; Hai, Nguyen Hoang; Phu, Nguyen Dang [Center for Materials Science, Faculty of Physics, Hanoi University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Hanoi (Viet Nam); MacLaren, D A, E-mail: luongnh@vnu.edu.vn [School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ (United Kingdom)

2011-07-15

Co-Pt nanoparticles encapsulated in carbon cages have been prepared by sonoelectrodeposition followed by annealing in a CO atmosphere. Sonoelectrodeposition is a useful technique to make metallic nanoparticles, using ultrasound during electrodeposition to remove nanoparticles as they grow on the cathode surface. We used an electrolyte containing chloroplatinic acid and cobalt chloride and found that the atomic ratio of Co:Pt in the as-formed materials varied from 0.2 to 0.8 as the deposition current density was changed from 15 to 35 mA cm{sup -2}. However, the as-deposited materials were inhomogeneous, comprising a mixture of Pt-rich and Co-rich nanoparticles. X-ray diffraction indicated that subsequent heat treatment (700 deg. C for 1 h) under CO gas created an ordered CoPt alloy phase that exhibited hard magnetic properties. Transmission electron microscopy showed many of the resulting nanoparticles to be encapsulated in carbon cages, which we ascribe to Co-catalyzed decomposition of CO during annealing. The thickness of the carbon cages was about ten layers, which may have helped reduce sintering during annealing. The size of the resultant nanoparticles was about 100 nm diameter, larger than the typical 5-10 nm diameter of as-deposited nanoparticles.

Antimicrobial drugs encapsulated in fibrin nanoparticles for treating microbial infested wounds.

Science.gov (United States)

Alphonsa, B Maria; Sudheesh Kumar, P T; Praveen, G; Biswas, Raja; Chennazhi, K P; Jayakumar, R

2014-05-01

In vitro evaluation of antibacterial and antifungal drugs encapsulated fibrin nanoparticles to prove their potential prospect of using these nanocomponent for effective treatment of microbial infested wounds. Surfactant-free oil-in-water emulsification-diffusion method was adopted to encapsulate 1 mg/ml each of antimicrobial drugs (Ciprofloxacin and Fluconazole) in 4 ml of aqueous fibrinogen suspension and subsequent thrombin mediated cross linking to synthesize drug loaded fibrin nanoparticles. Ciprofloxacin loaded fibrin nanoparticles (CFNPs) showed size range of 253 ± 6 nm whereas that of Fluconazole loaded fibrin nanoparticles (FFNPs) was 260 ± 10 nm. Physico chemical characterizations revealed the firm integration of antimicrobial drugs within fibrin nanoparticles. Drug release studies performed at physiological pH 7.4 showed a release of 16% ciprofloxacin and 8% of fluconazole while as the release of ciprofloxacin at alkaline pH 8.5, was 48% and that of fluconazole was 37%. The antimicrobial activity evaluations of both drug loaded systems independently showed good antibacterial activity against Escherichia coli (E.coli), Staphylococcus aureus (S. aureus) and antifungal activity against Candida albicans (C. albicans). The in vitro toxicity of the prepared drug loaded nanoparticles were further analyzed using Human dermal fibroblast cells (HDF) and showed adequate cell viability. The efficacies of both CFNPs and FFNPs for sustained delivery of encapsulated anti microbial drugs were evaluated in vitro suggesting its potential use for treating microbial infested wounds (diabetic foot ulcer).

Surface modification of protein enhances encapsulation in chitosan nanoparticles

Science.gov (United States)

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

2018-04-01

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

Graphene-bonded and -encapsulated si nanoparticles for lithium ion battery anodes.

Science.gov (United States)

Wen, Yang; Zhu, Yujie; Langrock, Alex; Manivannan, Ayyakkannu; Ehrman, Sheryl H; Wang, Chunsheng

2013-08-26

Silicon (Si) has been considered a very promising anode material for lithium ion batteries due to its high theoretical capacity. However, high-capacity Si nanoparticles usually suffer from low electronic conductivity, large volume change, and severe aggregation problems during lithiation and delithiation. In this paper, a unique nanostructured anode with Si nanoparticles bonded and wrapped by graphene is synthesized by a one-step aerosol spraying of surface-modified Si nanoparticles and graphene oxide suspension. The functional groups on the surface of Si nanoparticles (50-100 nm) not only react with graphene oxide and bind Si nanoparticles to the graphene oxide shell, but also prevent Si nanoparticles from aggregation, thus contributing to a uniform Si suspension. A homogeneous graphene-encapsulated Si nanoparticle morphology forms during the aerosol spraying process. The open-ended graphene shell with defects allows fast electrochemical lithiation/delithiation, and the void space inside the graphene shell accompanied by its strong mechanical strength can effectively accommodate the volume expansion of Si upon lithiation. The graphene shell provides good electronic conductivity for Si nanoparticles and prevents them from aggregating during charge/discharge cycles. The functionalized Si encapsulated by graphene sample exhibits a capacity of 2250 mAh g⁻¹ (based on the total mass of graphene and Si) at 0.1C and 1000 mAh g⁻¹ at 10C, and retains 85% of its initial capacity even after 120 charge/discharge cycles. The exceptional performance of graphene-encapsulated Si anodes combined with the scalable and one-step aerosol synthesis technique makes this material very promising for lithium ion batteries. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Directed Assembly of Gold Nanoparticles

DEFF Research Database (Denmark)

Westerlund, Axel Rune Fredrik; Bjørnholm, Thomas

2009-01-01

As a complement to common "top-down" lithography techniques, "bottom-up" assembly techniques are emerging as promising tools to build nanoscale structures in a predictable way. Gold nanoparticles that are stable and relatively easy to synthesize are important building blocks in many such structures...... due to their useful optical and electronic properties. Programmed assembly of gold nanoparticles in one, two, and three dimensions is therefore of large interest. This review focuses on the progress from the last three years in the field of directed gold nanoparticle and nanorod assembly using...

Application of Calixarenes as Macrocyclic Ligands for Uranium(VI: A Review

Directory of Open Access Journals (Sweden)

Katarzyna Kiegiel

2013-01-01

Full Text Available Calixarenes represent a well-known family of macrocyclic molecules with broad range of potential applications in chemical, analytical, and engineering materials fields. This paper covers the use of calixarenes as complexing agents for uranium(VI. The high effectiveness of calix[6]arenes in comparison to other calixarenes in uranium(VI separation process is also presented. Processes such as liquid-liquid extraction (LLE, liquid membrane (LM separation, and ion exchange are considered as potential fields for application of calixarenes as useful agents for binding UO22+ for effective separation from aqueous solutions containing other metal components.

Antiproliferative effect of Antrodia camphorata polysaccharides encapsulated in chitosan-silica nanoparticles strongly depends on the metabolic activity type of the cell line

Energy Technology Data Exchange (ETDEWEB)

Kong, Zwe-Ling, E-mail: kongzl@mail.ntou.edu.tw; Chang, Jenq-Sheng; Chang, Ke Liang B. [National Taiwan Ocean University, Department of Food Science (China)

2013-09-15

Chitosan molecules interact with silica and encapsulate the Antrodia camphorata extract (ACE) polysaccharides to form composite nanoparticles. The nanoparticle suspensions of ACE polysaccharides encapsulated in silica-chitosan and silica nanoparticles approach an average particle size of 210 and 294 nm in solution, respectively. The encapsulation efficiencies of ACE polysaccharides are 66 and 63.5 %, respectively. Scanning electron micrographs confirm the formation of near-spherical nanoparticles. ACE polysaccharides solution had better antioxidative capability than ACE polysaccharides encapsulated in silica or silica-chitosan nanoparticles suspensions. The antioxidant capacity of nanoparticles increases with increasing dissolution time. The antitumor effects of ACE polysaccharides, ACE polysaccharides encapsulated in silica, or silica-chitosan nanoparticles increased with increasing concentration of nanoparticles. This is the first report demonstrating the potential of ACE polysaccharides encapsulated in chitosan-silica nanoparticles for cancer chemoprevention. Furthermore, this study suggests that antiproliferative effect of nanoparticle-encapsulated bioactive could significantly depend on the metabolic activity type of the cell line.

Antiproliferative effect of Antrodia camphorata polysaccharides encapsulated in chitosan-silica nanoparticles strongly depends on the metabolic activity type of the cell line

Science.gov (United States)

Kong, Zwe-Ling; Chang, Jenq-Sheng; Chang, Ke Liang B.

2013-09-01

Chitosan molecules interact with silica and encapsulate the Antrodia camphorata extract (ACE) polysaccharides to form composite nanoparticles. The nanoparticle suspensions of ACE polysaccharides encapsulated in silica-chitosan and silica nanoparticles approach an average particle size of 210 and 294 nm in solution, respectively. The encapsulation efficiencies of ACE polysaccharides are 66 and 63.5 %, respectively. Scanning electron micrographs confirm the formation of near-spherical nanoparticles. ACE polysaccharides solution had better antioxidative capability than ACE polysaccharides encapsulated in silica or silica-chitosan nanoparticles suspensions. The antioxidant capacity of nanoparticles increases with increasing dissolution time. The antitumor effects of ACE polysaccharides, ACE polysaccharides encapsulated in silica, or silica-chitosan nanoparticles increased with increasing concentration of nanoparticles. This is the first report demonstrating the potential of ACE polysaccharides encapsulated in chitosan-silica nanoparticles for cancer chemoprevention. Furthermore, this study suggests that antiproliferative effect of nanoparticle-encapsulated bioactive could significantly depend on the metabolic activity type of the cell line.

Antiproliferative effect of Antrodia camphorata polysaccharides encapsulated in chitosan–silica nanoparticles strongly depends on the metabolic activity type of the cell line

International Nuclear Information System (INIS)

Kong, Zwe-Ling; Chang, Jenq-Sheng; Chang, Ke Liang B.

2013-01-01

Chitosan molecules interact with silica and encapsulate the Antrodia camphorata extract (ACE) polysaccharides to form composite nanoparticles. The nanoparticle suspensions of ACE polysaccharides encapsulated in silica–chitosan and silica nanoparticles approach an average particle size of 210 and 294 nm in solution, respectively. The encapsulation efficiencies of ACE polysaccharides are 66 and 63.5 %, respectively. Scanning electron micrographs confirm the formation of near-spherical nanoparticles. ACE polysaccharides solution had better antioxidative capability than ACE polysaccharides encapsulated in silica or silica–chitosan nanoparticles suspensions. The antioxidant capacity of nanoparticles increases with increasing dissolution time. The antitumor effects of ACE polysaccharides, ACE polysaccharides encapsulated in silica, or silica–chitosan nanoparticles increased with increasing concentration of nanoparticles. This is the first report demonstrating the potential of ACE polysaccharides encapsulated in chitosan–silica nanoparticles for cancer chemoprevention. Furthermore, this study suggests that antiproliferative effect of nanoparticle-encapsulated bioactive could significantly depend on the metabolic activity type of the cell line

Method of producing zeolite encapsulated nanoparticles

DEFF Research Database (Denmark)

2015-01-01

The invention therefore relates to a method for producing zeolite, zeolite-like or zeotype encapsulated metal nanoparticles, the method comprises the steps of: 1) Adding one or more metal precursors to a silica or alumina source; 2) Reducing the one or more metal precursors to form metal...... nanoparticles on the surface of the silica or alumina source; 3) Passing a gaseous hydrocarbon, alkyl alcohol or alkyl ether over the silica or alumina supported metal nanoparticles to form a carbon template coated zeolite, zeolite-like or zeotype precursor composition; 4a) Adding a structure directing agent...... to the carbon template coated zeolite, zeolite-like or zeotype precursor composition thereby creating a zeolite, zeolite-like or zeotype gel composition; 4b) Crystallising the zeolite, zeolite-like or zeotype gel composition by subjecting said composition to a hydrothermal treatment; 5) Removing the carbon...

Micro-‘‘factory’’ for self-assembled peptide nanostructures

DEFF Research Database (Denmark)

Castillo, Jaime; Rodriguez-Trujíllo, Romén; Gauthier, Sébastian

2011-01-01

This study describes an integrated micro ‘‘factory’’ for the preparation of biological self-assembled peptide nanotubes and nanoparticles on a polymer chip, yielding controlled growth conditions. Self-assembled peptides constitute attractive building blocks for the fabrication of biological...... nanostructures due to the mild conditions of their synthesis process. This biological material can form nanostructures in a rapid way and the synthesis method is less expensive as compared to that of carbon nanotubes or silicon nanowires. The present article thus reports on the on-chip fabrication of self-assembled...

Self-assembly nanoparticle based tripetaloid structure arrays as surface-enhanced Raman scattering substrates

International Nuclear Information System (INIS)

Sun Mingrui; Qian Chuang; Wu Wengang; Yu Wenxuan; Wang Yifei; Mao Haiyang

2012-01-01

This paper reports a novel highly ordered tripetaloid structure array (TPSA) which performs very well as an active surface-enhanced Raman scattering (SERS) substrate. The TPSA is easily fabricated by anisotropic etching of a self-assembly silica-nanoparticle bilayer and a subsequent metal deposition step, with notable uniformity and reproducibility. Electromagnetic simulation indicates that the narrow inter-gaps and edge protrusions in the TPSA act as hot spots. In addition, the peak electromagnetic field intensity in the inter-gaps changes slightly and periodically as the polarization of the incident light varies from 0° to 360°. SERS experiments show that the SERS enhancement factor (EF) of a Au-film-covered TPSA is 12 times higher than that of regular Au-film-over-nanoparticles, and not sensitive to the polarization of the incident light. The spatially averaged EF of the TPSA is as high as 5.7 × 10 6 , and the local EF of its hot spots is much higher. (paper)

Multilayer encapsulated mesoporous silica nanospheres as an oral sustained drug delivery system for the poorly water-soluble drug felodipine

Energy Technology Data Exchange (ETDEWEB)

Hu, Liang [Department of Pharmaceutics, Shenyang Pharmaceutical University, P.O. Box 32, Liaoning Province, Shenyang 110016 (China); Sun, Hongrui [English Teaching Department, School of Basic Courses, Shenyang Pharmaceutical University, Wenhua Road 103, Shenyang 110016 (China); Zhao, Qinfu; Han, Ning; Bai, Ling; Wang, Ying; Jiang, Tongying [Department of Pharmaceutics, Shenyang Pharmaceutical University, P.O. Box 32, Liaoning Province, Shenyang 110016 (China); Wang, Siling, E-mail: silingwang@syphu.edu.cn [Department of Pharmaceutics, Shenyang Pharmaceutical University, P.O. Box 32, Liaoning Province, Shenyang 110016 (China)

2015-02-01

We used a combination of mesoporous silica nanospheres (MSN) and layer-by-layer (LBL) self-assembly technology to establish a new oral sustained drug delivery system for the poorly water-soluble drug felodipine. Firstly, the model drug was loaded into MSN, and then the loaded MSN were repeatedly encapsulated by chitosan (CHI) and acacia (ACA) via LBL self-assembly method. The structural features of the samples were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption. The encapsulating process was monitored by zeta-potential and surface tension measurements. The physical state of the drug in the samples was characterized by differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). The influence of the multilayer with different number of layers on the drug release rate was studied using thermal gravimetric analysis (TGA) and surface tension measurement. The swelling effect and the structure changes of the multilayer were investigated to explore the relationship between the drug release behavior and the state of the multilayer under different pH conditions. The stability and mucosa adhesive ability of the prepared nanoparticles were also explored. After multilayer coating, the drug release rate was effectively controlled. The differences in drug release behavior under different pH conditions could be attributed to the different states of the multilayer. And the nanoparticles possessed good stability and strong mucosa adhesive ability. We believe that this combination offers a simple strategy for regulating the release rate of poorly water-soluble drugs and extends the pharmaceutical applications of inorganic materials and polymers. - Highlights: • A combination of inorganic and organic materials was applied. • Mesoporous silica nanospheres (MSN) were used as drug carriers. • Chitosan and acacia were encapsulated through layer-by-layer self-assembly. • The release rate of the poorly

Multilayer encapsulated mesoporous silica nanospheres as an oral sustained drug delivery system for the poorly water-soluble drug felodipine

International Nuclear Information System (INIS)

Hu, Liang; Sun, Hongrui; Zhao, Qinfu; Han, Ning; Bai, Ling; Wang, Ying; Jiang, Tongying; Wang, Siling

2015-01-01

We used a combination of mesoporous silica nanospheres (MSN) and layer-by-layer (LBL) self-assembly technology to establish a new oral sustained drug delivery system for the poorly water-soluble drug felodipine. Firstly, the model drug was loaded into MSN, and then the loaded MSN were repeatedly encapsulated by chitosan (CHI) and acacia (ACA) via LBL self-assembly method. The structural features of the samples were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption. The encapsulating process was monitored by zeta-potential and surface tension measurements. The physical state of the drug in the samples was characterized by differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). The influence of the multilayer with different number of layers on the drug release rate was studied using thermal gravimetric analysis (TGA) and surface tension measurement. The swelling effect and the structure changes of the multilayer were investigated to explore the relationship between the drug release behavior and the state of the multilayer under different pH conditions. The stability and mucosa adhesive ability of the prepared nanoparticles were also explored. After multilayer coating, the drug release rate was effectively controlled. The differences in drug release behavior under different pH conditions could be attributed to the different states of the multilayer. And the nanoparticles possessed good stability and strong mucosa adhesive ability. We believe that this combination offers a simple strategy for regulating the release rate of poorly water-soluble drugs and extends the pharmaceutical applications of inorganic materials and polymers. - Highlights: • A combination of inorganic and organic materials was applied. • Mesoporous silica nanospheres (MSN) were used as drug carriers. • Chitosan and acacia were encapsulated through layer-by-layer self-assembly. • The release rate of the poorly

Controlled-release and preserved bioactivity of proteins from (self-assembled core-shell double-walled microspheres

Directory of Open Access Journals (Sweden)

Yuan W

2012-01-01

Full Text Available Weien Yuan1,2, Zhenguo Liu11Department of Neurology, Xinhua Hospital, affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 2School of Pharmacy, Shanghai Jiao Tong University, Shanghai, People’s Republic of ChinaAbstract: In order to address preserved protein bioactivities and protein sustained-release problems, a method for preparing double-walled microspheres with a core (protein-loaded nanoparticles with a polymer-suspended granule system-formed core and a second shell (a polymer-formed shell for controlled drug release and preserved protein bioactivities has been developed using (solid-in-oil phase-in-hydrophilic oil-in-water (S/O/Oh/W phases. The method, based on our previous microsphere preparation method (solid-in-oil phase-in-hydrophilic oil-in-water (S/O/Oh/W, employs different concentric poly(D,L-lactide-co-glycolide, poly(D,L-lactide, and protein-loaded nanoparticles to produce a suspended liquid which then self-assembles to form shell-core microspheres in the hydrophilic oil phase, which are then solidified in the water phase. Variations in the preparation parameters allowed complete encapsulation by the shell phase, including the efficient formation of a poly(D,L-lactide shell encapsulating a protein-loaded nanoparticle-based poly(D,L-lactide-co-glycolide core. This method produces core-shell double-walled microspheres that show controlled protein release and preserved protein bioactivities for 60 days. Based upon these results, we concluded that the core-shell double-walled microspheres might be applied for tissue engineering and therapy for chronic diseases, etc.Keywords: protein delivery, protein stability, core-shell microspheres, dextran nanoparticles

Chemical and physical passivation of type II strained-layer superlattice devices by means of thiolated self-assembled monolayers and polymer encapsulates

Science.gov (United States)

Henry, Nathan C.; Knorr, Daniel B.; Williams, Kristen S.; Baril, Neil; Nallon, Eric; Lenhart, Joseph L.; Andzelm, Jan W.; Pellegrino, Joseph; Tidrow, Meimei; Cleveland, Erin; Bandara, Sumith

2015-05-01

The efficacy of solution deposition of thiolated self-assembled monolayers (SAMs) has been explored for the purpose of passivating III-V type II superlattice (T2SL) photodetectors, more specifically a p-type heterojunction device. Sulfur passivation has previously been achieved on T2SL devices. However, degradation over time, temperature sensitivity and inconsistent reproducibility necessitate a physical encapsulate that can chemically bond to the chemical passivant. Thus, this research investigates two passivation methods, surface passivation with a thiol monolayer and passivation with a polymer encapsulant with a view toward future combination of these techniques. Analysis of the physical and chemical condition of the surface prior to deposition assisted in the development of ideal processes for optimized film quality. Successful deposition was facilitated by in situ oxide removal. Various commercially available functional (cysteamine) and non-functional (alkane) thiolated monolayers were investigated. Dark current was reduced by 3 orders of magnitude and achieved negligible surface leakage at low bias levels. The lowest dark current result, 7.69 × 10-6 A/cm2 at 50 mV, was achieved through passivation with cysteamine.

Generic concept to program the time domain of self-assemblies with a self-regulation mechanism.

Science.gov (United States)

Heuser, Thomas; Steppert, Ann-Kathrin; Lopez, Catalina Molano; Zhu, Baolei; Walther, Andreas

2015-04-08

Nature regulates complex structures in space and time via feedback loops, kinetically controlled transformations, and under energy dissipation to allow non-equilibrium processes. Although man-made static self-assemblies realize excellent control over hierarchical structures via molecular programming, managing their temporal destiny by self-regulation is a largely unsolved challenge. Herein, we introduce a generic concept to control the time domain by programming the lifetimes of switchable self-assemblies in closed systems. We conceive dormant deactivators that, in combination with fast promoters, enable a unique kinetic balance to establish an autonomously self-regulating, transient pH-state, whose duration can be programmed over orders of magnitude-from minutes to days. Coupling this non-equilibrium state to pH-switchable self-assemblies allows predicting their assembly/disassembly fate in time, similar to a precise self-destruction mechanism. We demonstrate a platform approach by programming self-assembly lifetimes of block copolymers, nanoparticles, and peptides, enabling dynamic materials with a self-regulation functionality.

Efficient sampling of reversible cross-linking polymers: Self-assembly of single-chain polymeric nanoparticles

Science.gov (United States)

Oyarzún, Bernardo; Mognetti, Bortolo Matteo

2018-03-01

We present a new simulation technique to study systems of polymers functionalized by reactive sites that bind/unbind forming reversible linkages. Functionalized polymers feature self-assembly and responsive properties that are unmatched by the systems lacking selective interactions. The scales at which the functional properties of these materials emerge are difficult to model, especially in the reversible regime where such properties result from many binding/unbinding events. This difficulty is related to large entropic barriers associated with the formation of intra-molecular loops. In this work, we present a simulation scheme that sidesteps configurational costs by dedicated Monte Carlo moves capable of binding/unbinding reactive sites in a single step. Cross-linking reactions are implemented by trial moves that reconstruct chain sections attempting, at the same time, a dimerization reaction between pairs of reactive sites. The model is parametrized by the reaction equilibrium constant of the reactive species free in solution. This quantity can be obtained by means of experiments or atomistic/quantum simulations. We use the proposed methodology to study the self-assembly of single-chain polymeric nanoparticles, starting from flexible precursors carrying regularly or randomly distributed reactive sites. We focus on understanding differences in the morphology of chain nanoparticles when linkages are reversible as compared to the well-studied case of irreversible reactions. Intriguingly, we find that the size of regularly functionalized chains, in good solvent conditions, is non-monotonous as a function of the degree of functionalization. We clarify how this result follows from excluded volume interactions and is peculiar of reversible linkages and regular functionalizations.

Encapsulation of ethylhexyl methoxycinnamate, a light-sensitive UV filter, in lipid nanoparticles.

Science.gov (United States)

Durand, L; Habran, N; Henschel, V; Amighi, K

2010-01-01

The aim of this study was to encapsulate ethylhexyl methoxycinnamate (EMC), a commonly used UVB filter, in a solid lipid matrix in order to obtain microparticles and then nanoparticles to reduce its photo-instability under UV light exposure. Glyceryl behenate, rice bran wax and ozokerite were investigated for encapsulating EMC. The suspensions of nanoparticles contained 70% encapsulated EMC (relative to the lipid mass). The absorbance level at 310 nm of suspensions containing nanoparticles was more than twice that of those containing microparticles. So, decreasing the size of particles improved the efficiency of light protection, regardless of the lipid material used. Moreover, free EMC presented a 30% loss of its efficiency after 2 h of irradiation, whereas the three NLC formulations showed a loss of absorbency between 10% and 21%. The in vitro cutaneous penetration test did not show a higher potential penetration for EMC contained in nanosuspensions compared to free EMC.

The characters of self-assembly core/shell nanoparticles of amphiphilic hyperbranched polyethers as drug carriers

International Nuclear Information System (INIS)

Ajun Wan; Yuxia, Kou

2008-01-01

The characters of self-assembly core/shell nanoparticles of amphiphilic hyperbranched polyethers (HP-g-PEO) as drug carriers were investigated. The HP-g-PEO consisting of hydrophobic HP-g-PEO core and hydrophilic poly(ethylene glycol) arms was prepared by the cation ring-opening polymerization. A series of HP-g-PEO samples with different degree of branching (DB) were synthesized under various reaction temperatures. Nanoparticles (NP) were obtained by self-assembly of HP-g-PEO in aqueous media. The structure of resulting HP-g-PEO was characterized by IR, 13 CNMR and GPC. Dynamic light scattering and transmission electron microscopy were applied to characterize the sizes and size distributions of NP. The results demonstrated that the mean diameters of NP were less than 100 nm, which exhibited uniform spherical formations and narrow size distributions. Using hydrophobic drug Probucol (PRO) as model drug, the particle sizes of drug loaded NP were larger than relative blank NP. The drug loading efficiency (LE) and incorporation efficiency (IE) of these NP were achieved to 35 and 89%, respectively. The in vitro release of PRO from the NP exhibited a sustained release and the cumulative drugs released for more than 600 h. The most important factor to affect drug release was the value of DB of HP-g-PEO. With the DB of HP-g-PEO increasing, the size and size distribution of NP decreased as well as the release rate. However, the small DB was beneficial to the LE of NP. Nanoparticle size and size distribution, LE, IE, and drug release rate were slightly affected by the initial solution concentration of polyethers. The co-incorporated hydrophilic drug had influence slightly on the release of drug from drug loaded NP. The results of in vitro drug release suggested that the core/shell NP performed good controlled release behaviors with potential practice as novelty drug delivery vehicles

Dynamic Self-Assembly of Homogenous Microcyclic Structures Controlled by a Silver-Coated Nanopore.

Science.gov (United States)

Gao, Rui; Lin, Yao; Ying, Yi-Lun; Liu, Xiao-Yuan; Shi, Xin; Hu, Yong-Xu; Long, Yi-Tao; Tian, He

2017-07-01

The self-assembly of nanoparticles is a challenging process for organizing precise structures with complicated and ingenious structures. In the past decades, a simple, high-efficiency, and reproducible self-assembly method from nanoscale to microscale has been pursued because of the promising and extensive application prospects in bioanalysis, catalysis, photonics, and energy storage. However, microscale self-assembly still faces big challenges including improving the stability and homogeneity as well as pursuing new assembly methods and templates for the uniform self-assembly. To address these obstacles, here, a novel silver-coated nanopore is developed which serves as a template for electrochemically generating microcyclic structures of gold nanoparticles at micrometers with highly homogenous size and remarkable reproducibility. Nanopore-induced microcyclic structures are further applied to visualize the diffusion profile of ionic flux. Based on this novel strategy, a nanopore could potentially facilitate the delivery of assembled structures for many practical applications including drug delivery, cellular detection, catalysis, and plasmonic sensing. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Disulfide-induced self-assembled targets : A novel strategy for the label free colorimetric detection of DNAs/RNAs via unmodified gold nanoparticles

NARCIS (Netherlands)

Shokri, Ehsan; Hosseini, Morteza; Davari, Mehdi D.; Ganjali, Mohammad R.; Peppelenbosch, Maikel P.; Rezaee, Farhad

2017-01-01

A modified non-cross-linking gold-nanoparticles (Au-NPs) aggregation strategy has been developed for the label free colorimetric detection of DNAs/RNAs based on self-assembling target species in the presence of thiolated probes. Two complementary thiol-modified probes, each of which specifically

Disulfide-induced self-assembled targets: A novel strategy for the label free colorimetric detection of DNAs/RNAs via unmodified gold nanoparticles

NARCIS (Netherlands)

Shokri, E. (Ehsan); M. Hosseini (Morteza); Davari, M.D. (Mehdi D.); Ganjali, M.R. (Mohammad R.); M.P. Peppelenbosch (Maikel); F. Rezaee (Farhad)

2017-01-01

textabstractA modified non-cross-linking gold-nanoparticles (Au-NPs) aggregation strategy has been developed for the label free colorimetric detection of DNAs/RNAs based on self-assembling target species in the presence of thiolated probes. Two complementary thiol- modified probes, each of which

Co-encapsulation of lyoprotectants improves the stability of protein-loaded PLGA nanoparticles upon lyophilization

DEFF Research Database (Denmark)

Fonte, Pedro; Araújo, Francisca; Seabra, Vítor

2015-01-01

The purpose of this work was to evaluate the influence of the co-encapsulation of lyoprotectants with insulin into PLGA nanoparticles, on the stability of the protein and nanoparticles upon lyophilization. Different lyoprotectants were used, namely trehalose, glucose, sucrose, fructose and sorbitol...... formulations with externally added lyoprotectants, except trehalose, showed crystallinity. FTIR assessment showed that co-encapsulating lyoprotectants better preserved insulin structure upon lyophilization with a spectral area overlap of 82-87%, compared to only 72% in lyoprotectant absence. These results were...... confirmed by circular dichroism spectroscopy. Surprisingly, the simultaneous co-encapsulation and addition of lyoprotectants was detrimental to protein stabilization. The insulin in vitro release studies demonstrated that formulations with co-encapsulated trehalose, glucose, sucrose, fructose and sorbitol...

5-Fluorouracil Encapsulated Chitosan Nanoparticles for pH-Stimulated Drug Delivery: Evaluation of Controlled Release Kinetics

Directory of Open Access Journals (Sweden)

R. Seda Tığlı Aydın

2012-01-01

Full Text Available Nanoparticles consisting of human therapeutic drugs are suggested as a promising strategy for targeted and localized drug delivery to tumor cells. In this study, 5-fluorouracil (5-FU encapsulated chitosan nanoparticles were prepared in order to investigate potentials of localized drug delivery for tumor environment due to pH sensitivity of chitosan nanoparticles. Optimization of chitosan and 5-FU encapsulated nanoparticles production revealed 148.8±1.1 nm and 243.1±17.9 nm particle size diameters with narrow size distributions, which are confirmed by scanning electron microscope (SEM images. The challenge was to investigate drug delivery of 5-FU encapsulated chitosan nanoparticles due to varied pH changes. To achieve this objective, pH sensitivity of prepared chitosan nanoparticle was evaluated and results showed a significant swelling response for pH 5 with particle diameter of ∼450 nm. In vitro release studies indicated a controlled and sustained release of 5-FU from chitosan nanoparticles with the release amounts of 29.1–60.8% due to varied pH environments after 408 h of the incubation period. pH sensitivity is confirmed by mathematical modeling of release kinetics since chitosan nanoparticles showed stimuli-induced release. Results suggested that 5-FU encapsulated chitosan nanoparticles can be launched as pH-responsive smart drug delivery agents for possible applications of cancer treatments.

Self-assembled metallic nanoparticle template — a new approach of surface nanostructuring at nanometer scale

Directory of Open Access Journals (Sweden)

A. Taleb

2017-09-01

Full Text Available In the present work, the formation of silver and copper nanostructures on highly oriented pyrolytic graphite (HOPG modified with self-assembled gold nanoparticles (Au NPs is demonstrated. Surface patterning with nanometer resolution was achieved. Different methods such as field emission scanning electron microscopy (FEGSEM, energy dispersive spectrometry (EDS and X-ray photoelectron spectroscopy (XPS were used to illustrate a selective deposition of silver and copper on Au NPs. The mechanism of silver and copper ions reduction on Au NP with n-dodecanethiol coating is discussed.

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

Science.gov (United States)

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

2006-06-01

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

Formation of the self-assembled structures by the ultrasonic cavitation erosion-corrosion effect on carbon steel

Directory of Open Access Journals (Sweden)

Dayun Yan

2015-11-01

Full Text Available The cavitation erosion-corrosion effect on the metal surface always forms irregular oxide structures. In this study, we reported the formation of regular self-assembled structures of amorphous nanoparticles around the cavitation erosion pits on carbon steel upon the ultrasonic cavitation in methylene blue solution. Each self-assembled structure was composed of linearly aligned nanoparticles of about 100 nm. The formation of self-assembled structures might be due to the combined effect of corrosion, specific sonochemical reaction in methylene blue solution, and the magnetic domain structures on the carbon steel.

One-step engineered self-assembly Co3O4 nanoparticles to nanocubes for supercapacitors

Science.gov (United States)

Nagajyothi, P. C.; Pandurangan, M.; Sreekanth, T. V. M.; Shim, Jaesool

2018-02-01

Tricobalt tetraoxide or cobalt oxide (Co3O4) nanocubes (NCs) were synthesized from the self-assemblies of Co3O4 nanoparticles (NPs) via a simple one-step hydrothermal method. X-ray diffraction analysis confirmed the cubic crystal structure of Co3O4 NCs. The surface properties were investigated by x-ray photoelectron spectroscopy, which suggests the co-existence of Co in +2 and +3 states. The self-assemblies of aggregation of NPs to NCs were inspected using scanning electron microscopy, which is supported by transmission electron microscopy. The electrochemical properties of Co3O4 NCs were carried out by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) curves and impedance analysis. The areal capacitance of 3.04 mF cm-2 was obtained at current density of 10 μA cm-2. The Co3O4 NCs electrode exhibits good long-cyclic stability with 92.1% capacitance retention over 3000 cycles. The CV, GCD and impedance curves of Co3O4 NCs were recorded after cyclic test, which are similar to the curves recorded before the test. Therefore, the Co3O4 NCs serves good candidate as positive electrode materials for asymmetric supercapacitors.

Controlled self-assembly of multiferroic core-shell nanoparticles exhibiting strong magneto-electric effects

Energy Technology Data Exchange (ETDEWEB)

Sreenivasulu, Gollapudi; Hamilton, Sean L.; Lehto, Piper R.; Srinivasan, Gopalan, E-mail: srinivas@oakland.edu [Physics Department, Oakland University, Rochester, Michigan 48309-4401 (United States); Popov, Maksym [Physics Department, Oakland University, Rochester, Michigan 48309-4401 (United States); Radiophysics Department, Taras Shevchenko National University of Kyiv, Kyiv 01601 (Ukraine); Chavez, Ferman A. [Chemistry Department, Oakland University, Rochester, Michigan 48309-4401 (United States)

2014-02-03

Ferromagnetic-ferroelectric composites show strain mediated coupling between the magnetic and electric sub-systems due to magnetostriction and piezoelectric effects associated with the ferroic phases. We have synthesized core-shell multiferroic nano-composites by functionalizing 10–100 nm barium titanate and nickel ferrite nanoparticles with complementary coupling groups and allowing them to self-assemble in the presence of a catalyst. The core-shell structure was confirmed by electron microscopy and magnetic force microscopy. Evidence for strong strain mediated magneto-electric coupling was obtained by static magnetic field induced variations in the permittivity over 16–18 GHz and polarization and by electric field induced by low-frequency ac magnetic fields.

Monolayer-directed Assembly and Magnetic Properties of FePt Nanoparticles on Patterned Aluminum Oxide

NARCIS (Netherlands)

Yildirim, O.; Gang, T.; Kinge, S.S.; Reinhoudt, David; Blank, David H.A.; van der Wiel, Wilfred Gerard; Rijnders, Augustinus J.H.M.; Huskens, Jurriaan

2010-01-01

FePt nanoparticles (NPs) were assembled on aluminum oxide substrates, and their ferromagnetic properties were studied before and after thermal annealing. For the first time, phosph(on)ates were used as an adsorbate to form self-assembled monolayers (SAMs) on alumina to direct the assembly of NPs

Self-assembled albumin nanoparticles for combination therapy in prostate cancer

Directory of Open Access Journals (Sweden)

Lian H

2017-10-01

Full Text Available Huibo Lian,1 Jinhui Wu,2 Yiqiao Hu,2 Hongqian Guo1 1Department of Urology, Drum Tower Hospital, Medical School of Nanjing University, 2State Key Laboratory of Pharmaceutical Biotechnology, Medical School of Nanjing University, Nanjing, Jiangsu, People’s Republic of China Abstract: Resistance to regular treatment strategies is a big challenge in the treatment of castration-resistant prostate cancer. Combination of photothermal and photodynamic therapy (PTT/PDT with chemotherapy offers unique advantages over monotherapy alone. However, free drugs, such as photosensitizers and chemotherapeutic agents, lack tumor-targeted accumulation and can be easily eliminated from the body. Moreover, most of the PTT drugs are hydrophobic and their organic solvents have in vivo toxicity, thereby limiting their potential in clinical translation. Herein, simple multifunctional nanoparticles (NPs using IR780 (a near-infrared dye and docetaxel (DTX-loaded nanoplatform based on human serum albumin (HSA (HSA@IR780@DTX was developed for targeted imaging and for PTT/PDT with chemotherapy for the treatment of castration-resistant prostate cancer treatment. In this platform, HSA is a biocompatible nanocarrier that binds to both DTX and IR780. DTX and IR780, as hydrophobic drug, can induce the self-assembly of HSA proteins. Transmission electron microscopic imaging showed that NPs formed by self-assembly are spherical with a smooth surface with a hydrodynamic diameter of 146.5±10.8 nm. The cytotoxicity of HSA@IR780@DTX NPs with or without laser irradiation in prostate cancer cells (22RV1 was determined via CCK-8 assay. The antitumor effect of HSA@IR780@DTX plus laser irradiation was better than either HSA@IR780@DTX without laser exposure or single PTT heating induced by HSA@IR780 NPs under near-infrared laser, suggesting a significant combined effect in comparison to monotherapy. Near-infrared fluorescence imaging showed that HSA@IR780@DTX NPs could preferentially

A stochastic model of nanoparticle self-assembly on Cayley trees

International Nuclear Information System (INIS)

Mazilu, I; Schwen, E M; Banks, W E; Pope, B K; Mazilu, D A

2015-01-01

Nanomedicine is an emerging area of medical research that uses innovative nanotechnologies to improve the delivery of therapeutic and diagnostic agents with maximum clinical benefit. We present a versatile stochastic model that can be used to capture the basic features of drug encapsulation of nanoparticles on tree-like synthetic polymers called dendrimers. The geometry of a dendrimer is described mathematically as a Cayley tree. We use our stochastic model to study the dynamics of deposition and release of monomers (simulating the drug molecules) on Cayley trees (simulating dendrimers). We present analytical and Monte Carlo simulation results for the particle density on Cayley trees of coordination number three and four

Super-Hydrophobic/Icephobic Coatings Based on Silica Nanoparticles Modified by Self-Assembled Monolayers

Directory of Open Access Journals (Sweden)

Junpeng Liu

2016-12-01

Full Text Available A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS using spin coating and chemical vapor deposition methods. Scanning electron microscope images reveal the porous structure of the silica nanoparticles, which can trap small-scale air pockets. An average water contact angle of 163° and bouncing off of incoming water droplets suggest that a super-hydrophobic surface has been obtained based on the silica nanoparticles and POTS coating. The monitored water droplet icing test results show that icing is significantly delayed by silica-based nano-coatings compared with bare substrates and commercial icephobic products. Ice adhesion test results show that the ice adhesion strength is reduced remarkably by silica-based nano-coatings. The bouncing phenomenon of water droplets, the icing delay performance and the lower ice adhesion strength suggest that the super-hydrophobic coatings based on a combination of silica and POTS also show icephobicity. An erosion test rig based on pressurized pneumatic water impinging impact was used to evaluate the durability of the super-hydrophobic/icephobic coatings. The results show that durable coatings have been obtained, although improvement will be needed in future work aiming for applications in aerospace.

Block copolymer-nanoparticle hybrid self-assembly

KAUST Repository

Hoheisel, Tobias N.; Hur, Kahyun; Wiesner, Ulrich B.

2015-01-01

© 2014 Published by Elsevier Ltd. Polymer-inorganic hybrid materials provide exciting opportunities as they may display favorable properties from both constituents that are desired in applications including catalysis and energy conversion and storage. For the preparation of hybrid materials with well-defined morphologies, block copolymer-directed nanoparticle hybrids present a particularly promising approach. As will be described in this review, once the fundamental characteristics for successful nanostructure formation at or close to the thermodynamic equilibrium of these nanocomposites are identified, the approach can be generalized to various materials classes. In addition to the discussion of recent materials developments based on the use of AB diblock copolymers as well as ABC triblock terpolymers, this review will therefore emphasize progress in the fundamental understanding of the underlying formation mechanisms of such hybrid materials. To this end, critical experiments for, as well as theoretical progress in the description of these nanostructured block copolymer-based hybrid materials will be discussed. Rather than providing a comprehensive overview, the review will emphasize work by the Wiesner group at Cornell University, US, on block copolymer-directed nanoparticle assemblies as well as their use in first potential application areas. The results provide powerful design criteria for wet-chemical synthesis methodologies for the generation of functional nanomaterials for applications ranging from microelectronics to catalysis to energy conversion and storage.

Preparation and Characterization of Self-Assembled Nanoparticles of Hyaluronic Acid-Deoxycholic Acid Conjugates

Directory of Open Access Journals (Sweden)

Xuemeng Dong

2010-01-01

Full Text Available Novel amphiphilic biopolymers were synthesized using hyaluronic acid (HA as a hydrophilic segment and deoxycholic acid (DOCA as a hydrophobic segment by a 1-ethyl-3-(3-dimethylaminopropyl carbodiimide mediated coupling reaction. The structural characteristics of the HA-DOCA conjugates were investigated using H1 NMR. Self-assembled nanoparticles were prepared based on HA-DOCA conjugates, and its characteristics were investigated using dynamic laser light scattering, transmission electron microscopy (TEM, and fluorescence spectroscopy. The mean diameter was about 293.5 nm with unimodal size distribution in distilled water. The TEM images revealed that the shape of HA-DOCA self-aggregates was spherical. The critical aggregation concentration (CAC was in the range of 0.025–0.056 mg/mL. The partition equilibrium constant (Kv of pyrene in self-aggregates solution was from 1.45×104 to 3.64×104. The aggregation number of DOCA groups per hydrophobic microdomain, estimated by the fluorescence quenching method using cetylpyridinium chloride, increased with increasing degree of substitution.

A calixarene-based ion-selective electrode for thallium(I) detection

International Nuclear Information System (INIS)

Chester, Ryan; Sohail, Manzar; Ogden, Mark I.; Mocerino, Mauro; Pretsch, Ernö; De Marco, Roland

2014-01-01

Highlights: • Tuning of metal binding cavities in thallium(I) calixarene ionophores. • Novel calixarene-based ionophores with improved selectivity for thallium(I). • Sandwich membrane characterization of thallium(I) binding in novel calixarenes. • Improved selectivity and sensitivity with novel thallium(I) calixarene ionophores. • Solid contact ion-selective electrodes for novel thallium(I) calixarene ionophores. - Abstract: Three new calixarene Tl + ionophores have been utilized in Tl + ion-selective electrodes (ISEs) yielding Nernstian response in the concentration range of 10 −2 –10 −6 M TlNO 3 with a non-optimized filling solution in a conventional liquid contact ISE configuration. The complex formation constants (log β IL ) for two of the calixarene derivatives with thallium(I) (i.e. 6.44 and 5.85) were measured using the sandwich membrane technique, with the other ionophore immeasurable due to eventual precipitation of the ionophore during these long-term experiments. Furthermore, the unbiased selectivity coefficients for these ionophores displayed excellent selectivity against Zn 2+ , Ca 2+ , Ba 2+ , Cu 2+ , Cd 2+ and Al 3+ with moderate selectivity against Pb 2+ , Li + , Na + , H + , K + , NH 4 + and Cs + , noting that silver was the only significant interferent with these calixarene-based ionophores. When optimizing the filling solution in a liquid contact ISE, it was possible to achieve a lower limit of detection of approximately 8 nM according to the IUPAC definition. Last, the new ionophores were also evaluated in four solid-contact (SC) designs leading to Nernstian response, with the best response noted with a SC electrode utilizing a gold substrate, a poly(3-octylthiophene) (POT) ion-to-electron transducer and a poly(methyl methacrylate)–poly(decyl methacrylate) (PMMA–PDMA) co-polymer membrane. This electrode exhibited a slope of 58.4 mV decade −1 and a lower detection limit of 30.2 nM. Due to the presence of an undesirable

Preparation and anti-cancer activity of polymer-encapsulated curcumin nanoparticles

International Nuclear Information System (INIS)

Ha, Phuong Thu; Tran, Dai Lam; Nguyen, Xuan Phuc; Le, Mai Huong; Ha Tran, Thi Hong; Hoang, Thi My Nhung; Huong Le, Thi Thu; Duong, Tuan Quang

2012-01-01

Curcumin (Cur) is a yellow compound isolated from rhizome of the herb curcuma longa. Curcumin possesses antioxidant, anti-inflammatory, anti-carcinogenic and antimicrobial properties, and suppresses proliferation of many tumor cells. However, the clinical application of curcumin in cancer treatment is considerably limited due to its serious poor delivery characteristics. In order to increase the hydrophilicity and drug delivery capability, we encapsulated curcumin into copolymer PLA-TPGS, 1,3-beta-glucan (Glu), O-carboxymethyl chitosan (OCMCs) and folate-conjugated OCMCs (OCMCs-Fol). These polymer-encapsulated curcumin nanoparticles (Cur-PLA-TPGS, Cur-Glu, Cur-OCMCs and Cur-OCMCs-Fol) were characterized by infrared (IR), fluorescence (FL), photoluminescence (PL) spectra, field emission scanning electron microscopy (FE-SEM), and found to be spherical particles with an average size of 50–100 nm, being suitable for drug delivery applications. They were much more soluble in water than not only free curcumin but also other biodegradable polymer-encapsulated curcumin nanoparticles. The anti-tumor promoting assay was carried out, showing the positive effects of Cur-Glu and Cur-PLA-TPGS on tumor promotion of Hep-G2 cell line in vitro. Confocal microscopy revealed that the nano-sized curcumin encapsulated by polymers OCMCs and OCMCs-Fol significantly enhanced the cellular uptake (cancer cell HT29 and HeLa). (paper)

Preparation and anti-cancer activity of polymer-encapsulated curcumin nanoparticles

Science.gov (United States)

Thu Ha, Phuong; Huong Le, Mai; Nhung Hoang, Thi My; Thu Huong Le, Thi; Quang Duong, Tuan; Tran, Thi Hong Ha; Tran, Dai Lam; Phuc Nguyen, Xuan

2012-09-01

Curcumin (Cur) is a yellow compound isolated from rhizome of the herb curcuma longa. Curcumin possesses antioxidant, anti-inflammatory, anti-carcinogenic and antimicrobial properties, and suppresses proliferation of many tumor cells. However, the clinical application of curcumin in cancer treatment is considerably limited due to its serious poor delivery characteristics. In order to increase the hydrophilicity and drug delivery capability, we encapsulated curcumin into copolymer PLA-TPGS, 1,3-beta-glucan (Glu), O-carboxymethyl chitosan (OCMCs) and folate-conjugated OCMCs (OCMCs-Fol). These polymer-encapsulated curcumin nanoparticles (Cur-PLA-TPGS, Cur-Glu, Cur-OCMCs and Cur-OCMCs-Fol) were characterized by infrared (IR), fluorescence (FL), photoluminescence (PL) spectra, field emission scanning electron microscopy (FE-SEM), and found to be spherical particles with an average size of 50-100 nm, being suitable for drug delivery applications. They were much more soluble in water than not only free curcumin but also other biodegradable polymer-encapsulated curcumin nanoparticles. The anti-tumor promoting assay was carried out, showing the positive effects of Cur-Glu and Cur-PLA-TPGS on tumor promotion of Hep-G2 cell line in vitro. Confocal microscopy revealed that the nano-sized curcumin encapsulated by polymers OCMCs and OCMCs-Fol significantly enhanced the cellular uptake (cancer cell HT29 and HeLa).

Insitu synthesis of self-assembled gold nanoparticles on glass or silicon substrates through reactive inkjet printing

KAUST Repository

Abulikemu, Mutalifu

2013-12-18

A facile and low cost method for the synthesis of self-assembled nanoparticles (NPs) with minimal size variation and chemical waste by using reactive inkjet printing was developed. Gold NPs with diameters as small as (8±2)nm can be made at low temperature (120 °C). The size of the resulting NPs can be readily controlled through the concentration of the gold precursor and oleylamine ink. The pure gold composition of the synthesized NPs was confirmed by energy-dispersive X-ray spectroscopy (EDXS) analysis. High-resolution SEM (HRSEM) and TEM (HRTEM), and X-ray diffraction revealed their size and face-centered cubic (fcc) crystal structure, respectively. Owing to the high density of the NP film, UV/Vis spectroscopy showed a red shift in the intrinsic plasmonic resonance peak. We envision the extension of this approach to the synthesis of other nanomaterials and the production of tailored functional nanomaterials and devices. Midas touch: The use of low-cost manufacturing approaches in the synthesis of nanoparticles is critical for many applications. Reactive inkjet printing, along with a judicious choice of precursor/solvent system, was used to synthesize a relatively uniform assembly of crystalline gold nanoparticles, with diameters as small as (8±2)nm, over a given substrate surface. © 2014 WILEY-VCH Verlag GmbH.

Stress relaxation in quasi-two-dimensional self-assembled nanoparticle monolayers

Science.gov (United States)

Boucheron, Leandra S.; Stanley, Jacob T.; Dai, Yeling; You, Siheng Sean; Parzyck, Christopher T.; Narayanan, Suresh; Sandy, Alec R.; Jiang, Zhang; Meron, Mati; Lin, Binhua; Shpyrko, Oleg G.

2018-05-01

We experimentally probed the stress relaxation of a monolayer of iron oxide nanoparticles at the water-air interface. Upon drop-casting onto a water surface, the nanoparticles self-assembled into islands of two-dimensional hexagonally close packed crystalline domains surrounded by large voids. When compressed laterally, the voids gradually disappeared as the surface pressure increased. After the compression was stopped, the surface pressure (as measured by a Wilhelmy plate) evolved as a function of the film aging time with three distinct timescales. These aging dynamics were intrinsic to the stressed state built up during the non-equilibrium compression of the film. Utilizing x-ray photon correlation spectroscopy, we measured the characteristic relaxation time (τ ) of in-plane nanoparticle motion as a function of the aging time through both second-order and two-time autocorrelation analysis. Compressed and stretched exponential fitting of the intermediate scattering function yielded exponents (β ) indicating different relaxation mechanisms of the films under different compression stresses. For a monolayer compressed to a lower surface pressure (between 20 mN/m and 30 mN/m), the relaxation time (τ ) decreased continuously as a function of the aging time, as did the fitted exponent, which transitioned from being compressed (>1 ) to stretched (stress release through crystalline domain reorganization. However, for a monolayer compressed to a higher surface pressure (around 40 mN/m), the relaxation time increased continuously and the compressed exponent varied very little from a value of 1.6, suggesting that the system may have been highly stressed and jammed. Despite the interesting stress relaxation signatures seen in these samples, the structural ordering of the monolayer remained the same over the sample lifetime, as revealed by grazing incidence x-ray diffraction.

Nitrogen-Doped Carbon Encapsulated Nickel/Cobalt Nanoparticle Catalysts for Olefin Migration of Allylarenes

DEFF Research Database (Denmark)

Kramer, Søren; Mielby, Jerrik Jørgen; Buss, Kasper Spanggård

2017-01-01

Olefin migration of allylarenes is typically performed with precious metal-based homogeneous catalysts. In contrast, very limited progress has been made using cheap, earth-abundant base metals as heterogeneous catalysts for these transformations - in spite of the obvious economic and environmental...... advantages. Herein, we report on the use of an easily prepared heterogeneous catalyst material for the migration of olefins, in particular allylarenes. The catalyst material consists of nickel/cobalt alloy nanoparticles encapsulated in nitrogen-doped carbon shells. The encapsulated nanoparticles are stable...

Topographic characterization of the self-assembled nanostructures of chitosan on mica surface by atomic force microscopy

International Nuclear Information System (INIS)

Wang, Li; Wu, Jiafeng; Guo, Yan; Gong, Coucong; Song, Yonghai

2015-01-01

Graphical abstract: - Highlights: • Nanocomposites of chitosan film were prepared by simple self-assembly from solvent media. • Chitosan molecules assembled on mica surface of nanoparticles, fibril and membrane with varied chitosan concentration. • Chitosan molecules assembled with different nanostructure under varied pH. • The optimum drying temperature for forming chitosan membrane is about 65 °C. - Abstract: In this work, the self-assembled nanostructures of chitosan on mica surface formed from various solvents were investigated by using atomic force microscopy. The effects of various factors on the self-assembled nanostructures of chitosan on mica surface, including solvents, the concentration of chitosan, the pH of solution and the drying temperature, were explored in detail. Our experimental data resulted in the conclusion that chitosan molecules could self-assemble on mica surface to form various nanostructures such as nanoparticles, fibril and film. Nanoparticles were always formed on mica surface from CCl_4, C_6H_6, CH_2Cl_2 solution, fibril preferred to form on mica surface from CH_3CH_2OH and CH_3OH solution and the optimal solvent to form film was found to be CH_3CN. Low concentration, pH and temperature were helpful for the formation of nanoparticles, medium concentration, pH and temperature resulted in fibril and high concentration, pH and temperature were often beneficial to forming chitosan films. The study of self-assembled nanostructures of chitosan on mica surface would provide new insight into the development of chitosan-based load-bearing materials.

Oxidation and sensing of ascorbic acid and dopamine on self-assembled gold nanoparticles incorporated within polyaniline film

Energy Technology Data Exchange (ETDEWEB)

Chu, Wenya [College of Chemistry, Chemical Engineering and Materials Science, and Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, Soochow University, Suzhou 215123 (China); Zhou, Qun, E-mail: zhq@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, and Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, Soochow University, Suzhou 215123 (China); Li, Shuangshuang [College of Chemistry, Chemical Engineering and Materials Science, and Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, Soochow University, Suzhou 215123 (China); College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006 (China); Zhao, Wei; Li, Na [College of Chemistry, Chemical Engineering and Materials Science, and Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, Soochow University, Suzhou 215123 (China); Zheng, Junwei, E-mail: jwzheng@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, and Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, Soochow University, Suzhou 215123 (China); College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006 (China)

2015-10-30

Highlights: • Gold nanoparticles assembled on electrodes are incorporated into polyaniline film. • Composite film electrodes exhibit synergistic effect on electrocatalytic oxidation. • Ascorbic acid and dopamine can be detected simultaneously on composite electrodes. - Abstract: Electrochemical biosensors based on conducting polymers incorporated with metallic nanoparticles can greatly enhance sensitivity and selectivity. Herein, we report a facile fabrication approach for polyaniline (PAN) incorporated with a gold nanoparticle (AuNP) composite electrode by electrodeposition of PAN on a self-assembled AuNP layer on the surface of an indium tin oxide electrode. The resulting AuNP/PAN composite electrode exhibits a remarkable synergistic effect on the electrocatalytic oxidation of ascorbic acid (AA) and dopamine (DA). It is demonstrated that the oxidation reaction of AA mainly occurs at AuNPs inside the PAN film as the ascorbate anions are doped into the polymer during the oxidation of the PAN film. Conversely, the oxidation of positively charged DA may only take place at the PAN/solution interface. The different mechanisms of the electrode reactions result in the oxidation of AA and DA occurring at different potentials. As a result, the AuNP/PAN composite electrode can be employed to simultaneously detect AA and DA with a good linear range, high sensitivity, and low detection limit.

Oxidation and sensing of ascorbic acid and dopamine on self-assembled gold nanoparticles incorporated within polyaniline film

International Nuclear Information System (INIS)

Chu, Wenya; Zhou, Qun; Li, Shuangshuang; Zhao, Wei; Li, Na; Zheng, Junwei

2015-01-01

Highlights: • Gold nanoparticles assembled on electrodes are incorporated into polyaniline film. • Composite film electrodes exhibit synergistic effect on electrocatalytic oxidation. • Ascorbic acid and dopamine can be detected simultaneously on composite electrodes. - Abstract: Electrochemical biosensors based on conducting polymers incorporated with metallic nanoparticles can greatly enhance sensitivity and selectivity. Herein, we report a facile fabrication approach for polyaniline (PAN) incorporated with a gold nanoparticle (AuNP) composite electrode by electrodeposition of PAN on a self-assembled AuNP layer on the surface of an indium tin oxide electrode. The resulting AuNP/PAN composite electrode exhibits a remarkable synergistic effect on the electrocatalytic oxidation of ascorbic acid (AA) and dopamine (DA). It is demonstrated that the oxidation reaction of AA mainly occurs at AuNPs inside the PAN film as the ascorbate anions are doped into the polymer during the oxidation of the PAN film. Conversely, the oxidation of positively charged DA may only take place at the PAN/solution interface. The different mechanisms of the electrode reactions result in the oxidation of AA and DA occurring at different potentials. As a result, the AuNP/PAN composite electrode can be employed to simultaneously detect AA and DA with a good linear range, high sensitivity, and low detection limit.

Engineering self-assembled bioreactors from protein microcompartments

Energy Technology Data Exchange (ETDEWEB)

Savage, David [Univ. of California, Berkeley, CA (United States)

2016-10-12

The goals of this research are to understand how organisms such as bacteria segregate certain metabolic processes inside of specific structures, or “microcompartments,” in the cell and apply this knowledge to develop novel engineered microcompartments for use in nanotechnology and metabolic engineering. For example, in some bacteria, self-assembling protein microcompartments called carboxysomes encapsulate the enzymes involved in carbon fixation, enabling the cell to utilize carbon dioxide more effectively than if the enzymes were free in the cell. The proposed research will determine how structures such as carboxysomes assemble and function in bacteria and develop a means for creating novel, synthetic microcompartments for optimizing production of specific energy-rich compounds.

pH-dependent Self-Assembling Behaviour of KA₆ Surfactant Peptide

DEFF Research Database (Denmark)

Gurevich, Leonid; Fojan, Peter

  Self-assembly is one of the major driving forces in biological systems. It has been found to play an important role in disease development (Alzheimer, Creutzfeldt-Jacob Disease), drug action (self-assembly of anti-microbial peptides (AMP) on the membrane surface) as well as developmental self-a...... be easily tailored on-demand. On the other hand they are fairly simple and inexpensive to produce and may find applications in purification and crystallization of membrane proteins, drug delivery and encapsulation systems or as mild surfactants in the cosmetic industry....

Niobium-Doped Titania Nanoparticles: Synthesis and Assembly into Mesoporous Films and Electrical Conductivity

Czech Academy of Sciences Publication Activity Database

Liu, Y.; Szeifert, J. M.; Feckl, J. M.; Mandlmeier, B.; Rathouský, Jiří; Heyden, O.; Fattakhova-Rohlfing, D.; Bein, T.

2010-01-01

Roč. 4, č. 9 (2010), s. 5373-5381 ISSN 1936-0851 R&D Projects: GA ČR GA104/08/0435 Institutional research plan: CEZ:AV0Z40400503 Keywords : nanoparticle synthesis * nanoparticle self-assembly * conducting Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 9.855, year: 2010

Behavior of cesium and thallium cations inside a calixarene cavity as probed by nuclear spin relaxation. Evidence of cation-pi interactions in water.

Science.gov (United States)

Cuc, Diana; Bouguet-Bonnet, Sabine; Morel-Desrosiers, Nicole; Morel, Jean-Pierre; Mutzenhardt, Pierre; Canet, Daniel

2009-08-06

We have studied the complexes formed between the p-sulfonatocalix[4]arene and cesium or thallium metal cation, first by carbon-13 longitudinal relaxation of the calixarene molecule at two values of the magnetic field B(0). From the longitudinal relaxation times of an aromatic carbon directly bonded to a proton, thus subjected essentially to the dipolar interaction with that proton, we could obtain the correlation time describing the reorientation of the CH bond. The rest of this study has demonstrated that it is also the correlation time describing the tumbling of the whole calixarene assembly. From three non-proton-bearing carbons of the aromatic cycles (thus subjected to the chemical shift anisotropy and dipolar mechanisms), we have been able to determine the variation of the chemical shift anisotropy when going from the free to the complex form of the calixarene. These variations not only provide the location of the cation inside the calixarene cavity but also constitute a direct experimental proof of the cation-pi interactions. These results are complemented by cesium and thallium relaxation measurements performed again at two values of the magnetic field B(0). An estimation of the mean distance between the cation and the calixarene protons could be obtained. These measurements have also revealed an important chemical shift anisotropy of thallium upon complexation.

Amidase encapsulated O-carboxymethyl chitosan nanoparticles for vaccine delivery.

Science.gov (United States)

Smitha, K T; Sreelakshmi, M; Nisha, N; Jayakumar, R; Biswas, Raja

2014-02-01

This work reports the development of amidase encapsulated O-carboxymethyl chitosan nanoparticles (Ami-O-CMC NPs) of 300±50 nm size by ionic cross-linking method. The prepared Ami-O-CMC NPs had an encapsulation efficiency of 55.39%. Haemolysis assay and cytotoxicity studies proved the hemocompatibility and cytocompatibility of the prepared NPs. The sustained release of Ami from the NPs is expected to prolong its immunogenicity and in turn lead to development of better protective immunity against Staphylococcus aureus infections. Copyright © 2013 Elsevier B.V. All rights reserved.

Amphiphilic invertible polymers: Self-assembly into functional materials driven by environment polarity

Science.gov (United States)

Hevus, Ivan

Stimuli-responsive polymers adapt to environmental changes by adjusting their chain conformation in a fast and reversible way. Responsive polymeric materials have already found use in electronics, coatings industry, personal care, and bio-related areas. The current work aims at the development of novel responsive functional polymeric materials by manipulating environment-dependent self-assembly of a new class of responsive macromolecules strategically designed in this study,—amphiphilic invertible polymers (AIPs). Environment-dependent micellization and self-assembly of three different synthesized AIP types based on poly(ethylene glycol) as a hydrophilic fragment and varying hydrophobic constituents was demonstrated in polar and nonpolar solvents, as well as on the surfaces and interfaces. With increasing concentration, AIP micelles self-assemble into invertible micellar assemblies composed of hydrophilic and hydrophobic domains. Polarity-responsive properties of AIPs make invertible micellar assemblies functional in polar and nonpolar media including at interfaces. Thus, invertible micellar assemblies solubilize poorly soluble substances in their interior in polar and nonpolar solvents. In a polar aqueous medium, a novel stimuli-responsive mechanism of drug release based on response of AIP-based drug delivery system to polarity change upon contact with the target cell has been established using invertible micellar assemblies loaded with curcumin, a phytochemical drug. In a nonpolar medium, invertible micellar assemblies were applied simultaneously as nanoreactors and stabilizers for size-controlled synthesis of silver nanoparticles stable in both polar and nonpolar media. The developed amphiphilic nanosilver was subsequently used as seeds to promote anisotropic growth of CdSe semiconductor nanoparticles that have potential in different applications ranging from physics to medicine. Amphiphilic invertible polymers were shown to adsorb on the surface of silica

Manipulation of extinction spectra of P3HT/PMMA medium arrays on silicon substrate containing self-assembled gold nanoparticles

International Nuclear Information System (INIS)

Wu, Ming-Chung; Chen, Shih-Wen; Li, Jia-Han; Chou, Yi; Lin, Jhih-Fong; Chen, Yang-Fang; Su, Wei-Fang

2012-01-01

In this study, we report a simple novel approach to modulate the extinction spectra of P3HT/PMMA by manipulating the medium arrays on a substrate that is coated with self-assembled gold nanoparticles. The 20 nm gold nanoparticles were synthesized and then self-assembled on the APTMS/silicon substrate surface by immersing the substrate into the gold colloid suspension. A high-resolution P3HT/PMMA photoluminescent electron beam resist was used to fabricate various square hole arrays on the substrate containing gold nanoparticles. The P3HT/PMMA medium composition causes the blue shifts in the extinction peaks of up to 40.6 nm by decreasing the period from 500 nm to 200 nm for P3HT/PMMA square hole arrays with a diameter of 100 nm. The magnitude of blue shift is directly proportional to the product of the changes of medium refractive index and the array structure factor. These peak shifts and intensity of extinction spectra for various P3HT/PMMA medium arrays are well described by the finite-difference time-domain (FDTD) simulation results. Since this simple cost-effective technique can tune the extinction spectrum of medium and adding the gold nanoparticles can give more functionalities for sensing applications, such as surface-enhanced Raman scattering (SERS), that provides good opportunities for the design and fabrication of new optoelectronic devices and sensors. Highlights: ► We can tune the extinction spectra of P3HT/PMMA by manipulating the medium arrays. ► These optical behaviors of P3HT/PMMA medium arrays are well described by FDTD simulation results. ► Adding the Au nanoparticles can give more functionalities for sensing applications.

Manipulation of extinction spectra of P3HT/PMMA medium arrays on silicon substrate containing self-assembled gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wu, Ming-Chung [Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 333-02, Taiwan (China); Chen, Shih-Wen; Li, Jia-Han [Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei 106-17, Taiwan (China); Chou, Yi; Lin, Jhih-Fong [Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan (China); Chen, Yang-Fang [Department of Physics, National Taiwan University, Taipei 106-17, Taiwan (China); Su, Wei-Fang, E-mail: suwf@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan (China)

2012-11-15

In this study, we report a simple novel approach to modulate the extinction spectra of P3HT/PMMA by manipulating the medium arrays on a substrate that is coated with self-assembled gold nanoparticles. The 20 nm gold nanoparticles were synthesized and then self-assembled on the APTMS/silicon substrate surface by immersing the substrate into the gold colloid suspension. A high-resolution P3HT/PMMA photoluminescent electron beam resist was used to fabricate various square hole arrays on the substrate containing gold nanoparticles. The P3HT/PMMA medium composition causes the blue shifts in the extinction peaks of up to 40.6 nm by decreasing the period from 500 nm to 200 nm for P3HT/PMMA square hole arrays with a diameter of 100 nm. The magnitude of blue shift is directly proportional to the product of the changes of medium refractive index and the array structure factor. These peak shifts and intensity of extinction spectra for various P3HT/PMMA medium arrays are well described by the finite-difference time-domain (FDTD) simulation results. Since this simple cost-effective technique can tune the extinction spectrum of medium and adding the gold nanoparticles can give more functionalities for sensing applications, such as surface-enhanced Raman scattering (SERS), that provides good opportunities for the design and fabrication of new optoelectronic devices and sensors. Highlights: Black-Right-Pointing-Pointer We can tune the extinction spectra of P3HT/PMMA by manipulating the medium arrays. Black-Right-Pointing-Pointer These optical behaviors of P3HT/PMMA medium arrays are well described by FDTD simulation results. Black-Right-Pointing-Pointer Adding the Au nanoparticles can give more functionalities for sensing applications.

Spin-dependent transport properties of oleic acid molecule self-assembled La0.7Sr0.3MnO3 nanoparticles

International Nuclear Information System (INIS)

Xi, L.; Du, J.H.; Ma, J.H.; Wang, Z.; Zuo, Y.L.; Xue, D.S.

2013-01-01

Highlights: ► Spin-dependent transport property of LSMO/oleic acid nanoparticles is investigated. ► Transport properties and MR measured by Cu/nanoparticle assembly/elargol device. ► Non-linear I–V curve indicates a tunneling type transport properties. ► Tunnel barrier height around 1.3 ± 0.15 eV was obtained by fitting I–V curves. ► LFMR of LSMO/oleic acid molecules value reaches −18% with current of 0.1 μA at 10 K. - Abstract: Spin-dependent transport property through molecules is investigated using a monolayer of oleic acid molecule self-assembled half metallic La 0.7 Sr 0.3 MnO 3 (LSMO) nanoparticles, which was synthesized using a coprecipitation method. Fourier transform infrared spectroscopy was used to confirm that one-monolayer oleic acid molecules chemically bond to the LSMO nanoparticles. The transport properties and magnetoresistance (MR) effect of the oleic acid molecule coated LSMO nanoparticles were measured by a direct current four probes method using a Cu/nanoparticle assembly/elargol electrode sandwich device with various temperatures and bias voltages. The non-linear I–V curve indicates a tunneling type transport properties. The tunnel barrier height around 1.3 ± 0.15 eV was obtained by fitting the I–V curve according to the Simmons equation. The magnetoresistance curves can be divided to high-field MR and low-field MR (LFMR) parts. The former is ascribed to the influence of spin disorder or canting within the LSMO nanoparticle surface and the latter one with strong bias dependence is attributed to the spin-dependent tunneling effect through the insulating surface layer of LSMO and oleic acid molecules. The enhanced LFMR effect for oleic acid coated LSMO with respect to the bare LSMO was attributed to the enhanced tunneling transport and weak spin scattering in oleic acid molecule barrier.

Physicochemical and biological properties of self-assembled antisense/poly(amidoamine dendrimer nanoparticles: the effect of dendrimer generation and charge ratio

Directory of Open Access Journals (Sweden)

Alireza Nomani

2010-05-01

Full Text Available Alireza Nomani1,6, Ismaeil Haririan1,5, Ramin Rahimnia2,4, Shamileh Fouladdel2, Tarane Gazori1, Rassoul Dinarvand1, Yadollah Omidi3, Ebrahim Azizi2,41Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran; 2Molecular Research Lab, Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran; 3Department of Pharmaceutics, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran; 4Department of Medical Biotechnology, School of Advanced Medical Technologies, Tehran University of Medical Sciences, Tehran, Iran; 5Biomaterials Research Center (BRC Tehran, Iran; 6Department of Pharmaceutics, Faculty of Pharmacy, Zanjan University of Medical Sciences, Zanjan, IranAbstract: To gain a deeper understanding of the physicochemical phenomenon of self-assembled nanoparticles of different generations and ratios of poly (amidoamine dendrimer (PAMAM dendrimer and a short-stranded DNA (antisense oligonucleotide, multiple methods were used to characterize these nanoparticles including photon correlation spectroscopy (PCS; zeta potential measurement; and atomic force microscopy (AFM. PCS and AFM results revealed that, in contrast to larger molecules of DNA, smaller molecules produce more heterodisperse and large nanoparticles when they are condensed with a cationic dendrimer. AFM images also showed that such nanoparticles were spherical. The stability of the antisense content of the nanoparticles was investigated over different charge ratios using polyacrylamide gel electrophoresis. It was clear from such analyses that much more than charge neutrality point was required to obtain stable nanoparticles. For cell uptake, self-assembled nanoparticles were prepared with PAMAM G5 and 5’-FITC labeled antisense and the uptake experiment was carried out in T47D cell culture. This investigation also shows that the cytotoxicity of the nanoparticles was

Multiple-trapping in pentacene field-effect transistors with a nanoparticles self-assembled monolayer

Directory of Open Access Journals (Sweden)

Keanchuan Lee

2012-06-01

Full Text Available A silver nanoparticles self-assembled monolayer (SAM was incorporated in pentacene field-effect transistor and its effects on the carrier injection and transport were investigated using the current-voltage (I − V and impedance spectroscopy (IS measurements. The I − V results showed that there was a significant negative shift of the threshold voltage, indicating the hole trapping inside the devices with about two orders higher in the contact resistance and an order lower in the effective mobility when a SAM was introduced. The IS measurements with the simulation using a Maxwell-Wagner equivalent circuit model revealed the existence of multiple trapping states for the devices with NPs, while the devices without NPs exhibited only a single trap state.

Self-assembly of nitrogen-doped carbon nanoparticles: a new ratiometric UV-vis optical sensor for the highly sensitive and selective detection of Hg(2+) in aqueous solution.

Science.gov (United States)

Ruan, Yudi; Wu, Lie; Jiang, Xiue

2016-05-23

Water-soluble nitrogen-doped carbon nanoparticles (N-CNPs) prepared by the one-step hydrothermal treatment of uric acid were found to show ratiometric changes in their UV-vis spectra due to Hg(2+)-mediated self-assembly. For the first time, such a property was developed into a UV-vis optical sensor for detecting Hg(2+) in aqueous solutions with high sensitively and selectively (detection limit = 1.4 nM). More importantly, this novel sensor exhibits a higher linear sensitivity over a wider concentration range compared with the fluorescence sensor based on the same N-CNPs. This work opens an exciting new avenue to explore the use of carbon nanoparticles in constructing UV-vis optical sensors for the detection of metal ions and the use of carbon nanoparticles as a new building block to self-assemble into superlattices.

Enhanced lifetime characteristics in flexible polymer light-emitting devices by encapsulation of epoxy/silica-coated gold nanoparticles resin (ESGR)

International Nuclear Information System (INIS)

Chiu, Pin-Hsiang; Huang, Chien-Jung; Yang, Cheng-Fu; Meen, Teen-Hang; Wang, Yeong-Her

2010-01-01

This paper reports the effects of a new multilayer encapsulation for the lifetime of flexible PLEDs on plastic substrate. The multilayer encapsulation consisted of a novel epoxy/silica-coated gold nanoparticles resin (ESGR) as the pre-encapsulation layer and a SiO 2 layer as the encapsulation cap. The ESGR was prepared by mixing UV-curable epoxy resin and powders of silica-coated gold nanoparticles. The silica-coated gold nanoparticles is a necessity because the epoxy resin is not a good moisture barrier. The flexible PLEDs with multilayer encapsulation exhibited no dark spots after being stored for over 300 h at 25 deg. C and 60% relative humidity. Also, the operational half-luminance decay time of device was 1360 h, seven times longer than that of a device without encapsulation. These results confirmed that the multilayer encapsulation, which restricted the moisture that penetrated into the devices, could be applied to the encapsulation of flexible PLEDs.

Nanocomposite Membrane via Magnetite Nanoparticle Assembly

KAUST Repository

Xie, Yihui

2012-07-01

Membrane technology is one of the most promising technologies for addressing the global water crisis as well as in many other applications. One of the drawbacks of current ultra- and nanofiltration membranes is the relatively broad pore size distribution. Block copolymer membranes with ultrahigh permeability and very regular pore sizes have been recently demonstrated with pores being formed by the supramolecular assembly of core/shell micelles. Our study aimed at developing an innovative and economically efficient alternative method to fabricate isoporous membrane by self-assembly of magnetic nanoparticle with a polystyrene shell, mimicking the behavior of block copolymer micelle. Fe3O4 nanoparticles of ~13 nm diameter were prepared by co-precipitation as cores. The initiator for ATRP was covalently bonded onto the surface of magnetic nanoparticles with two strategies. Then the surface initiated ATRP of styrene was carried out to functionalize nanoparticles with polystyrene through a “grafting from” method. Finally, the nanocomposite membrane was cast from 50 wt % Fe3O4@PS brush polymer solution in DMF via non solvent phase inversion. Microscopies reveal an asymmetric membrane with a dense thin layer on top of a porous sponge-like layer. This novel class of asymmetric membrane, based on the pure assembly of functionalized nanoparticles was prepared for the first time. The nanoparticles are well distributed however with no preferential order yet in the as-cast film.I would like to thank my committee chair and advisor, Prof. Suzana Nunes, and other committee members, Prof. Klaus-Viktor Peinemann and Prof. Gary Amy, for their guidance and support throughout the course of this research. My appreciation also goes to my colleagues in our group for useful discussions and suggestions. I also want to extend my gratitude to the staff from the KAUST Core Lab for Advanced Nanofabrication, Imaging and Characterization, especially Dr. Ali Reza Behzad, Dr. Rachid Sougrat, and

A calixarene-based ion-selective electrode for thallium(I) detection

Energy Technology Data Exchange (ETDEWEB)

Chester, Ryan [Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box U1987, Perth, Western Australia 6845 (Australia); Sohail, Manzar [Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland 4556 (Australia); Ogden, Mark I.; Mocerino, Mauro [Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box U1987, Perth, Western Australia 6845 (Australia); Pretsch, Ernö [ETH Zürich, Institute of Biogeochemistry and Pollutant Dynamics (IBP), Universitätstrasse 16, CH-8092, Zürich (Switzerland); De Marco, Roland, E-mail: rdemarc1@usc.edu.au [Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box U1987, Perth, Western Australia 6845 (Australia); Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland 4556 (Australia)

2014-12-03

Highlights: • Tuning of metal binding cavities in thallium(I) calixarene ionophores. • Novel calixarene-based ionophores with improved selectivity for thallium(I). • Sandwich membrane characterization of thallium(I) binding in novel calixarenes. • Improved selectivity and sensitivity with novel thallium(I) calixarene ionophores. • Solid contact ion-selective electrodes for novel thallium(I) calixarene ionophores. - Abstract: Three new calixarene Tl{sup +} ionophores have been utilized in Tl{sup +} ion-selective electrodes (ISEs) yielding Nernstian response in the concentration range of 10{sup −2}–10{sup −6} M TlNO{sub 3} with a non-optimized filling solution in a conventional liquid contact ISE configuration. The complex formation constants (log β{sub IL}) for two of the calixarene derivatives with thallium(I) (i.e. 6.44 and 5.85) were measured using the sandwich membrane technique, with the other ionophore immeasurable due to eventual precipitation of the ionophore during these long-term experiments. Furthermore, the unbiased selectivity coefficients for these ionophores displayed excellent selectivity against Zn{sup 2+}, Ca{sup 2+}, Ba{sup 2+}, Cu{sup 2+}, Cd{sup 2+} and Al{sup 3+} with moderate selectivity against Pb{sup 2+}, Li{sup +}, Na{sup +}, H{sup +}, K{sup +}, NH{sub 4}{sup +} and Cs{sup +}, noting that silver was the only significant interferent with these calixarene-based ionophores. When optimizing the filling solution in a liquid contact ISE, it was possible to achieve a lower limit of detection of approximately 8 nM according to the IUPAC definition. Last, the new ionophores were also evaluated in four solid-contact (SC) designs leading to Nernstian response, with the best response noted with a SC electrode utilizing a gold substrate, a poly(3-octylthiophene) (POT) ion-to-electron transducer and a poly(methyl methacrylate)–poly(decyl methacrylate) (PMMA–PDMA) co-polymer membrane. This electrode exhibited a slope of 58.4 mV decade

A Lipophilic IR-780 Dye-Encapsulated Zwitterionic Polymer-Lipid Micellar Nanoparticle for Enhanced Photothermal Therapy and NIR-Based Fluorescence Imaging in a Cervical Tumor Mouse Model

Directory of Open Access Journals (Sweden)

Santhosh Kalash Rajendrakumar

2018-04-01

Full Text Available To prolong blood circulation and avoid the triggering of immune responses, nanoparticles in the bloodstream require conjugation with polyethylene glycol (PEG. However, PEGylation hinders the interaction between the nanoparticles and the tumor cells and therefore limits the applications of PEGylated nanoparticles for therapeutic drug delivery. To overcome this limitation, zwitterionic materials can be used to enhance the systemic blood circulation and tumor-specific delivery of hydrophobic agents such as IR-780 iodide dye for photothermal therapy. Herein, we developed micellar nanoparticles using the amphiphilic homopolymer poly(12-(methacryloyloxydodecyl phosphorylcholine (PCB-lipid synthesized via reversible addition–fragmentation chain transfer (RAFT polymerization. The PCB-lipid can self-assemble into micelles and encapsulate IR-780 dye (PCB-lipid–IR-780. Our results demonstrated that PCB-lipid–IR-780 nanoparticle (NP exhibited low cytotoxicity and remarkable photothermal cytotoxicity to cervical cancer cells (TC-1 upon near-infrared (NIR laser irradiation. The biodistribution of PCB-lipid–IR-780 showed higher accumulation of PCB-lipid–IR-780 than that of free IR-780 in the TC-1 tumor. Furthermore, following NIR laser irradiation of the tumor region, the PCB-lipid–IR-780 accumulated in the tumor facilitated enhanced tumor ablation and subsequent tumor regression in the TC-1 xenograft model. Hence, these zwitterionic polymer-lipid hybrid micellar nanoparticles show great potential for cancer theranostics and might be beneficial for clinical applications.

Directed self-assembly of nanoporous metallic- and bimetallic nanoparticle thin films

Energy Technology Data Exchange (ETDEWEB)

Pietsch, Torsten [Fachbereich Physik, Universitaet Konstanz (Germany); Gindy, Nabil; Fahmi, Amir [Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham (United Kingdom)

2010-07-01

Nanoporous thin films attracted considerable interest due to potential applications in optical coatings, catalysis, sensors as well as electronic devices. Recently, such films were prepared by post deposition treatments. The present study is focused on the fabrication of nanoporous thin films via directed self-assembly of hybrid materials. Due to the nature of this process no additional treatments are necessary to develop the pores. Hierarchical nanoporous structures are fabricated directly via deposition of polymer templated Au-nanoparticles onto hydrophilic substrates. These films exhibit two different pore diameters and a total pore density of more than 10{sup 10} holes per cm{sup 2}. Control over the pore size is achieved by changing the molecular weight of the PS-b-P4VP diblock copolymer. Moreover, the porous morphology is used as a template to fabricate bimetallic nanostructured thin films. Such well-defined nanostructures, not only exhibit unique physical properties but also provide control over the hydrophobicity of the coated surfaces.

Carbide Nanoparticles Encapsulated in the Caves of Carbon Nanotubes by an In Situ Reduction-Carbonization Route

Directory of Open Access Journals (Sweden)

Chunli Guo

2011-01-01

Full Text Available Carbides (TiC, WC, and NbC nanoparticles fully encapsulated in the caves of carbon nanotubes (CNTs were synthesized via an in situ reduction-carbonization route at 600∘C in an autoclave. The structural features and morphologies of as-obtained products were investigated using by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy (HRTEM. HRTEM studies showed that the average diameter of CNTs encapsulated with carbide nanoparticles are in the range of 15–40 nm. The reaction temperature, the reaction time, and the metal catalyst are found to play crucial roles to the product morphology. The growth mechanism of carbide nanoparticles encapsulated in CNTs was discussed in detail.

Construction and Self-Assembly of Single-Chain Polymer Nanoparticles via Coordination Association and Electrostatic Repulsion in Water.

Science.gov (United States)

Zhu, Zhengguang; Xu, Na; Yu, Qiuping; Guo, Lei; Cao, Hui; Lu, Xinhua; Cai, Yuanli

2015-08-01

Simultaneous coordination-association and electrostatic-repulsion interactions play critical roles in the construction and stabilization of enzymatic function metal centers in water media. These interactions are promising for construction and self-assembly of artificial aqueous polymer single-chain nanoparticles (SCNPs). Herein, the construction and self-assembly of dative-bonded aqueous SCNPs are reported via simultaneous coordination-association and electrostatic-repulsion interactions within single chains of histamine-based hydrophilic block copolymer. The electrostatic-repulsion interactions are tunable through adjusting the imidazolium/imidazole ratio in response to pH, and in situ Cu(II)-coordination leads to the intramolecular association and single-chain collapse in acidic water. SCNPs are stabilized by the electrostatic repulsion of dative-bonded block and steric shielding of nonionic water-soluble block, and have a huge specific surface area of function metal centers accessible to substrates in acidic water. Moreover, SCNPs can assemble into micelles, networks, and large particles programmably in response to the solution pH. These unique media-sensitive phase-transformation behaviors provide a general, facile, and versatile platform for the fabrication of enzyme-inspired smart aqueous catalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liposomal nanoparticles encapsulating iloprost exhibit enhanced vasodilation in pulmonary arteries

Directory of Open Access Journals (Sweden)

Jain PP

2014-07-01

Full Text Available Pritesh P Jain,1 Regina Leber,1,2 Chandran Nagaraj,1 Gerd Leitinger,3 Bernhard Lehofer,4 Horst Olschewski,1,5 Andrea Olschewski,1,6 Ruth Prassl,1,4 Leigh M Marsh11Ludwig Boltzmann Institute for Lung Vascular Research, 2Biophysics Division, Institute of Molecular Biosciences, University of Graz, 3Research Unit Electron Microscopic Techniques, Institute of Cell Biology, Histology, and Embryology, 4Institute of Biophysics, 5Division of Pulmonology, Department of Internal Medicine, 6Department of Anesthesiology and Intensive Care Medicine, Medical University of Graz, Graz, AustriaAbstract: Prostacyclin analogues are standard therapeutic options for vasoconstrictive diseases, including pulmonary hypertension and Raynaud’s phenomenon. Although effective, these treatment strategies are expensive and have several side effects. To improve drug efficiency, we tested liposomal nanoparticles as carrier systems. In this study, we synthesized liposomal nanoparticles tailored for the prostacyclin analogue iloprost and evaluated their pharmacologic efficacy on mouse intrapulmonary arteries, using a wire myograph. The use of cationic lipids, stearylamine, or 1,2-di-(9Z-octadecenoyl-3-trimethylammonium-propane (DOTAP in liposomes promoted iloprost encapsulation to at least 50%. The addition of cholesterol modestly reduced iloprost encapsulation. The liposomal nanoparticle formulations were tested for toxicity and pharmacologic efficacy in vivo and ex vivo, respectively. The liposomes did not affect the viability of human pulmonary artery smooth muscle cells. Compared with an equivalent concentration of free iloprost, four out of the six polymer-coated liposomal formulations exhibited significantly enhanced vasodilation of mouse pulmonary arteries. Iloprost that was encapsulated in liposomes containing the polymer polyethylene glycol exhibited concentration-dependent relaxation of arteries. Strikingly, half the concentration of iloprost in liposomes elicited

Iron nanoparticle assemblies: structures and magnetic behavior

International Nuclear Information System (INIS)

Farrell, D; Cheng, Y; Kan, S; Sachan, M; Ding, Y; Majetich, S A; Yang, L

2005-01-01

Self-assembly of spherical, surfactant-coated nanoparticles is discussed, an examples are presented to demonstrate the variety of structures that can be formed, and the conditions that lead to them. The effect of the concentration on the magnetic properties is then examined for 8.5 nm Fe nanoparticles. Dilute dispersions, arrays formed by evaporation of the dispersions, and nanoparticle crystals grown by slow diffusion of a poorly coordinating solvent were characterized by zero field-cooled magnetization, remanent hysteresis loop, and magnetic relaxation measurements. The average spacing between the particles was determined from a combination of transmission electron microscopy and small angle x-ray scattering. In the arrays the spacing was 2.5 nm between the edges of the particle cores, while in the nanoparticle crystals the particles were more tightly packed, with a separation of 1.1 nm. The reduced separation increased the magnetostatic interaction strength in the nanoparticle crystals, which showed distinctly different behavior in the rate of approach to saturation in the remanent hysteresis loops, and in the faster rate of time-dependent magnetic relaxation

Direct hierarchical assembly of nanoparticles

Science.gov (United States)

Xu, Ting; Zhao, Yue; Thorkelsson, Kari

2014-07-22

The present invention provides hierarchical assemblies of a block copolymer, a bifunctional linking compound and a nanoparticle. The block copolymers form one micro-domain and the nanoparticles another micro-domain.

DNA-mediated self-assembly of tetrahedral plasmonic clusters for metafluids

Science.gov (United States)

Schade, Nicholas; Sun, Li; Lee, You-Jin; Fan, Jonathan; Capasso, Federico; Yi, Gi-Ra; Manoharan, Vinothan

2014-03-01

We direct the self-assembly of clusters of gold nanospheres with the goal of creating a bulk, isotropic, optical metafluid. We use spherical gold nanoparticles that are exceptionally smooth, monocrystalline, and monodisperse. These particles exhibit highly reproducible scattering spectra compared with commercially available gold colloids. We label them with DNA sequences and mix them together to self-assemble small clusters. By controlling the particle sizes and the interactions between them, we maximize the yield of tetrahedral clusters, the ideal structures for isotropic metamaterials.

Self-assembly of green tea catechin derivatives in nanoparticles for oral lycopene delivery.

Science.gov (United States)

Li, Weikun; Yalcin, Murat; Lin, Qishan; Ardawi, Mohammed-Salleh M; Mousa, Shaker A

2017-02-28

Lycopene is a natural anti-oxidant that has attracted much attention due to its varied applications such as protection against loss of bone mass, chronic diseases, skin cancer, prostate cancer, and cardiovascular disease. However, high instability and extremely low oral bioavailability limit its further clinical development. We selected a green tea catechin derivative, oligomerized (-)-epigallocatechin-3-O-gallate (OEGCG) as a carrier for oral lycopene delivery. Lycopene-loaded OEGCG nanoparticles (NPs) were prepared by a nano-precipitation method, followed by coating with chitosan to form a shell. This method not only can easily control the size of the NP to be around 200nm to improve its bioavailability, but also can effectively protect the lycopene against degradation due to EGCG's anti-oxidant property. OEGCG was carefully characterized with nuclear magnetic resonance spectroscopy and mass spectrometry. Lycopene-loaded polylactic-co-glycolic acid (PLGA) NPs were prepared by the same method. Chitosan-coated OEGCG/lycopene NPs had a diameter of 152±32nm and a ζ-potential of 58.3±4.2mv as characterized with transmission electron microscopy and dynamic light scattering. The loading capacity of lycopene was 9% and encapsulation efficiency was 89%. FT-IR spectral analysis revealed electrostatic interaction between OEGCG and chitosan. Freeze drying of the NPs was also evaluated as a means to improve shelf life. Dynamic light scattering data showed that no aggregation occurred, and the size of the NP increased 1.2 times (S f /S i ratio) in the presence of 10% sucrose after freeze drying. The in vitro release study showed slow release of lycopene in simulated gastric fluid at acidic pH and faster release in simulated intestinal fluid. In an in vivo study in mice, lycopene pharmacokinetic parameters were improved by lycopene/OEGCG/chitosan NPs, but not improved by lycopene/PLGA/chitosan NPs. The self-assembled nanostructure of OEGCG combined with lycopene may be a

Dimensional scale effects on surface enhanced Raman scattering efficiency of self-assembled silver nanoparticle clusters

International Nuclear Information System (INIS)

Fasolato, C.; Domenici, F.; De Angelis, L.; Luongo, F.; Postorino, P.; Sennato, S.; Mura, F.; Costantini, F.; Bordi, F.

2014-01-01

A study of the Surface Enhanced Raman Scattering (SERS) from micrometric metallic nanoparticle aggregates is presented. The sample is obtained from the self-assembly on glass slides of micro-clusters of silver nanoparticles (60 and 100 nm diameter), functionalized with the organic molecule 4-aminothiophenol in water solution. For nanoparticle clusters at the micron scale, a maximum enhancement factor of 10 9 is estimated from the SERS over the Raman intensity ratio normalized to the single molecule contribution. Atomic force microscopy, correlated to spatially resolved Raman measurements, allows highlighting the connection between morphology and efficiency of the plasmonic system. The correlation between geometric features and SERS response of the metallic structures reveals a linear trend of the cluster maximum scattered intensity as a function of the surface area of the aggregate. On given clusters, the intensity turns out to be also influenced by the number of stacking planes of the aggregate, thus suggesting a plasmonic waveguide effect. The linear dependence results weakened for the largest area clusters, suggesting 30 μm 2 as the upper limit for exploiting the coherence over large scale of the plasmonic response.

A synergetic analysis method for antifouling behavior investigation on PES ultrafiltration membrane with self-assembled TiO2 nanoparticles.

Science.gov (United States)

Li, Xin; Li, Jiansheng; Fang, Xiaofeng; Bakzhan, Kariboz; Wang, Lianjun; Van der Bruggen, Bart

2016-05-01

Fouling of ultrafiltration (UF) membranes is a major impediment for their use in drinking water production. Mixed matrix membranes (MMMs) may have great opportunities in dealing with this challenge due to their hierarchical structures and multiple functionalities. In this study, a synergetic analysis method based on intermolecular adhesion force measurement and fouling process simulation was applied to investigate the fouling mechanism of polyethersulfone (PES) UF membranes containing in situ self-assembled TiO2 nanoparticles (NPs). The fouling resistance behavior and antifouling mechanism of the newly developed composite membranes were investigated with sodium alginate (SA), bovine serum albumin (BSA) and humic acid (HA) as model organic foulants. An improved antifouling effect was conspicuously observed for the composite membranes, expressed by a lower flux decline and significantly better cleaning efficiency. A strong correlation between the self-assembled structure of TiO2 NPs and the antifouling behavior of the composite membrane was observed. A lower magnitude and a narrower distribution of adhesion forces for the composite membrane suggest the effective suppression of foulants adsorption on the clean or fouled membrane. The simulation analysis indicates that the main fouling mechanism was standard blocking and cake filtration, further confirming the superiority of the NPs self-assembled structure in mitigating membrane fouling. This dual analysis method may provide a promising technological support for the application of modified UF membranes with self-assembled NPs in drinking water production. Copyright © 2016 Elsevier Inc. All rights reserved.

High-Yield Excited Triplet States in Pentacene Self-Assembled Monolayers on Gold Nanoparticles through Singlet Exciton Fission.

Science.gov (United States)

Kato, Daiki; Sakai, Hayato; Tkachenko, Nikolai V; Hasobe, Taku

2016-04-18

One of the major drawbacks of organic-dye-modified self-assembled monolayers on metal nanoparticles when employed for efficient use of light energy is the fact that singlet excited states on dye molecules can be easily deactivated by means of energy transfer to the metal surface. In this study, a series of 6,13-bis(triisopropylsilylethynyl)pentacene-alkanethiolate monolayer protected gold nanoparticles with different particle sizes and alkane chain lengths were successfully synthesized and were employed for the efficient generation of excited triplet states of the pentacene derivatives by singlet fission. Time-resolved transient absorption measurements revealed the formation of excited triplet states in high yield (172±26 %) by suppressing energy transfer to the gold surface. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrostatic Self-Assembly of Fe3O4 Nanoparticles on Graphene Oxides for High Capacity Lithium-Ion Battery Anodes

Directory of Open Access Journals (Sweden)

Jung Kyoo Lee

2013-09-01

Full Text Available Magnetite, Fe3O4, is a promising anode material for lithium ion batteries due to its high theoretical capacity (924 mA h g−1, high density, low cost and low toxicity. However, its application as high capacity anodes is still hampered by poor cycling performance. To stabilize the cycling performance of Fe3O4 nanoparticles, composites comprising Fe3O4 nanoparticles and graphene sheets (GS were fabricated. The Fe3O4/GS composite disks of mm dimensions were prepared by electrostatic self-assembly between negatively charged graphene oxide (GO sheets and positively charged Fe3O4-APTMS [Fe3O4 grafted with (3-aminopropyltrimethoxysilane (APTMS] in an acidic solution (pH = 2 followed by in situ chemical reduction. Thus prepared Fe3O4/GS composite showed an excellent rate capability as well as much enhanced cycling stability compared with Fe3O4 electrode. The superior electrochemical responses of Fe3O4/GS composite disks assure the advantages of: (1 electrostatic self-assembly between high storage-capacity materials with GO; and (2 incorporation of GS in the Fe3O4/GS composite for high capacity lithium-ion battery application.

Preparation of pH-sensitive amphiphilic block star polymers, their self-assembling characteristics and release behavior on encapsulated molecules

KAUST Repository

Song, Xiaowan

2016-05-28

Poly(ethylene glycol) (PEG), a polymer with excellent biocompatibility, was widely used to form nanoparticles for drug delivery applications. In this paper, based on PEG, a series of pH-sensitive amphiphilic block star polymers of poly(ethylene glycol)-block-poly(ethoxy ethyl glycidyl ether) (PEG-b-PEEGE) with different hydrophobic length were synthesized by living anionic ring-opening polymerization method. The products were characterized using 1H NMR and gel permeation chromatography. These copolymers could self-assemble in aqueous solution to form micellar structure with controlled morphologies. Transmission electron microscopy showed that the nanoparticles are spherical or rodlike with different hydrophilic mass fractions. The pH response of polymeric aggregates from PEG-b-PEEGE was detected by fluorescence probe technique at different pH. A pH-dependent release behavior was observed and pH-responsiveness of PEG-b-PEEGE was affected by the hydrophobic block length. These results demonstrated that star-shaped polymers (PEG-b-PEEGE) are attractive candidates as anticancer drug delivery carriers. © 2016 Springer-Verlag Berlin Heidelberg

Novel extractants with high selectivity for valuable metals in seawater. Calixarene derivatives

International Nuclear Information System (INIS)

Kakoi, Takahiko; Goto, Masahiro

1997-01-01

Seawater contains various valuable metals such as uranium and lithium. Therefore, attempts are being made to develop highly selective extractants which recognize target metal ions in reclaimed seawater. In this review, we have focused our study on the application of novel cyclic compound calixarene based extractants. A novel host compound calixarene, which is a cyclic compound connecting some phenol rings, is capable of forming several different extractant ring sizes and introducing various kinds of functional groups towards targeting of metal ions in seawater. Therefore, calixarene derivatives are capable of extracting valuable metals such as uranium, alkaline metals, heavy metals, rare earth metals and noble metals selectively by varying structural ring size and functional groups. The novel host compound calixarene has given promising results which line it up as a potential extractant for the separation of valuable metal ions in seawater. (author)

Synthesis, characterization, and application of novel biodegradable self-assembled 2-(N-phthalimido) ethyl-palmitate nanoparticles for cancer therapy

Science.gov (United States)

Kasoju, Naresh; Bora, Debajeet K.; Bhonde, Ramesh R.; Bora, Utpal

2010-03-01

We report the synthesis of novel biodegradable nanoparticles (NPs) which can kill the cancer cells without any additional drug loading. The NP was a self-assembled form of a phthalimide based conjugate, in which the phthalimide moiety was responsible for the anticancer activity. We describe the synthesis of a novel 2-(N-phthalimido) ethyl palmitate (PHEP-Pal) conjugate and subsequent preparation of NPs by a simple self assembly process. The successful synthesis of conjugate was confirmed by various characterization studies including nuclear magnetic resonance spectroscope, Fourier transform infrared spectroscope, TOF-liquid chromatography mass spectroscope, differential scanning calorimetry, and X-ray diffraction unit. The synthesis, shape, size, and size distribution of PHEP-Pal NPs were determined by transmission electron microscope, atomic force microscope, and dynamic light scattering technique. Finally, cell culture studies using A549 and HeLa cells were done to evaluate the anticancer effect of PHEP-Pal NPs, which demonstrated the potency of these NPs for use in cancer chemotherapy.

Novel tumor-targeting, self-assembling peptide nanofiber as a carrier for effective curcumin delivery

Directory of Open Access Journals (Sweden)

Liu J

2013-12-01

Full Text Available Jianfeng Liu, Jinjian Liu, Hongyan Xu, Yumin Zhang, Liping Chu, Qingfen Liu, Naling Song, Cuihong YangTianjin Key Laboratory of Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Science and Peking Union Medical College, People's Republic of ChinaAbstract: The poor aqueous solubility and low bioavailability of curcumin restrict its clinical application for cancer treatment. In this study, a novel tumor-targeting nanofiber carrier was developed to improve the solubility and tumor-targeting ability of curcumin using a self-assembled Nap-GFFYG-RGD peptide. The morphologies of the peptide nanofiber and the curcumin-encapsulated nanofiber were visualized by transmission electron microscopy. The tumor-targeting activity of the curcumin-encapsulated Nap-GFFYG-RGD peptide nanofiber (f-RGD-Cur was studied in vitro and in vivo, using Nap-GFFYG-RGE peptide nanofiber (f-RGE-Cur as the control. Curcumin was encapsulated into the peptide nanofiber, which had a diameter of approximately 10–20 nm. Curcumin showed sustained-release behavior from the nanofibers in vitro. f-RGD-Cur showed much higher cellular uptake in αvβ3 integrin-positive HepG2 liver carcinoma cells than did non-targeted f-RGE-Cur, thereby leading to significantly higher cytotoxicity. Ex vivo studies further demonstrated that curcumin could accumulate markedly in mouse tumors after administration of f-RGD-Cur via the tail vein. These results indicate that Nap-GFFYG-RGD peptide self-assembled nanofibers are a promising hydrophobic drug delivery system for targeted treatment of cancer.Keywords: nanofiber, tumor-targeting, self-assembling, curcumin, drug delivery

One-pot nucleation, growth, morphogenesis, and passivation of 1.4 nm Au nanoparticles on self-assembled rosette nanotubes.

Science.gov (United States)

Chhabra, Rahul; Moralez, Jesus G; Raez, Jose; Yamazaki, Takeshi; Cho, Jae-Young; Myles, Andrew J; Kovalenko, Andriy; Fenniri, Hicham

2010-01-13

A one-pot strategy for the nucleation, growth, morphogenesis, and passivation of 1.4 nm Au nanoparticles (NPs) on self-assembled rosette nanotubes (RNTs) is described. Tapping-mode atomic force microscopy, transmission electron microscopy, energy-dispersive X-ray analysis, and selected-area electron diffraction were used to establish the structure and organization of this hybrid material. Notably, we found that the Au NPs formed were nearly monodisperse clusters of Au(55) (1.4-1.5 nm) nestled in pockets on the RNT surface.

Fabrication of Localized Surface Plasmon Resonance Fiber Probes Using Ionic Self-Assembled Gold Nanoparticles

Directory of Open Access Journals (Sweden)

Miao Wan

2010-07-01

Full Text Available An nm-thickness composite gold thin film consisting of gold nanoparticles and polyelectrolytes is fabricated through ionic self-assembled multilayers (ISAM technique and is deposited on end-faces of optical fibers to construct localized surface plasmon resonance (LSPR fiber probes. We demonstrate that the LSPR spectrum induced by ISAM gold films can be fine-tuned through the ISAM procedure. We investigate variations of reflection spectra of the probe with respect to the layer-by-layer adsorption of ISAMs onto end-faces of fibers, and study the spectral variation mechanism. Finally, we demonstrated using this fiber probe to detect the biotin-streptavidin bioconjugate pair. ISAM adsorbed on optical fibers potentially provides a simple, fast, robust, and low-cost, platform for LSPR biosensing applications.

Anisotropic Self-Assembly of Organic–Inorganic Hybrid Microtoroids

KAUST Repository

Al-Rehili, Safa’a

2016-10-24

Toroidal structures based on self-assembly of predesigned building blocks are well-established in the literature, but spontaneous self-organization to prepare such structures has not been reported to date. Here, organic–inorganic hybrid microtoroids synthesized by simultaneous coordination-driven assembly of amphiphilic molecules and hydrophilic polymers are reported. Mixing amphiphilic molecules with iron(III) chloride and hydrophilic polymers in water leads, within minutes, to the formation of starlike nanostructures. A spontaneous self-organization of these nanostructures is then triggered to form stable hybrid microtoroids. Interestingly, the toroids exhibit anisotropic hierarchical growth, giving rise to a layered toroidal framework. These microstructures are mechanically robust and can act as templates to host metallic nanoparticles such as gold and silver. Understanding the nature of spontaneous assembly driven by coordination multiple non-covalent interactions can help explain the well-ordered complexity of many biological organisms in addition to expanding the available tools to mimic such structures at a molecular level.

Nanoparticles and self-organisation: the emergence of hierarchical properties from the nanoparticle soup (i.e., the small is getting bigger). Concluding remarks for Faraday Discussion: Nanoparticle Synthesis and Assembly.

Science.gov (United States)

Schiffrin, David J

2015-01-01

Some four years ago, one of the participants in this Discussion (Prof. Nicholas Kotov) predicted that: "within five years we shall see multiple examples of electronic, sensor, optical and other devices utilizing self-assembled superstructures" (N. A. Kotov, J. Mater. Chem., 2011, 21, 16673-16674). Although this prediction came partially to fruition, we have witnessed an unprecedented interest in the properties of materials at the nanoscale. The point highlighted by Kotov, however, was the importance of self-assembly of structures from well characterised building blocks to yield hierarchical structures, hopefully with predictable properties, a concept that is an everyday pursuit of synthetic chemists. This Discussion has brought together researchers from a wide range of disciplines, i.e., colloid science, modelling, nanoparticle synthesis and organisation, magnetic and optical materials, and new imaging methods, within the excellent traditional Faraday Discussion format, to discuss advances in areas relevant to the main theme of the meeting.

Bioengineering towards self-assembly of particulate vaccines.

Science.gov (United States)

Rehm, Bernd H A

2017-12-01

There is an unmet demand for safe and efficient vaccines for prevention of various infectious diseases. Subunit vaccines comprise selected pathogen specific antigens are a safe alternative to whole organism vaccines. However they often lack immunogenicity. Natural and synthetic self-assembling polymers and proteins will be reviewed in view their use to encapsulate and/or display antigens to serve as immunogenic antigen carriers for induction of protective immunity. Recent advances made in in vivo assembly of antigen-displaying polyester inclusions will be a focus. Particulate vaccines are inherently immunogenic due to enhanced uptake by antigen presenting cells which process antigens mediating adaptive immune responses. Bioengineering approaches enable the design of tailor-made particulate vaccines to fine tune immune responses towards protective immunity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Two-dimensional self-assembly of DNA-functionalized gold nanoparticles

Science.gov (United States)

Wang, Wenjie; Zhang, Honghu; Hagen, Noah; Kuzmenko, Ivan; Akinc, Mufit; Travesset, Alex; Mallapragada, Surya; Vaknin, David

2D superlattices of nanoparticles (NPs) are promising candidates for nano-devices. It is still challenging to develop a simple yet efficient protocol to assemble NPs in a controlled manner. Here, we report on formation of 2D Gibbs monolayers of single-stranded DNA-coated gold nanoparticles (ssDNA-AuNPs) at the air-water interface by manipulation of salts contents. MgCl2 and CaCl2 in solutions facilitate the accumulation of the non-complementary ssDNA-AuNPs on aqueous surfaces. Grazing-incidence small-angle X-ray scattering (GISAXS) and X-ray reflectivity show that the surface AuNPs assembly forms a mono-particle layer and undergoes a transformation from short-range to long-range (hexagonal) order above a threshold of [MgCl2] or [CaCl2]. For solutions that include two kinds of ssDNA-AuNPs with complementary base-pairing, the surface AuNPs form a thicker film and only in-plane short-range order is observed. By using other salts (NaCl or LaCl3) at concentrations of similar ionic strength to those of MgCl2 or CaCl2, we find that surface adsorbed NPs lack any orders. X-ray fluorescence measurements provide direct evidence of surface enrichment of AuNPs and divalent ions (Ca2 +) . The work was supported by the Office of Basic Energy Sciences, USDOE under Contract No. DE-AC02-07CH11358 and DE-AC02-06CH11357.

Self-assembly of an electronically conductive network through microporous scaffolds.

Science.gov (United States)

Sebastian, H Bri; Bryant, Steven L

2017-06-15

Electron transfer spanning significant distances through a microporous structure was established via the self-assembly of an electronically conductive iridium oxide nanowire matrix enveloping the pore walls. Microporous formations were simulated using two scaffold materials of varying physical and chemical properties; paraffin wax beads, and agar gel. Following infiltration into the micropores, iridium nanoparticles self-assembled at the pore wall/ethanol interface. Subsequently, cyclic voltammetry was employed to electrochemically crosslink the metal, erecting an interconnected, and electronically conductive metal oxide nanowire matrix. Electrochemical and spectral characterization techniques confirmed the formation of oxide nanowire matrices encompassing lengths of at least 1.6mm, 400× distances previously achieved using iridium nanoparticles. Nanowire matrices were engaged as biofuel cell anodes, where electrons were donated to the nanowires by a glucose oxidizing enzyme. Copyright © 2017 Elsevier Inc. All rights reserved.

DNA-guided nanoparticle assemblies

Science.gov (United States)

Gang, Oleg; Nykypanchuk, Dmytro; Maye, Mathew; van der Lelie, Daniel

2013-07-16

In some embodiments, DNA-capped nanoparticles are used to define a degree of crystalline order in assemblies thereof. In some embodiments, thermodynamically reversible and stable body-centered cubic (bcc) structures, with particles occupying <.about.10% of the unit cell, are formed. Designs and pathways amenable to the crystallization of particle assemblies are identified. In some embodiments, a plasmonic crystal is provided. In some aspects, a method for controlling the properties of particle assemblages is provided. In some embodiments a catalyst is formed from nanoparticles linked by nucleic acid sequences and forming an open crystal structure with catalytically active agents attached to the crystal on its surface or in interstices.

Electro-spray ionization - mass spectrometry (ESI/MS) and molecular modelling, two complementary approaches. Application to calixarenes; Electrospray - spectrometrie de masse (ESI/MS) et modelisation moleculaire, deux approches complementaires. Application aux calixarenes

Energy Technology Data Exchange (ETDEWEB)

Allain, F.; Virelizier, H.; Moulin, Ch. [CEA Saclay, Dept. des Procedes d' Enrichissement, 91 - Gif-sur-Yvette (France); Lamare, V.; Dozol, J.F. [CEA Cadarache, Dept. d' Entreposage et de Stockage des Dechets, 13 - Saint-Paul-lez-Durance (France)

2001-07-01

The molecular dynamics simulation and the experimental results obtained by the ESI/MS technique have shown that the stability of the calixarene - alkaline cation complexes is dependent of the medium. Indeed, in solution, the calixarene presents a strong affinity for cesium whereas in gaseous phase, the strong affinity is for sodium. The stability of the [calixarene+Na]{sup +} complexes depends of the nature of the medium too; these two techniques having shown that the presence of a small quantity of water in the dilution solvent stabilizes the complex. At last, calixarenes with benzo groups on their crown have an affinity for sodium which is weak in solution but strong in gaseous phase. These different results show the excellent complementarity between the two techniques. (O.M.)

Understanding the Formation of the Self-Assembly of Colloidal Copper Nanoparticles by Surfactant: A Molecular Velcro

Directory of Open Access Journals (Sweden)

Raquel Kely Bortoleto-Bugs

2013-01-01

Full Text Available Self-assembly procedure is employed to synthesize colloidal copper nanoparticles (ccNPs with cationic surfactant in an environmentally friendly method. Scanning electron microscopy images provide a clear view of the ccNPs formed having an approximate size of 15 nm. The X-ray diffraction reveals that the ccNPs have the two types of copper oxide as well as the metallic copper. The new procedure shows that the cationic surfactant CTAB plays an important role in the understanding and development of self-assembly. There is a strong relationship between the ccNPs formation with the critical micelle concentration of the CTAB which influences both shape and size. The outcomes allowed the development of a molecular model for the ccNPs synthesis showing that the CTAB monomer on the surface has the function of a molecular velcro making the linkage of ccNPs to form an agglomerate with size around 600 nm. Finally, with the emerging new technologies, the synthesis of copper oxide takes a new perspective for their applicability in diverse integrated areas such as the flexible electronics and energy.

DNA-encapsulated magnesium phosphate nanoparticles elicit both humoral and cellular immune responses in mice

Directory of Open Access Journals (Sweden)

Gajadhar Bhakta

2014-01-01

Full Text Available The efficacy of pEGFP (plasmid expressing enhanced green fluorescent protein-encapsulated PEGylated (meaning polyethylene glycol coated magnesium phosphate nanoparticles (referred to as MgPi-pEGFP nanoparticles for the induction of immune responses was investigated in a mouse model. MgPi-pEGFP nanoparticles induced enhanced serum antibody and antigen-specific T-lymphocyte responses, as well as increased IFN-γ and IL-12 levels compared to naked pEGFP when administered via intravenous, intraperitoneal or intramuscular routes. A significant macrophage response, both in size and activity, was also observed when mice were immunized with the nanoparticle formulation. The response was highly specific for the antigen, as the increase in interaction between macrophages and lymphocytes as well as lymphocyte proliferation took place only when they were re-stimulated with recombinant green fluorescence protein (rGFP. Thus the nanoparticle formulation elicited both humoral as well as cellular responses. Cytokine profiling revealed the induction of Th-1 type responses. The results suggest DNA-encapsulated magnesium phosphate (MgPi nanoparticles may constitute a safer, more stable and cost-efficient DNA vaccine formulation.

Disulfide-induced self-assembled targets: A novel strategy for the label free colorimetric detection of DNAs/RNAs via unmodified gold nanoparticles

Science.gov (United States)

Shokri, Ehsan; Hosseini, Morteza; Davari, Mehdi D.; Ganjali, Mohammad R.; Peppelenbosch, Maikel P.; Rezaee, Farhad

2017-04-01

A modified non-cross-linking gold-nanoparticles (Au-NPs) aggregation strategy has been developed for the label free colorimetric detection of DNAs/RNAs based on self-assembling target species in the presence of thiolated probes. Two complementary thiol- modified probes, each of which specifically binds at one half of the target introduced SH groups at both ends of dsDNA. Continuous disulfide bond formation at 3‧ and 5‧ terminals of targets leads to the self-assembly of dsDNAs into the sulfur- rich and flexible products with different lengths. These products have a high affinity for the surface of Au-NPs and efficiently protect the surface from salt induced aggregation. To evaluate the assay efficacy, a small part of the citrus tristeza virus (CTV) genome was targeted, leading to a detection limit of about 5 × 10-9 mol.L-1 over a linear ranged from 20 × 10-9 to 10 × 10-7 mol.L-1. This approach also exhibits good reproducibility and recovery levels in the presence of plant total RNA or human plasma total circulating RNA extracts. Self-assembled targets can be then sensitively distinguished from non-assembled or mismatched targets after gel electrophoresis. The disulfide reaction method and integrating self-assembled DNAs/RNAs targets with bare AuNPs as a sensitive indicator provide us a powerful and simple visual detection tool for a wide range of applications.

Nitrogen-doped graphene network supported copper nanoparticles encapsulated with graphene shells for surface-enhanced Raman scattering

Science.gov (United States)

Zhang, Xiang; Shi, Chunsheng; Liu, Enzuo; Li, Jiajun; Zhao, Naiqin; He, Chunnian

2015-10-01

In this study, we demonstrated nitrogen-doped graphene network supported few-layered graphene shell encapsulated Cu nanoparticles (NPs) (Cu@G-NGNs) as a sensing platform, which were constructed by a simple and scalable in situ chemical vapor deposition (CVD) technique with the assistance of a self-assembled three-dimensional (3D) NaCl template. Compared with pure Cu NPs and graphene decorated Cu NPs, the graphene shells can strengthen the plasmonic coupling between graphene and Cu, thereby contributing to an obvious improvement in the local electromagnetic field that was validated by finite element numerical simulations, while the 3D nitrogen-doped graphene walls with a large surface area facilitated molecule adsorption and the doped nitrogen atoms embedded in the graphene lattice can reduce the surface energy of the system. With these merits, a good surface enhanced Raman spectroscopy (SERS) activity of the 3D Cu@G-NGN painting film on glass was demonstrated using rhodamine 6G and crystal violet as model analytes, exhibiting a satisfactory sensitivity, reproducibility and stability. As far as we know, this is the first report on the in situ synthesis of nitrogen-doped graphene/copper nanocomposites and this facile and low-cost Cu-based strategy tends to be a good supplement to Ag and Au based substrates for SERS applications.In this study, we demonstrated nitrogen-doped graphene network supported few-layered graphene shell encapsulated Cu nanoparticles (NPs) (Cu@G-NGNs) as a sensing platform, which were constructed by a simple and scalable in situ chemical vapor deposition (CVD) technique with the assistance of a self-assembled three-dimensional (3D) NaCl template. Compared with pure Cu NPs and graphene decorated Cu NPs, the graphene shells can strengthen the plasmonic coupling between graphene and Cu, thereby contributing to an obvious improvement in the local electromagnetic field that was validated by finite element numerical simulations, while the 3D nitrogen

Unexpected self-sorting self-assembly formation of a [4:4] sulfate:ligand cage from a preorganized tripodal urea ligand.

Science.gov (United States)

Pandurangan, Komala; Kitchen, Jonathan A; Blasco, Salvador; Boyle, Elaine M; Fitzpatrick, Bella; Feeney, Martin; Kruger, Paul E; Gunnlaugsson, Thorfinnur

2015-04-07

The design and synthesis of tripodal ligands 1-3 based upon the N-methyl-1,3,5-benzenetricarboxamide platform appended with three aryl urea arms is reported. This ligand platform gives rise to highly preorganized structures and is ideally suited for binding SO4 (2-) and H2 PO4 (-) ions through multiple hydrogen-bonding interactions. The solid-state crystal structures of 1-3 with SO4 (2-) show the encapsulation of a single anion within a cage structure, whereas the crystal structure of 1 with H2 PO4 (-) showed that two anions are encapsulated. We further demonstrate that ligand 4, based on the same platform but consisting of two bis-urea moieties and a single ammonium moiety, also recognizes SO4 (2-) to form a self-assembled capsule with [4:4] SO4 (2-) :4 stoichiometry in which the anions are clustered within a cavity formed by the four ligands. This is the first example of a self-sorting self-assembled capsule where four tetrahedrally arranged SO4 (2-) ions are embedded within a hydrophobic cavity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-assembled gold coating enhances X-ray imaging of alginate microcapsules

Science.gov (United States)

Qie, Fengxiang; Astolfo, Alberto; Wickramaratna, Malsha; Behe, Martin; Evans, Margaret D. M.; Hughes, Timothy C.; Hao, Xiaojuan; Tan, Tianwei

2015-01-01

Therapeutic biomolecules produced from cells encapsulated within alginate microcapsules (MCs) offer a potential treatment for a number of diseases. However the fate of such MCs once implanted into the body is difficult to establish. Labelling the MCs with medical imaging contrast agents may aid their detection and give researchers the ability to track them over time thus aiding the development of such cellular therapies. Here we report the preparation of MCs with a self-assembled gold nanoparticle (AuNPs) coating which results in distinctive contrast and enables them to be readily identified using a conventional small animal X-ray micro-CT scanner. Cationic Reversible Addition-Fragmentation chain Transfer (RAFT) homopolymer modified AuNPs (PAuNPs) were coated onto the surface of negatively charged alginate MCs resulting in hybrids which possessed low cytotoxicity and high mechanical stability in vitro. As a result of their high localized Au concentration, the hybrid MCs exhibited a distinctive bright circular ring even with a low X-ray dose and rapid scanning in post-mortem imaging experiments facilitating their positive identification and potentially enabling them to be used for in vivo tracking experiments over multiple time-points.Therapeutic biomolecules produced from cells encapsulated within alginate microcapsules (MCs) offer a potential treatment for a number of diseases. However the fate of such MCs once implanted into the body is difficult to establish. Labelling the MCs with medical imaging contrast agents may aid their detection and give researchers the ability to track them over time thus aiding the development of such cellular therapies. Here we report the preparation of MCs with a self-assembled gold nanoparticle (AuNPs) coating which results in distinctive contrast and enables them to be readily identified using a conventional small animal X-ray micro-CT scanner. Cationic Reversible Addition-Fragmentation chain Transfer (RAFT) homopolymer modified Au

Self-Assembly of Fluorescent Hybrid Core-Shell Nanoparticles and Their Application.

Science.gov (United States)

Wang, Chun; Tang, Fu; Wang, Xiaoyu; Li, Lidong

2015-06-24

In this work, a fluorescent hybrid core-shell nanoparticle was prepared by coating a functional polymer shell onto silver nanoparticles via a facile one-pot method. The biomolecule poly-L-lysine (PLL) was chosen as the polymer shell and assembled onto the silver core via the amine-reactive cross-linker, 3,3'-dithiobis(sulfosuccinimidylpropionate). The fluorescent anticancer drug, doxorubicin, was incorporated into the PLL shell through the same linkage. As the cross-linker possesses a thiol-cleavable disulfide bond, disassembly of the PLL shell was observed in the presence of glutathione, leading to controllable doxorubicin release. The silver core there provided an easily modified surface to facilitate the shell coating and ensures the efficient separation of as-prepared nanoparticles from their reaction mixture through centrifugation. Cell assays show that the prepared hybrid fluorescent nanoparticles can internalize into cells possessing excellent biocompatibility prior to the release of doxorubicin, terminating cancer cells efficiently as the doxorubicin is released at the intracellular glutathione level. Such properties are important for designing smart containers for target drug delivery and cellular imaging.

A novel approach to fabricate dye-encapsulated polymeric micro- and nanoparticles by thin film dewetting technique.

Science.gov (United States)

Chatterjee, Manosree; Hens, Abhiram; Mahato, Kuldeep; Jaiswal, Namita; Mahato, Nivedita; Nagahanumaiah; Chanda, Nripen

2017-11-15

A new method is reported for fabrication of polymeric micro- and nanoparticles from an intermediate patterned surface originated by dewetting of a polymeric thin film. Poly (d, l-lactide-co-glycolide) or PLGA, a biocompatible polymer is used to develop a thin film over a clean glass substrate which dewets spontaneously in the micro-/nano-patterned surface of size range 50nm to 3.5µm. Since another water-soluble polymer, poly vinyl alcohol (PVA) is coated on the same glass substrate before PLGA thin film formation, developed micro-/nano-patterns are easily extracted in water in the form of micro- and nanoparticle mixture of size range 50nm to 3.0µm. This simplified method is also used to effectively encapsulate a dye molecule, rhodamine B inside the PLGA micro-/nanoparticles. The developed dye-encapsulated nanoparticles, PLGA-rhodamine are separated from the mixture and tested for in-vitro delivery application of external molecules inside human lung cancer cells. For the first time, the use of thin film dewetting technique is reported as a potential route for the synthesis of polymeric micro-/nanoparticles and effective encapsulation of external species therein. Copyright © 2017 Elsevier Inc. All rights reserved.

Self-assembly of self-assembled molecular triangles

Indian Academy of Sciences (India)

While the solution state structure of 1 can be best described as a trinuclear complex, in the solidstate well-fashioned intermolecular - and CH- interactions are observed. Thus, in the solid-state further self-assembly of already self-assembled molecular triangle is witnessed. The triangular panels are arranged in a linear ...

Synthesis, solid and solution studies of paraquat dichloride calixarene complexes. Molecular modelling

International Nuclear Information System (INIS)

Garcia S, I.; Ramirez, F. M.

2010-01-01

The interaction of the herbicide paraquat dichloride (P Q, substrate) with p-tert-butylcalix arenas (L, receptor) was investigated in both the solution and solid states. The isolated paraquat calixarene complexes were characterised by UV-visible, 1 H NMR, ESI-Ms, Luminescence and IR spectroscopies and elemental analysis. The stoichiometry of complexes 1 and 2 was 1:1 (1 herbicide: 1 calixarene) and both revealed a biexponential luminescence decay with lifetimes depending on the size and the conformational particularity of the calixarenes. Molecular modelling suggested that both calixarenes interact with the herbicide through cation-π interaction. P Q in included in the p-tert butylcalix a rene cavity, a situation favoured by its pinched conformation in polar solvent while it is partially included in the p-tert butylcalix a rene cavity because of its in-out cone conformation. The theoretical results, in particular using Mopac procedures, were in agreement with the experimental findings. (Author)

Synthesis, solid and solution studies of paraquat dichloride calixarene complexes. Molecular modelling

Energy Technology Data Exchange (ETDEWEB)

Garcia S, I.; Ramirez, F. M., E-mail: flor.ramirez@inin.gob.m [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2010-07-01

The interaction of the herbicide paraquat dichloride (P Q, substrate) with p-tert-butylcalix arenas (L, receptor) was investigated in both the solution and solid states. The isolated paraquat calixarene complexes were characterised by UV-visible, {sup 1}H NMR, ESI-Ms, Luminescence and IR spectroscopies and elemental analysis. The stoichiometry of complexes 1 and 2 was 1:1 (1 herbicide: 1 calixarene) and both revealed a biexponential luminescence decay with lifetimes depending on the size and the conformational particularity of the calixarenes. Molecular modelling suggested that both calixarenes interact with the herbicide through cation-{pi} interaction. P Q in included in the p-tert butylcalix a rene cavity, a situation favoured by its pinched conformation in polar solvent while it is partially included in the p-tert butylcalix a rene cavity because of its in-out cone conformation. The theoretical results, in particular using Mopac procedures, were in agreement with the experimental findings. (Author)

Self-assembling protein nanoparticles with built-in flagellin domains increases protective efficacy of a Plasmodium falciparum based vaccine.

Science.gov (United States)

Kaba, Stephen A; Karch, Christopher P; Seth, Labdhi; Ferlez, Karen M B; Storme, Casey K; Pesavento, Danielle M; Laughlin, Paige Y; Bergmann-Leitner, Elke S; Burkhard, Peter; Lanar, David E

2018-02-01

To eliminate the problems associated with the use of extraneous adjuvants we have designed a Self-Assembling Protein Nanoparticle (SAPN) containing epitopes from the Plasmodium falciparum circumsporozoite protein (PfCSP) (designated FMP014) and portions of the TLR5 agonist flagellin (designated FMP014 D0D1 ) as an intrinsic adjuvant. By combining different molar ratios of FMP014 to FMP014 D0D1 monomers before self-assembly, we generated multiple nanoparticles and investigated their biophysical characteristics, immunogenicity and protective efficacy. Immunization with the construct formulated with the ratio 58:2 of FMP014 to FMP014 D0D1 had the highest protective efficacy against a challenge with a transgenic P. berghei sporozoite expressing PfCSP. Increasing the proportion of flagellin per particle resulted in an inverse relationship with levels of both antibody titers and protection. The cytokine profiles of the various immunization groups were evaluated and quantitative amounts of the cytokines IL-2, IFN-γ, IL-12/p70 (Th1); IL4, IL5 (Th2); TNF-α, IL1β, IL-6, KC/GRO (pro-inflammatory), and IL-10 (immunomodulatory) were measured. The relationship of the cytokines to each other revealed a strong immunomodulatory effect depending on the proportion of flagellin in the construct. Our results demonstrate that SAPNs with flagellin may be a promising strategy for the development and delivery of a safe vaccine for infectious diseases. Published by Elsevier Ltd.

Polymeric nanoparticles encapsulating white tea extract for nutraceutical application.

Science.gov (United States)

Sanna, Vanna; Lubinu, Giuseppe; Madau, Pierluigi; Pala, Nicolino; Nurra, Salvatore; Mariani, Alberto; Sechi, Mario

2015-02-25

With the aim to obtain controlled release and to preserve the antioxidant activity of the polyphenols, nanoencapsulation of white tea extract into polymeric nanoparticles (NPs) based on poly(ε-caprolactone) (PCL) and alginate was successfully performed. NPs were prepared by nanoprecipitation method and were characterized in terms of morphology and chemical properties. Total polyphenols and catechins contents before and after encapsulation were determined. Moreover, in vitro release profiles of encapsulated polyphenols from NPs were investigated in simulated gastrointestinal fluids. The antioxidant activity and stability of encapsulated extract were further evaluated. Interestingly, NPs released 20% of the polyphenols in simulated gastric medium, and 80% after 5 h at pH 7.4, showing a good capacity to control the polyphenols delivery. Furthermore, DPPH(•) assay confirmed that white tea extract retained its antioxidant activity and NPs protected tea polyphenols from degradation, thus opening new perspectives for the exploitation of white tea extract-loaded NPs for nutraceutical applications.

Nanoparticle/Polymer assembled microcapsules with pH sensing property.

Science.gov (United States)

Zhang, Pan; Song, Xiaoxue; Tong, Weijun; Gao, Changyou

2014-10-01

The dual-labeled microcapsules via nanoparticle/polymer assembly based on polyamine-salt aggregates can be fabricated for the ratiometric intracellular pH sensing. After deposition of SiO2 nanoparticles on the poly(allylamine hydrochloride)/multivalent anionic salt aggregates followed by silicic acid treatment, the generated microcapsules are stable in a wide pH range (3.0 ∼ 8.0). pH sensitive dye and pH insensitive dye are simultaneously labeled on the capsules, which enable the ratiometric pH sensing. Due to the rough and positively charged surface, the microcapsules can be internalized by several kinds of cells naturally. Real-time measurement of intracellular pH in several living cells shows that the capsules are all located in acidic organelles after being taken up. Furthermore, the negatively charged DNA and dyes can be easily encapsulated into the capsules via charge interaction. The microcapsules with combination of localized pH sensing and drug loading abilities have many advantages, such as following the real-time transportation and processing of the carriers in cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural and functional features of self-assembling protein nanoparticles produced in endotoxin-free Escherichia coli.

Science.gov (United States)

Rueda, Fabián; Céspedes, María Virtudes; Sánchez-Chardi, Alejandro; Seras-Franzoso, Joaquin; Pesarrodona, Mireia; Ferrer-Miralles, Neus; Vázquez, Esther; Rinas, Ursula; Unzueta, Ugutz; Mamat, Uwe; Mangues, Ramón; García-Fruitós, Elena; Villaverde, Antonio

2016-04-08

Production of recombinant drugs in process-friendly endotoxin-free bacterial factories targets to a lessened complexity of the purification process combined with minimized biological hazards during product application. The development of nanostructured recombinant materials in innovative nanomedical activities expands such a need beyond plain functional polypeptides to complex protein assemblies. While Escherichia coli has been recently modified for the production of endotoxin-free proteins, no data has been so far recorded regarding how the system performs in the fabrication of smart nanostructured materials. We have here explored the nanoarchitecture and in vitro and in vivo functionalities of CXCR4-targeted, self-assembling protein nanoparticles intended for intracellular delivery of drugs and imaging agents in colorectal cancer. Interestingly, endotoxin-free materials exhibit a distinguishable architecture and altered size and target cell penetrability than counterparts produced in conventional E. coli strains. These variant nanoparticles show an eventual proper biodistribution and highly specific and exclusive accumulation in tumor upon administration in colorectal cancer mice models, indicating a convenient display and function of the tumor homing peptides and high particle stability under physiological conditions. The observations made here support the emerging endotoxin-free E. coli system as a robust protein material producer but are also indicative of a particular conformational status and organization of either building blocks or oligomers. This appears to be promoted by multifactorial stress-inducing conditions upon engineering of the E. coli cell envelope, which impacts on the protein quality control of the cell factory.

Self-assembly of gas-phase synthesized magnesium nanoparticles on room temperature substrates

International Nuclear Information System (INIS)

Venturi, F; Calizzi, M; Pasquini, L; Bals, S; Perkisas, T

2015-01-01

Magnesium nanoparticles (NPs) with initial size in the 10–50 nm range were synthesized by inert gas condensation under helium flow and deposited on room temperature substrates. The morphology and crystal structure of the NPs ensemble were investigated as a function of the deposition time by complementary electron microscopy techniques, including high resolution imaging and chemical mapping. With increasing amount of material, strong coarsening phenomena were observed at room temperature: small NPs disappeared while large faceted NPs developed, leading to a 5-fold increase of the average NPs size within a few minutes. The extent of coarsening and the final morphology depended also on the nature of the substrate. Furthermore, large single-crystal NPs were seen to arise from the self-organization of primary NPs units, providing a mechanism for crystal growth. The dynamics of the self-assembly process involves the basic steps of NPs sticking, diffusion on substrate, coordinated rotation and attachment/coalescence. Key features are the surface energy anisotropy, reflected by the faceted shape of the NPs, and the low melting point of the material. The observed phenomena have strong implications in relation to the synthesis and stability of nanostructures based on Mg or other elements with similar features. (paper)

A two-state stochastic model for nanoparticle self-assembly: theory, computer simulations and applications

International Nuclear Information System (INIS)

Schwen, E M; Mazilu, I; Mazilu, D A

2015-01-01

We introduce a stochastic cooperative model for particle deposition and evaporation relevant to ionic self-assembly of nanoparticles with applications in surface fabrication and nanomedicine, and present a method for mapping our model onto the Ising model. The mapping process allows us to use the established results for the Ising model to describe the steady-state properties of our system. After completing the mapping process, we investigate the time dependence of particle density using the mean field approximation. We complement this theoretical analysis with Monte Carlo simulations that support our model. These techniques, which can be used separately or in combination, are useful as pedagogical tools because they are tractable mathematically and they apply equally well to many other physical systems with nearest-neighbour interactions including voter and epidemic models. (paper)

Preparation and characterization of highly water-soluble magnetic Fe3O4 nanoparticles via surface double-layered self-assembly method of sodium alpha-olefin sulfonate

International Nuclear Information System (INIS)

Li, Honghong; Qin, Li; Feng, Ying; Hu, Lihua; Zhou, Chunhua

2015-01-01

A kind of double-layered self-assembly sodium alpha-olefin sulfonate (AOS) capped Fe 3 O 4 magnetic nanoparticles (Fe 3 O 4 -AOS-MN) with highly water-solubility was prepared by a wet co-precipitation method with a pH of 4.8. The resulting Fe 3 O 4 -AOS-MN could be dispersed into water to form stable magnetic fluid without other treatments. The result of X-ray diffraction (XRD) indicated that the Fe 3 O 4 -AOS-MN maintained original crystalline structure and exhibited a diameter of about 7.5 nm. The iron oxide phase of nanoparticles determined by Raman spectroscopy is Fe 3 O 4 . Transmission electron microscopy (TEM) analysis confirmed that the Fe 3 O 4 -AOS-MN with spherical morphology were uniformly dispersed in water. FT-IR spectroscopy (FT-IR) and thermo-gravimetric analysis (TGA) verified the successful preparation of Fe 3 O 4 -AOS-MN capped with double-layered self-assembled AOS. The corresponding capacities of monolayer chemical absorption and the second-layer self-assembly absorption were respectively 4.07 and 14.71 wt% of Fe 3 O 4 -MN, which were much lower than those of other surfactants. Vibrating sample magnetometer (VSM) test result showed Fe 3 O 4 -AOS-MN possessed superparamagnetic behavior with the saturation magnetization value of about 44.45 emu/g. The blocking temperature T B of Fe 3 O 4 -AOS-MN capped with double-layered AOS is 170 K. - Highlights: • Double-layered self-assembly sodium alpha-olefin sulfonate (AOS) capped Fe 3 O 4 magnetic nanoparticles are prepared by a wet co-precipitation method. • Double-layered Fe 3 O 4 -AOS-MN exhibits highly water-solubility. • The iron oxide phase is determined by Raman spectroscopy. • Fe 3 O 4 -AOS-MN capped with double-layered AOS possesses super-paramagnetic behavior. • The blocking temperature T B of Fe 3 O 4 -AOS-MN capped with double-layered AOS is 170 K

Dendrimer encapsulated Silver nanoparticles as novel catalysts for reduction of aromatic nitro compounds

Science.gov (United States)

Asharani, I. V.; Thirumalai, D.; Sivakumar, A.

2017-11-01

Polyethylene glycol (PEG) core dendrimer encapsulated silver nanoparticles (AgNPs) were synthesized through normal chemical reduction method, where dendrimer acts as reducing and stabilizing agent. The encapsulated AgNPs were well characterized using TEM, DLS and XPS techniques. The synthesized AgNPs showed excellent catalytic activity towards the reduction of aromatic nitro compounds with sodium borohydride as reducing agent and the results substantiate that dendrimer encapsulated AgNPs can be an effective catalyst for the substituted nitro aromatic reduction reactions. Also the kinetics of different nitro compounds reductions was studied and presented.

Reusable fluorescent sensor for captopril based on energy transfer from photoluminescent graphene oxide self-assembly multilayers to silver nanoparticles.

Science.gov (United States)

Sun, Xiangying; Liu, Bin; Li, Shuchun; Li, Fang

2016-05-15

In this work we designed a self-assembly multilayers, in which photoluminescent graphene oxide was employed as a fluorescence probe. This multilayers film can effectively recognize captopril by resonance energy transfer from graphite oxide to silver nanoparticles. A new interfacial sensing method for captopril with high signal to noise ratio was established, by means of that multilayers was quenched by silver nanoparticles and subsequently recovered by adding captopril. The linear relation between intensity and captopril concentration was good, and the detection limit was found to be 0.1578 μM. Also, this novel detection platform demonstrated intriguing reusable properties, and the sensor could be repeated more than ten times without obviously losing its sensing performance. Copyright © 2016 Elsevier B.V. All rights reserved.

New self-assembled material based on Ru nanoparticles and 4-sulfocalix[4]arene as an efficient and recyclable catalyst for reduction of brilliant yellow azo dye in water: a new model catalytic reaction

Energy Technology Data Exchange (ETDEWEB)

Rambabu, Darsi; Pradeep, Chullikkattil P.; Dhir, Abhimanew, E-mail: abhimanew@iitmandi.ac.in [Indian Institute of Technology (India)

2016-12-15

New self-assembled material (Ru@SC) with ruthenium nanoparticles (Ru NPs) and 4-sulfocalix[4]arene (SC) is synthesized in water at room temperature. Ru@SC is characterized by thermal gravimetric analysis, FT-IR, powder x-ray diffraction, TEM and SEM analysis. The size of Ru nanoparticles in the self-assembly is approximately 5 nm. The self-assembled material Ru@SC shows an efficient catalytic reduction of toxic ‘brilliant yellow’ (BY) azo dye. The reduced amine products were successfully separated and confirmed by single-crystal XRD, NMR and UV-Vis spectroscopy. Ru@SC showed a better catalytic activity in comparison with commercial catalysts Ru/C (ruthenium on charcoal 5 %) and Pd/C (palladium on charcoal 5 and 10 %). The catalyst also showed a promising recyclability and heterogeneous nature as a catalyst for reduction of ‘BY’ azo dye.

Calixarenes synthesized for seducing and trapping cations

International Nuclear Information System (INIS)

Dozol, J.F.

1997-01-01

Calixarenes are known to be selective extractants for cesium radioactive cations. This liquid-liquid extraction is still to be studied and would allow to reduce the volume of years living radioactive wastes before they were stored and perhaps to remove then the cesium by transmutation. Calixarenes are macrocycles with phenolic units bridged by methylene groups. They have the important property to have a flexible structure. On this basic structure, all kinds of chemical functions can be branched. They thus confer particular properties to the molecule. A computerized virtual construction phase of molecules is actually studied in order to optimize the extraction. It is currently known that with small modifications it will be possible to selectively extract heavy metals (Hg, Cd..) coming from industrial pollution. (O.M.)

Versatility of {l_brace}M(30-crown-10){r_brace} (M = K{sup +}, Ba{sup 2+}) as a guest in UO{sub 2}{sup 2+} complexes of 3.1.3.1 - and 3.3.3 homo-oxa-calixarenes

Energy Technology Data Exchange (ETDEWEB)

Masci, B. [Univ Roma La Sapienza, Dipartimento Chim, I-00185 Rome, (Italy); Thuery, P. [CEA Saclay, DSM/DRECAM/SCM, CNRS-URA 331, F-91191 Gif Sur Yvette, (France)

2007-07-01

The reaction between p-R-[3.1.3.1]- or [3.3.3] homo-oxa-calixarenes and uranyl salts in the presence of 30-crown-10 and the alkali or alkaline-earth metal cations K{sup +} or Ba{sup 2+} gives various supramolecular assemblages characterized by 'complex-within-complex' architectures. These can be of the simple nesting or sandwich types, as in [{l_brace}Ba(30-crown-10){r_brace}{l_brace}UO{sub 2}(L{sup 1}){r_brace}]. 2H{sub 2}O.3CHCl{sub 3} (L{sup 1}H{sub 4} p-tert-butyl[3.1.3.1] homo-oxa-calixarene) and [{l_brace}Ba(30-crown-10){r_brace}{l_brace}UO{sub 2}(L{sup 4}){r_brace}{sub 2}].2CHCl{sub 3} (L{sup 4}H{sub 3} p-bromo[3.3.3]homo-oxa-calixarene), respectively, with the cation held in the cavity of the homo-oxa-calixarene complexes in cone conformation by weak interactions, but more original structures arise when uranyl-cation bonds are present. In [{l_brace}Ba(30-crown-10){r_brace}{l_brace}UO{sub 2}(L{sup 2}){r_brace}] (L{sup 2}H{sub 4} p-phenyl[3.1.3.1] homo-oxa-calixarene), the barium ion included in the crown ether is bound to the uranyl oxo group located out of the calixarene cavity, resulting in the formation of a neutral species which self-organizes to form a columnar assembly by auto-inclusion. In [{l_brace}K(30-crown-10){r_brace}{l_brace}UO{sub 2}K(L{sup 1})(H{sub 2}O){sub 3}{r_brace}]{sub 2}.6H{sub 2}O, the nesting-type subunit dimerizes around two oxo-bound potassium ions. Finally, the use of the coordinating solvent dimethylsulfoxide leads to the neutral complex [UO{sub 2}Ba(L{sup 3})(dmso){sub 2}(MeOH)]{sub 2} (L{sup 3}H{sub 4} = p-methyl[3.1.3.1] homo-oxa-calixarene), in which the crown ether is absent and two oxo-, phenoxo- and ether-bound barium atoms ensure the dimerization of the uranyl complex. (authors)

Poly(ethyl glyoxylate)-Poly(ethylene oxide) Nanoparticles: Stimuli-Responsive Drug Release via End-to-End Polyglyoxylate Depolymerization.

Science.gov (United States)

Fan, Bo; Gillies, Elizabeth R

2017-08-07

The ability to disrupt polymer assemblies in response to specific stimuli provides the potential to release drugs selectively at certain sites or conditions in vivo. However, most stimuli-responsive delivery systems require many stimuli-initiated events to release drugs. "Self-immolative polymers" offer the potential to provide amplified responses to stimuli as they undergo complete end-to-end depolymerization following the cleavage of a single end-cap. Herein, linker end-caps were developed to conjugate self-immolative poly(ethyl glyoxylate) (PEtG) with poly(ethylene oxide) (PEO) to form amphiphilic block copolymers. These copolymers were self-assembled to form nanoparticles in aqueous solution. Cleavage of the linker end-caps were triggered by a thiol reducing agent, UV light, H 2 O 2 , and combinations of these stimuli, resulting in nanoparticle disintegration. Low stimuli concentrations were effective in rapidly disrupting the nanoparticles. Nile red, doxorubin, and curcumin were encapsulated into the nanoparticles and were selectively released upon application of the appropriate stimulus. The ability to tune the stimuli-responsiveness simply by changing the linker end-cap makes this new platform highly attractive for applications in drug delivery.

Surface-enhanced Raman scattering on molecular self-assembly in nanoparticle-hydrogel composite.

Science.gov (United States)

Miljanić, Snezana; Frkanec, Leo; Biljan, Tomislav; Meić, Zlatko; Zinić, Mladen

2006-10-24

Surface-enhanced Raman scattering has been applied to study weak intermolecular interactions between small organic gelling molecules involved in the silver nanoparticle-hydrogel composite formation. Assembly and disassembly of the gelator molecules in close vicinity to embedded silver nanoparticles were followed by changes in Raman intensity of the amide II and carboxyl vibrational bands, whereas the strength of the bands related to benzene modes remained constant. This implied that the gelator molecules were strongly attached to the silver particles through the benzene units, while participating in gel structure organization by intermolecular hydrogen bonding between oxalyl amide and carboxyl groups.

Folding Up of Gold Nanoparticle Strings into Plasmonic Vesicles for Enhanced Photoacoustic Imaging

KAUST Repository

Liu, Yijing

2015-11-11

The stepwise self-assembly of hollow plasmonic vesicles with vesicular membranes containing strings of gold nanoparticles (NPs) is reported. The formation of chain vesicles can be controlled by tuning the density of the polymer ligands on the surface of the gold NPs. The strong absorption of the chain vesicles in the near-infrared (NIR) region leads to a much higher efficiency in photoacoustic (PA) imaging than for non-chain vesicles. The chain vesicles were further employed for the encapsulation of drugs and the NIR light triggered release of payloads. This work not only offers a new platform for controlling the hierarchical self-assembly of NPs, but also demonstrates that the physical properties of the materials can be tailored by controlling the spatial arrangement of NPs within assemblies to achieve a better performance in biomedical applications.

Ag nanoparticles formed by femtosecond pulse laser ablation in water: self-assembled fractal structures

Energy Technology Data Exchange (ETDEWEB)

Santillán, Jesica M. J. [CONICET La Plata-CIC, Centro de Investigaciones Ópticas (CIOp) (Argentina); Fernández van Raap, Marcela B., E-mail: raap@fisica.unlp.edu.ar; Mendoza Zélis, Pedro; Coral, Diego [CONICET, Instituto de Física La Plata (IFLP) (Argentina); Muraca, Diego [Universidade Estadual de Campinas, Instituto de Física “Gleb Wataghin” (IFGW) (Brazil); Schinca, Daniel C.; Scaffardi, Lucía B., E-mail: lucias@ciop.unlp.edu.ar [CONICET La Plata-CIC, Centro de Investigaciones Ópticas (CIOp) (Argentina)

2015-02-15

We report for the first time on the formation of self-assembled fractals of spherical Ag nanoparticles (Nps) fabricated by femtosecond pulse laser ablation of a solid silver target in water. Fractal structures grew both in two and three Euclidean dimensions (d). Ramified-fractal assemblies of 2 nm height and 5–14 μm large, decorated with Ag Nps of 3 nm size, were obtained in a 2d geometry when highly diluted drops of colloidal suspension were dried at a fast heating rate over a mica substrate. When less-diluted drops were dried at slow heating rate, isolated single Nps or rosette-like structures were formed. Fractal aggregates about 31 nm size in 3d geometry were observed in the as-prepared colloidal suspension. Electron diffraction and optical extinction spectroscopy (OES) analyses performed on the samples confirmed the presence of Ag and Ag{sub 2}O. The analysis of the optical extinction spectrum, using the electrostatic approximation of Mie theory for small spheres, showed the existence of Ag bare core, Ag–Ag{sub 2}O and air–Ag core–shell Nps, Ag–Ag{sub 2}O being the most frequent type [69 % relative abundance (r.a.)]. Core-size and shell-thickness distribution was derived from OES. In situ scattering measurements of the Ag colloidal suspension, carried out by small-angle X-ray scattering, indicate a mass fractal composed of packaged 〈D{sub SAXS}〉 = (5 ± 1) nm particles and fractal dimension d{sub f} = 2.5. Ex situ atomic force microscopy imaging displayed well-ramified structures, which, analyzed with box-counting method, yield a fractal dimension d{sub f} = 1.67. The growing behavior of these 2d and 3d self-assembled fractals is consistent with the diffusion-limited aggregation model.

Systematic Study on the Self-Assembled Hexagonal Au Voids, Nano-Clusters and Nanoparticles on GaN (0001.

Directory of Open Access Journals (Sweden)

Puran Pandey

Full Text Available Au nano-clusters and nanoparticles (NPs have been widely utilized in various electronic, optoelectronic, and bio-medical applications due to their great potentials. The size, density and configuration of Au NPs play a vital role in the performance of these devices. In this paper, we present a systematic study on the self-assembled hexagonal Au voids, nano-clusters and NPs fabricated on GaN (0001 by the variation of annealing temperature and deposition amount. At relatively low annealing temperatures between 400 and 600°C, the fabrication of hexagonal shaped Au voids and Au nano-clusters are observed and discussed based on the diffusion limited aggregation model. The size and density of voids and nano-clusters can systematically be controlled. The self-assembled Au NPs are fabricated at comparatively high temperatures from 650 to 800°C based on the Volmer-Weber growth model and also the size and density can be tuned accordingly. The results are symmetrically analyzed and discussed in conjunction with the diffusion theory and thermodynamics by utilizing AFM and SEM images, EDS maps and spectra, FFT power spectra, cross-sectional line-profiles and size and density plots.

Laser-induced atomic assembling of periodic layered nanostructures of silver nanoparticles in fluoro-polymer film matrix

International Nuclear Information System (INIS)

Bagratashvili, V N; Minaev, N V; Timashev, P S; Yusupov, V I; Rybaltovsky, A O; Firsov, V V

2010-01-01

Fluorinated acrylic polymer (FAP) films have been impregnated with silver precursor (Ag(hfac)COD) by supercritical fluid technique and next irradiated with laser (λ = 532 nm). Laser-chemically reduced Ag atoms have been assembled into massifs of Ag nanoparticles (3 – 8 nm) in FAP/Ag(hfac)COD films matrix in the form of periodic layered nanostructures (horizontal to film surface) with unexpectedly short period (90 – 180 nm). The wavelet analysis of TEM images reveals the existence of even shorter-period structures in such films. Photolysis with non-coherent light or pyrolysis of FAP/Ag(hfac)COD film results in formation of Ag nanoparticles massifs but free of any periodic nanoparticle assemblies. Our interpretation of the observed effect of laser formation of short-period nano-sized Ag nanoparticle assemblies is based on self-enhanced interference process in the course of modification of optical properties of film

Study of the alkaline cations complexation by photo-isomerizable calixarenes; Etude de la complexation de cations alcalins par des calixarenes photoisomerisables

Energy Technology Data Exchange (ETDEWEB)

Reynier, N.

1996-04-25

The first step to reduce the volume and the toxicity of radioactive waste coming from the spent fuel reprocessing is to separate long life radioisotopes from others ones with a shorter period. The aim of this study is to show that the control of the two phenomenons, complexation of the cation by the calixarenes and its de-complexation, can be envisaged by the introduction on the molecule of a chromophore group, azo benzene, able to modify the complexing site structure of the calixarenes with an isomerization trans-cis induced by ultraviolet radiation, and isomerization cis-trans thermally induced by a visible radiation. (N.C.). 112 refs., 78 figs., 23 tabs.

Directed self-assembly of nanogold using a chemically modified nanopatterned surface

Science.gov (United States)

Nidetz, Robert; Kim, Jinsang

2012-02-01

Electron-beam lithography (EBL) was used to define an aminosilane nanopatterned surface in order to electrostatically self-assemble gold nanoparticles (Au NPs). The chemically modified nanopatterned surfaces were immersed into a Au NP solution to allow the Au NPs to self-assemble. Equilibrium self-assembly was achieved in only 20 min. The number of Au NPs that self-assembled on an aminosilane dot was controlled by manipulating the diameters of both the Au NPs and the dots. Adding salt to the Au NP solution enabled the Au NPs to self-assemble in greater numbers on the same sized dot. However, the preparation of the Au NP solution containing salt was sensitive to spikes in the salt concentration. These spikes led to aggregation of the Au NPs and non-specific deposition of Au NPs on the substrate. The Au NP patterned surfaces were immersed in a sodium hydroxide solution in order to lift-off the patterned Au NPs, but no lift-off was observed without adequate physical agitation. The van der Waals forces are too strong to allow for lift-off despite the absence of electrostatic forces.

Directed self-assembly of nanogold using a chemically modified nanopatterned surface

International Nuclear Information System (INIS)

Nidetz, Robert; Kim, Jinsang

2012-01-01

Electron-beam lithography (EBL) was used to define an aminosilane nanopatterned surface in order to electrostatically self-assemble gold nanoparticles (Au NPs). The chemically modified nanopatterned surfaces were immersed into a Au NP solution to allow the Au NPs to self-assemble. Equilibrium self-assembly was achieved in only 20 min. The number of Au NPs that self-assembled on an aminosilane dot was controlled by manipulating the diameters of both the Au NPs and the dots. Adding salt to the Au NP solution enabled the Au NPs to self-assemble in greater numbers on the same sized dot. However, the preparation of the Au NP solution containing salt was sensitive to spikes in the salt concentration. These spikes led to aggregation of the Au NPs and non-specific deposition of Au NPs on the substrate. The Au NP patterned surfaces were immersed in a sodium hydroxide solution in order to lift-off the patterned Au NPs, but no lift-off was observed without adequate physical agitation. The van der Waals forces are too strong to allow for lift-off despite the absence of electrostatic forces. (paper)

Dynamics of magnetic nano-particle assembly

International Nuclear Information System (INIS)

Kondratyev, V N

2010-01-01

Ferromagnetically coupled nano-particle assembly is analyzed accounting for inter- and intra- particle electronic structures within the randomly jumping interacting moments model including quantum fluctuations due to the discrete levels and disorder. At the magnetic jump anomalies caused by quantization the magnetic state equation and phase diagram are found to indicate an existence of spinodal regions and critical points. Arrays of magnetized nano-particles with multiple magnetic response anomalies are predicted to display some specific features. In a case of weak coupling such arrays exhibit the well-separated instability regions surrounding the anomaly positions. With increasing coupling we observe further structure modification, plausibly, of bifurcation type. At strong coupling the dynamical instability region become wide while the stable regime arises as a narrow islands at small disorders. It is shown that exploring correlations of magnetic noise amplitudes represents convenient analytical tool for quantitative definition, description and study of supermagnetism, as well as self-organized criticality.

The structural coloration of textile materials using self-assembled silica nanoparticles.

Science.gov (United States)

Gao, Weihong; Rigout, Muriel; Owens, Huw

2017-01-01

The work presented investigates how to produce structural colours on textile materials by applying a surface coating of silica nanoparticles (SNPs). Uniform SNPs with particle diameters in a controlled micron size range (207-350 nm) were synthesized using a Stöber-based solvent varying (SV) method which has been reported previously. Photonic crystals (PCs) were formed on the surface of a piece of textile fabric through a process of natural sedimentation self-assembly of the colloidal suspension containing uniform SNPs. Due to the uniformity and a particular diameter range of the prepared SNPs, structural colours were observed from the fabric surface due to the Bragg diffraction of white light with the ordered structure of the silica PCs. By varying the mean particle diameter, a wide range of spectral colours from red to blue were obtained. The comparison of structural colours on fabrics and on glasses suggests that a smooth substrate is critical when producing materials with high colour intensity and spatial uniformity. This work suggested a promising approach to colour textile materials without the need for traditional dyes and/or pigments. Graphical abstract.

Layer-by-Layer Self-Assembled Ferrite Multilayer Nanofilms for Microwave Absorption

Directory of Open Access Journals (Sweden)

Jiwoong Heo

2015-01-01

Full Text Available We demonstrate a simple method for fabricating multilayer thin films containing ferrite (Co0.5Zn0.5Fe2O4 nanoparticles, using layer-by-layer (LbL self-assembly. These films have microwave absorbing properties for possible radar absorbing and stealth applications. To demonstrate incorporation of inorganic ferrite nanoparticles into an electrostatic-interaction-based LbL self-assembly, we fabricated two types of films: (1 a blended three-component LbL film consisting of a sequential poly(acrylic acid/oleic acid-ferrite blend layer and a poly(allylamine hydrochloride layer and (2 a tetralayer LbL film consisting of sequential poly(diallyldimethylammonium chloride, poly(sodium-4-sulfonate, bPEI-ferrite, and poly(sodium-4-sulfonate layers. We compared surface morphologies, thicknesses, and packing density of the two types of ferrite multilayer film. Ferrite nanoparticles (Co0.5Zn0.5Fe2O4 were prepared via a coprecipitation method from an aqueous precursor solution. The structure and composition of the ferrite nanoparticles were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, and scanning electron microscopy. X-ray diffraction patterns of ferrite nanoparticles indicated a cubic spinel structure, and energy dispersive X-ray spectroscopy revealed their composition. Thickness growth and surface morphology were measured using a profilometer, atomic force microscope, and scanning electron microscope.

Self-assembly of palladium nanoparticles on functional TiO{sub 2} nanotubes for a nonenzymatic glucose sensor

Energy Technology Data Exchange (ETDEWEB)

Chen, Xianlan [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Li, Gang; Zhang, Guowei [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); Hou, Keyu [College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Pan, Haibo, E-mail: hbpan@fzu.edu.cn [College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Du, Min [Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China)

2016-05-01

Polydiallyldimethylammonium chloride, PDDA, was used as a stabilizer and linker for functionalized TiO{sub 2} nanotubes (TiO{sub 2} NTs). Self-assembled process with palladium nanoparticles (NPs) was successfully synthesized and used for the oxidation of glucose on glassy carbon electrodes. Based on the voltammetric and amperometric results, Pd NPs efficiently catalyzed the oxidation of glucose at − 0.05 V in the presence of 0.1 M NaCl and showed excellent resistance toward interference poisoning from such interfering species as ascorbic acid, uric acid and urea. To further increase sensitivity, the Pd NPs-PDDA-TiO{sub 2} NTs/GCE was electrochemically treated with H{sub 2}SO{sub 4} and NaOH, the glucose oxidation current was magnified 2.5 times than that before pretreatments due to greatly enhancing the electron transport property of the sensor based on the increased defect sites and surface oxide species. In view of the physiological level of glucose, the wide linear concentration range of glucose (4 × 10{sup −7}–8 × 10{sup −4} M) with a detection limit of 8 × 10{sup −8} M (S/N = 3) was obviously good enough for clinical application. - Highlights: • PDDA was used as a stabilizer and linker for functionalized TiO{sub 2} nanotubes. • Self-assembled process with palladium nanoparticles was synthesized. • After treated both H{sub 2}SO{sub 4} and NaOH, the glucose response was magnified to 2.5 times. • The wide linear concentration range of glucose was obtained with a limit of 8 × 10{sup −8} M.

Imipenem/cilastatin encapsulated polymeric nanoparticles for destroying carbapenem-resistant bacterial isolates.

Science.gov (United States)

Shaaban, Mona I; Shaker, Mohamed A; Mady, Fatma M

2017-04-11

Carbapenem-resistance is an extremely growing medical threat in antibacterial therapy as the incurable resistant strains easily develop a multi-resistance action to other potent antimicrobial agents. Nonetheless, the protective delivery of current antibiotics using nano-carriers opens a tremendous approach in the antimicrobial therapy, allowing the nano-formulated antibiotics to beat these health threat pathogens. Herein, we encapsulated imipenem into biodegradable polymeric nanoparticles to destroy the imipenem-resistant bacteria and overcome the microbial adhesion and dissemination. Imipenem loaded poly Ɛ-caprolactone (PCL) and polylactide-co-glycolide (PLGA) nanocapsules were formulated using double emulsion evaporation method. The obtained nanocapsules were characterized for mean particle diameter, morphology, loading efficiency, and in vitro release. The in vitro antimicrobial and anti adhesion activities were evaluated against selected imipenem-resistant Klebsiella pneumoniae and Pseudomonas aeruginosa clinical isolates. The obtained results reveal that imipenem loaded PCL nano-formulation enhances the microbial susceptibility and antimicrobial activity of imipenem. The imipenem loaded PCL nanoparticles caused faster microbial killing within 2-3 h compared to the imipenem loaded PLGA and free drug. Successfully, PCL nanocapsules were able to protect imipenem from enzymatic degradation by resistant isolates and prevent the emergence of the resistant colonies, as it lowered the mutation prevention concentration of free imipenem by twofolds. Moreover, the imipenem loaded PCL eliminated bacterial attachment and the biofilm assembly of P. aeruginosa and K. pneumoniae planktonic bacteria by 74 and 78.4%, respectively. These promising results indicate that polymeric nanoparticles recover the efficacy of imipenem and can be considered as a new paradigm shift against multidrug-resistant isolates in treating severe bacterial infections.

Chitosan/siRNA nanoparticles encapsulated in PLGA nanofibers for siRNA delivery

DEFF Research Database (Denmark)

Chen, Menglin; Gao, Shan; Dong, Mingdong

2012-01-01

Composite nanofibers of biodegradable poly(d,l-lactic-co-glycolic acid) (PLGA) encapsulating chitosan/siRNA nanoparticles (NPs) were prepared by electrospinning. Acidic/alkaline hydrolysis and a bulk/surface degradation mechanism were investigated in order to achieve an optimized release profile...... for prolonged and efficient gene silencing. Thermo-controlled AFM in situ imaging not only revealed the integrity of the encapsulated chitosan/siRNA polyplex but also shed light on the decreasing Tg of PLGA on the fiber surfaces during release. A triphasic release profile based on bulk erosion was obtained at p......RNA transfection, where the encapsulated chitosan/siRNA NPs exhibited up to 50% EGFP gene silencing activity after 48 h post-transfection on H1299 cells....

A Method for Promoting Assembly of Metallic and Nonmetallic Nanoparticles into Interfacial Monolayer Films.

Science.gov (United States)

Xu, Yikai; Konrad, Magdalena P; Lee, Wendy W Y; Ye, Ziwei; Bell, Steven E J

2016-08-10

Two-dimensional metal nanoparticle arrays are normally constructed at liquid-oil interfaces by modifying the surfaces of the constituent nanoparticles so that they self-assemble. Here we present a general and facile new approach for promoting such interfacial assembly without any surface modification. The method use salts that have hydrophobic ions of opposite charge to the nanoparticles, which sit in the oil layer and thus reduce the Coulombic repulsion between the particles in the organic phase, allowing the particles to sit in close proximity to each other at the interface. The advantage of this method is that because it does not require the surface of the particles to be modified it allows nonmetallic particles including TiO2 and SiO2 to be assembled into dense interfacial layers using the same procedure as is used for metallic particles. This opens up a route to a new family of nanostructured functional materials.

Controlled self-assembly of PbS nanoparticles into macrostar-like hierarchical structures

International Nuclear Information System (INIS)

Li, Guowei; Li, Changsheng; Tang, Hua; Cao, Kesheng; Chen, Juan

2011-01-01

Graphical abstract: The aggregation and rotation of nanoparticles to adopt parallel orientations in three dimensions was indirectly illustrated by TEM and HRTEM images. Highlights: → Macrostar-like PbS hierarchical structures was successfully synthesized by a simple hydrothermal method and mesostars were assembled from the PbS nanocube building blocks with edge lengths of about 100 nm. → Ostwald-ripening-assisted oriented attachment is believed to play a key role in the growth behavior of novel 3D structures. → Optical properties indicating few defects on the surface of the PbS structure and exhibit large blue-shifts compared to bulk PbS. -- Abstract: The synthesis of macrostar-like PbS hierarchical structures by a simple hydrothermal method at 180 o C for 24 h is proven successful with the assistance of a new surfactant called tetrabutylammonium bromide (TBAB). The as-obtained product is characterized by means of X-ray powder diffraction, field emission scanning electron microscopy, energy dispersive spectrometry, high resolution transmission electron microscopy, and selected area electron diffraction. The presence of TBAB and NaF plays an important role in the formation of PbS macrostructures. Ostwald-ripening-assisted oriented attachment is believed to play a key role in the growth behavior of novel 3D structures. As such, a possible self-assembly mechanism is proposed to explain the formation of the said structures. The present study aims to introduce new insights into understanding the formation process of such unique hierarchical superstructures.

Unique self-assembly properties of a bridge-shaped protein dimer with quantum dots

International Nuclear Information System (INIS)

Wang, Jianhao; Jiang, Pengju; Gao, Liqian; Yu, Yongsheng; Lu, Yao; Qiu, Lin; Wang, Cheli; Xia, Jiang

2013-01-01

How protein–protein interaction affects protein–nanoparticle self-assembly is the key to the understanding of biomolecular coating of nanoparticle in biological fluids. However, the relationship between protein shape and its interaction with nanoparticles is still under-exploited because of lack of a well-conceived binding system and a method to detect the subtle change in the protein–nanoparticle assemblies. Noticing this unresolved need, we cloned and expressed a His-tagged SpeA protein that adopts a bridge-shaped dimer structure, and utilized a high-resolution capillary electrophoresis method to monitor assembly formation between the protein and quantum dots (QDs, 5 nm in diameter). We observed that the bridge-shaped structure rendered a low SpeA:QD stoichiometry at saturation. Also, close monitoring of imidazole (Im) displacement of surface-bound protein revealed a unique two-step process. High-concentration Im could displace surface-bound SpeA protein and form a transient QD–protein intermediate, through a kinetically controlled displacement process. An affinity-driven equilibrium step then followed, resulting in re-assembling of the QD–protein complex in about 1 h. Through a temporarily formed intermediate, Im causes a rearrangement of His-tagged proteins on the surface. Thus, our work showcases that the synergistic interplay between QD–His-tag interaction and protein–protein interaction can result in unique properties of protein–nanoparticle assembly for the first time

Unique self-assembly properties of a bridge-shaped protein dimer with quantum dots

Science.gov (United States)

Wang, Jianhao; Jiang, Pengju; Gao, Liqian; Yu, Yongsheng; Lu, Yao; Qiu, Lin; Wang, Cheli; Xia, Jiang

2013-09-01

How protein-protein interaction affects protein-nanoparticle self-assembly is the key to the understanding of biomolecular coating of nanoparticle in biological fluids. However, the relationship between protein shape and its interaction with nanoparticles is still under-exploited because of lack of a well-conceived binding system and a method to detect the subtle change in the protein-nanoparticle assemblies. Noticing this unresolved need, we cloned and expressed a His-tagged SpeA protein that adopts a bridge-shaped dimer structure, and utilized a high-resolution capillary electrophoresis method to monitor assembly formation between the protein and quantum dots (QDs, 5 nm in diameter). We observed that the bridge-shaped structure rendered a low SpeA:QD stoichiometry at saturation. Also, close monitoring of imidazole (Im) displacement of surface-bound protein revealed a unique two-step process. High-concentration Im could displace surface-bound SpeA protein and form a transient QD-protein intermediate, through a kinetically controlled displacement process. An affinity-driven equilibrium step then followed, resulting in re-assembling of the QD-protein complex in about 1 h. Through a temporarily formed intermediate, Im causes a rearrangement of His-tagged proteins on the surface. Thus, our work showcases that the synergistic interplay between QD-His-tag interaction and protein-protein interaction can result in unique properties of protein-nanoparticle assembly for the first time.

"Cloud" assemblies: quantum dots form electrostatically bound dynamic nebulae around large gold nanoparticles.

Science.gov (United States)

Lilly, G Daniel; Lee, Jaebeom; Kotov, Nicholas A

2010-10-14

Dynamic self-assembled structures of nanoparticles can be produced using predominantly electrostatic interactions. Such assemblies were made from large, positively charged Au metal nanoparticles surrounded by an electrostatically bound cloud of smaller, negatively charged CdSe/ZnS or CdTe quantum dots. At low concentrations they are topologically similar to double electric layers of ions and corona-like assemblies linked by polymer chains. They can also be compared to the topological arrangement of some planetary systems in space. The great advantages of the cloud assemblies are (1) their highly dynamic nature compared to more rigid covalently bound assemblies, (2) simplicity of preparation, and (3) exceptional versatility in components and resulting optical properties. Photoluminescence intensity enhancement originating from quantum resonance between excitons and plasmons was observed for CdSe/ZnS quantum dots, although CdTe dots displayed emission quenching. To evaluate more attentively their dynamic behavior, emission data were collected for the cloud-assemblies with different ratios of the components and ionic strengths of the media. The emission of the system passes through a maximum for 80 QDs ∶ 1 Au NP as determined by the structure of the assemblies and light absorption conditions. Ionic strength dependence of luminescence intensity contradicts the predictions based on the Gouy-Chapman theory and osmotic pressure at high ionic strengths due to formation of larger chaotic colloidally stable assemblies. "Cloud" assemblies made from different nanoscale components can be used both for elucidation of most fundamental aspects of nanoparticle interactions, as well as for practical purposes in sensing and biology.

Lanthanides and actinides extraction by calixarenes containing CMPO groups

International Nuclear Information System (INIS)

Garcia Carrera, A.

2001-01-01

In the framework of the French program SPIN concerning the radioactive waste management, researches are performed to develop processes allowing the separation of long-lived radioisotopes in order to their transmutation or their specific conditioning. These studies deal with the extraction and the separation of trivalent lanthanides and actinides in acid solution. Many systems ''calixarene-diluent-aqueous phase'' are examined by extraction liquid-liquid and membrane transport. The extraction efficiency and the selectivity of the synthesized calixarene-CMPO and of the CMPO are compared with these cations, as the nitric acid extraction by these molecules. (A.L.B.)

Nanoparticle assembled microcapsules for application as pH and ammonia sensor.

Science.gov (United States)

Amali, Arlin Jose; Awwad, Nour H; Rana, Rohit Kumar; Patra, Digambara

2011-12-05

The encapsulation of molecular probes in a suitable nanostructured matrix can be exploited to alter their optical properties and robustness for fabricating efficient chemical sensors. Despite high sensitivity, simplicity, selectivity and cost effectiveness, the photo-destruction and photo-bleaching are the serious concerns while utilizing molecular probes. Herein we demonstrate that hydroxy pyrene trisulfonate (HPTS), a pH sensitive molecular probe, when encapsulated in a microcapsule structure prepared via the assembly of silica nanoparticles mediated by poly-L-lysine and trisodium citrate, provides a robust sensing material for pH sensing under the physiological conditions. The temporal evolution under continuous irradiation indicates that the fluorophore inside the silica microcapsule is extraordinarily photostable. The fluorescence intensity alternation at dual excitation facilitates for a ratiometic sensing of the pH, however, the fluorescence lifetime is insensitive to hydrogen ion concentration. The sensing scheme is found to be robust, fast and simple for the measurement of pH in the range 5.8-8.0, and can be successfully applied for the determination of ammonia in the concentration range 0-1.2 mM, which is important for aquatic life and the environment. Copyright © 2011 Elsevier B.V. All rights reserved.

Annealing of magnetic nanoparticles for their encapsulation into microcarriers guided by vascular magnetic resonance navigation

Energy Technology Data Exchange (ETDEWEB)

Pouponneau, Pierre; Segura, Vincent [Ecole Polytechnique de Montreal (EPM), NanoRobotics Laboratory, Department of Computer and Software Engineering and Institute of Biomedical Engineering (Canada); Savadogo, Oumarou [Ecole Polytechnique de Montreal (EPM), Laboratoire de Nouveaux Materiaux pour l' electrochimie et l' energie (Canada); Leroux, Jean-Christophe [Universite de Montreal, Faculty of Pharmacy (Canada); Martel, Sylvain, E-mail: sylvain.martel@polymtl.ca [Ecole Polytechnique de Montreal (EPM), NanoRobotics Laboratory, Department of Computer and Software Engineering and Institute of Biomedical Engineering (Canada)

2012-12-15

Iron, cobalt and iron-cobalt nanoparticle properties, such as diameter, saturation magnetization (Ms), crystal structure, surface composition and stability in physiological solutions, were investigated according to the annealing temperature used prior to their encapsulation into poly(d, l-lactic-co-glycolic acid) (PLGA) microcarriers. These new 60-{mu}m microparticles should exhibit an Ms around 70 emu g{sup -1} to be guided in real time from their intravascular injection site to a tumor with a magnetic resonance imaging scanner. The challenge in the preparation of the nanoparticles consisted in limiting Ms loss by oxidation and the release of metallic ions. It was found that when the annealing temperature reached 650 Degree-Sign C, Fe nanoparticles coalesced, the mean diameter reached (O) 361 {+-} 138 nm and Ms increased to 171 emu g{sup -1}. These nanoparticles exhibited a core of {alpha}-Fe and a shell of Fe{sub 3}O{sub 4}. On the opposite, Co nanoparticle properties were not affected by the annealing temperature: O and Ms were around 120 nm and 140 emu g{sup -1}, respectively. FeCo (60:40, atomic percent) nanoparticles coalesced at an annealing temperature >550 Degree-Sign C, O and Ms reached 217 nm and 213 emu g{sup -1}, respectively. Co and FeCo nanoparticles with a Co atomic proportion >15 % were coated with a graphite shell when the temperature was set to 550 Degree-Sign C. In physiological solution, Fe and Co nanoparticles significantly released more ions than FeCo nanoparticles. After the preparation steps prior to their encapsulation, the Ms of Fe and FeCo nanoparticles decreased by 25 and 3 %, respectively. FeCo-PLGA microparticles possessed a relatively high Ms (73 emu g{sup -1}) while that of Fe-PLGA microparticle (20 emu g{sup -1}) was too low for efficient targeting. The graphite shell was efficient to preserve Ms during the encapsulation.

New amphiphilic glycopolypeptide conjugate capable of self-assembly in water into reduction-sensitive micelles for triggered drug release

Energy Technology Data Exchange (ETDEWEB)

Yang, Hui-Kang [DSAPM Lab and PCFM Lab, Department of Polymer and Materials Science, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Zhang, Li-Ming, E-mail: ceszhlm@mail.sysu.edu.cn [DSAPM Lab and PCFM Lab, Department of Polymer and Materials Science, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Science, Sun Yat-sen University, Guangzhou 510006 (China)

2014-08-01

For the development of biomimetic carriers for stimuli-sensitive delivery of anticancer drugs, a novel amphiphilic glycopolypeptide conjugate containing the disulfide bond was prepared for the first time by the ring-opening polymerization of benzyl glutamate N-carboxy anhydride in the presence of (propargyl carbamate)ethyl dithio ethylamine and then click conjugation with α-azido dextran. Its structure was characterized by Fourier-transform infrared spectroscopy and nuclear magnetic resonance analyses. Owing to its amphiphilic nature, such a conjugate could self assemble into nanosize micelles in aqueous medium, as confirmed by fluorometry, transmission electron microscopy and dynamic light scattering. For the resultant micelles, it was found to encapsulate poorly water-soluble anticancer drug (methotrexate, MTX) with the loading efficiency of 45.2%. By the in vitro drug release tests, the release rate of encapsulated MTX was observed to be accelerated significantly in the presence of 10 mM 1,4-dithio-DL-threitol (DTT), analogous to the intracellular redox potential. - Graphical abstract: New amphiphilic glycopolypeptide conjugate containing the disulfide bond could self-assemble in aqueous solution into reduction-sensitive micelles for triggered release of an anticancer drug (methotrexate, MTX) in the presence of 10 mM 1,4-dithio-DL-threitol (DTT). - Highlights: • Amphiphilic glycopolypeptide conjugate containing disulfide bond was prepared. • Such a conjugate self assembled in aqueous solution into nanosize micelles. • The resultant micelles could encapsulate effectively methotrexate drug. • The drug-loaded micelles showed a reduction-sensitive drug release behavior.

New amphiphilic glycopolypeptide conjugate capable of self-assembly in water into reduction-sensitive micelles for triggered drug release

International Nuclear Information System (INIS)

Yang, Hui-Kang; Zhang, Li-Ming

2014-01-01

For the development of biomimetic carriers for stimuli-sensitive delivery of anticancer drugs, a novel amphiphilic glycopolypeptide conjugate containing the disulfide bond was prepared for the first time by the ring-opening polymerization of benzyl glutamate N-carboxy anhydride in the presence of (propargyl carbamate)ethyl dithio ethylamine and then click conjugation with α-azido dextran. Its structure was characterized by Fourier-transform infrared spectroscopy and nuclear magnetic resonance analyses. Owing to its amphiphilic nature, such a conjugate could self assemble into nanosize micelles in aqueous medium, as confirmed by fluorometry, transmission electron microscopy and dynamic light scattering. For the resultant micelles, it was found to encapsulate poorly water-soluble anticancer drug (methotrexate, MTX) with the loading efficiency of 45.2%. By the in vitro drug release tests, the release rate of encapsulated MTX was observed to be accelerated significantly in the presence of 10 mM 1,4-dithio-DL-threitol (DTT), analogous to the intracellular redox potential. - Graphical abstract: New amphiphilic glycopolypeptide conjugate containing the disulfide bond could self-assemble in aqueous solution into reduction-sensitive micelles for triggered release of an anticancer drug (methotrexate, MTX) in the presence of 10 mM 1,4-dithio-DL-threitol (DTT). - Highlights: • Amphiphilic glycopolypeptide conjugate containing disulfide bond was prepared. • Such a conjugate self assembled in aqueous solution into nanosize micelles. • The resultant micelles could encapsulate effectively methotrexate drug. • The drug-loaded micelles showed a reduction-sensitive drug release behavior

Lanthanides and actinides extraction by calixarenes containing CMPO groups; Extraction des lanthanides et des actinides au moyen de calixarenes portant des groupements CMPO

Energy Technology Data Exchange (ETDEWEB)

Garcia Carrera, A

2001-07-01

In the framework of the French program SPIN concerning the radioactive waste management, researches are performed to develop processes allowing the separation of long-lived radioisotopes in order to their transmutation or their specific conditioning. These studies deal with the extraction and the separation of trivalent lanthanides and actinides in acid solution. Many systems ''calixarene-diluent-aqueous phase'' are examined by extraction liquid-liquid and membrane transport. The extraction efficiency and the selectivity of the synthesized calixarene-CMPO and of the CMPO are compared with these cations, as the nitric acid extraction by these molecules. (A.L.B.)

Binary self-assembly of highly symmetric DNA nanocages via sticky-end engineering

Institute of Scientific and Technical Information of China (English)

Xiao-Rong Wu; Chen-Wei Wu; Fei Ding; Cheng Tian; Wen Jiang; Cheng-De Mao; Chuan Zhang

2017-01-01

Discrete and symmetric three-dimensional (3D) DNA nanocages have been revoked as excellent candidates for various applications,such as guest component encapsulation and organization (e.g.dye molecules,proteins,inorganic nanoparticles,etc.) to construct new materials and devices.To date,a large variety of DNA nanocages has been synthesized through assembling small individual DNA motifs into predesigned structures in a bottom-up fashion.Most of them rely on the assembly using multiple copies of single type of motifs and a few sophisticated nanostructures have been engineered by co-assembling multi-types of DNA tiles simultaneously.However,the availability of complex DNA nanocages is still limited.Herein,we demonstrate that highly symmetric DNA nanocages consisted of binary DNA pointstar motifs can be easily assembled by deliberately engineering the sticky-end interaction between the component building blocks.As such,DNA nanocages with new geometries,including elongated tetrahedron (E-TET),rhombic dodecahedron (R-DOD),and rhombic triacontahedron (R-TRI) are successfully synthesized.Moreover,their design principle,assembly process,and structural features are revealed by polyacryalmide gel electrophoresis (PAGE),atomic force microscope (AFM) imaging,and cryogenic transmission electron microscope imaging (cryo-TEM) associated with single particle reconstruction.

Self-assembled tunable photonic hyper-crystals.

Science.gov (United States)

Smolyaninova, Vera N; Yost, Bradley; Lahneman, David; Narimanov, Evgenii E; Smolyaninov, Igor I

2014-07-16

We demonstrate a novel artificial optical material, the "photonic hyper-crystal", which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing.

Synthesis and Catalytic Evaluation of Dendrimer-Encapsulated Cu Nanoparticles: An Undergraduate Experiment Exploring Catalytic Nanomaterials

Science.gov (United States)

Feng, Z. Vivian; Lyon, Jennifer L.; Croley, J. Sawyer; Crooks, Richard M.; Vanden Bout, David A.; Stevenson, Keith J.

2009-01-01

Copper nanoparticles were synthesized using generation 4 hydroxyl-terminated (G4-OH) poly(amidoamine) (PAMAM) dendrimers as templates. The synthesis is conducted by coordinating copper ions with the interior amines of the dendrimer, followed by chemical reduction to form dendrimer-encapsulated copper nanoparticles (Cu-DEN). The catalytic…

Water-soluble light-emitting nanoparticles prepared by non-covalent bond self-assembly of a hydroxyl group functionalized oligo(p-phenyleneethynylene) with different water-soluble polymers

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

Water-soluble light-emitting nanoparticles were prepared from hydroxyl group functionalized oligos(p-phenyleneethynylene) (OHOPEL) and water-soluble polymers(PEG,PAA,and PG) by non-covalent bond self-assembly.Their structure and optoelectronic properties were investigated through dynamic light scattering(DLS) ,UV and PL spectroscopy.The optical properties of OHOPEL-based water-soluble nanoparticles exhibited the same properties as that found in OHOPEL films,indicating the existence of interchain-aggregation of OHOPELs in the nanoparticles.OHOPEL-based nanoparticles prepared from conjugated oligomers show smaller size and lower dispersity than nanoparticles from conjugated polymers,which means that the structures of water-soluble nanoparticles are linked to the conjugated length.Furthermore,the OHOPEL/PG and OHOPEL/PAA systems produced smaller particles and lower polydispersity than the OHOPEL/PEG system,indicating that there may exist influence of the strength of non-covalent bonds on the size and degree of dispersity of the nanoparticles.

Inducing self-assembly of Y2BaCuO5 nanoparticles via Ca-doping for improved pinning in YBa2Cu3O7-x

International Nuclear Information System (INIS)

Barnes, P.N.; Haugan, T.J.; Baca, F.J.; Varanasi, C.V.; Wheeler, R.; Meisenkothen, F.; Sathiraju, S.

2009-01-01

Different mechanisms may exists as a means to provide additional or specialized enhancement of existing nanoparticulate pinning in YBa 2 Cu 3 O 7-x (YBCO) thin films. In the particular case of Y 2 BaCuO 5 (Y211) nanoparticles, Ca-doping of these nanoparticles via addition to the Y211 target material provides an additional increase to the J c (H). YBCO + Y211 samples were created by pulsed laser deposition with alternating targets of YBCO with Y211 and Y211 doped with Ca. Initial indications suggest that this improvement in pinning results from some scattered short-ranged self-assembly of the nanoparticles into short nanocolumns.

ParaCEST agents encapsulated in Reverse nano-Assembled Capsules (RACs): How slow molecular tumbling can quench CEST

Science.gov (United States)

Farashishiko, Annah; Slack, Jacqueline R.; Botta, Mauro; Woods, Mark

2018-04-01

Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the series the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM3+ into a Reverse Assembled nano-Capsule. An aggregate can be generated between this chelate and polyacrylic acid after the addition of ethylene diamine. Subsequent addition of polyallylamine hydrochloride followed by silica nanoparticles generated a robust encapsulating shell and afforded capsule with a mean hydrodynamic diameter of 650 ± 250 nm. Unfortunately this encapsulation did not have the effect of amplifying the CEST effect per agent, but quenched the CEST altogether. A significant proportion of the quenching effect of encapsulation could be attributed to the effect of slowing molecular tumbling, which is inevitable when the chelate is incorporated into a nano-scale material. This increases the transverse relaxation rate of chelate protons and a theoretical examination using Solomon Bloembergen Morgan theory and the Bloch equations shows that the increase in the transverse relaxation rate constant for the amide protons, in even modestly sized nano-materials, is sufficient to significantly quench CEST.

Self-organized architectures from assorted DNA-framed nanoparticles

Science.gov (United States)

Liu, Wenyan; Halverson, Jonathan; Tian, Ye; Tkachenko, Alexei V.; Gang, Oleg

2016-09-01

The science of self-assembly has undergone a radical shift from asking questions about why individual components self-organize into ordered structures, to manipulating the resultant order. However, the quest for far-reaching nanomanufacturing requires addressing an even more challenging question: how to form nanoparticle (NP) structures with designed architectures without explicitly prescribing particle positions. Here we report an assembly concept in which building instructions are embedded into NPs via DNA frames. The integration of NPs and DNA origami frames enables the fabrication of NPs with designed anisotropic and selective interactions. Using a pre-defined set of different DNA-framed NPs, we show it is possible to design diverse planar architectures, which include periodic structures and shaped meso-objects that spontaneously emerge on mixing of the different topological types of NP. Even objects of non-trivial shapes, such as a nanoscale model of Leonardo da Vinci's Vitruvian Man, can be self-assembled successfully.

Redox-sensitive self-assembled nanoparticles based on alpha-tocopherol succinate-modified heparin for intracellular delivery of paclitaxel.

Science.gov (United States)

Yang, Xiaoye; Cai, Xiaoqing; Yu, Aihua; Xi, Yanwei; Zhai, Guangxi

2017-06-15

To remedy the problems riddled in cancer chemotherapy, such as poor solubility, low selectivity, and insufficient intra-cellular release of drugs, novel heparin-based redox-sensitive polymeric nanoparticles were developed. The amphiphilic polymer, heparin-alpha-tocopherol succinate (Hep-cys-TOS) was synthesized by grafting hydrophobic TOS to heparin using cystamine as the redox-sensitive linker, which could self-assemble into nanoparticles in phosphate buffer saline (PBS) with low critical aggregation concentration (CAC) values ranging from 0.026 to 0.093mg/mL. Paclitaxel (PTX)-loaded Hep-cys-TOS nanoparticles were prepared via a dialysis method, exhibiting a high drug-loading efficiency of 18.99%. Physicochemical properties of the optimized formulation were characterized by dynamic light scattering (DLS), transmission electron microscope (TEM) and differential scanning calorimetry (DSC). Subsequently, the redox-sensitivity of Hep-cys-TOS nanoparticles was confirmed by the changes in size distribution, morphology and appearance after dithiothreitol (DTT) treatment. Besides, the in vitro release of PTX from Hep-cys-TOS nanoparticles also exhibited a redox-triggered profile. Also, the uptake behavior and pathways of coumarin 6-loaded Hep-cys-TOS nanoparticles were investigated, suggesting the nanoparticles could be taken into MCF-7 cells in energy-dependent, caveolae-mediated and cholesterol-dependent endocytosis manners. Later, MTT assays of different PTX-free and PTX-loaded formulations revealed the desirable safety of PTX-free nanoparticles and the enhanced anti-cancer activity of PTX-loaded Hep-cys-TOS nanoparticles (IC 50 =0.79μg/mL). Apoptosis study indicated the redox-sensitive formulation could induce more apoptosis of MCF-7 cells than insensitive one (55.2% vs. 41.7%), showing the importance of intracellular burst release of PTX. Subsequently, the hemolytic toxicity confirmed the safety of the nanoparticles for intravenous administration. The results

Flower-like self-assembly of gold nanoparticles for highly sensitive electrochemical detection of chromium(VI)

International Nuclear Information System (INIS)

Ouyang Ruizhuo; Bragg, Stefanie A.; Chambers, James Q.; Xue Ziling

2012-01-01

Highlights: ► Fabrication of a flower-like self-assembly of two AuNP layers on a GCE. ► Cr(VI) detection: 10–1200 ng L −1 concentration range; 2.9 ng L −1 detection limit. ► The 1st AuNP layer on the GCE surface as anchors for a thiol sol–gel film. ► The sol–gel film link the 1st AuNP layer to the 2nd AuNP layer. ► Functionalization of the 2nd AuNP layer by a thiol pyridinium for HCrO 4 − detection. - Abstract: We report here the fabrication of a flower-like self-assembly of gold nanoparticles (AuNPs) on a glassy carbon electrode (GCE) as a highly sensitive platform for ultratrace Cr(VI) detection. Two AuNP layers are used in the current approach, in which the first is electroplated on the GCE surface as anchors for binding to an overcoated thiol sol–gel film derived from 3-mercaptopropyltrimethoxysilane (MPTS). The second AuNP layer is then self-assembled on the surface of the sol–gel film, forming flower-like gold nanoelectrodes enlarging the electrode surface. When functionalized by a thiol pyridinium, the fabricated electrode displays a well-defined peak for selective Cr(VI) reduction with an unusually large, linear concentration range of 10–1200 ng L −1 and a low detection limit of 2.9 ng L −1 . In comparison to previous approaches using MPTS and AuNPs on Au electrodes, the current work expands the use of AuNPs to the GCE. Subsequent functionalization of the secondary AuNPs by a thiol pyridinium and adsorption/preconcentration of Cr(VI) lead to the unusually large detection range and high sensitivity. The stepwise preparation of the electrode has been characterized by electrochemical impedance spectroscopy (EIS), scanning electronic microscopy (SEM), and IR. The newly designed electrode exhibits good stability, and has been successfully employed to measure chromium in a pre-treated blood sample. The method demonstrates acceptable fabrication reproducibility and accuracy.

Selective inhibition of MG-63 osteosarcoma cell proliferation induced by curcumin-loaded self-assembled arginine-rich-RGD nanospheres.

Science.gov (United States)

Chang, Run; Sun, Linlin; Webster, Thomas J

2015-01-01

Osteosarcoma is the most frequent primary malignant form of bone cancer, comprising 30% of all bone cancer cases. The objective of this in vitro study was to develop a treatment against osteosarcoma with higher selectivity toward osteosarcoma cells and lower cytotoxicity toward normal healthy osteoblast cells. Curcumin (or diferuloylmethane) has been found to have antioxidant and anticancer effects by multiple cellular pathways. However, it has lower water solubility and a higher degradation rate in alkaline conditions. In this study, the amphiphilic peptide C18GR7RGDS was used as a curcumin carrier in aqueous solution. This peptide contains a hydrophobic aliphatic tail group leading to their self-assembly by hydrophobic interactions, as well as a hydrophilic head group composed of an arginine-rich and an arginine-glycine-aspartic acid structure. Through characterization by transmission electron microscopy, self-assembled structures of spherical amphiphilic nanoparticles (APNPs) with diameters of 10-20 nm in water and phosphate-buffered saline were observed, but this structure dissociated when the pH value was reduced to 4. Using a method of codissolution with acetic acid and dialysis tubing, the solubility of curcumin was enhanced and a homogeneous solution was formed in the presence of APNPs. Successful encapsulation of curcumin in APNPs was then confirmed by Fourier transform infrared and X-ray diffraction analyses. The cytotoxicity and cellular uptake of the APNP/curcumin complexes on both osteosarcoma and normal osteoblast cell lines were also evaluated by methyl-thiazolyl-tetrazolium assays and confocal fluorescence microscopy. The results showed that the curcumin-loaded APNPs had significant selective cytotoxicity against MG-63 osteosarcoma cells when compared with normal osteoblasts. We have demonstrated for the first time that APNPs can encapsulate hydrophobic curcumin in their hydrophobic cores, and curcumin-loaded APNPs could be an innovative treatment

Surface-Engineered Nanocontainers Based on Molecular Self-Assembly and Their Release of Methenamine

Directory of Open Access Journals (Sweden)

Minghui Zhang

2018-02-01

Full Text Available The mixing of polymers and nanoparticles is opening pathways for engineering flexible composites that exhibit advantageous functional properties. To fabricate controllable assembling nanocomposites for efficiently encapsulating methenamine and releasing them on demand, we functionalized the surface of natural halloysite nanotubes (HNTs selectively with polymerizable gemini surfactant which has peculiar aggregation behavior, aiming at endowing the nanomaterials with self-assembly and stimulative responsiveness characteristics. The micromorphology, grafted components and functional groups were identified using transmission electron microscopy (TEM, thermogravimetric analysis (TGA, Fourier transform infrared (FTIR spectroscopy, and X-ray photoelectron spectroscopy (XPS. The created nanocomposites presented various characteristics of methenamine release with differences in the surface composition. It is particularly worth mentioning that the controlled release was more efficient with the increase of geminized monomer proportion, which is reasonably attributed to the fact that the amphiphilic geminized moieties with positive charge and obvious hydrophobic interactions interact with the outer and inner surface in different ways through fabricating polymeric shell as release stoppers at nanotube ends and forming polymer brush into the nanotube lumen for guest immobilization. Meanwhile, the nanocomposites present temperature and salinity responsive characteristics for the release of methenamine. The combination of HNTs with conjugated functional polymers will open pathways for engineering flexible composites which are promising for application in controlled release fields.

Self-Assembled Nanoparticles of Glycyrrhetic Acid-Modified Pullulan as a Novel Carrier of Curcumin

Directory of Open Access Journals (Sweden)

Roufen Yuan

2014-08-01

Full Text Available Glycyrrhetic acid (GA-modified pullulan nanoparticles (GAP NPs were synthesized as a novel carrier of curcumin (CUR with a degree of substitution (DS of GA moieties within the range of 1.2–6.2 groups per hundred glucose units. In the present study, we investigated the physicochemical characteristics, release behavior, in vitro cytotoxicity and cellular uptake of the particles. Self-assembled GAP NPs with spherical shapes could readily improve the water solubility and stability of CUR. The CUR release was sustained and pH-dependent. The cellular uptake of CUR-GAP NPs was confirmed by green fluorescence in the cells. An MTT study showed CUR-GAP NPs with higher cytotoxicity in HepG2 cells than free CUR, but GAP NPs had no significant cytotoxicity. GAP is thus an excellent carrier for the solubilization, stabilization, and controlled delivery of CUR.

Investigating self-assembly and metal nanoclusters in aqueous di-block copolymers solutions

CERN Document Server

Lo Celso, F; Triolo, R; Triolo, A; Strunz, P; Bronstein, L; Zwanziger, J; Lin, J S

2002-01-01

Self-assembling properties of di-block copolymers/ surfactant hybrids in aqueous solution can be exploited to obtain metal nanoparticles stable dispersion. Results will be presented here for polystyrene-block-poly(ethylene oxide) solutions. A SANS structural investigation has been performed over different molecular weights of both hydrophilic and hydrophobic block, by varying temperature and concentration of the copolymer. A SAXS characterization of micellar systems containing Pt nanoparticles is reported. (orig.)

The Assembly of Cell-Encapsulating Microscale Hydrogels Using Acoustic Waves

Science.gov (United States)

Xu, Feng; Finley, Thomas Dylan; Turkaydin, Muge; Sung, Yuree; Gurkan, Umut Atakan; Yavuz, Ahmet Sinan; Guldiken, Rasim; Demirci, Utkan

2011-01-01

Microscale hydrogels find widespread applications in medicine and biology, e.g., as building blocks for tissue engineering and regenerative medicine. In these applications, these microgels are assembled to fabricate large complex 3D constructs. The success of this approach requires non-destructive and high throughput assembly of the microgels. Although various assembly methods have been developed based on modifying interfaces, and using microfluidics, so far, none of the available assembly technologies have shown the ability to assembly microgels using non-invasive fields rapidly within seconds in an efficient way. Acoustics has been widely used in biomedical area to manipulatedroplets, cells and biomolecules. In this study, we developed a simple, non-invasiveacoustic assembler for cell-encapsulating microgels with maintained cell viability (>93%). We assessed the assembler for both microbeads (with diameter of 50 µm and 100 µm) and microgels of different sizes and shapes (e.g., cubes, lock-and-key shapes, tetris, saw) in microdroplets (with volume of 10 µL, 20 µL, 40 µL, 80 µL). The microgels were assembled in second sin a non-invasive manner. These results indicate that the developed acoustic approach could become an enabling biotechnology tool for tissue engineering, regenerative medicine, pharmacology studies and high throughput screening applications. PMID:21820734

Icosahedral plant viral nanoparticles - bioinspired synthesis of nanomaterials/nanostructures.

Science.gov (United States)

Narayanan, Kannan Badri; Han, Sung Soo

2017-10-01

Viral nanotechnology utilizes virus nanoparticles (VNPs) and virus-like nanoparticles (VLPs) of plant viruses as highly versatile platforms for materials synthesis and molecular entrapment that can be used in the nanotechnological fields, such as in next-generation nanoelectronics, nanocatalysis, biosensing and optics, and biomedical applications, such as for targeting, therapeutic delivery, and non-invasive in vivo imaging with high specificity and selectivity. In particular, plant virus capsids provide biotemplates for the production of novel nanostructured materials with organic/inorganic moieties incorporated in a very precise and controlled manner. Interestingly, capsid proteins of spherical plant viruses can self-assemble into well-organized icosahedral three-dimensional (3D) nanoscale multivalent architectures with high monodispersity and structural symmetry. Using viral genetic and protein engineering of icosahedral viruses with a variety of sizes, the interior, exterior and the interfaces between coat protein (CP) subunits can be manipulated to fabricate materials with a wide range of desirable properties allowing for biomineralization, encapsulation, infusion, controlled self-assembly, and multivalent ligand display of nanoparticles or molecules for varied applications. In this review, we discuss the various functional nanomaterials/nanostructures developed using the VNPs and VLPs of different icosahedral plant viruses and their nano(bio)technological and nanomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

ICAM-1 targeted catalase encapsulated PLGA-b-PEG nanoparticles against vascular oxidative stress.

Science.gov (United States)

Sari, Ece; Tunc-Sarisozen, Yeliz; Mutlu, Hulya; Shahbazi, Reza; Ucar, Gulberk; Ulubayram, Kezban

2015-01-01

Targeted delivery of therapeutics is the favourable idea, whereas it is possible to distribute the therapeutically active drug molecule only to the site of action. For this purpose, in this study, catalase encapsulated poly(D,L-lactide-co-glycolide)-block-poly(ethylene glycol) (PLGA-b-PEG) nanoparticles were developed and an endothelial target molecule (anti-ICAM-1) was conjugated to this carrier system in order to decrease the oxidative stress level in the target site. According to the enzymatic activity results, initial catalase activity of nanoparticles was increased from 27.39 U/mg to up to 45.66 U/mg by adding 5 mg/mL bovine serum albumin (BSA). After 4 h, initial catalase activity was preserved up to 46.98% while free catalase retained less than 4% of its activity in proteolytic environment. Furthermore, FITC labelled anti-ICAM-1 targeted catalase encapsulated nanoparticles (anti-ICAM-1/CatNPs) were rapidly taken up by cultured endothelial cells and concomitantly endothelial cells were resistant to H2O2 induced oxidative impairment.

A Switchable Gold Catalyst by Encapsulation in a Self-Assembled Cage

KAUST Repository

Jans, Anne C. H.

2016-08-19

Dinuclear gold complexes have the ability to interact with one or more substrates in a dual-activation mode, leading to different reactivity and selectivity than their mononuclear relatives. In this contribution, this difference was used to control the catalytic properties of a gold-based catalytic system by site-isolation of mononuclear gold complexes by selective encapsulation. The typical dual-activation mode is prohibited by this catalyst encapsulation, leading to typical behavior as a result of mononuclear activation. This strategy can be used as a switch (on/off) for a catalytic reaction and also permits reversible control over the product distribution during the course of a reaction.

A Switchable Gold Catalyst by Encapsulation in a Self-Assembled Cage

KAUST Repository

Jans, Anne C. H.; Gó mez-Suá rez, Adriá n; Nolan, Steven P.; Reek, Joost N. H.

2016-01-01

Dinuclear gold complexes have the ability to interact with one or more substrates in a dual-activation mode, leading to different reactivity and selectivity than their mononuclear relatives. In this contribution, this difference was used to control the catalytic properties of a gold-based catalytic system by site-isolation of mononuclear gold complexes by selective encapsulation. The typical dual-activation mode is prohibited by this catalyst encapsulation, leading to typical behavior as a result of mononuclear activation. This strategy can be used as a switch (on/off) for a catalytic reaction and also permits reversible control over the product distribution during the course of a reaction.

Electro-spray ionization - mass spectrometry (ESI/MS) and molecular modelling, two complementary approaches. Application to calixarenes

International Nuclear Information System (INIS)

Allain, F.; Virelizier, H.; Moulin, Ch.; Lamare, V.; Dozol, J.F.

2001-01-01

The molecular dynamics simulation and the experimental results obtained by the ESI/MS technique have shown that the stability of the calixarene - alkaline cation complexes is dependent of the medium. Indeed, in solution, the calixarene presents a strong affinity for cesium whereas in gaseous phase, the strong affinity is for sodium. The stability of the [calixarene+Na] + complexes depends of the nature of the medium too; these two techniques having shown that the presence of a small quantity of water in the dilution solvent stabilizes the complex. At last, calixarenes with benzo groups on their crown have an affinity for sodium which is weak in solution but strong in gaseous phase. These different results show the excellent complementarity between the two techniques. (O.M.)

Semiconducting, Magnetic or Superconducting Nanoparticles encapsulated in Carbon Shells by RAPET method.

Directory of Open Access Journals (Sweden)

Aharon Gedanken

2008-06-01

Full Text Available An efficient, solvent-free, environmentally friendly, RAPET (Reactions under Autogenic Pressure at Elevated Temperaturesynthetic approach is discussed for the fabrication of core-shell nanostructures. The semiconducting, magnetic orsuperconducting nanoparticles are encapsulated in a carbon shell. RAPET is a one-step, thermal decomposition reaction ofchemical compound (s followed by the formation of core-shell nanoparticles in a closed stainless steel reactor. Therepresentative examples are discussed, where a variety of nanomaterials are trapped in situ in a carbon shell that offersfascinating properties.

Nano self-assembly of recombinant human gelatin conjugated with α-tocopheryl succinate for Hsp90 inhibitor, 17-AAG, delivery.

Science.gov (United States)

Won, Young-Wook; Yoon, Sun-Mi; Sonn, Chung Hee; Lee, Kyung-Mi; Kim, Yong-Hee

2011-05-24

A wide variety of drug delivery systems have been developed for the delivery of anticancer agents. One of the most frequently used natural biomaterials in drug delivery systems is polysaccharides; however, they are difficult to digest and to eliminate from the body after systemic administration due to their high molecular weight natures and the absence of degrading enzymes. Therefore, the development of degradable and eliminable natural biomaterials is critical for successful in vivo applications. In the present study, we report the development of self-assembled biodegradable nanoparticles based on recombinant human gelatin (rHG) modified with alpha-tocopheryl succinate (TOS). The rHG-TOS nanoparticles efficiently encapsulated 17-AAG (17-allylamino-17-demethoxygeldanamycin), a small molecular anticancer drug targeting heat shock protein 90. The formation of 17-AAG-loaded nanoparticles was confirmed using TEM and dynamic light scattering analysis and found to be within the size of 90-220 nm. The loading efficiency, sustained release pattern, and stability of 17-AAG from the rHG-TOS nanoparticles were determined using HPLC. Furthermore, the passive targeting of rHG-TOS nanoparticles to the tumor area via enhanced permeability and retention effect was examined by noninvasive live animal imaging in a tumor mouse model. Finally, the 17-AAG-loaded nanoparticles were nonimmunogenic and more efficient than free 17-AAG in manifesting an anticancer effect in the tumor model. Overall, our data demonstrate rHG-TOS as a promising tool for the delivery of 17-AAG featuring therapeutic efficacy and biocompatibility.

Self-assembled liquid crystalline nanoparticles as a novel ophthalmic delivery system for dexamethasone: Improving preocular retention and ocular bioavailability.

Science.gov (United States)

Gan, Li; Han, Shun; Shen, Jinqiu; Zhu, Jiabi; Zhu, Chunliu; Zhang, Xinxin; Gan, Yong

2010-08-30

The object of this study was to design novel self-assembled liquid crystalline nanoparticles (cubosomes) as an ophthalmic delivery system for dexamethasone (DEX) to improve its preocular retention and ocular bioavailability. DEX cubosome particles were produced by fragmenting a cubic crystalline phase of monoolein and water in the presence of stabilizer Poloxamer 407. Small angle X-ray diffraction (SAXR) profiles revealed its internal structure as Pn3m space group, indicating the diamond cubic phase. In vitro, the apparent permeability coefficient of DEX administered in cubosomes exhibited a 4.5-fold (F1) and 3.5-fold (F2) increase compared to that of Dex-Na phosphate eye drops. Preocular retention studies revealed that the retention of cubosomes was significantly longer than that of solution and carbopol gel, with AUC(0-->180min) of Rh B cubosomes being 2-3-fold higher than that of the other two formulations. In vivo pharmacokinetics in aqueous humor was evaluated by microdialysis, which indicated a 1.8-fold (F1) increase in AUC(0-->240min) of DEX administered in cubosomes relative to that of Dex-Na phosphate eye drops, with about an 8-fold increase compared to that of DEX suspension. Corneal cross-sections after incubation with DEX cubosomes demonstrated an unaffected corneal structure and tissue integrity, which indicated the good biocompatibility of DEX cubosomes. In conclusion, self-assembled liquid crystalline nanoparticles might represent a promising vehicle for effective ocular drug delivery. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

Assembly of nanoparticles on patterned surfaces by noncovalent interachtions

NARCIS (Netherlands)

Maury, P.A.; Reinhoudt, David; Huskens, Jurriaan

2008-01-01

This article reviews the recent developments in the assembly of nanoparticles into patterned arrays. An introduction is given on nanoparticles assembly and its applications. This is followed by a discussion on recent papers, seen from the perspective of the interaction between particle and

Polymer Assembly Encapsulation of Lanthanide Nanoparticles as Contrast Agents for In Vivo Micro-CT.

Science.gov (United States)

Cruje, Charmainne; Dunmore-Buyze, Joy; MacDonald, Jarret P; Holdsworth, David W; Drangova, Maria; Gillies, Elizabeth R

2018-03-12

Despite recent technological advancements in microcomputed tomography (micro-CT) and contrast agent development, preclinical contrast agents are still predominantly iodine-based. Higher contrast can be achieved when using elements with higher atomic numbers, such as lanthanides; lanthanides also have X-ray attenuation properties that are ideal for spectral CT. However, the formulation of lanthanide-based contrast agents at the high concentrations required for vascular imaging presents a significant challenge. In this work, we developed an erbium-based contrast agent that meets micro-CT imaging requirements, which include colloidal stability upon redispersion at high concentrations, evasion of rapid renal clearance, and circulation times of tens of minutes in small animals. Through systematic studies with poly(ethylene glycol) (PEG)-poly(propylene glycol), PEG-polycaprolactone, and PEG-poly(l-lactide) (PLA) block copolymers, the amphiphilic block copolymer PEG 114 -PLA 53 was identified to be ideal for encapsulating oleate-coated lanthanide-based nanoparticles for in vivo intravenous administration. We were able to synthesize a contrast agent containing 100 mg/mL of erbium that could be redispersed into colloidally stable particles in saline after lyophilization. Contrast enhancement of over 250 HU was achieved in the blood pool for up to an hour, thereby meeting the requirements of live animal micro-CT.

Correction: One-step coelectrodeposition-assisted layer-by-layer assembly of gold nanoparticles and reduced graphene oxide and its self-healing three-dimensional nanohybrid for an ultrasensitive DNA sensor.

Science.gov (United States)

Jayakumar, Kumarasamy; Camarada, María Belén; Dharuman, Venkataraman; Ju, Huangxian; Dey, Ramendra Sundar; Wen, Yangping

2018-02-01

Correction for 'One-step coelectrodeposition-assisted layer-by-layer assembly of gold nanoparticles and reduced graphene oxide and its self-healing three-dimensional nanohybrid for an ultrasensitive DNA sensor' by Jayakumar Kumarasamy, et al., Nanoscale, 2018, DOI: 10.1039/c7nr06952a.

A Comparative Cytotoxic Evaluation of Disulfiram Encapsulated PLGA Nanoparticles on MCF-7 Cells.

Science.gov (United States)

Fasehee, Hamidreza; Ghavamzadeh, Ardeshir; Alimoghaddam, Kamran; Ghaffari, Seyed-Hamidollah; Faghihi, Shahab

2017-04-01

Background: Disulfiram is oral aldehyde dehydrogenase (ALDH) inhibitor that has been used in the treatment of alcoholism. Recent studies show that this drug has anticancer properties; however, its rapid degradation has limited its clinical application. Encapsulation of disulfiram polymeric nanoparticles (NPs) may improve its anticancer activities and protect rapid degradation of the drug. Materials and Methods: A poly (lactide-co-Glycolide) (PLGA) was developed for encapsulation of disulfiram and its delivery into breast cancer cells. Disulfiram encapsulated PLGA NPs were prepared by nanoprecipitation method and were characterized by Scanning Electron Microscopy (SEM). The loading and encapsulation efficiency of NPs were determined using UV-Visible spectroscopy. Cell cytotoxicity of free and encapsulated form of disulfiram is also determined using MTT assay. Results: Disulfiram encapsulated PLGA NPs had uniform size with 165 nm. Drug loading and entrapment efficiency were 5.35 ±0.03% and 58.85±1.01%. The results of MTT assay showed that disulfiram encapsulated PLGA NPs were more potent in induction of apoptosis compare to free disulfiram. Conclusion: Based on the results obtained in the present study it can be concluded that encapsulation of disulfiram with PLGA can protect its degradation in improve its cytotoxicity on breast cancer cells.

Design and Synthesis of Self-Assembled Polymeric Nanoparticles for Cancer Drug Delivery

Science.gov (United States)

Logie, Jennifer

Current chemotherapeutics are plagued by poor solubility and selectivity, requiring toxic excipients in formulations and causing a number of dose limiting side effects. Nanoparticle delivery has emerged as a strategy to more effectively deliver chemotherapeutics to the tumour site. Specifically, polymeric micelles enable the solubilization of hydrophobic small molecule drugs within the core and mitigate the necessity of excipients. Notwithstanding the significant progress made in polymeric micelle delivery, translation is limited by poor stability and low drug loading. In this work, a rational design approach is used to chemically modify poly(D,L-lactide-co-2-methyl-2-carboxytrimethylene carbonate)-graft-poly(ethylene glycol) (P(LA-co-TMCC)-g-PEG) in order to overcome these limitations and effectively deliver drug to tumours. The PEG density of the polymer system was optimized to enhance the stability of our polymeric micelles. Higher PEG densities permitted the lyophilization of micelles and enhanced the serum stability of the system. To increase the drug loading of our system, we facilitated specific intermolecular interactions within the micelle core. For drugs that form colloidal aggregates, such as pentyl-PABC doxazolidine, polymers were used to stabilize the colloidal core against aggregation and protein adsorption. For more challenging molecules, where self-assembly cannot be controlled, such as docetaxel, we modified the polymeric backbone with a peptide from the binding site of the drug to achieve loadings five times higher than those achieved in conventional micelle systems. This novel docetaxel nanoparticle was assessed in vivo in an orthotopic mouse model of breast cancer, where it showed a wider therapeutic index than the conventional ethanolic polysorbate 80 formulation. The improved tolerability of this formulation enabled higher dosing regimens and led to heightened efficacy and survival in this mouse model. Combined, these studies validated P

Dynamic Self-Assembly of Gold/Polymer Nanocomposites: pH-Encoded Switching between 1D Nanowires and 3D Nanosponges.

Science.gov (United States)

Zhang, Qi; Xu, Tian-Yi; Zhao, Cai-Xin; Jin, Wei-Hang; Wang, Qian; Qu, Da-Hui

2017-10-05

The design of tunable dynamic self-assembly of nanoparticles with switchable assembled dimensions and morphologies is a challenging goal whose realization is vital for the evolution of smart nanomaterials. Herein, we report on chitosan polymer as an effective supramolecular "glue" for aldehyde-modified Au nanoparticles to reversibly modulate the states of self-assembled nanocomposites. By simultaneous integration of dynamic covalent Schiff base interactions and noncovalent hydrogen bonds, the chitosan/Au nanocomposites could reversibly transform their assembled morphologies from one-dimensional nanowires to three-dimensional nanosponges in response to the variation of pH value. Moreover, the obtained nanosponges could be used as an efficient pH-controlled cargo release system. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enzyme sensitive smart inulin-dehydropeptide conjugate self-assembles into nanostructures useful for targeted delivery of ornidazole.

Science.gov (United States)

Shivhare, Kriti; Garg, Charu; Priyam, Ayushi; Gupta, Alka; Sharma, Ashwani Kumar; Kumar, Pradeep

2018-01-01

Molecular self-assembly of biodegradable amphiphilic polymers allows rational design of biocompatible nanomaterials for drug delivery. Use of substituted polysaccharides for such applications offers the ease of design and synthesis, and provides higher biofunctionality and biocompatibility to nanomaterials. The present work focuses on the synthesis, characterization and potential biomedical applications of self-assembled polysaccharide-based materials. We demonstrated that the synthesized amphiphilic inulin self-assembled in aqueous medium into nanostructures with average size in the range of 146-486nm and encapsulated hydrophobic therapeutic molecule, ornidazole. Hydrophophic dehydropeptide was conjugated with inulin via a biocompatible ester linkage. Dehydrophenylalanine, an unusual amino acid, was incorporated in the peptide to make it stable at a broader range of pH as well as against proteases. The resulting core-shell type of nanostructures could encapsulate ornidazole in the hydrophobic core and released it in a controlled fashion. By taking the advantage of inulin, which gets degraded in the colon by colonic bacteria, the effect of enzyme, inulinase, present in the microflora of the large intestine, on inulin-peptide degradation followed by drug release has been studied. Altogether, small peptide conjugated to inulin offers novel scaffold for the future design of nanostructures with potential applications in the field of targeted drug delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

Dispersion of nanoparticulate suspensions using self-assembled surfactant aggregates

Science.gov (United States)

Singh, Pankaj Kumar

The dispersion of particles is critical for several industrial applications such as paints, inks, coatings, and cosmetics. Several emerging applications such as abrasives for precision polishing, and drug delivery systems are increasingly relying on nanoparticulates to achieve the desired performance. In the case of nanoparticles, the dispersion becomes more challenging because of the lack of fundamental understanding of dispersant adsorption and interparticle force prediction. Additionally, many of these processes use severe processing environments such as high normal forces (>100 mN/m), high shear forces (>10,000 s -1), and high ionic strengths (>0.1 M). Under such processing conditions, traditionally used dispersants based on electrostatics, and steric force repulsion mechanism may not be adequate. Hence, the development of optimally performing dispersants requires a fundamental understanding of the dispersion mechanism at the atomic/molecular scale. This study explores the use of self-assembled surfactant aggregates at the solid-liquid interface for dispersing nanoparticles in severe processing environments. Surfactant molecules can provide a feasible alternative to polymeric or inorganic dispersants for stabilizing ultrafine particles. The barrier to aggregation in the presence of surfactant molecules was measured using atomic force microscopy. The barrier heights correlated to suspension stability. To understand the mechanism for nanoparticulate suspension stability in the presence of surfactant films, the interface was characterized using zeta potential, contact angle, adsorption, and FT-IR (adsorbed surfactant film structure measurements). The effect of solution conditions such as pH and ionic strength on the suspension stability, and the self-assembled surfactant films was also investigated. It was determined that a transition from a random to an ordered orientation of the surfactant molecules at the interface was responsible for stability of

Self-assembled nanostructures

CERN Document Server

Zhang, Jin Z; Liu, Jun; Chen, Shaowei; Liu, Gang-yu

2003-01-01

Nanostructures refer to materials that have relevant dimensions on the nanometer length scales and reside in the mesoscopic regime between isolated atoms and molecules in bulk matter. These materials have unique physical properties that are distinctly different from bulk materials. Self-Assembled Nanostructures provides systematic coverage of basic nanomaterials science including materials assembly and synthesis, characterization, and application. Suitable for both beginners and experts, it balances the chemistry aspects of nanomaterials with physical principles. It also highlights nanomaterial-based architectures including assembled or self-assembled systems. Filled with in-depth discussion of important applications of nano-architectures as well as potential applications ranging from physical to chemical and biological systems, Self-Assembled Nanostructures is the essential reference or text for scientists involved with nanostructures.

Selective inhibition of MG-63 osteosarcoma cell proliferation induced by curcumin-loaded self-assembled arginine-rich-RGD nanospheres

Directory of Open Access Journals (Sweden)

Chang R

2015-05-01

Full Text Available Run Chang,1 Linlin Sun,1 Thomas J Webster1,2 1Department of Chemical Engineering, Northeastern University, Boston, MA, USA; 2Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia Abstract: Osteosarcoma is the most frequent primary malignant form of bone cancer, comprising 30% of all bone cancer cases. The objective of this in vitro study was to develop a treatment against osteosarcoma with higher selectivity toward osteosarcoma cells and lower cytotoxicity toward normal healthy osteoblast cells. Curcumin (or diferuloylmethane has been found to have antioxidant and anticancer effects by multiple cellular pathways. However, it has lower water solubility and a higher degradation rate in alkaline conditions. In this study, the amphiphilic peptide C18GR7RGDS was used as a curcumin carrier in aqueous solution. This peptide contains a hydrophobic aliphatic tail group leading to their self-assembly by hydrophobic interactions, as well as a hydrophilic head group composed of an arginine-rich and an arginine-glycine-aspartic acid structure. Through characterization by transmission electron microscopy, self-assembled structures of spherical amphiphilic nanoparticles (APNPs with diameters of 10–20 nm in water and phosphate-buffered saline were observed, but this structure dissociated when the pH value was reduced to 4. Using a method of codissolution with acetic acid and dialysis tubing, the solubility of curcumin was enhanced and a homogeneous solution was formed in the presence of APNPs. Successful encapsulation of curcumin in APNPs was then confirmed by Fourier transform infrared and X-ray diffraction analyses. The cytotoxicity and cellular uptake of the APNP/curcumin complexes on both osteosarcoma and normal osteoblast cell lines were also evaluated by methyl-thiazolyl-tetrazolium assays and confocal fluorescence microscopy. The results showed that the curcumin-loaded APNPs had significant selective

Thermal dewetting with a chemically heterogeneous nano-template for self-assembled L1(0) FePt nanoparticle arrays.

Science.gov (United States)

Wang, Liang-Wei; Cheng, Chung-Fu; Liao, Jung-Wei; Wang, Chiu-Yen; Wang, Ding-Shuo; Huang, Kuo-Feng; Lin, Tzu-Ying; Ho, Rong-Ming; Chen, Lih-Juann; Lai, Chih-Huang

2016-02-21

A design for the fabrication of metallic nanoparticles is presented by thermal dewetting with a chemically heterogeneous nano-template. For the template, we fabricate a nanostructured polystyrene-b-polydimethylsiloxane (PS-b-PDMS) film on a Si|SiO2 substrate, followed by a thermal annealing and reactive ion etching (RIE) process. This gives a template composed of an ordered hexagonal array of SiOC hemispheres emerging in the polystyrene matrix. After the deposition of a FePt film on this template, we utilize the rapid thermal annealing (RTA) process, which provides in-plane stress, to achieve thermal dewetting and structural ordering of FePt simultaneously. Since the template is composed of different composition surfaces with periodically varied morphologies, it offers more tuning knobs to manipulate the nanostructures. We show that both the decrease in the area of the PS matrix and the increase in the strain energy relaxation transfer the dewetted pattern from the randomly distributed nanoparticles into a hexagonal periodic array of L10 FePt nanoparticles. Transmission electron microscopy with the in situ heating stage reveals the evolution of the dewetting process, and confirms that the positions of nanoparticles are aligned with those of the SiOC hemispheres. The nanoparticles formed by this template-dewetting show an average diameter and center-to-center distance of 19.30 ± 2.09 nm and 39.85 ± 4.80 nm, respectively. The hexagonal array of FePt nanoparticles reveals a large coercivity of 1.5 T, much larger than the nanoparticles fabricated by top-down approaches. This approach offers an efficient pathway toward self-assembled nanostructures in a wide range of material systems.

ParaCEST Agents Encapsulated in Reverse Nano-Assembled Capsules (RACs: How Slow Molecular Tumbling Can Quench CEST Contrast

Directory of Open Access Journals (Sweden)

Annah Farashishiko

2018-04-01

Full Text Available Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM3+ into a Reverse Assembled nano-Capsule. An aggregate can be generated between this chelate and polyacrylic acid (PAA after the addition of ethylene diamine. Subsequent addition of polyallylamine hydrochloride (PAH followed by silica nanoparticles generated a robust encapsulating shell and afforded capsule with a mean hydrodynamic diameter of 650 ± 250 nm. Unfortunately this encapsulation did not have the effect of amplifying the CEST effect per agent, but quenched the CEST altogether. The quenching effect of encapsulation could be attributed to the effect of slowing molecular tumbling, which is inevitable when the chelate is incorporated into a nano-scale material. This increases the transverse relaxation rate of chelate protons and a theoretical examination using Solomon Bloembergen Morgan theory and the Bloch equations shows that the increase in the transverse relaxation rate constant for the amide protons, in even modestly sized nano-materials, is sufficient to significantly quench CEST.

ParaCEST Agents Encapsulated in Reverse Nano-Assembled Capsules (RACs): How Slow Molecular Tumbling Can Quench CEST Contrast.

Science.gov (United States)

Farashishiko, Annah; Slack, Jacqueline R; Botta, Mauro; Woods, Mark

2018-01-01

Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM 3+ into a Reverse Assembled nano-Capsule. An aggregate can be generated between this chelate and polyacrylic acid (PAA) after the addition of ethylene diamine. Subsequent addition of polyallylamine hydrochloride (PAH) followed by silica nanoparticles generated a robust encapsulating shell and afforded capsule with a mean hydrodynamic diameter of 650 ± 250 nm. Unfortunately this encapsulation did not have the effect of amplifying the CEST effect per agent, but quenched the CEST altogether. The quenching effect of encapsulation could be attributed to the effect of slowing molecular tumbling, which is inevitable when the chelate is incorporated into a nano-scale material. This increases the transverse relaxation rate of chelate protons and a theoretical examination using Solomon Bloembergen Morgan theory and the Bloch equations shows that the increase in the transverse relaxation rate constant for the amide protons, in even modestly sized nano-materials, is sufficient to significantly quench CEST.

Liposomes self-assembled from electrosprayed composite microparticles

International Nuclear Information System (INIS)

Yu Dengguang; Yang Junhe; Wang Xia; Tian Feng

2012-01-01

Composite microparticles, consisting of polyvinylpyrrolidone (PVP), naproxen (NAP) and lecithin (PC), have been successfully prepared using an electrospraying process and exploited as templates to manipulate molecular self-assembly for the synthesis of liposomes in situ. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) observations demonstrate that the microparticles have an average diameter of 960 ± 140 nm and a homogeneous structure. X-ray diffraction (XRD) patterns, differential scanning calorimetry (DSC) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) results verify that the building blocks NAP and PC are scattered in the polymer matrix in a molecular way owing to the very fast drying of the electrospraying process and the favorable secondary interactions among the components. FESEM, scanning probe microscope (SPM) and TEM observations demonstrate that the liposomes can be achieved through molecular self-assembly in situ when the microparticles contact water thanks to ‘like prefers like’ and by means of the confinement effect of the microparticles. The liposomes have an encapsulation rate of 91.3%, and 80.7% of the drug in the liposomes can be freed into the dissolution medium in a sustained way and by a diffusion mechanism over a period of 24 h. The developed strategy not only provides a new, facile, and effective method to assemble and organize molecules of multiple components into liposomes with electrosprayed microparticles as templates, but also opens a new avenue for nanofabrication in a step-by-step and controllable way. (paper)

Titanium dioxide encapsulation of supported Ag nanoparticles on the porous silica bead for increased photocatalytic activity

Science.gov (United States)

Liu, Hui; Deng, Lu; Sun, Chaochao; Li, Junqi; Zhu, Zhenfeng

2015-01-01

A new synthetic strategy has been developed to encapsulate Ag nanoparticles in heterogeneous catalysts to prevent their dropping and sintering. Ag nanoparticles with diameters about 5-10 nm were first supported on the porous silica bead. These were then covered with a fresh layer of titanium dioxide with the thickness about 5 nm. SEM and TEM images were used to confirm the success of each synthesis step, and the photocatalytic activity of the as-synthesized samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. The resulting titanium dioxide encapsulated Ag nanoparticles exhibited an enhanced photocatalytic activity under both UV and visible light irradiation, this can be attributed to effective charge separation and light harvesting of the plasmonic silver nanoparticles decoration, even the reducing of the exciton recombination rate caused by the small grain size of anatase TiO2 nanocrystals.

Oxidation and sensing of ascorbic acid and dopamine on self-assembled gold nanoparticles incorporated within polyaniline film

Science.gov (United States)

Chu, Wenya; Zhou, Qun; Li, Shuangshuang; Zhao, Wei; Li, Na; Zheng, Junwei

2015-10-01

Electrochemical biosensors based on conducting polymers incorporated with metallic nanoparticles can greatly enhance sensitivity and selectivity. Herein, we report a facile fabrication approach for polyaniline (PAN) incorporated with a gold nanoparticle (AuNP) composite electrode by electrodeposition of PAN on a self-assembled AuNP layer on the surface of an indium tin oxide electrode. The resulting AuNP/PAN composite electrode exhibits a remarkable synergistic effect on the electrocatalytic oxidation of ascorbic acid (AA) and dopamine (DA). It is demonstrated that the oxidation reaction of AA mainly occurs at AuNPs inside the PAN film as the ascorbate anions are doped into the polymer during the oxidation of the PAN film. Conversely, the oxidation of positively charged DA may only take place at the PAN/solution interface. The different mechanisms of the electrode reactions result in the oxidation of AA and DA occurring at different potentials. As a result, the AuNP/PAN composite electrode can be employed to simultaneously detect AA and DA with a good linear range, high sensitivity, and low detection limit.

Preparation and self-assembly of nanostructured BaCrO4 from CTAB reverse microemulsions

International Nuclear Information System (INIS)

Li Zhonghao; Zhang Jianling; Du Jimin; Han Buxing; Mu Tiancheng; Gao Yanan; Liu Zhimin

2005-01-01

Well-defined superstructures of rectangular-shaped BaCrO 4 and extensive network of BaCrO 4 nanoparticles constructed by self-assembly were prepared in cetyltrimethylammonium bromide (CTAB) reverse microemulsions. The effects of aging time and reactant concentrations on the morphology and the self-assemble pattern of the nanostructured BaCrO 4 were investigated. TEM combined with the electron diffraction was used to characterize the morphology and the crystal structure of the prepared nanostructured BaCrO 4 at different conditions

Self-Assembled Complexes of Horseradish Peroxidase with Magnetic Nanoparticles Showing Enhanced Peroxidase Activity

KAUST Repository

Corgié, Stéphane C.

2012-02-15

Bio-nanocatalysts (BNCs) consisting of horseradish peroxidase (HRP) self-assembled with magnetic nanoparticles (MNPs) enhance enzymatic activity due to the faster turnover and lower inhibition of the enzyme. The size and magnetization of the MNPs affect the formation of the BNCs, and ultimately control the activity of the bound enzymes. Smaller MNPs form small clusters with a low affinity for the HRP. While the turnover for the bound fraction is drastically increased, there is no difference in the H 2O 2 inhibitory concentration. Larger MNPs with a higher magnetization aggregate in larger clusters and have a higher affinity for the enzyme and a lower substrate inhibition. All of the BNCs are more active than the free enzyme or the MNPs (BNCs > HRP ≤laquo; MNPs). Since the BNCs show surprising resilience in various reaction conditions, they may pave the way towards new hybrid biocatalysts with increased activities and unique catalytic properties for magnetosensitive enzymatic reactions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-assembly Ag nanoparticle monolayer film as SERS Substrate for pesticide detection

Energy Technology Data Exchange (ETDEWEB)

Zhang, Li, E-mail: zhlisuzh@163.com [School of Chemistry and Life Science, Anhui Key Laboratory of Spin Electron and Nanomaterials (Cultivating Base), Suzhou University, SuZhou 234000 (China)

2013-04-01

A self-assembled protocol is introduced to provide effective platforms for the fabrication of ordered Ag nanosized monolayer film. The assembled Ag nanosized monolayer film was characterized using scanning electronic microscopy and surface-enhanced Raman scattering (SERS). The results show that the assembled SERS substrate own excellent Raman enhancement and reproducibility. The synthesized SERS-active substrate was further used to detect methyl-parathion, and the limitation of detection can reach 10{sup −7} M.

A facile method to prepare superparamagnetic iron oxide and hydrophobic drug-encapsulated biodegradable polyurethane nanoparticles

Directory of Open Access Journals (Sweden)

Cheng K

2017-03-01

Full Text Available Kuo-Wei Cheng, Shan-hui Hsu Institute of Polymer Science and Engineering, College of Engineering, National Taiwan University, Taipei, Taiwan, Republic of China Abstract: Superparamagnetic iron oxide nanoparticles (SPIO NPs have a wide range of biomedical applications such as in magnetic resonance imaging, targeting, and hyperthermia therapy. Aggregation of SPIO NPs can occur because of the hydrophobic surface and high surface energy of SPIO NPs. Here, we developed a facile method to encapsulate SPIO NPs in amphiphilic biodegradable polymer. Anionic biodegradable polyurethane nanoparticles (PU NPs with ~35 nm size and different chemistry were prepared by waterborne processes. SPIO NPs were synthesized by chemical co-precipitation. SPIO NPs were then added to the aqueous dispersion of PU NPs, followed by application of high-frequency (~20 kHz ultrasonic vibration for 3 min. This method rendered SPIO-PU hybrid NPs (size ~110 nm suspended in water. SPIO-PU hybrid NPs contained ~50–60 wt% SPIO and retained the superparamagnetic property (evaluated by a magnetometer as well as high contrast in magnetic resonance imaging. SPIO-PU NPs also showed the ability to provide cell hyperthermic treatment. Using the same ultrasonic method, hydrophobic drug (Vitamin K3 [VK3] or (9-(methylaminomethylanthracene [MAMA] could also be encapsulated in PU NPs. The VK3-PU or MAMA-PU hybrid NPs had ~35 nm size and different release profiles for PUs with different chemistry. The encapsulation efficiency for VK3 and MAMA was high (~95% without burst release. The encapsulation mechanism may be attributed to the low glass transition temperature (Tg and good mechanical compliance of PU NPs. The new encapsulation method involving waterborne biodegradable PU NPs is simple, rapid, and effective to produce multimodular NP carriers. Keywords: superparamagnetic iron oxide, polyurethane, drug release, hybrid nanoparticles

Preliminary evaluation of the encapsulation of new antidiabetic sulphonylhydrazone and antitumor N-acylhydrazone derivatives using PLGA nanoparticles

International Nuclear Information System (INIS)

Costa, F N; Ibiapino, A L; De Figueiredo, L P; De Castro, C E; Giacomelli, F C; Ferreira, F F; Barreiro, E J; Lima, L M; Do Amaral, D N

2015-01-01

It has been demonstrated the feasibly of using PLGA nanoparticles to promote the encapsulation of novel anti-diabetic sulphonylhydrazone and antitumor N-acylhydrazone derivatives. The motivation is to further demonstrate the possibility of long-term release of anti-diabetic as well as higher accumulation of the antitumor derivative by using the nanotechnology-based production. The produced nanoparticles were obtained by the nanoprecipitation method, which revealed to be effective in the encapsulation of the bioactive compounds. The determined sizes were in the range of ∼100 nm, which are supposed to be suitable for both potential applications. The preliminary experimental data demonstrated the formation of stable nanosystems and further experiments are underway in order to determine the loading content, encapsulation efficiency and release profile of the hydrophobic bioactive compounds. (paper)

Antiplasmodial Activity and Toxicological Assessment of Curcumin PLGA-Encapsulated Nanoparticles

Directory of Open Access Journals (Sweden)

Zulaikha A. Busari

2017-09-01

Full Text Available Curcumin is a polyphenolic pigment isolated from the rhizomes of Curcuma longa (turmeric, a medicinal plant widely used in the ancient Indian and Chinese medicine. The antiplasmodial activity of curcumin is often hampered by its fast metabolism and poor water solubility, thus its incorporation into a delivery system could circumvent this problem. This study aimed to evaluate the in vivo antiplasmodial activity and the toxicity assessment of curcumin incorporated into poly (lactic-co-glycolic acid (PLGA nanoparticles. Curcumin was loaded with poly (D,L-lactic-co-glycolic acid (PLGA using solvent evaporation from oil-in-water single emulsion method. The nanoparticles were characterized and evaluated in vivo for antimalarial activities using Peter’s 4-day suppressive protocol in mice model. Hematological and hepatic toxicity assays were performed on whole blood and plasma, respectively. In vivo anti-parasitic test and toxicity assays for free and encapsulated drug were performed at 5 and 10 mg/kg. In vitro cytotoxicity of free and PLGA encapsulated curcumin (Cur-PLGA to RAW 264.7 cell line was also determined at varying concentrations (1000–7.8 μg/mL. The size and entrapment efficiency of the nanoparticulate drug formulated was 291.2 ± 82.1 nm and 21.8 ± 0.4 respectively. The percentage parasite suppression (56.8% at 5 mg/kg was significantly higher than in free drug (40.5% of similar concentration (p < 0.05 but not at 10 mg/kg (49.5% at 4-day post-treatment. There were no significant differences in most of the recorded blood parameters in free curcumin and PLGA encapsulated nanoparticulate form (p > 0.05 except in lymphocytes which were significantly higher in Cur-PLGA compared to the free drug (p < 0.05. There were no significant differences in hepatotoxic biomarkers; aspartate aminotransferase and alanine aminotransferase concentrations in various treatment groups (p > 0.05. At higher concentrations (1000 and 500 μg/mL, Cur

Self-assembly of calcium phosphate nanoparticles into hollow spheres induced by dissolved amino acids

NARCIS (Netherlands)

Hagmeyer, D.; Ganesan, K.; Ruesing, J.; Schunk, D.; Mayer, C.; Dey, A.; Sommerdijk, N.A.J.M.; Epple, M.

2011-01-01

Nanoparticles of calcium phosphate assemble spontaneously within a few seconds into hollow spheres with a diameter around 200–300 nm in the presence of dissolved amino acids and dipeptides. The process of formation was followed by cryo-transmission electron microscopy (cryoTEM), proving their hollow

Colorimetric Analysis on Flocculation of Bioinspired Au Self-Assembly for Biophotonic Application

Directory of Open Access Journals (Sweden)

Wan-Joong Kim

2009-01-01

Full Text Available Gold nanoparticles exhibited strong surface plasmon absorption and couplings between neighboring particles within bioactivated self-assembly modified their optical properties. Colorimetric analysis on the optical modification of surface plasmon resoanance (SPR shift and flocculation parameter functionalized bioinspired gold assembly for biophotonic application. The physical origin of bioinspired gold aggregation-induced shifting, decreasing, or broadening of the plasmon absorption spectra could be explained in terms of dynamic depolarization, collisional damping, and shadowing effects.

Fabrication of glucose biosensor for whole blood based on Au/hyperbranched polyester nanoparticles multilayers by antibiofouling and self-assembly technique

International Nuclear Information System (INIS)

Sun, Chong; Chen, Xiaohan; Han, Qiaorong; Zhou, Min; Mao, Chun; Zhu, Qinshu; Shen, Jian

2013-01-01

Highlight: •A novel method for detection of glucose in whole blood has been developed. •The method based on antibiofouling and self-assembly technology was investigated. •The antibiofouling technique utilized for sensor is significant for diagnostics. -- Abstract: Acknowledging the benefits of hyperbranched polymers and their nanoparticles, herein we report the design and synthesis of sulfonic acid group functionalized hydroxyl-terminated hyperbranched polyester (H30-SO 3 H) nanoparticles and their biomedical application. The H30-SO 3 H nanoparticles were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy ( 1 H NMR). The good hemocompatibility of H30-SO 3 H nanoparticles was also investigated by coagulation tests, complement activation and platelet activation. The novel glucose biosensor was fabricated by immobilizing the positively charged Au nanoparticles, H30-SO 3 H nanoparticles and glucose oxidase (GOx) onto the surface of glassy carbon electrode (GCE). It can be applied in whole blood directly, which was based on the good hemocompatibility and antibiofouling property of H30-SO 3 H nanoparticles. The biosensor had good electrocatalytic activity toward glucose with a wide linear range (0.2–20 mM), a low detection limit 1.2 × 10 −5 M in whole blood and good anti-interference property. The development of materials science will offer a novel platform for application to substance detection in whole blood

Fabrication of glucose biosensor for whole blood based on Au/hyperbranched polyester nanoparticles multilayers by antibiofouling and self-assembly technique

Energy Technology Data Exchange (ETDEWEB)

Sun, Chong [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Key Laboratory for Soft Chemistry and Functional Materials of Ministry of Education, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Chen, Xiaohan; Han, Qiaorong [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Zhou, Min [Department of Vascular Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008 (China); Mao, Chun, E-mail: maochun127@yahoo.cn [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Zhu, Qinshu [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China); Shen, Jian, E-mail: jshen@njnu.edu.cn [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023 (China)

2013-05-07

Highlight: •A novel method for detection of glucose in whole blood has been developed. •The method based on antibiofouling and self-assembly technology was investigated. •The antibiofouling technique utilized for sensor is significant for diagnostics. -- Abstract: Acknowledging the benefits of hyperbranched polymers and their nanoparticles, herein we report the design and synthesis of sulfonic acid group functionalized hydroxyl-terminated hyperbranched polyester (H30-SO{sub 3}H) nanoparticles and their biomedical application. The H30-SO{sub 3}H nanoparticles were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy ({sup 1}H NMR). The good hemocompatibility of H30-SO{sub 3}H nanoparticles was also investigated by coagulation tests, complement activation and platelet activation. The novel glucose biosensor was fabricated by immobilizing the positively charged Au nanoparticles, H30-SO{sub 3}H nanoparticles and glucose oxidase (GOx) onto the surface of glassy carbon electrode (GCE). It can be applied in whole blood directly, which was based on the good hemocompatibility and antibiofouling property of H30-SO{sub 3}H nanoparticles. The biosensor had good electrocatalytic activity toward glucose with a wide linear range (0.2–20 mM), a low detection limit 1.2 × 10{sup −5} M in whole blood and good anti-interference property. The development of materials science will offer a novel platform for application to substance detection in whole blood.

Cisplatin encapsulated nanoparticle as a therapeutic agent for anticancer treatment

Science.gov (United States)

Eka Putra, Gusti Ngurah Putu; Huang, Leaf; Hsu, Yih-Chih

2016-03-01

The knowledge of manipulating size of biomaterials encapsulated drug into nano-scale particles has been researched and developed in treating cancer. Cancer is the second worldwide cause of death, therefore it is critical to treat cancers challenging with therapeutic modality of various mechanisms. Our preliminary investigation has studied cisplatin encapsulated into lipid-based nanoparticle and examined the therapeutic effect on xenografted animal model. We used mice with tumor volume ranging from 195 to 214 mm3 and then few mice were grouped into three groups including: control (PBS), lipid platinum chloride (LPC) nanoparticles and CDDP (cis-diamminedichloroplatinum(II) at dose of 3mg cisplatin /kg body weight. The effect of the treatment was observed for 12 days post-injection. It showed that LPC NPs demonstrated a better therapeutic effect compared to CDDP at same 3mg cisplatin/kg drug dose of tumor size reduction, 96.6% and 11.1% respectively. In addition, mouse body weight loss of LPC, CDDP and PBS treated group are 12.1%, 24.3% and 1.4%. It means that by compared to CDDP group, LPC group demonstrated less side effect as not much reduction of body weight have found. Our findings have shown to be a potential modality to further investigate as a feasible cancer therapy modality.