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Sample records for water soluble self-assembled

  1. Self-assembly of water-soluble nanocrystals

    Science.gov (United States)

    Fan, Hongyou [Albuquerque, NM; Brinker, C Jeffrey [Albuquerque, NM; Lopez, Gabriel P [Albuquerque, NM

    2012-01-10

    A method for forming an ordered array of nanocrystals where a hydrophobic precursor solution with a hydrophobic core material in an organic solvent is added to a solution of a surfactant in water, followed by removal of a least a portion of the organic solvent to form a micellar solution of nanocrystals. A precursor co-assembling material, generally water-soluble, that can co-assemble with individual micelles formed in the micellar solution of nanocrystals can be added to this micellar solution under specified reaction conditions (for example, pH conditions) to form an ordered-array mesophase material. For example, basic conditions are used to precipitate an ordered nanocrystal/silica array material in bulk form and acidic conditions are used to form an ordered nanocrystal/silica array material as a thin film.

  2. From Cooperative Self-Assembly to Water-Soluble Supramolecular Polymers Using Coarse-Grained Simulations.

    Science.gov (United States)

    Bochicchio, Davide; Pavan, Giovanni M

    2017-01-24

    Supramolecular polymers, formed via noncovalent self-assembly of elementary monomers, are extremely interesting for their dynamic bioinspired properties. In order to understand their behavior, it is necessary to access their dynamics while maintaining high resolution in the treatment of the monomer structure and monomer-monomer interactions, which is typically a difficult task, especially in aqueous solution. Focusing on 1,3,5-benzenetricarboxamide (BTA) water-soluble supramolecular polymers, we have developed a transferable coarse-grained model that allows studying BTA supramolecular polymerization in water, while preserving remarkable consistency with the atomistic models in the description of the key interactions between the monomers (hydrophobic, H-bonding, etc.), self-assembly cooperativity, and amplification of order into the growing fibers. This permitted us to monitor the amplification of the key interactions between the monomers (including H-bonding) in the BTA fibers during the dynamic polymerization process. Our molecular dynamics simulations provide a picture of a stepwise cooperative polymerization mechanism, where initial fast hydrophobic aggregation of the BTA monomers in water is followed by the slower reorganization of these disordered aggregates into ordered directional oligomers. Supramolecular polymer growth then proceeds on a slower time scale. We challenged our models via comparison with the experimental evidence, capturing the effect of temperature variations and subtle changes in the monomer structure on the polymerization and on the properties of the fibers seen in the real systems. This work provides a multiscale spatiotemporal characterization of BTA self-assembly in water and a useful platform to study a variety of BTA-based supramolecular polymers toward structure-property relationships.

  3. Fluorescent polystyrene photonic crystals self-assembled with water-soluble conjugated polyrotaxanes

    Directory of Open Access Journals (Sweden)

    Francesco Di Stasio

    2013-10-01

    Full Text Available We demonstrate control of the photoluminescence spectra and decay rates of water-soluble green-emitting conjugated polyrotaxanes by incorporating them in polystyrene opals with a stop-band spectrally tuned on the rotaxane emission (405–650 nm. We observe a suppression of the luminescence within the photonic stop-band and a corresponding enhancement of the high-energy edge (405–447 nm. Time-resolved measurements reveal a wavelength-dependent modification of the emission lifetime, which is shortened at the high-energy edge (by ∼11%, in the range 405–447 nm, but elongated within the stop-band (by ∼13%, in the range 448–482 nm. We assign both effects to the modification of the density of photonic states induced by the photonic crystal band structure. We propose the growth of fluorescent composite photonic crystals from blends of “solvent-compatible” non-covalently bonded nanosphere-polymer systems as a general method for achieving a uniform distribution of polymeric dopants in three-dimensional self-assembling photonic structures.

  4. Encapsulation and Characterization of Proton-Bound Amine Homodimers in a Water Soluble, Self-Assembled Supramolecular Host

    Energy Technology Data Exchange (ETDEWEB)

    Pluth, Michael; Fiedler, Dorothea; Mugridge, Jeffrey; Bergman, Robert; Raymond, Kenneth

    2008-10-01

    Cyclic amines can be encapsulated in a water-soluble self-assembled supramolecular host upon protonation. The hydrogen bonding ability of the cyclic amines, as well as the reduced degrees of rotational freedom, allows for the formation of proton-bound homodimers inside of the assembly which are otherwise not observable in aqueous solution. The generality of homodimer formation was explored with small N-alkyl aziridines, azetidines, pyrrolidines and piperidines. Proton-bound homodimer formation is observed for N-alkylaziridines (R = methyl, isopropyl, tert-butyl), N-alkylazetidines (R = isopropyl, tertbutyl), and N-methylpyrrolidine. At high concentration, formation of a proton-bound homotrimer is observed in the case of N-methylaziridine. The homodimers stay intact inside the assembly over a large concentration range, thereby suggesting cooperative encapsulation. Both G3(MP2)B3 and G3B3 calculations of the proton-bound homodimers were used to investigate the enthalpy of the hydrogen bond in the proton-bound homodimers and suggest that the enthalpic gain upon formation of the proton-bound homodimers may drive guest encapsulation.

  5. Positional isomers of linear sodium dodecyl benzene sulfonate: solubility, self-assembly, and air/water interfacial activity.

    Science.gov (United States)

    Ma, Jian-Guo; Boyd, Ben J; Drummond, Calum J

    2006-10-10

    Commercial linear alkyl benzene sulfonates (ABS) are a very important class of anionic surfactants that are employed in a wide variety of applications, especially those involving wetting and detergency. Linear ABS surfactants generally consist of a complex mixture of different chain lengths and positional isomers. This diversity and level of complexity makes it difficult to develop fundamental structure-property correlations for the commercial surfactants. In this work, six monodisperse headgroup positional isomers of sodium para-dodecyl benzene sulfonate (Na-x-DBS, x = 1-6) have been studied. The influence of headgroup position and added electrolyte (NaCl) on the solubility and self-assembly (micellar and vesicular aggregation and lyotropic liquid crystalline phase behavior) in the temperature range from 10 to 90 degrees C have been investigated. Additionally, the air-aqueous solution interfacial adsorption at 25 (no added NaCl) and 50 degrees C (from 0 to 1.0 M added NaCl) has been examined. The observed physicochemical behavior is interpreted in terms of local molecular packing constraints, and in the case of the lyotropic liquid crystalline behavior global aggregate packing constraints as well.

  6. Synthesis and Electrochemical, Photophysical, and Self-Assembly Studies on Water-Soluble pH-Responsive Alkynylplatinum(II) Terpyridine Complexes.

    Science.gov (United States)

    Chung, Clive Yik-Sham; Li, Steve Po-Yam; Lo, Kenneth Kam-Wing; Yam, Vivian Wing-Wah

    2016-05-02

    A series of water-soluble pH-responsive alkynylplatinum(II) terpyridine complexes have been synthesized and characterized. The electronic absorption, emission, and electrochemical properties of the complexes have been studied. The self-assembly processes of representative complexes in aqueous media, presumably through Pt···Pt and/or π-π interactions, have been investigated by concentration- and temperature-dependent UV-vis absorption measurements and dynamic light scattering experiments. Interestingly, some of the complexes have been found to undergo induced self-assembly and disassembly in aqueous media through modulation of the pH value of the solutions, resulting in remarkable UV-vis absorption and emission spectral changes. The emission spectral changes have been rationalized by the change in the hydrophilicity of the complexes, electrostatic repulsion among the complex molecules, and/or the extent of photoinduced electron transfer (PET) quenching upon protonation/deprotonation of the pH-responsive groups on the complexes. By simple modifications of the chemical structures of the complexes, induced self-assembly/disassembly of the complexes can occur at different and/or multiple pH regions, thus allowing the probing of changes at the desired pH region by triplet metal-metal-to-ligand charge-transfer emission of the complexes in the near-infrared (NIR) region. Fixed-cell imaging experiments have further demonstrated the potential of this class of complexes as pH-responsive NIR luminescent probes in vitro, while the NIR emissions of the complexes from live cells have been found to show good differentiation of acidic organelles such as lysosomes from other cellular compartments.

  7. A New Water-Soluble Nanomicelle Formed through Self-Assembly of Pectin-Curcumin Conjugates: Preparation, Characterization, and Anticancer Activity Evaluation.

    Science.gov (United States)

    Bai, Feng; Diao, Jiajing; Wang, Ying; Sun, Shixin; Zhang, Hongmei; Liu, Yunyun; Wang, Yanqing; Cao, Jian

    2017-08-16

    Curcumin is a dominating active component of Curcuma longa and has been studied widely because of its prominent biological activities. The extremely low aqueous solubility, stability, and bioavailability of curcumin limit its application in the field of medicine. In this study, we developed pectin-curcumin (PEC-CCM) conjugates that could self-assemble water-soluble nanomicelles in aqueous solution. The structure of PEC-CCM conjugates was characterized by ultraviolet-visible spectra, fluorescence spectra, Fourier transform infrared spectroscopy, and (1)H nuclear magnetic resonance spectroscopy. The thermal property of PEC-CCM conjugates was investigated by thermogravimetric analysis. It was found that PEC-CCM conjugates had formed nanomicelles in aqueous medium via self-assembly. These nanomicelles were observed as small spheres or ellipsoids and aggregated with a size range of 70-190 nm by transmission electron microscopy analysis. In a solution of nanomicelles, the stability of curcumin was improved, and its antioxidant property was preserved. The anticancer activity of PEC-CCM conjugates was quantified by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay using a hepatic cancer cell line (HepG2), a breast cancer cell line (MCF-7), a cervical cancer cell line (HeLa), and a human normal kidney cell line (293A). It was found that the curcumin of PEC-CCM conjugates had a more significant inhibitory effect on cancer cells and was less cytotoxic to normal cells than free curcumin was. PEC-CCM conjugates have great potential for some food and pharmaceutical applications.

  8. Ternary self-assemblies in water

    DEFF Research Database (Denmark)

    Hill, Leila R.; Blackburn, Octavia A.; Jones, Michael W.

    2013-01-01

    The self-assembly of higher order structures in water is realised by using the association of 1,3-biscarboxylates to binuclear meta-xylyl bridged DO3A complexes. Two dinicotinate binding sites are placed at a right-angle in a rhenium complex, which is shown to form a 1 : 2 complex with α,α'-bis(E......The self-assembly of higher order structures in water is realised by using the association of 1,3-biscarboxylates to binuclear meta-xylyl bridged DO3A complexes. Two dinicotinate binding sites are placed at a right-angle in a rhenium complex, which is shown to form a 1 : 2 complex with α...

  9. Glycyrrhetinic acid-poly(ethylene glycol)-glycyrrhetinic acid tri-block conjugates based self-assembled micelles for hepatic targeted delivery of poorly water soluble drug.

    Science.gov (United States)

    Wu, Fengbo; Xu, Ting; Liu, Chi; Chen, Can; Song, Xiangrong; Zheng, Yu; He, Gu

    2013-01-01

    The triblock 18β-glycyrrhetinic acid-poly(ethylene glycol)18β-glycyrrhetinic acid conjugates (GA-PEG-GA) based self-assembled micelles were synthesized and characterized by FTIR, NMR, transmission electron microscopy, and particle size analysis. The GA-PEG-GA conjugates having the critical micelle concentration of 6 × 10(-5) M were used to form nanosized micelles, with mean diameters of 159.21 ± 2.2 nm, and then paclitaxel (PTX) was incorporated into GA-PEG-GA micelles by self-assembly method. The physicochemical properties of the PTX loaded GA-PEG-GA micelles were evaluated including in vitro cellular uptake, cytotoxicity, drug release profile, and in vivo tissue distribution. The results demonstrate that the GA-PEG-GA micelles had low cytotoxicity and good ability of selectively delivering drug to hepatic cells in vitro and in vivo by the targeting moiety glycyrrhetinic acid. In conclusion, the GA-PEG-GA conjugates have potential medical applications for targeted delivery of poor soluble drug delivery.

  10. Self-assembly behaviour of conjugated terthiophene surfactants in water

    NARCIS (Netherlands)

    van Rijn, Patrick; Janeliunas, Dainius; Brizard, Aurelie M.; Stuart, Marc C. A.; Koper, Ger J. M.; Eelkema, Rienk; van Esch, Jan H.

    2011-01-01

    Conjugated self-assembled systems in water are of great interest because of their potential application in biocompatible supramolecular electronics, but so far their supramolecular chemistry remains almost unexplored. Here we present amphiphilic terthiophenes as a general self-assembling platform

  11. Living photolytic ring-opening polymerization of amino-functionalized [1]ferrocenophanes: synthesis and layer-by-layer self-assembly of well-defined water-soluble polyferrocenylsilane polyelectrolytes.

    Science.gov (United States)

    Wang, Zhuo; Masson, Georgeta; Peiris, Frank C; Ozin, Geoffrey A; Manners, Ian

    2007-01-01

    Facile synthetic routes have been developed that provide access to cationic and anionic water-soluble polyferrocenylsilane (PFS) polyelectrolytes with controlled molecular weight and narrow polydispersity. Living photolytic ring-opening polymerization of amino-functionalized [1]ferrocenophane (fc) monomers [fcSiMe{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)}] (3), [fcSi{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)}(2)] (10), [fcSiMe(C[triple chemical bond]CCH(2)NMe(2))] (14), and [fcSiMe(p-C(6)H(4)CH(2)NMe(2))] (20) yielded the corresponding polyferrocenylsilanes [(fcSiMe{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)})(n)](5), [(fcSi{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)}(2))(n)] (11), [{fcSiMe(C[triple chemical bond]CCH(2)NMe(2))}(n)] (15), and [{fcSiMe(p-C(6)H(4)CH(2)NMe(2))}(n)] (21) with controlled architectures. Further derivatization of 5, 15, and 21 generated water-soluble polyelectrolytes [(fcSiMe{C[triple chemical bond]CCH(2)N(CH(2)CH(2)CH(2)SO(3)Na)(2)})(n)] (6), [{fcSiMe(C[triple chemical bond]CCH(2)NMe(3)OSO(3)Me)}(n)] (7), and [{fcSiMe(p-C(6)H(4)CH(2)NMe(3)OSO(3)Me)}(n)] (22), respectively. The polyelectrolytes were readily soluble in water and NaCl aqueous solutions, with 6 and 22 exhibiting long-term stability in aqueous media. The PFS materials 6 and 22, have been utilized in the layer-by-layer (LbL) self-assembly of electrostatic superlattices. Our preliminary studies have indicated that films made from controlled low molecular-weight PFSs possess a considerably thinner bilayer thickness and higher refractive index than those made from PFSs that have an uncontrolled high molecular-weight. These results suggest that the structure and optical properties of LbL ultra-thin films can be tuned by varying polyelectrolyte chain length. The water-soluble low molecular weight PFSs are also useful materials for a range of applications including LbL self-assembly in highly confined spaces.

  12. Self-assembly of chiral fluorescent nanoparticles based on water-soluble L-tryptophan derivatives of p-tert-butylthiacalix[4]arene

    Directory of Open Access Journals (Sweden)

    Pavel L. Padnya

    2017-09-01

    Full Text Available New water-soluble tetra-substituted derivatives of p-tert-butylthiacalix[4]arene containing fragments of L-tryptophan in cone and 1,3-alternate conformations were obtained. It was shown that the resulting compounds form stable, positively charged aggregates of 86–134 nm in diameter in water at a concentration of 1 × 10−4 M as confirmed by dynamic light scattering, scanning electron microscopy and transmission electron microscopy. It was established that these aggregates are fluorescently active and chiral. A distinctive feature of the compounds is the pronounced dependence of their spectral (emission and chiroptical properties on the polarity of the solvent and the length of the linker between the macrocyclic and fluorophore parts of the molecule.

  13. Self-assembly of chiral fluorescent nanoparticles based on water-soluble L-tryptophan derivatives of p-tert-butylthiacalix[4]arene.

    Science.gov (United States)

    Padnya, Pavel L; Khripunova, Irina A; Mostovaya, Olga A; Mukhametzyanov, Timur A; Evtugyn, Vladimir G; Vorobev, Vyacheslav V; Osin, Yuri N; Stoikov, Ivan I

    2017-01-01

    New water-soluble tetra-substituted derivatives of p-tert-butylthiacalix[4]arene containing fragments of L-tryptophan in cone and 1,3-alternate conformations were obtained. It was shown that the resulting compounds form stable, positively charged aggregates of 86-134 nm in diameter in water at a concentration of 1 × 10-4 M as confirmed by dynamic light scattering, scanning electron microscopy and transmission electron microscopy. It was established that these aggregates are fluorescently active and chiral. A distinctive feature of the compounds is the pronounced dependence of their spectral (emission and chiroptical) properties on the polarity of the solvent and the length of the linker between the macrocyclic and fluorophore parts of the molecule.

  14. Heme-Protein Active Site Models via Self-Assembly in Water

    NARCIS (Netherlands)

    Fiammengo, R.; Wojciechowski, Kamil; Crego Calama, Mercedes; Figoli, A.; Wessling, Matthias; Reinhoudt, David; Timmerman, P.

    2003-01-01

    Water-soluble models of heme-protein active sites are obtained via the self-assembly of cationic porphyrins 1 and tetrasulfonato calix[4]arene 2 (K1·2 = 105 M-1). Selective binding of ligands either outside or inside the cavity of assemblies 1·2 via coordination to the zinc center has been observed.

  15. Artificial Photosynthesis at Dynamic Self-Assembled Interfaces in Water.

    Science.gov (United States)

    Hansen, Malte; Troppmann, Stefan; König, Burkhard

    2016-01-04

    Artificial photosynthesis is one of the big scientific challenges of today. Self-assembled dynamic interfaces, such as vesicles or micelles, have been used as microreactors to mimic biological photosynthesis. These aggregates can help to overcome typical problems of homogeneous photocatalytic water splitting. Microheterogeneous environments organize catalyst-photosensitizer assemblies at the interface in close proximity and thus enhance intermolecular interactions. Thereby vesicles and micelles may promote photoinitiated charge separation and suppress back electron transfer. The dynamic self-assembled interfaces solubilize non-polar compounds and protect sensitive catalytic units and intermediates against degradation. In addition, vesicles provide compartmentation that was used to separate different redox environments needed for an overall water splitting system. This Minireview provides an overview of the applications of micellar and vesicular microheterogeneous systems for solar energy conversion by photosensitized water oxidation and hydrogen generation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. High-Resolution Structure of a Self-Assembly-Competent Form of a Hydrophobic Peptide Captured in a Soluble [beta]-Sheet Scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Makabe, Koki; Biancalana, Matthew; Yan, Shude; Tereshko, Valentina; Gawlak, Grzegorz; Miller-Auer, Hélène; Meredith, Stephen C.; Koide, Shohei (UC)

    2010-02-08

    {beta}-Rich self-assembly is a major structural class of polypeptides, but still little is known about its atomic structures and biophysical properties. Major impediments for structural and biophysical studies of peptide self-assemblies include their insolubility and heterogeneous composition. We have developed a model system, termed peptide self-assembly mimic (PSAM), based on the single-layer {beta}-sheet of Borrelia outer surface protein A. PSAM allows for the capture of a defined number of self-assembly-like peptide repeats within a water-soluble protein, making structural and energetic studies possible. In this work, we extend our PSAM approach to a highly hydrophobic peptide sequence. We show that a penta-Ile peptide (Ile{sub 5}), which is insoluble and forms {beta}-rich self-assemblies in aqueous solution, can be captured within the PSAM scaffold in a form capable of self-assembly. The 1.1-{angstrom} crystal structure revealed that the Ile{sub 5} stretch forms a highly regular {beta}-strand within this flat {beta}-sheet. Self-assembly models built with multiple copies of the crystal structure of the Ile5 peptide segment showed no steric conflict, indicating that this conformation represents an assembly-competent form. The PSAM retained high conformational stability, suggesting that the flat {beta}-strand of the Ile{sub 5} stretch primed for self-assembly is a low-energy conformation of the Ile{sub 5} stretch and rationalizing its high propensity for self-assembly. The ability of the PSAM to 'solubilize' an otherwise insoluble peptide stretch suggests the potential of the PSAM approach to the characterization of self-assembling peptides.

  17. Novel Soluble Dietary Fiber-Tannin Self-Assembled Film: A Promising Protein Protective Material.

    Science.gov (United States)

    Song, Guo-Bin; Xu, Juan; Zheng, Hua; Feng, Ying; Zhang, Wen-Wen; Li, Kun; Ge, Shuang-shuang; Li, Kai; Zhang, Hong

    2015-06-24

    In this experiment, a natural promising protein protective film was fabricated through soluble dietary fiber (SDF)-tannin nanocluster self-assembly. FT-IR, XRD, and DSC tests were employed to investigate the interaction between the SDF and tannins before and after cross-linking induced by calcium ion. On the other hand, referring to the SEM and TEM results, the self-assembly process of the protein protective film could be indicated as follows: first, calcium ion, with its cross-ability, served as the "nucleus"; SDF and tannins were combined to prepare the nanoscale SDF-tannin clusters; then, the clusters were homogeneously deposited on the surface of protein to form a protective film by self-assembling hydrogen bond between tannin component of clusters as "adhesive" and protein in aqueous solutions under very mild conditions. Film thickness could also be controlled by tannin of different concentrations ranging from 114 to 1384 μm. Antibacterial test and in vitro cytotoxicity test proved that the film had a broad spectrum of antimicrobial properties and excellent cell biocompatibility, respectively, which might open up new applications in the food preservation and biomedical fields.

  18. Self-assembly of soluble unlinked and cross-linked fibrin oligomers.

    Science.gov (United States)

    Rosenfeld, M A; Leonova, V B; Biryukova, M I; Vasileva, M V

    2011-10-01

    Self-assembly of soluble unlinked and cross-linked fibrin oligomers formed from desA-fibrin monomer under the influence of factor XIIIa was studied in the presence of non-denaturing urea concentrations. By methods of elastic and dynamic light scattering combined with analytical ultracentrifugation, desA-fibrin oligomers formed in both the presence and absence of the factor XIIIa were shown to be ensembles consisting of soluble rod-like double-stranded protofibrils with diverse weight and size. Unlinked and cross-linked soluble double-stranded protofibrils can reach the length of 350-450 nm. The structure of soluble covalently-linked protofibrils is stabilized by isopeptide γ-dimers. Electrophoretic data indicate a complete absence of isopeptide bonds between α-chains of desA-fibrin molecules. The molecular mechanism of formation of soluble rod-like fibrin structures and specific features of its covalent stabilization under the influence of factor XIIIa are discussed.

  19. Chirality controlled responsive self-assembled nanotubes in water

    NARCIS (Netherlands)

    van Dijken, D. J.; Stacko, P.; Stuart, M. C. A.; Browne, W. R.; Feringa, B. L.

    2017-01-01

    The concept of using chirality to dictate dimensions and to store chiral information in self-assembled nanotubes in a fully controlled manner is presented. We report a photoresponsive amphiphile that co-assembles with its chiral counterpart to form nanotubes and demonstrate how chirality can be used

  20. Dynamic and programmable self-assembly of micro-rafts at the air-water interface.

    Science.gov (United States)

    Wang, Wendong; Giltinan, Joshua; Zakharchenko, Svetlana; Sitti, Metin

    2017-05-01

    Dynamic self-assembled material systems constantly consume energy to maintain their spatiotemporal structures and functions. Programmable self-assembly translates information from individual parts to the collective whole. Combining dynamic and programmable self-assembly in a single platform opens up the possibilities to investigate both types of self-assembly simultaneously and to explore their synergy. This task is challenging because of the difficulty in finding suitable interactions that are both dissipative and programmable. We present a dynamic and programmable self-assembling material system consisting of spinning at the air-water interface circular magnetic micro-rafts of radius 50 μm and with cosinusoidal edge-height profiles. The cosinusoidal edge-height profiles not only create a net dissipative capillary repulsion that is sustained by continuous torque input but also enable directional assembly of micro-rafts. We uncover the layered arrangement of micro-rafts in the patterns formed by dynamic self-assembly and offer mechanistic insights through a physical model and geometric analysis. Furthermore, we demonstrate programmable self-assembly and show that a 4-fold rotational symmetry encoded in individual micro-rafts translates into 90° bending angles and square-based tiling in the assembled structures of micro-rafts. We anticipate that our dynamic and programmable material system will serve as a model system for studying nonequilibrium dynamics and statistical mechanics in the future.

  1. Water-triggered self-assembly polycondensation for the one-pot synthesis of cyclomatrix polyphosphazene nanoparticles from amino acid ester.

    Science.gov (United States)

    Huang, Zhangjun; Chen, Shuangshuang; Lu, Xuemin; Lu, Qinghua

    2015-05-14

    Water-triggered self-assembly polycondensation was proposed for preparation of cyclomatrix polyphosphazene nanoparticles from amino acid esters, and a critical solubility parameter was found to determine whether the nanoparticles were formed. Based on this rule, we also investigated the control of the size of its nanoparticles.

  2. 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.

  3. Robust aqua material. A pressure-resistant self-assembled membrane for water purification

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Erez; Weissman, Haim; Rybtchinski, Boris [Department of Organic Chemistry, Weizmann Institute of Science, 234 Herzl Street, Rehovot, 7610001 (Israel); Shimoni, Eyal; Kaplan-Ashiri, Ifat [Department of Chemical Research Support, Weizmann Institute of Science, 234 Herzl Street, Rehovot, 7610001 (Israel); Werle, Kai; Wohlleben, Wendel [Department of Material Physics, Materials and Systems Research, BASF SE, 67056, Ludwigshafen (Germany)

    2017-02-13

    ''Aqua materials'' that contain water as their major component and are as robust as conventional plastics are highly desirable. Yet, the ability of such systems to withstand harsh conditions, for example, high pressures typical of industrial applications has not been demonstrated. We show that a hydrogel-like membrane self-assembled from an aromatic amphiphile and colloidal Nafion is capable of purifying water from organic molecules, including pharmaceuticals, and heavy metals in a very wide range of concentrations. Remarkably, the membrane can sustain high pressures, retaining its function. The robustness and functionality of the water-based self-assembled array advances the idea that aqua materials can be very strong and suitable for demanding industrial applications. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. 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.

  5. CO₂-Responsive Pillar[5]arene-Based Molecular Recognition in Water: Establishment and Application in Gas-Controlled Self-Assembly and Release.

    Science.gov (United States)

    Jie, Kecheng; Zhou, Yujuan; Yao, Yong; Shi, Bingbing; Huang, Feihe

    2015-08-26

    Here we developed a novel CO2-responsive pillararene-based molecular recognition motif established from a water-soluble pillar[5]arene and an anionic surfactant, sodium dodecyl sulfonate (SDS). The inclusion complex acted as a supramolecular amphiphile and self-assembled into spherical bilayer vesicles as confirmed by DLS, SEM, and TEM experiments. These vesicles were disrupted upon bubbling N2 or adding much more SDS to eliminate the inclusion complex. The assembly and disassembly of vesicles were successfully employed in gas and surfactant triggered releases of calcein, a water-soluble dye.

  6. Solvent-free, molecular-level modeling of self-assembling amphiphiles in water

    Science.gov (United States)

    Dey, Somajit; Saha, Jayashree

    2017-02-01

    Aggregation mesophases of self-assembling amphiphiles in water are highly important in the context of biology (biomembranes), therapy (liposomes), industry (polymer surfactants), and condensed-matter physics (lyotropic liquid crystals). Besides helping to increase fundamental understanding of collective molecular behavior, simulations of these lyotropic phases are pivotal to technological and medical developments such as smart drug carriers for gene therapy. Implicit-solvent, coarse-grained, low resolution modeling with a simple pair potential is the key to realizing the larger length and time scales associated with such mesoscopic phenomena during a computer simulation. Modeling amphiphiles by directed, soft, ellipsoidal cores interacting via a computationally simple yet tunable anisotropic pair potential, we have come to such a single-site model amphiphile that can rapidly self-assemble to give diverse lyotropic phases (such as fluid bilayers, micelles, etc.) without requiring the explicit incorporation of solvent particles. The model directly represents a tunable packing parameter that manifests in the spontaneous curvature of the amphiphile aggregates. Besides the all-important hydrophobic interaction, the hydration force is also treated implicitly. Thanks to the efficient solvent-free molecular-level coarse graining, this model is suitable for generic mesoscale studies of phenomena such as self-assembly, amphiphile mixing, domain formation, fusion, elasticity, etc., in amphiphile aggregates.

  7. Chiral amplification of oligopeptides in two-dimensional crystalline self-assemblies on water

    DEFF Research Database (Denmark)

    Zepik, H.; Shavit, E.; Tang, M.

    2002-01-01

    Differences in the two-dimensional packing arrangements of racemic and enantiomeric crystalline self-assemblies on the water surface of amphiphilic activated analogs of lysine and glutamic acid have been used to prepare oligopeptides of homochiral sequence and oligopeptides of single handedness...... from chiral nonracemic mixtures. The crystalline structures on the water surface were determined by grazing incidence x-ray diffraction and the diastereomeric composition of the oligopeptides by matrix-assisted laser desorption time-of-flight mass spectrometry with enantio-labeling. These results...... suggest that reactivity of ordered clusters at interfaces might have played a role in the generation of early homochiral biopolymers....

  8. Effect of Monomer Solubility on the Evolution of Copolymer Morphology during Polymerization-Induced Self-Assembly in Aqueous Solution.

    Science.gov (United States)

    Cockram, Amy A; Neal, Thomas J; Derry, Matthew J; Mykhaylyk, Oleksandr O; Williams, Neal S J; Murray, Martin W; Emmett, Simon N; Armes, Steven P

    2017-02-14

    Polymerization-induced self-assembly (PISA) has become a widely used technique for the rational design of diblock copolymer nano-objects in concentrated aqueous solution. Depending on the specific PISA formulation, reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization typically provides straightforward access to either spheres, worms, or vesicles. In contrast, RAFT aqueous emulsion polymerization formulations often lead to just kinetically-trapped spheres. This limitation is currently not understood, and only a few empirical exceptions have been reported in the literature. In the present work, the effect of monomer solubility on copolymer morphology is explored for an aqueous PISA formulation. Using 2-hydroxybutyl methacrylate (aqueous solubility = 20 g dm-3 at 70 °C) instead of benzyl methacrylate (0.40 g dm-3 at 70 °C) for the core-forming block allows access to an unusual "monkey nut" copolymer morphology over a relatively narrow range of target degrees of polymerization when using a poly(methacrylic acid) RAFT agent at pH 5. These new anisotropic nanoparticles have been characterized by transmission electron microscopy, dynamic light scattering, aqueous electrophoresis, shear-induced polarized light imaging (SIPLI), and small-angle X-ray scattering.

  9. Oligomerization of hydrophobin SC3 in solution : From soluble state to self-assembly

    NARCIS (Netherlands)

    Wang, Xiaoqin; Graveland-Bikker, Johanna F.; Kruif, Cornelis G. de; Robillard, George T.

    2004-01-01

    Hydrophobin SC3 is a protein with special self-association properties that differ depending on whether it is in solution, on an air/water interface or on a solid surface. Its self-association on an air/water interface and solid surface have been extensively characterized. The current study focuses

  10. Crystalline mono- and multilayer self-assemblies of oligothiophenes at the air-water interface

    DEFF Research Database (Denmark)

    Isz, S.; Weissbuch, I.; Kjær, K.

    1997-01-01

    The formation of Langmuir monolayers at the air-water interface has long been believed to be limited to amphiphilic molecules containing a hydrophobic chain and a hydrophilic headgroup. Here we report the formation of crystalline mono- and multilayer self-assemblies of oligothiophenes, a class...... of aromatic nonamphiphilic molecules, self-aggregated at the air-water interface. As model systems we have examined the deposition of quaterthiophene (S-4), quinquethiophene (S-5). and sexithiophene (S-6) from chloroform solutions on the water surface. The structures of the films were determined by surface...... pressure-area isotherms, by scanning force microscopy (SFM) after transfer of the films onto atomically smooth mica, by cryo-transmission electron microscopy (Cryo-TEM) on vitreous ice, and by grazing incidence synchrotron X-ray diffraction (GID) directly on the water surface. S-4 forms two polymorphic...

  11. Water droplets as template for next-generation self-assembled poly-(etheretherketone) with cardo membranes.

    Science.gov (United States)

    Gugliuzza, Annarosa; Aceto, Marianna Carmela; Macedonio, Francesca; Drioli, Enrico

    2008-08-28

    Next generation PEEK-WC membranes have been fabricated by using an innovative self-assembly technique. Patterned architectures have been achieved via a solvent-reduced and water-assisted process, resulting in honeycomb packed geometry. The membranes exhibit monodisperse pores with size and shape comparable to those left by templating water droplets. Influencing factors for the formation of self-assembled poly-(etheretherketone) with Cardo [PEEK-WC] membranes have been evaluated, identifying the critical parameters for nucleation, growth, and propagation of the droplet-mobile arrays through the overall films. Structure-transport relationships have been discussed according to the results achieved from the implementation of membrane distillation processes, yielding indication about the suitability of self-assembled PEEK-WC films to work as interfaces in contactor operations.

  12. Trace Water as Prominent Factor to Induce Peptide Self-Assembly: Dynamic Evolution and Governing Interactions in Ionic Liquids.

    Science.gov (United States)

    Wang, Juan; Yuan, Chengqian; Han, Yuchun; Wang, Yilin; Liu, Xiaomin; Zhang, Suojiang; Yan, Xuehai

    2017-11-01

    The interaction between water and biomolecules including peptides is of critical importance for forming high-level architectures and triggering life's functions. However, the bulk aqueous environment has limitations in detecting the kinetics and mechanisms of peptide self-assembly, especially relating to interactions of trace water. With ionic liquids (ILs) as a nonconventional medium, herein, it is discovered that trace amounts of water play a decisive role in triggering self-assembly of a biologically derived dipeptide. ILs provide a suitable nonaqueous environment, enabling us to mediate water content and follow the dynamic evolution of peptide self-assembly. The trace water is found to be involved in the assembly process of dipeptide, especially leading to the formation of stable noncovalent dipeptide oligomers in the early stage of nucleation, as evident by both experimental studies and theoretical simulations. The thermodynamics of the growth process is mainly governed by a synergistic effect of hydrophobic interaction and hydrogen bonds. Each step of assembly presents a different trend in thermodynamic energy. The dynamic evolution of assembly process can be efficiently mediated by changing trace water content. The decisive role of trace water in triggering and mediating self-assembly of biomolecules provides a new perspective in understanding supramolecular chemistry and molecular self-organization in biology. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Low-molecular-weight gelators: elucidating the principles of gelation based on gelator solubility and a cooperative self-assembly model.

    Science.gov (United States)

    Hirst, Andrew R; Coates, Ian A; Boucheteau, Thomas R; Miravet, Juan F; Escuder, Beatriu; Castelletto, Valeria; Hamley, Ian W; Smith, David K

    2008-07-16

    This paper highlights the key role played by solubility in influencing gelation and demonstrates that many facets of the gelation process depend on this vital parameter. In particular, we relate thermal stability ( T gel) and minimum gelation concentration (MGC) values of small-molecule gelation in terms of the solubility and cooperative self-assembly of gelator building blocks. By employing a van't Hoff analysis of solubility data, determined from simple NMR measurements, we are able to generate T calc values that reflect the calculated temperature for complete solubilization of the networked gelator. The concentration dependence of T calc allows the previously difficult to rationalize "plateau-region" thermal stability values to be elucidated in terms of gelator molecular design. This is demonstrated for a family of four gelators with lysine units attached to each end of an aliphatic diamine, with different peripheral groups (Z or Boc) in different locations on the periphery of the molecule. By tuning the peripheral protecting groups of the gelators, the solubility of the system is modified, which in turn controls the saturation point of the system and hence controls the concentration at which network formation takes place. We report that the critical concentration ( C crit) of gelator incorporated into the solid-phase sample-spanning network within the gel is invariant of gelator structural design. However, because some systems have higher solubilities, they are less effective gelators and require the application of higher total concentrations to achieve gelation, hence shedding light on the role of the MGC parameter in gelation. Furthermore, gelator structural design also modulates the level of cooperative self-assembly through solubility effects, as determined by applying a cooperative binding model to NMR data. Finally, the effect of gelator chemical design on the spatial organization of the networked gelator was probed by small-angle neutron and X

  14. Water-Soluble Metallocene-Containing Polymers.

    Science.gov (United States)

    Alkan, Arda; Wurm, Frederik R

    2016-09-01

    Metallocenes are organometallic compounds with reversible redox profiles and tunable oxidation and reduction potentials, depending on the metal and substituents at the cyclopentadienyl rings. Metallocenes have been introduced in macromolecules to combine the redox-activity with polymer properties. There are many examples of such hydrophobic polymer materials, but much fewer water-soluble examples are found scattered across the polymer literature. However, in terms of drug delivery and other biological applications, water solubility is essential. For this very reason, all the synthetic routes to water-soluble metallocene containing polymers are collected and discussed here. The focus is on neutral ferrocene- and ruthenocene-containing and charged cobaltocenium-containing macromolecules (i.e., symmetrical sandwich complexes). The synthetic protocols, self-assembly behavior, and other benefits of the obtained materials are discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Photocurable oil/water interfaces as a universal platform for 2-D self-assembly.

    Science.gov (United States)

    Benkoski, Jason J; Jones, Ronald L; Douglas, Jack F; Karim, Alamgir

    2007-03-27

    We present a novel platform, dubbed fossilized liquid assembly, for the creation of 2-D assemblies from nanoscale building blocks. The system consists of an oil/water interface in which the oil phase can be flash-cured upon UV exposure. The photopolymerizable material, 1,12-dodecanediol dimethacrylate, solidifies in as little as 1 s when exposed to UV light. The rapid cross-linking allows one to obtain a "snapshot" of the assembly process for particles that segregate to the oil/water interface. Among the particles investigated were nonpolar 0.39 microm poly(methyl methacrylate) latex spheres, nonpolar 10 microm polystyrene latex spheres, highly polarizable 5 nm Au nanocrystals, dipolar 10 nm CdTe quantum dots, and magnetic 25 nm magnetite nanoparticles. The aggregates formed by this process were typically either globular or fractal in appearance. By comparing with simulation, we can perform quantitative image analysis on the resulting micrographs to define a rigorous set of standards for distinguishing among the main classes of aggregation: flocculation, equilibrium phase separation, and true self-assembly.

  16. Characterization of biodegradable polyurethane nanoparticles and thermally induced self-assembly in water dispersion.

    Science.gov (United States)

    Ou, Chun-Wei; Su, Chiu-Hun; Jeng, U-Ser; Hsu, Shan-hui

    2014-04-23

    Waterborne polyurethanes (PU) with different compositions of biodegradable oligodiols as the soft segment were synthesized as nanoparticles (NPs) in this study. Using dynamic light scattering (DLS), multiangle light scattering (MALS), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS), we demonstrated that these NPs were compact spheres with different shape factors. The temperature-dependent swelling of the PU NPs in water was distinct. In particular, PU NPs with 80 mol % polycaprolactone (PCL) diol and 20 mol % poly(L-lactide) (PLLA) diol as the soft segment had significant swelling (∼450%) at 37 °C. This was accompanied by a sol-gel transition observed in about 2 min for the NP dispersion. The thermally induced swelling and self-assembly of these NPs were associated with the secondary force (mainly hydrogen bonding) and degree of crystallinity, which depended on the soft segment compositions. The thermo-responsiveness of the PU NPs with mixed biodegradable oligodiols may be employed to design smart biodegradable carriers for delivery of cells or drugs near body temperature.

  17. Hydrophobic-induced Surface Reorganization: Molecular Dynamics Simulations of Water Nanodroplet on Perfluorocarbon Self-Assembled Monolayers

    OpenAIRE

    Park, Sung Hyun; Carignano, Marcelo A.; Nap, Rikkert J.; Szleifer, Igal

    2010-01-01

    We carried out molecular dynamics simulations of water droplets on self-assembled monolayers of perfluorocarbon molecules. The interactions between the water droplet and the hydrophobic fluorocarbon surface were studied by systematically changing the molecular surface coverage and the mobility of the tethered head groups of the surface chain molecules. The microscopic contact angles were determined for different fluorocarbon surface densities. The contact angle at a nanometer length scale doe...

  18. 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...

  19. Self-Assembly, Guest Capture, and NMR Spectroscopy of a Metal-Organic Cage in Water

    Science.gov (United States)

    Go, Eun Bin; Srisuknimit, Veerasak; Cheng, Stephanie L.; Vosburg, David A.

    2016-01-01

    A green organic-inorganic laboratory experiment has been developed in which students prepare a self-assembling iron cage in D[subscript 2]O at room temperature. The tetrahedral cage captures a small, neutral molecule such as cyclohexane or tetrahydrofuran. [Superscript 1]H NMR analysis distinguishes captured and free guests through diagnostic…

  20. Compartmentalization Technologies via Self-Assembly and Cross-Linking of Amphiphilic Random Block Copolymers in Water.

    Science.gov (United States)

    Matsumoto, Mayuko; Terashima, Takaya; Matsumoto, Kazuma; Takenaka, Mikihito; Sawamoto, Mitsuo

    2017-05-31

    Orthogonal self-assembly and intramolecular cross-linking of amphiphilic random block copolymers in water afforded an approach to tailor-make well-defined compartments and domains in single polymer chains and nanoaggregates. For a double compartment single-chain polymer, an amphiphilic random block copolymer bearing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic dodecyl, benzyl, and olefin pendants was synthesized by living radical polymerization (LRP) and postfunctionalization; the dodecyl and benzyl units were incorporated into the different block segments, whereas PEG pendants were statistically attached along a chain. The copolymer self-folded via the orthogonal self-assembly of hydrophobic dodecyl and benzyl pendants in water, followed by intramolecular cross-linking, to form a single-chain polymer carrying double yet distinct hydrophobic nanocompartments. A single-chain cross-linked polymer with a chlorine terminal served as a globular macroinitiator for LRP to provide an amphiphilic tadpole macromolecule comprising a hydrophilic nanoparticle and a hydrophobic polymer tail; the tadpole thus self-assembled into multicompartment aggregates in water.

  1. Quantitative self-assembly of a purely organic three-dimensional catenane in water

    Science.gov (United States)

    Li, Hao; Zhang, Huacheng; Lammer, Aaron D.; Wang, Ming; Li, Xiaopeng; Lynch, Vincent M.; Sessler, Jonathan L.

    2015-12-01

    Self-assembly by means of coordinative bond formation has opened up opportunities for the high-yield synthesis of molecules with complex topologies. However, the preparation of purely covalent molecular architectures in aqueous media has remained a challenging task. Here, we present the preparation of a three-dimensional catenane through a self-assembly process that relies on the formation of dynamic hydrazone linkages in an acidic aqueous medium. The quantitative synthesis process and the mechanically interlocked structure of the resulting catenane were established by NMR spectroscopy, mass spectrometry, X-ray crystallography and HPLC studies. In addition, the labile hydrazone linkages of the individual [2]catenane components may be ‘locked’ by increasing the pH of the solution, yielding a relatively kinetically stable molecule. The present study thus details a simple approach to the creation and control of complex molecular architectures under reaction conditions that mimic biological milieux.

  2. Comparing and correlating solubility parameters governing the self-assembly of molecular gels using 1,3:2,4-dibenzylidene sorbitol as the gelator.

    Science.gov (United States)

    Lan, Yaqi; Corradini, Maria G; Liu, Xia; May, Tim E; Borondics, Ferenc; Weiss, Richard G; Rogers, Michael A

    2014-12-02

    Solvent properties play a central role in mediating the aggregation and self-assembly of molecular gelators and their growth into fibers. Numerous attempts have been made to correlate the solubility parameters of solvents and gelation abilities of molecular gelators, but a comprehensive comparison of the most important parameters has yet to appear. Here, the degree to which partition coefficients (log P), Henry's law constants (HLC), dipole moments, static relative permittivities (ε(r)), solvatochromic E(T)(30) parameters, Kamlet-Taft parameters (β, α, and π), Catalan's solvatochromic parameters (SPP, SB, and SA), Hildebrand solubility parameters (δ(i)), and Hansen solubility parameters (δ(p), δ(d), δ(h)) and the associated Hansen distance (R(ij)) of 62 solvents (covering a wide range of properties) can be correlated with the self-assembly and gelation of 1,3:2,4-dibenzylidene sorbitol (DBS) gelation, a classic molecular gelator, is assessed systematically. The approach presented describes the basis for each of the parameters and how it can be applied. As such, it is an instructional blueprint for how to assess the appropriate type of solvent parameter for use with other molecular gelators as well as with molecules forming other types of self-assembled materials. The results also reveal several important insights into the factors favoring the gelation of solvents by DBS. The ability of a solvent to accept or donate a hydrogen bond is much more important than solvent polarity in determining whether mixtures with DBS become solutions, clear gels, or opaque gels. Thermodynamically derived parameters could not be correlated to the physical properties of the molecular gels unless they were dissected into their individual HSPs. The DBS solvent phases tend to cluster in regions of Hansen space and are highly influenced by the hydrogen-bonding HSP, δ(h). It is also found that the fate of this molecular gelator, unlike that of polymers, is influenced not only by

  3. Comparing and Correlating Solubility Parameters Governing the Self-Assembly of Molecular Gels Using 1,3:2,4-Dibenzylidene Sorbitol as the Gelator

    Science.gov (United States)

    2014-01-01

    Solvent properties play a central role in mediating the aggregation and self-assembly of molecular gelators and their growth into fibers. Numerous attempts have been made to correlate the solubility parameters of solvents and gelation abilities of molecular gelators, but a comprehensive comparison of the most important parameters has yet to appear. Here, the degree to which partition coefficients (log P), Henry’s law constants (HLC), dipole moments, static relative permittivities (εr), solvatochromic ET(30) parameters, Kamlet–Taft parameters (β, α, and π), Catalan’s solvatochromic parameters (SPP, SB, and SA), Hildebrand solubility parameters (δi), and Hansen solubility parameters (δp, δd, δh) and the associated Hansen distance (Rij) of 62 solvents (covering a wide range of properties) can be correlated with the self-assembly and gelation of 1,3:2,4-dibenzylidene sorbitol (DBS) gelation, a classic molecular gelator, is assessed systematically. The approach presented describes the basis for each of the parameters and how it can be applied. As such, it is an instructional blueprint for how to assess the appropriate type of solvent parameter for use with other molecular gelators as well as with molecules forming other types of self-assembled materials. The results also reveal several important insights into the factors favoring the gelation of solvents by DBS. The ability of a solvent to accept or donate a hydrogen bond is much more important than solvent polarity in determining whether mixtures with DBS become solutions, clear gels, or opaque gels. Thermodynamically derived parameters could not be correlated to the physical properties of the molecular gels unless they were dissected into their individual HSPs. The DBS solvent phases tend to cluster in regions of Hansen space and are highly influenced by the hydrogen-bonding HSP, δh. It is also found that the fate of this molecular gelator, unlike that of polymers, is influenced not only by the

  4. Encapsulation of Polythiophene by Glycopolymer for Water Soluble Nano-wire

    Energy Technology Data Exchange (ETDEWEB)

    T Fukuda; Y Inoue; T Koga; M Matsuoka; Y Miura

    2011-12-31

    A water-soluble polythiophene (PT) was prepared by the self-assembling complex with a glycopolymer. The glycopolymer of poly(N-p-vinylbenzyl-D-lactonamide) (PVLA) formed self-assembling cylindrical structure based on the amphiphilicity even after the complexation with PT. We confirmed the improved optical functionality of PT due to the longer conjugated {pi}-orbital. It suggested that PT behaved like molecular nanowire with the self-assembled structure in the hydrophobic core of PVLA. PVLA-PT also showed specific biorecognition against corresponding lectin. These results suggested that the bioactive nanowire formation of PT with the glycopolymer was developed.

  5. Self-assembly of polar food lipids.

    Science.gov (United States)

    Leser, Martin E; Sagalowicz, Laurent; Michel, Martin; Watzke, Heribert J

    2006-11-16

    Polar lipids, such as monoglycerides and phospholipids, are amphiphilic molecules commonly used as processing and stabilization aids in the manufacturing of food products. As all amphiphilic molecules (surfactants, emulsifiers) they show self-assembly phenomena when added into water above a certain concentration (the critical aggregation concentration). The variety of self-assembly structures that can be formed by polar food lipids is as rich as it is for synthetic surfactants: micelles (normal and reverse micelles), microemulsions, and liquid crystalline phases can be formulated using food-grade ingredients. In the present work we will first discuss microemulsion and liquid crystalline phase formation from ingredients commonly used in food industry. In the last section we will focus on three different potential application fields, namely (i) solubilization of poorly water soluble ingredients, (ii) controlled release, and (iii) chemical reactivity. We will show how the interfacial area present in self-assembly structures can be used for (i) the delivery of functional molecules, (ii) controlling the release of functional molecules, and (iii) modulating the chemical reactivity between reactive molecules, such as aromas.

  6. Isoporous PS-b-PEO ultrafiltration membranes via self-assembly and water-induced phase separation

    KAUST Repository

    Karunakaran, Madhavan

    2014-03-01

    A simple and efficient approach towards the fabrication of a skinned membrane with highly ordered pores in the nanometer range is presented here. We successfully combined the self-assembly of PS-b-PEO block copolymer and water induced phase separation for the preparation of isoporous PS-b-PEO block copolymer membranes. We produced for the first time asymmetric isoporous PS-b-PEO membranes with a 100nm thin isoporous separating layer using water at room temperature as coagulant. This was possible by careful selection of the block lengths and the solvent system. FESEM, AFM and TEM measurements were employed to characterize the nanopores of membranes. The pure water fluxes were measured and the flux of membrane was exceptionally high (around 800Lm-2h-1bar-1). Protein rejection measurements were carried out for this membrane and the membrane had a retention of about 67% of BSA and 99% of γ-globulin. © 2013 Elsevier B.V.

  7. Self-assembly of neuroprotective carbazolium based small molecules at octane/water interface: A simulation investigation

    Science.gov (United States)

    Zolghadr, Amin Reza; Heydari Dokoohaki, Maryam

    2016-11-01

    The self-assembly of dibromocarbazole based small molecule (P7C3) and its analogues is studied at the octane/water interface by using molecular dynamics simulations. P7C3 protects newborn neurons from apoptotic cell death and enhances neurogenesis. The bromines on the carbazole appear particularly important, as the derivatives with dichloro and parent carbazole did not appear active at the concentrations tested. We are mainly focused on the question that why is dibromocarbazole derivative an effective neuroprotective drug, but not dichlorocarbazole or parent carbazole? It was found that P7C3 and P7C3-Cl were concentrated in the interfacial region, whereas the parent carbazole derivative were distributed throughout the water phase. The diffusion of P7C3 molecules in the interfacial region are higher than P7C3-Cl. This approach could use by experimentalist to evaluate the permeability of drug candidates prior to their synthesis.

  8. Drug delivery by water-soluble organometallic cages.

    Science.gov (United States)

    Therrien, Bruno

    2012-01-01

    Until recently, organometallic derivatives were generally viewed as moisture- and air-sensitive compounds, and consequently very challenging to synthesise and very demanding in terms of laboratory requirements (Schlenk techniques, dried solvent, glove box). However, an increasing number of stable, water-soluble organometallic compounds are now available, and organometallic chemistry in aqueous phase is a flourishing area of research. As such, coordination-driven self-assemblies using organometallic building blocks are compatible with water, thus opening new perspectives in bio-organometallic chemistry.This chapter gives a short history of coordination-driven self-assembly, with a special attention to organometallic metalla-cycles, especially those composed of half-sandwich complexes. These metalla-assemblies have been used as sensors, as anticancer agents, as well as drug carriers.

  9. Ionic self-assembly of surface functionalized metal-organic polyhedra nanocages and their ordered honeycomb architecture at the air/water interface.

    Science.gov (United States)

    Li, Yantao; Zhang, Daojun; Gai, Fangyuan; Zhu, Xingqi; Guo, Ya-nan; Ma, Tianliang; Liu, Yunling; Huo, Qisheng

    2012-08-18

    Metal-organic polyhedra (MOP) nanocages were successfully surface functionalized via ionic self-assembly and the ordered honeycomb architecture of the encapsulated MOP nanocages was also fabricated at the air/water surface. The results provide a novel synthetic method and membrane processing technique of amphiphilic MOP nanocages for various applications.

  10. Haemozoin (B-haematin) biomineralization occurs by self-assembly near the lipid/water interface

    CSIR Research Space (South Africa)

    Egan, TJ

    2006-09-01

    Full Text Available remained unknown, although lipids or proteins have been suggested to catalyse its formation. We have found that B-haematin (synthetic haemozoin) forms rapidly under physiologically realistic conditions near octanol/water, pentanol/water and lipid...

  11. Facile synthesis of a peptidic Au(i)-metalloamphiphile and its self-assembly into luminescent micelles in water

    NARCIS (Netherlands)

    Kemper, Benedict; Hristova, Yana R; Tacke, Sebastian; Stegemann, Linda; van Bezouwen, Laura S; Stuart, Marc C A; Klingauf, Jürgen; Strassert, Cristian A; Besenius, Pol

    2014-01-01

    We report a short synthetic route for the preparation of a peptidic Au(i)-metalloamphiphile which, in buffered environments of physiological ionic strength, self-assembles into luminescent micellar nanostructures of 14 nm in diameter.

  12. Highly permeable artificial water channels that can self-assemble into two-dimensional arrays

    OpenAIRE

    Shen, Yue-xiao; Si, Wen; Erbakan, Mustafa; Decker, Karl; De Zorzi, Rita; Saboe, Patrick O.; Kang, You Jung; Majd, Sheereen; Butler, Peter J.; Walz, Thomas; Aksimentiev, Aleksei; Hou, Jun-Li; Kumar, Manish

    2015-01-01

    This study focuses on the design of highly permeable artificial water channels for the use in membrane-based separation materials. A platform was developed for the systematic characterization of the single-channel water conduction of artificial channels, which is based on permeability measurement by stopped-flow light-scattering experiments and single-molecule counting by fluorescence correlation spectroscopy. With this platform the water conduction of the redesigned peptide-appended pillar[5...

  13. Fluid-flow-templated self-assembly of calcium carbonate tubes in the laboratory and in biomineralization: The tubules of the watering-pot shells, Clavagelloidea.

    Science.gov (United States)

    Cardoso, Silvana S S; Cartwright, Julyan H E; Checa, Antonio G; Sainz-Díaz, C Ignacio

    2016-10-01

    We show with laboratory experiments that self-assembled mineral tube formation involving precipitation around a templating jet of fluid - a mechanism well-known in the physical sciences from the tubular growth of so-called chemical gardens - functions with carbonates, and we analyse the microstructures and compositions of the precipitates. We propose that there should exist biological examples of fluid-flow-templated tubes formed from carbonates. We present observational and theoretical modelling evidence that the complex structure of biomineral calcium carbonate tubules that forms the 'rose' of the watering-pot shells, Clavagelloidea, may be an instance of this mechanism in biomineralization. We suggest that this is an example of self-organization and self-assembly processes in biomineralization, and that such a mechanism is of interest for the production of tubes as a synthetic biomaterial. The work discussed in the manuscript concerns the self-assembly of calcium carbonate micro-tubes and nano-tubes under conditions of fluid flow together with chemical reaction. We present the results of laboratory experiments on tube self-assembly together with theoretical calculations. We show how nature may already be making use of this process in molluscan biomineralization of the so-called watering-pot shells, and we propose that we may be able to take advantage of the formation mechanism to produce synthetic biocompatible micro- and nano-tubes. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. Self-Assembly and Intermolecular Forces When Cellulose and Water Interact Using Molecular Modeling

    Directory of Open Access Journals (Sweden)

    Ali Chami Khazraji

    2013-01-01

    Full Text Available Cellulose chains are linear and aggregation occurs via both intra- and intermolecular hydrogen bonds. Cellulose has a strong affinity to itself and toward materials containing hydroxyls groups. Based on the preponderance of hydroxyl functional groups, cellulose is very reactive with water. At room temperature, cellulose chains will have at least a monomolecular layer of water associated to it. The formation of hydrogen bonds at the cellulose/water interface is shown to depend essentially on the adsorption site, for example, the equatorial hydroxyls or OH moieties pointing outward from the cellulose chains. The vdW forces also contribute significantly to the adsorption energy. They are a considerable cohesive energy into the cellulose network. At the surface of the cellulose chains, many intermolecular hydrogen bonds of the cellulose chains are lost. However, they are compensated by hydrogen bonds with water molecules. Electronic clouds can be distorted and create electrostatic dipoles. The large antibonding electron cloud that exists around the glucosidic bonds produces an induced polarization at the approach of water molecules. The electron cloud can be distorted and create an electrostatic dipole. It applies to the total displacement of the atoms within the material. Orbitals play a special role in reaction mechanism. Hydrophilic/hydrophobic nature of cellulose is based on its structural anisotropy. Cellulose-water interactions are exothermic reactions. These interactions may occur spontaneously and result in higher randomness of the system. They are denoted by a negative heat flow (heat is lost to the surroundings. Energy does not need to be inputted in order for cellulose-water interactions to occur.

  15. Silk-collagen-like block copolymers with charged blocks : self-assembly into nanosized ribbons and macroscopic gels

    OpenAIRE

    Martens, A.A.

    2008-01-01

    The research described in this thesis concerns the design, biotechnological production, and physiochemical study of large water-soluble (monodisperse) protein triblock-copolymers with sequential blocks, some of which are positively or negatively charged and self-assemble in response to a change in pH or co-assemble in response to oppositely charged polyelectrolytes (including each other). Such molecules displaying controlled self-assembly may lead to new biocompatible nano-structured material...

  16. Towards field detection of polycyclic aromatic hydrocarbons (PAHs) in environment water using a self-assembled SERS sensor

    Science.gov (United States)

    Yan, Xia; Shi, Xiaofeng; Yang, Jie; Zhang, Xu; Jia, Wenjie; Ma, Jun

    2017-10-01

    A self-assembled surface enhanced Raman scattering (SERS) sensor is reported in this paper. To achieve high sensitivity, a high sensitive SERS substrate and a high efficient self-constructed light path were made. The SERS substrate was composed by gold nanoparticles (AuNPs, pH=13), glycidyl methacrylate-ethylene dimethacrylate (GMA-EDMA) porous material and syringe filter. The substrate had a good repeatability, and the relative standard deviation (RSD) of the same substrate was less than 5%. The efficiency of the self-constructed light path is about two times better than RPB Y type reflection fiber when the energy density was roughly equal on samples. The size of the SERS sensor is 350×300×180 mm and the weight is 15 kg. Its miniaturization and portable can comply with the requirements of field detection. Besides, it has good sensitivity, stability and selectivity. For lab experiments, strong enhancements of Raman scattering from organic pollutant polycyclic aromatic hydrocarbons (PAHs) molecules were exhibited. The dependences of SERS intensities on concentrations of PAHs were investigated, and the results indicated that they revealed a satisfactory linear relationship in low concentrations. The limits of detection (LODs) of PAHs phenanthrene and fluorene are 8.3×10-10 mol/L and 7.1×10-10 mol/L respectively [signal to noise ratio (S/N) =3]. Based on this SERS sensor, signals of benzo (a) pyrene and pyrene were found in environmental water and the sensor would be an ideal candidate for field detection of PAHs.

  17. Interactions of Gaseous HNO3 and Water with Individual and Mixed Alkyl Self-Assembled Monolayers at Room Temperature

    Science.gov (United States)

    Nishino, Noriko; Hollingsworth, Scott A.; Stern, Abraham C.; Roeselová, Martina; Tobias, Douglas J.; Finlayson-Pitts, Barbara J.

    2014-01-01

    The major removal processes for gaseous nitric acid (HNO3) in the atmosphere are dry and wet deposition onto various surfaces. The surface in the boundary layer is often covered with organic films, but the interaction of gaseous HNO3 with them is not well understood. To better understand the factors controlling the uptake of gaseous nitric acid and its dissociation in organic films, studies were carried out using single component and mixtures of C8 and C18 alkyl self-assembled monolayers (SAMs) attached to a germanium (Ge) attenuated total reflectance (ATR) crystal upon which a thin layer of SiOx had been deposited. For comparison, diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) studies were also carried out using a C18 SAM attached to the native oxide layer on the surface of silicon powder. These studies show that the alkyl chain length and order/disorder of the SAMs does not significantly affect the uptake or dissociation/recombination of molecular HNO3. Thus, independent of the nature of the SAM, molecular HNO3 is observed up to 70–90 % relative humidity. After dissociation, molecular HNO3 is regenerated on all SAM surfaces when water is removed. Results of molecular dynamics simulations are consistent with experiments and show that defects and pores on the surfaces control the uptake, dissociation and recombination of molecular HNO3. Organic films on surfaces in the boundary layer will certainly be more irregular and less ordered than SAMs studied here, therefore undissociated HNO3 may be present on surfaces in the boundary layer to a greater extent than previously thought. The combination of this observation with the results of recent studies showing enhanced photolysis of nitric acid on surfaces suggests that renoxification of deposited nitric acid may need to be taken into account in atmospheric models. PMID:24352159

  18. Water-soluble vitamins.

    Science.gov (United States)

    Konings, Erik J M

    2006-01-01

    Simultaneous Determination of Vitamins.--Klejdus et al. described a simultaneous determination of 10 water- and 10 fat-soluble vitamins in pharmaceutical preparations by liquid chromatography-diode-array detection (LC-DAD). A combined isocratic and linear gradient allowed separation of vitamins in 3 distinct groups: polar, low-polar, and nonpolar. The method was applied to pharmaceutical preparations, fortified powdered drinks, and food samples, for which results were in good agreement with values claimed. Heudi et al. described a separation of 9 water-soluble vitamins by LC-UV. The method was applied for the quantification of vitamins in polyvitaminated premixes used for the fortification of infant nutrition products. The repeatability of the method was evaluated at different concentration levels and coefficients of variation were principle in a specific and sensitive method for the determination of free and bound pantothenic acid in a large variety of foods. A French laboratory invited European laboratories to participate in a series of collaborative studies for this method, which will be carried out in 2005/2006. A more sophisticated method was described by Mittermayer et al. They developed an LC-mass spectrometry (LC/MS) method for the determination of vitamin B5 in a wide range of fortified food products. Application of the method to various samples showed consistent results with those obtained by microbiology. Vitamin B6.-Method 2004.07, an LC method for the analysis of vitamin B6 in reconstituted infant formula, was published by Mann et al. In contrast with this method, which quantifies vitamin B6 after converting the phosphorylated and free vitamers into pyridoxine, Viñas et al. published an LC method which determines 6 vitamin B6 related compounds, the 3 B6 vitamers, their corresponding phosphorylated esters, and a metabolite. Accuracy was determined using 2 CRMs. Results were within the certified ranges. Vitamin C.-Franke et al. described an extensive

  19. Self-assembled systems of water soluble metal 8-hydroxyquinolates with surfactants and conjugated polyelectrolytes

    DEFF Research Database (Denmark)

    Burrows, Hugh D.; Costa, Telma; Luisa Ramos, M.

    2016-01-01

    We have studied the interaction of 8-hydroxyquinoline-5-sulfonate (8-HQS) with the metal ions Al(III) and Zn(II) in aqueous solution in the presence of tetraalkylammonium surfactants using UV/vis absorption, fluorescence, NMR spectroscopy and electrical conductivity measurements, complemented...

  20. 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.

  1. Protein-directed self-assembly of a fullerene crystal

    Science.gov (United States)

    Kim, Kook-Han; Ko, Dong-Kyun; Kim, Yong-Tae; Kim, Nam Hyeong; Paul, Jaydeep; Zhang, Shao-Qing; Murray, Christopher B.; Acharya, Rudresh; Degrado, William F.; Kim, Yong Ho; Grigoryan, Gevorg

    2016-04-01

    Learning to engineer self-assembly would enable the precise organization of molecules by design to create matter with tailored properties. Here we demonstrate that proteins can direct the self-assembly of buckminsterfullerene (C60) into ordered superstructures. A previously engineered tetrameric helical bundle binds C60 in solution, rendering it water soluble. Two tetramers associate with one C60, promoting further organization revealed in a 1.67-Å crystal structure. Fullerene groups occupy periodic lattice sites, sandwiched between two Tyr residues from adjacent tetramers. Strikingly, the assembly exhibits high charge conductance, whereas both the protein-alone crystal and amorphous C60 are electrically insulating. The affinity of C60 for its crystal-binding site is estimated to be in the nanomolar range, with lattices of known protein crystals geometrically compatible with incorporating the motif. Taken together, these findings suggest a new means of organizing fullerene molecules into a rich variety of lattices to generate new properties by design.

  2. Polystyrene-b-poly(tert-butyl acrylate) and polystyrene-b-poly(acrylic acid) dendrimer-like copolymers: two-dimensional self-assembly at the air-water interface.

    Science.gov (United States)

    Joncheray, Thomas J; Bernard, Sophie A; Matmour, Rachid; Lepoittevin, Bénédicte; El-Khouri, Rita J; Taton, Daniel; Gnanou, Yves; Duran, Randolph S

    2007-02-27

    The two-dimensional self-assembly at the air/water (A/W) interface of two dendrimer-like copolymers based on polystyrene and poly(tert-butyl acrylate) (PS-b-PtBA) or poly(acrylic acid) (PS-b-PAA) was investigated through surface pressure measurements (isotherms, isochores, and compression-expansion hysteresis experiments) and atomic force microscopy (AFM) imaging. The two dendrimer-like block copolymers have an 8-arm PS core (Mn = 10 000 g/mol, approximately 12 styrene repeat units per arm) with a 16-arm PtBA (Mn = 230 000 g/mol, approximately 112 tert-butyl acrylate repeat units per arm) or PAA (Mn = 129 000 g/mol, approximately 112 acrylic acid repeat units per arm) corona. The PS-b-PtBA sample forms stable Langmuir monolayers and aggregates into circular surface micelles up to a plateau observed in the corresponding isotherm around 24 mN/m. Beyond this threshold, the monolayers collapse above the interface, resulting in the formation of large and irregular desorbed aggregates. The PS-b-PAA sample has ionizable carboxylic acid groups, and its A/W interfacial self-assembly was therefore investigated for various subphase pH values. Under basic conditions (pH = 11), the carboxylic acid groups are deprotonated, and the PS-b-PAA sample is therefore highly water-soluble and does not form stable monolayers, instead irreversibly dissolving in the aqueous subphase. Under acidic conditions (pH = 2.5), the PS-b-PAA sample is less water-soluble and becomes surface-active. The pseudoplateau observed in the isotherm around 5 mN/m corresponds to a pancake-to-brush transition with the PAA chains dissolving in the water subphase and stretching underneath the anchoring PS cores. AFM imaging revealed the presence of circular surface micelles for low surface pressures, whereas the biphasic nature of the pseudoplateau region was confirmed with the gradual aggregation of the micellar PS cores above the PAA chains. The aggregation numbers for both samples were estimated around 3

  3. Photovoltaic self-assembly.

    Energy Technology Data Exchange (ETDEWEB)

    Lavin, Judith; Kemp, Richard Alan; Stewart, Constantine A.

    2010-10-01

    This late-start LDRD was focused on the application of chemical principles of self-assembly on the ordering and placement of photovoltaic cells in a module. The drive for this chemical-based self-assembly stems from the escalating prices in the 'pick-and-place' technology currently used in the MEMS industries as the size of chips decreases. The chemical self-assembly principles are well-known on a molecular scale in other material science systems but to date had not been applied to the assembly of cells in a photovoltaic array or module. We explored several types of chemical-based self-assembly techniques, including gold-thiol interactions, liquid polymer binding, and hydrophobic-hydrophilic interactions designed to array both Si and GaAs PV chips onto a substrate. Additional research was focused on the modification of PV cells in an effort to gain control over the facial directionality of the cells in a solvent-based environment. Despite being a small footprint research project worked on for only a short time, the technical results and scientific accomplishments were significant and could prove to be enabling technology in the disruptive advancement of the microelectronic photovoltaics industry.

  4. Microtubule Self- Assembly

    Science.gov (United States)

    Jho, Yongseok; Choi, M. C.; Farago, O.; Kim, Mahnwon; Pincus, P. A.

    2008-03-01

    Microtubules are important structural elements for neurons. Microtubles are cylindrical pipes that are self-assembled from tubulin dimers, These structures are intimately related to the neuron transport system. Abnormal microtubule disintegration contributes to neuro-disease. For several decades, experimentalists investigated the structure of the microtubules using TEM and Cryo-EM. However, the detailed structure at a molecular level remain incompletely understood. . In this presentation, we report numerically studies of the self-assembly process using a toy model for tubulin dimers. We investigate the nature of the interactions which are essential to stabilize such the cylindrical assembly of protofilaments. We use Monte Carlo simulations to suggest the pathways for assembly and disassembly of the microtubules.

  5. A self-assembled ionophore

    Science.gov (United States)

    Tirumala, Sampath K.

    1997-11-01

    G-cation complexes are either tetramers or octamers, as determined by UV-vis and NMR spectroscopic methods. In particular, Nasp+ forms a tetramer (isoG)sb4-Nasp+, while Ksp+, Cssp+ and Basp{+2} form octamers, (isoG)sb8-Msp+. The (isoG)sb8-Msp+ complexes are likely stabilized by coaxial stacking of two (isoG)sb4 tetramers around the central cation. We conclude in Chapter 4 with studies on the Cssp+ binding and Cssp+ vs Ksp+ selectivity of isoG tetramer 51. IsoG's Cssp+ binding affinity, estimated by NMR competition experiments with known Cssp+ ionophores had a value of log Ksba 9.3 in CDClsb3, a remarkably high binding constant for a self-assembled ionophore. Importantly, 5sp'-t-butyldimethylsilyl-2sp',3sp'-isopropylidene isoG 30 is a Cssp+ vs Ksp+ selective ionophore. The Cssp+ vs Ksp+ selectivity for isoG 30, determined using sp1H NMR spectroscopy, is approximately 333/1 for extraction of CsI vs KI into CDClsb3 from water. This self-assembled ionophore's Cssp+ vs Ksp+ selectivity is particularly significant in terms of potential use in nuclear waste cleanup.

  6. Interfacial rheological properties of self-assembling biopolymer microcapsules.

    Science.gov (United States)

    Xie, Kaili; de Loubens, Clément; Dubreuil, Frédéric; Gunes, Deniz Z; Jaeger, Marc; Léonetti, Marc

    2017-09-20

    Tuning the mechanical properties of microcapsules through a cost-efficient route of fabrication is still a challenge. The traditional method of layer-by-layer assembly of microcapsules allows building a tailored composite multi-layer membrane but is technically complex as it requires numerous steps. The objective of this article is to characterize the interfacial rheological properties of self-assembling biopolymer microcapsules that were obtained in one single facile step. This thorough study provides new insights into the mechanics of these weakly cohesive membranes. Firstly, suspensions of water-in-oil microcapsules were formed in microfluidic junctions by self-assembly of two oppositely charged polyelectrolytes, namely chitosan (water soluble) and phosphatidic fatty acid (oil soluble). In this way, composite membranes of tunable thickness (between 40 and 900 nm measured by AFM) were formed at water/oil interfaces in a single step by changing the composition. Secondly, microcapsules were mechanically characterized by stretching them up to break-up in an extensional flow chamber which extends the relevance and convenience of the hydrodynamic method to weakly cohesive membranes. Finally, we show that the design of microcapsules can be 'engineered' in an extensive way since they present a wealth of interfacial rheological properties in terms of elasticity, plasticity and yield stress whose magnitudes can be controlled by the composition. These behaviors are explained by the variation of the membrane thickness with the physico-chemical parameters of the process.

  7. Silk-collagen-like block copolymers with charged blocks : self-assembly into nanosized ribbons and macroscopic gels

    NARCIS (Netherlands)

    Martens, A.A.

    2008-01-01

    The research described in this thesis concerns the design, biotechnological production, and physiochemical study of large water-soluble (monodisperse) protein triblock-copolymers with sequential blocks, some of which are positively or negatively charged and self-assemble in response to a change in

  8. Self-Assembly, Surface Activity and Structure of n-Octyl-β-D-thioglucopyranoside in Ethylene Glycol-Water Mixtures

    Directory of Open Access Journals (Sweden)

    Cristóbal Carnero Ruiz

    2013-02-01

    Full Text Available The effect of the addition of ethylene glycol (EG on the interfacial adsorption and micellar properties of the alkylglucoside surfactant n-octyl-β-D-thioglucopyranoside (OTG has been investigated. Critical micelle concentrations (cmc upon EG addition were obtained by both surface tension measurements and the pyrene 1:3 ratio method. A systematic increase in the cmc induced by the presence of the co-solvent was observed. This behavior was attributed to a reduction in the cohesive energy of the mixed solvent with respect to pure water, which favors an increase in the solubility of the surfactant with EG content. Static light scattering measurements revealed a decrease in the mean aggregation number of the OTG micelles with EG addition. Moreover, dynamic light scattering data showed that the effect of the surfactant concentration on micellar size is also controlled by the content of the co-solvent in the system. Finally, the effect of EG addition on the microstructure of OTG micelles was investigated using the hydrophobic probe Coumarin 153 (C153. Time-resolved fluorescence anisotropy decay curves of the probe solubilized in micelles were analyzed using the two-step model. The results indicate a slight reduction of the average reorientation time of the probe molecule with increasing EG in the mixed solvent system, thereby suggesting a lesser compactness induced by the presence of the co-solvent.

  9. Water-Soluble Nanodiamond (Postprint)

    Science.gov (United States)

    2012-03-01

    nanodiamond salt that reacts with either alkyl or aryl halides by electron transfer to yield radical anions that dissociate spontaneously into free radicals...sodium in liquid ammonia leads to the nanodiamond salt 1. This material can be reacted with either alkyl or aryl halides to yield a radical anion that...From - To) March 2012 Technical Paper 1 October 2008 – 1 March 2012 4. TITLE AND SUBTITLE WATER-SOLUBLE NANODIAMOND (POSTPRINT) 5a. CONTRACT

  10. Effect of self-assembly on triiodide diffusion in water based polymer gel electrolytes: an application in dye solar cell.

    Science.gov (United States)

    Soni, S S; Fadadu, K B; Vekariya, R L; Debgupta, J; Patel, K D; Gibaud, A; Aswal, V K

    2014-07-01

    The preparation of ordered polymer gels from the amphiphilic block copolymers, Pluronic® F77, P123 and polyethylene glycol in the presence of ionic liquid, iodine and organic additives is presented. At 35%(w/w) concentration these copolymers (F77 and P123) self-assembled into cubic liquid crystalline phase in aqueous solution and characterized by using SAXS and AFM measurements. The effects of micellar aggregation formed by polymers on the ionic transport and triiodide diffusion have been studied by electrochemistry and SANS experiments. The ionic migration or triiodide diffusion through these polymer gels is found to be affected by the PEO/PPO content in the polymer backbone. These gels were successfully employed as an electrolyte in a dye sensitized solar cell. A remarkable solar to electricity conversion efficiency and good stability was obtained using Pluronic® F77 based gel, which is attributed to its thermoreversible sol to gel transition. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. 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 ...

  12. In situ etching-induced self-assembly of metal cluster decorated one-dimensional semiconductors for solar-powered water splitting: unraveling cooperative synergy by photoelectrochemical investigations.

    Science.gov (United States)

    Xiao, Fang-Xing; Liu, Bin

    2017-11-09

    Although recent years have witnessed considerable progress in the synthesis of metal clusters, there is still a paucity of reports on photoelectrochemical (PEC) properties of metal cluster/semiconductor systems for solar energy conversion. In this work, highly ordered glutathione (GSH)-protected gold (Au) cluster (Aux@GSH) enwrapped ZnO nanowire array (NW) heterostructures (Aux/ZnO NWs) were designed by a facile, green, simple yet efficient in situ etching-induced electrostatic self-assembly strategy by modulating the intrinsic surface charge properties of building blocks, which renders negatively charged Aux clusters spontaneously and uniformly self-assembles them on positively charged ZnO NWs framework with intimate interfacial integration. It was unraveled that such Aux/ZnO NWs heterostructures demonstrated significantly enhanced PEC water splitting performance in comparison with single ZnO NWs, Au nanoparticles (Au/ZnO NWs) and GSH-capped Agx clusters (Agx/ZnO NWs) decorated ZnO NWs counterparts under both simulated solar and visible light irradiation. The vitally important role of Aux clusters as photosensitizer was unambiguously revealed and the merits of Aux clusters in boosting charge transfer arising from their unique core-shell architecture were highlighted by systematic comparison under identical conditions, based on which Aux cluster-mediated PEC water splitting mechanism is delineated. It is anticipated that our work can highlight the possibility of harnessing metal clusters as efficient light-harvest antennas and open new avenues for rational construction of various highly energy efficient metal cluster/semiconductor heterostructures for widespread photocatalytic and PEC applications.

  13. Amphiphilic Perylene-Calix[4]arene hybrids:synthesis and tunable self-assembly

    OpenAIRE

    Rodler, Fabian; Schade, Boris; Jaeger, Christof M.; Backes, Susanne; Hampel, Frank; Boettcher, Christoph; Clark, Timothy; Hirsch, Andreas

    2015-01-01

    The first highly water-soluble perylene–calix[4]arene hybrid with the calixarene scaffold acting as a structure-determining central platform is presented. In this tetrahedrally shaped amphiphilic architecture the hydrophilic and hydrophobic subunits are oriented at the opposite side of the calixarene platform. The hydrophobic part contains the two perylene diimide moieties, which enable strong π–π interactions in self-assembly processes. Two hydrophilic Newkome-type dendrons provide sufficien...

  14. 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.

  15. Behaviour of hybrid inside/out Janus nanotubes at an oil/water interface. A route to self-assembled nanofluidics?

    Science.gov (United States)

    Picot, P; Taché, O; Malloggi, F; Coradin, T; Thill, A

    2016-10-06

    Imogolites are natural aluminosilicate nanotubes that have a diameter of a few nanometers and can be several microns long. These nanotubes have different chemical groups on their internal (Si-OH) and external (Al-OH-Al) surfaces, that can be easily functionalised independently on both surfaces. Here we show that taking advantage of the particular shape and chemistry of imogolite, it is possible to prepare inside/out Janus nanotubes. Two kinds of symmetric Janus nanotubes are prepared: one with an external hydrophilic surface and an internal hydrophobic cavity (imo-CH3) and one with an external hydrophobic surface and a hydrophilic internal cavity (OPA-imo). The behaviour of such inside/out Janus nanotubes at oil/water interfaces is studied. The OPA-imo adsorbs strongly at the oil/water interface and is very efficient in stabilising water-in-oil emulsions through an arrested coalescence mechanism. Imo-CH3 also adsorbs at the oil/water interface. It stabilises oil-in-water emulsions by inducing slow oil-triggered modifications of the viscosity of the continuous phase. The possible transport of small molecules inside the imo-CH3 nanotubes is evidenced, opening up routes towards self-assembled nanofluidics.

  16. Water adsorption on hydrophilic and hydrophobic self-assembled monolayers as proxies for atmospheric surfaces. A grand canonical Monte Carlo simulation study.

    Science.gov (United States)

    Szori, Milán; Jedlovszky, Pál; Roeselová, Martina

    2010-05-14

    Grand canonical Monte Carlo simulations are used to determine water adsorption on prototypical organic surfaces as a function of relative humidity at 300 K. Three model surfaces formed by well-ordered self-assembled monolayers (SAMs) of alkanethiolate chains on gold are investigated: (i) a smooth hydrophobic surface of methyl-terminated C(7)-CH(3) SAM; (ii) a rough hydrophobic surface of randomly mixed two-component SAM, composed of equal fractions of C(5)-CH(3) and C(7)-CH(3) chains (C(5)/C(7)-CH(3) SAM); and (iii) a smooth hydrophilic surface of carboxyl-terminated C(7)-COOH SAM. The all atom CHARMM22 force field is used for the SAM chains together with the SPC/E model for water. No noticeable water adsorption is observed on the smooth hydrophobic surface up to saturation. The mild surface roughness introduced by the uneven chain length of the two components constituting the C(5)/C(7)-CH(3) SAM has no significant effect on the surface hydrophobicity, and the rough hydrophobic surface also remains dry up to the point when water condensation occurs. In contrast, water readily adsorbs onto the hydrophilic surface by forming hydrogen bonds with the COOH groups of the substrate. In addition, hydrogen bonding with pre-adsorbed water molecules contributes to the mechanism of water uptake. Under low humidity conditions, water is present on the hydrophilic surface as individual molecules or small water clusters and, with increasing relative humidity, the surface coverage grows continuously beyond a monolayer formation. The adsorbed water film is observed to be rather inhomogeneous with patches of bare surface exposed. The amount of water constituting a stable adsorption layer prior to condensation is estimated to consist of about 2-5 molecular layers. Detailed analysis of the simulation results is used to obtain important insights into the structure and energetics of water adsorbed on highly oxidized organic surfaces exposed to ambient air of increasing relative humidity.

  17. Self-assembled Nanomaterials for Chemotherapeutic Applications

    Science.gov (United States)

    Shieh, Aileen

    The self-assembly of short designed peptides into functional nanostructures is becoming a growing interest in a wide range of fields from optoelectronic devices to nanobiotechnology. In the medical field, self-assembled peptides have especially attracted attention with several of its attractive features for applications in drug delivery, tissue regeneration, biological engineering as well as cosmetic industry and also the antibiotics field. We here describe the self-assembly of peptide conjugated with organic chromophore to successfully deliver sequence independent micro RNAs into human non-small cell lung cancer cell lines. The nanofiber used as the delivery vehicle is completely non-toxic and biodegradable, and exhibit enhanced permeability effect for targeting malignant tumors. The transfection efficiency with nanofiber as the delivery vehicle is comparable to that of the commercially available RNAiMAX lipofectamine while the toxicity is significantly lower. We also conjugated the peptide sequence with camptothecin (CPT) and observed the self-assembly of nanotubes for chemotherapeutic applications. The peptide scaffold is non-toxic and biodegradable, and drug loading of CPT is high, which minimizes the issue of systemic toxicity caused by extensive burden from the elimination of drug carriers. In addition, the peptide assembly drastically increases the solubility and stability of CPT under physiological conditions in vitro, while active CPT is gradually released from the peptide chain under the slight acidic tumor cell environment. Cytotoxicity results on human colorectal cancer cells and non-small cell lung cancer cell lines display promising anti-cancer properties compared to the parental CPT drug, which cannot be used clinically due to its poor solubility and lack of stability in physiological conditions. Moreover, the peptide sequence conjugated with 5-fluorouracil formed a hydrogel with promising topical chemotherapeutic applications that also display

  18. Programmed Self-Assembly of Branched Nanocrystals with an Amphiphilic Surface Pattern.

    Science.gov (United States)

    Taniguchi, Yuki; Sazali, Muhammad Adli Bin; Kobayashi, Yusei; Arai, Noriyoshi; Kawai, Tsuyoshi; Nakashima, Takuya

    2017-09-26

    Site-selective surface modification on the shape-controlled nanocrystals is a key approach in the programmed self-assembly of inorganic colloidal materials. This study demonstrates a simple methodology to gain self-assemblies of semiconductor nanocrystals with branched shapes through tip-to-tip attachment. Short-chained water-soluble cationic thiols are employed as a surface ligand for CdSe tetrapods and CdSe/CdS core/shell octapods. Because of the less affinity of arm-tip to the surface ligands compared to the arm-side wall, the tip-surface becomes uncapped to give a hydrophobic nature, affording an amphiphilic surface pattern. The amphiphilic tetrapods aggregated into porous agglomerates through tip-to-tip connection in water, while they afforded a hexagonally arranged Kagome-like two-dimensional (2D) assembly by the simple casting of aqueous dispersion with the aid of a convective self-assembly mechanism. A 2D net-like assembly was similarly obtained from amphiphilic octapods. A dissipative particle dynamics simulation using a planar tripod model with an amphiphilic surface pattern reproduced the formation of the Kagome-like assembly in a 2D confined space, demonstrating that the lateral diffusion of nanoparticles and the firm contacts between the hydrophobic tips play crucial roles in the self-assembly.

  19. Electrochemical detection of Hg(II in water using self-assembled single walled carbon nanotube-poly(m-amino benzene sulfonic acid on gold electrode

    Directory of Open Access Journals (Sweden)

    Gauta Gold Matlou

    2016-09-01

    Full Text Available This work reports on the detection of mercury using single walled carbon nanotube-poly (m-amino benzene sulfonic acid (SWCNT-PABS modified gold electrode by self-assembled monolayers (SAMs technique. A thiol containing moiety (dimethyl amino ethane thiol (DMAET was used to facilitate the assembly of the SWCNT-PABS molecules onto the Au electrode surface. The successfully assembled monolayers were characterised using atomic force microscopy (AFM. Cyclic voltammetric and electrochemical impedance spectroscopic studies of the modified electrode (Au-DMAET-(SWCNT-PABS showed improved electron transfer over the bare Au electrode and the Au-DMAET in [Fe (CN6]3−/4− solution. The Au-DMAET-(SWCNT-PABS was used for the detection of Hg in water by square wave anodic stripping voltammetry (SWASV analysis at the following optimized conditions: deposition potential of −0.1 V, deposition time of 30 s, 0.1 M HCl electrolyte and pH 3. The sensor showed a good sensitivity and a limit of detection of 0.06 μM with a linear concentration range of 20 ppb to 250 ppb under the optimum conditions. The analytical applicability of the proposed method with the sensor electrode was tested with real water sample and the method was validated with inductively coupled plasma – optical emission spectroscopy.

  20. Homochiral oligopeptides by chiral amplification within two-dimensional crystalline self-assemblies at the air-water interface; Relevance to biomolecular handedness

    DEFF Research Database (Denmark)

    Weissbuch, I.; Zepik, H.; Bolbach, G.

    2003-01-01

    A possible role that might have been played by ordered clusters at interfaces for the generation of homochiral oligopeptides under prebiotic conditions has been probed by a catalyzed polymerization of amphiphilic activated a-amino acids, in racemic and chiral non-racemic forms, which had self......-stearyl-glutamic thioacid (C-18-thio-Glu). According to insitu grazing incidence X-ray diffraction measurements on the water surface, (R,S)-C-18-TE-Lys, (RA-C-18-TE-Glu, and (R,S)-C-18-Glu-NCA amphiphiles self-assembled into ordered racemic 2D crystallites. Oligopeptides 2-12 units long were obtained at the air......-aqueous solution interface after injection of appropriate catalysts into the water subphase. The experimental relative abundance of oligopeptides with homochiral sequence generated from (R,S)-C-18-TE-Lys and (R,S)-C-18-TE-Glu, as determined by mass spectrometry on enantioselectively deuterium-labeled samples...

  1. Effect of H-bonding interactions of water molecules in the self assembly of supramolecular architecture-joint experimental and computational studies

    Science.gov (United States)

    Jassal, Amanpreet Kaur; Kaur, Rajwinder; Islam, Nasarul; Anu; Mudsainiyan, Rahul Kumar

    2017-08-01

    A new {[Cu(4,4‧-BP)2.(H2O)4].2,6-NDC.3(H2O)} complex has been synthesized by refluxing Cu(NO3)2, 2,6-NDC and 4,4‧-BP (1:1:1 ratio) (2,6-NDC = 2,6-Naphthalene Dicarboxylic acid, 4,4‧-BP = 4,4'-bipyridine) in methanol/ammonia mixture and characterized by various spectroscopic techniques. The geometry around Cu2+ ion is typical octahedral in cationic complex, while the deprotonated 2,6-NDC act as a charge balancing counter anionic part. Water molecules (lattice and coordinated) also play important role in the self-assembly by forming Hsbnd bonded supramolecular architecture involving strong inter/intramolecular secondary interactions. The luminescence property and thermogravimetric analyses were also investigated. Both the intermolecular interactions of molecular and crystal structures of this complex were compared and discussed using Hirshfeld surface analysis and 2D-fingerprint plots. Hirshfeld surface analysis indicates that H⋯H, O⋯H and π···π contacts can account for 40.4, 19.3 and 7.7% respectively of the total Hirshfeld surface area. The DFT calculation at the CAM-B3LYP level of theory revealed the existence of three hydrogens binds in the complex. These hydrogen bonds exist between the oxygen atom of ligand and the hydrogen of coordinated water molecules.

  2. Aqueous dispersions of nanostructures formed through the self-assembly of iminolipids with exchangeable hydrophobic termini.

    Science.gov (United States)

    Li, Wen; McManus, Daryl; Liu, Han; Casiraghi, Cinzia; Webb, Simon J

    2017-07-14

    The addition of amines to an aldehyde surfactant, which was designed to be analogous to didodecyldimethylammonium bromide, gave exchangeable "iminolipids" that self-assembled to give stable aqueous dispersions of nano-sized vesicles. For example, sonication of suspensions of the n-hexylamine-derived iminolipid gave vesicles 50 to 200 nm in diameter that could encapsulate a water-soluble dye. The iminolipids could undergo dynamic exchange with added amines, and the resulting equilibrium constants (Krel) were quantified by (1)H NMR spectroscopy. In the absence of lipid self-assembly, in CDCl3, the assayed primary amines gave very similar Krel values. However in D2O the value of Krel generally increased with increasing amine hydrophobicity, consistent with partitioning into a self-assembled bilayer. Amines with aromatic groups showed significantly higher values of Krel in D2O compared to similarly hydrophobic alkylamines, suggesting that π-π interactions favor lipid self-assembly. Given this synergistic relationship, π-rich pyrenyliminolipids were created and used to exfoliate graphite, leading to aqueous dispersions of graphene flakes that were stable over several months.

  3. Protein-directed self-assembly of a fullerene crystal

    Science.gov (United States)

    Kim, Kook-Han; Ko, Dong-Kyun; Kim, Yong-Tae; Kim, Nam Hyeong; Paul, Jaydeep; Zhang, Shao-Qing; Murray, Christopher B.; Acharya, Rudresh; DeGrado, William F.; Kim, Yong Ho; Grigoryan, Gevorg

    2016-01-01

    Learning to engineer self-assembly would enable the precise organization of molecules by design to create matter with tailored properties. Here we demonstrate that proteins can direct the self-assembly of buckminsterfullerene (C60) into ordered superstructures. A previously engineered tetrameric helical bundle binds C60 in solution, rendering it water soluble. Two tetramers associate with one C60, promoting further organization revealed in a 1.67-Å crystal structure. Fullerene groups occupy periodic lattice sites, sandwiched between two Tyr residues from adjacent tetramers. Strikingly, the assembly exhibits high charge conductance, whereas both the protein-alone crystal and amorphous C60 are electrically insulating. The affinity of C60 for its crystal-binding site is estimated to be in the nanomolar range, with lattices of known protein crystals geometrically compatible with incorporating the motif. Taken together, these findings suggest a new means of organizing fullerene molecules into a rich variety of lattices to generate new properties by design. PMID:27113637

  4. Dispersive micro-solid phase extraction based on self-assembling, ionic liquid-coated magnetic particles for the determination of clofentezine and chlorfenapyr in environmental water samples.

    Science.gov (United States)

    Peng, Bing; Zhang, Jiaheng; Lu, Runhua; Zhang, Sanbing; Zhou, Wenfeng; Gao, Haixiang

    2013-11-21

    Two ionic liquid-coated-Fe3O4 magnetic particles (IL-Fe3O4 MPs) were developed for use in two types of dispersive micro-solid phase extraction (D-μ-SPE) for the high-performance liquid chromatographic analysis of clofentezine and chlorfenapyr in environmental water samples. Self-assembling IL-Fe3O4 MPs were used in D-μ-SPE as adsorbents. Two D-μ-SPE extraction methods, namely, direct dispersive micro-solid phase extraction (d-D-μ-SPE) and in situ solvent formation-based dispersive micro-solid phase extraction (ISF-D-μ-SPE), were proposed, using [C8MIM][PF6] to extract analytes through two pathways. Lower IL doses were required in the extraction process compared with those in other IL-based methods. Fe3O4 MPs can also be recycled and reused after extraction and are thus environmentally friendly. These newly developed methods were demonstrated to be feasible for use in the quantitation of clofentezine and chlorfenapyr at trace levels, with lower limit of detection values ranging from 0.4 to 0.5 ng mL(-1) for d-D-μ-SPE and 0.4 ng mL(-1) for ISF-D-μ-SPE. Finally, relative standard deviations of less than 6.0% were obtained.

  5. Oil-in-water microfluidics on the colloidal scale: new routes to self-assembly and glassy packings

    Science.gov (United States)

    Meissner, Max; Dong, Jun; Eggers, Jens; Seddon, Annela M.; Royall, C. Patrick

    We have developed Norland Optical Adhesive (NOA) flow focusing devices, making use of the excellent solvent compatibility and surface properties of NOA to generate micron scale oil-in-water emulsions with polydispersities as low as 5%. While current work on microfluidic oil-in-water emulsification largely concerns the production of droplets with sizes on the order of 10s of micrometres, large enough that Brownian motion is negligible, our NOA devices can produce droplets with radii ranging from 2 {\\mu}m to 12 {\\mu}m. To demonstrate the utility of these emulsions as colloidal model systems we produce fluorescently labelled polydimethylsiloxane droplets suitable for particle resolved studies with confocal microscopy. We analyse the structure of the resulting emulsion in 3D using coordinate tracking and the topological cluster classification and reveal a new mono-disperse thermal system.

  6. Water-soluble conductive polymers

    Science.gov (United States)

    Aldissi, Mahmoud

    1989-01-01

    Polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

  7. Synthesis of Janus-like gold nanoparticles with hydrophilic/hydrophobic faces by surface ligand exchange and their self-assemblies in water.

    Science.gov (United States)

    Iida, Ryo; Kawamura, Hitoshi; Niikura, Kenichi; Kimura, Takashi; Sekiguchi, Shota; Joti, Yasumasa; Bessho, Yoshitaka; Mitomo, Hideyuki; Nishino, Yoshinori; Ijiro, Kuniharu

    2015-04-14

    This study aims at the synthesis of Janus gold nanoparticles (Janus GNPs) with hydrophilic/hydrophobic faces by a simple ligand exchange reaction in an homogeneous system and at the elucidation of the self-assembled structures of the Janus GNPs in water. As hydrophilic surface ligands, we synthesized hexaethylene glycol (E6)-terminated thiolate ligands with C3, C7, or C11 alkyl chains, referred to as E6C3, E6C7, and E6C11, respectively. As a hydrophobic ligand, a butyl-headed thiolate ligand C4-E6C11, in which a C4 alkyl was introduced on the E6C11 terminus, was synthesized. The degree of segregation between the two ligands on the GNPs (5 nm in diameter) was examined by matrix-assisted laser desorption/ionization time-of fright mass spectrometry (MALDI-TOF MS) analysis. We found that the choice of immobilization methods, one-step or two-step addition of the two ligands to the GNP solution, crucially affects the degree of segregation. The two-step addition of a hydrophilic ligand (E6C3) followed by a hydrophobic ligand (C4-E6C11) produced a large degree of segregation on the GNPs, providing Janus-like GNPs. When dispersed in water, these Janus-like GNPs formed assemblies of ∼160 nm in diameter, whereas Domain GNPs, in which the two ligands formed partial domains on the surface, were precipitated even when the molar ratio of the hydrophilic ligand and the hydrophobic ligand on the surface of the NPs was almost 1:1. The assembled structure of the Janus-like GNPs in water was directly observed by pulsed coherent X-ray solution scattering using an X-ray free-electron laser, revealing irregular spherical structures with uneven surfaces.

  8. Peptide amphiphile self-assembly

    Science.gov (United States)

    Iscen, Aysenur; Schatz, George C.

    2017-08-01

    Self-assembly is a process whereby molecules organize into structures with hierarchical order and complexity, often leading to functional materials. Biomolecules such as peptides, lipids and DNA are frequently involved in self-assembly, and this leads to materials of interest for a wide variety of applications in biomedicine, photonics, electronics, mechanics, etc. The diversity of structures and functions that can be produced provides motivation for developing theoretical models that can be used for a molecular-level description of these materials. Here we overview recently developed computational methods for modeling the self-assembly of peptide amphiphiles (PA) into supramolecular structures that form cylindrical nanoscale fibers using molecular-dynamics simulations. Both all-atom and coarse-grained force field methods are described, and we emphasize how these calculations contribute insight into fiber structure, including the importance of β-sheet formation. We show that the temperature at which self-assembly takes place affects the conformations of PA chains, resulting in cylindrical nanofibers with higher β-sheet content as temperature increases. We also present a new high-density PA model that shows long network formation of β-sheets along the long axis of the fiber, a result that correlates with some experiments. The β-sheet network is mostly helical in nature which helps to maintain strong interactions between the PAs both radially and longitudinally. Contribution to Focus Issue Self-assemblies of Inorganic and Organic Nanomaterials edited by Marie-Paule Pileni.

  9. Counterion identity effects on the self-assembly processes in a series of perfluorinated surfactant-water mixtures

    CERN Document Server

    Zhou, R

    2003-01-01

    The effects of counterion on the lyotropic liquid crystalline phase behaviour of some quaternary ammonium salts of perfluorodecanoic acid in water have been studied using a combination of optical polarising microscopy (OPM), deuterium nuclear magnetic resonance ( sup 2 H NMR) and cryo-transmission electron microscopy (cryo-TEM). The results from the phase diagram studies fall into two groups. Firstly the ammonium (A) and tetramethylammonium (TMA) counterions show a phase behaviour with nematic (N) and random mesh (Mh sub 1 (0)) phase which possess non-uniform interfacial curvature. The second group of surfactants with counterions, butyltrimethylammonium (BTMA), dibutyidimetylammonium (DBDMA), and tetrabutylammonium (TEA), form only a classical lamellar phase (L subalpha). For both DBDMA and TBA lower consolute behaviour has been observed. At fixed concentration in all five systems cryo-TEM visualises isotropic liquid phase structures that vary from sphere / rod micelles for A and TMA to vesicles / bilayer pie...

  10. Self-Assembly of Nanoparticle Surfactants

    Science.gov (United States)

    Lombardo, Michael T.

    Self-assembly utilizes non-covalent forces to organize smaller building blocks into larger, organized structures. Nanoparticles are one type of building block and have gained interest recently due to their unique optical and electrical properties which have proved useful in fields such as energy, catalysis, and advanced materials. There are several techniques currently used to self-assemble nanoparticles, each with its own set of benefits and drawbacks. Here, we address the limited number of techniques in non-polar solvents by introducing a method utilizing amphiphilic gold nanoparticles. Grafted polymer chains provide steric stabilization while small hydrophilic molecules induce assembly through short range attractive forces. The properties of these self-assembled structures are found to be dependent on the polymer and small molecules surface concentrations and chemistries. These particles act as nanoparticle surfactants and can effectively stabilize oil-water interfaces, such as in an emulsion. In addition to the work in organic solvent, similar amphiphilic particles in aqueous media are shown to effectively stabilize oil-in-water emulsions that show promise as photoacoustic/ultrasound theranostic agents.

  11. Self-assembly of cyclodextrins

    DEFF Research Database (Denmark)

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

    2012-01-01

    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......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...

  12. Lipid self-assemblies and nanostructured emulsions for cosmetic formulations

    OpenAIRE

    Kulkarni, C

    2016-01-01

    A majority of cosmetic products that we encounter on daily basis contain lipid constituents in solubilized or insolubilized forms. Due to their amphiphilic nature, the lipid molecules spontaneously self-assemble into a remarkable range of nanostructures when mixed with water. This review illustrates the formation and finely tunable properties of self-assembled lipid nanostructures and their hierarchically organized derivatives, as well as their relevance to the development of cosmetic formula...

  13. Interfacial structure in thin water layers formed by forced dewetting on self-assembled monolayers of omega-terminated alkanethiols on Ag.

    Science.gov (United States)

    Tiani, Domenic J; Yoo, Heemin; Mudalige, Anoma; Pemberton, Jeanne E

    2008-12-02

    A method for the spectroscopic characterization of interfacial fluid molecular structure near solid substrates is reported. The thickness and interfacial molecular structure of residual ultrathin D20 films remaining after forced dewetting on alkanethiolate self-assembled monolayers (SAMs) of 11 1-mercaptoundecanoic acid (11-MUA), 11-mercaptoundecanol (11-MUD), and undecanethiol (UDT) on Ag are investigated using ellipsometry and surface Raman spectroscopy. The residual film thickness left after withdrawal is greater on hydrophilic SAMs than on hydrophobic SAMs. This behavior is rationalized on the basis of differing degrees of fluid slip within the interfacial region due to different interfacial molecular structure. The v(O-D) regions of surface Raman spectra clearly indicate unique interfacial molecular properties within these films that differ from bulk D20. Although the residual films are created by shear forces and Marangoni flow at the three-phase line during the forced dewetting process, the nature of the films sampled optically must also be considered from the standpoint of thin film stability after dewetting. Thus, the resulting D20 films exist in vastly different morphologies depending on the nature of the water-SAM interactions. Residual D20 is proposed to exist as small nanodroplets on UDT surfaces due tospontaneous rupture of the film after dewetting. In contrast, on 11-MUD and 11-MUA surfaces, these films exist in a metastable state that retains their conformal nature on the underlying modified surface. Analysis of the peak intensity ratios of the so-called "ice-like" to "liquid-like" v(O-D) modes suggests more ice-like D20 character near 11-MUD surfaces, but more liquid-like character near 11-MUA and UDT surfaces. The creation of residual ultrathin films by forced dewetting is thus demonstrated to be a powerful method for characterizing interfacial molecular structure of fluids near a solid substrate under ambient conditions of temperature and

  14. Coded nanoscale self-assembly

    Indian Academy of Sciences (India)

    the number of starting particles. Figure 6. Coded self-assembly results in specific shapes. When the con- stituent particles are coded to only combine in a certain defined rules, it al- ways manages to generate the same shape. The simplest case of linear coding with multiseed option is presented here. in place the resultant ...

  15. Water soluble polymer–surfactant complexes-stabilized Pd(0) nanocatalysts: Characterization and structure–activity relationships in biphasic hydrogenation of alkenes and α,β-unsaturated ketones

    OpenAIRE

    Albuquerque, Brunno L.; Denicourt-Nowicki, Audrey; Mériadec, Cristelle; Domingos,Josiel B.; Roucoux, Alain

    2016-01-01

    International audience; A suitable approach to stabilize palladium nanoparticles in water as a green reaction medium for catalytic hydrogenation reactions is described. Supramolecular self-assemblies, obtained through the mixture of modified polyethyleneimines as amphiphilic polymers and water-soluble ammonium salts as surfactants, were used as efficient protective agents in the synthesis of Pd(0) nanospecies. The size and dispersion of the nanoparticles prepared with these original self-asse...

  16. Heterogeneous self-assembled media for biopolymerization

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain

    2011-01-01

    compartments and lipid-bilayer lattices. Another kind of media is represented by self-assembled phases in the reaction medium, e.g., in water-ice matrices that are formed by two co-existing aqueous phases (a solid phase and a concentrated liquid phase) when an aqueous solution is cooled below its freezing...... point, but above the eutectic point. These media have the capacity to assemble chemical molecules or complex catalytic assemblies into unique configurations that are unstable or unavailable in bulk aqueous phases. Reactions can then proceed which do not readily occur in homogeneous solutions. To gauge...

  17. Chromatographic determination of solubilities in superheated water.

    Science.gov (United States)

    Jones, Neil; Clifford, Anthony A; Bartle, Keith D; Myers, Peter

    2010-10-01

    Superheated water (SHW) is an effective solvent for the extraction of a variety of environmental pollutants, but knowledge of the solubilities in water at elevated temperatures necessary to maximise the efficiency of the process is often lacking. Ambient temperature aqueous solubilities have been measured by reverse-phase HPLC from correlations with retention factors, k, but for poorly soluble organics the eluent must contain a proportion of organic modifier followed by extrapolation to pure water. The use of SHW as mobile phase allows direct determination of aqueous solubility from measurement of k on a modified HPLC system in which the eluent is cooled before detection to improve baseline stability. Alumina-bonded octadecylsilane columns were found to be more stable in SHW chromatography than their silica-bonded counterparts. To validate the procedure, measurements of k were made between 100 and 200°C for toluene and correlated with literature solubilities; the solubilities at 170°C of a number of related aromatics were then determined from their k-values.

  18. One-step self-assembled nanomicelles for improving the oral bioavailability of nimodipine.

    Science.gov (United States)

    Luo, Jing-Wen; Zhang, Zhi-Rong; Gong, Tao; Fu, Yao

    2016-01-01

    Our study aimed to develop a self-assembled nanomicelle for oral administration of nimodipine (NIM) with poor water solubility. Using Solutol(®) HS15, the NIM-loaded self-assembled nanomicelles displayed a near-spherical morphology with a narrow size distribution of 12.57 ± 0.21 nm (polydispersity index =0.071 ± 0.011). Compared with Nimotop(®) (NIM tablets), the intestinal absorption of NIM from NIM nanomicelle in rats was improved by 3.13- and 2.25-fold in duodenum and jejunum at 1 hour after oral administration. The cellular transport of NIM nanomicelle in Caco-2 cell monolayers was significantly enhanced compared to that of Nimotop(®). Regarding the transport pathways, clathrin, lipid raft/caveolae, and macropinocytosis mediated the cell uptake of NIM nanomicelles, while P-glycoprotein and endoplasmic reticulum/Golgi complex (ER/Golgi) pathways were involved in exocytosis. Pharmacokinetic studies in our research laboratory have showed that the area under the plasma concentration-time curve (AUC0-∞) of NIM nanomicelles was 3.72-fold that of Nimotop(®) via oral administration in rats. Moreover, the NIM concentration in the brain from NIM nanomicelles was dramatically improved. Therefore, Solutol(®) HS15-based self-assembled nanomicelles represent a promising delivery system to enhance the oral bioavailability of NIM.

  19. β-Cyclodextrin functionalized carbon quantum dots as sensors for determination of water-soluble C60 fullerenes in water.

    Science.gov (United States)

    Cayuela, Angelina; Laura Soriano, M; Valcárcel, Miguel

    2016-04-25

    A selective photoluminescence method based on Carbon Quantum Dots (CQDs) functionalized with carboxymethyl-β-cyclodextrin for the direct determination of water-soluble C60 fullerene has been developed. CQDs were synthesized using a top-down methodology from multiwall carbon nanotubes (MWCNTs) and further functionalized with N-Boc-ethylenediamine to confer monoprotected amine groups onto their surface. Once amine-functionalized CQDs were obtained after deprotection, an amidation reaction with carboxymethyl-β-cyclodextrin cavitands was achieved and the obtained fluorescent β-cyclodextrin functionalized Carbon Quantum Dots (cd-CQDs) were investigated for the inclusion complexation of water-soluble C60. Quenching of their fluorescence was observed owing to the non-covalent self-assembly of cd-CQDs and C60, making possible the quantification of C60. A method to determine water-soluble C60 is then proposed with detection and quantification limits of 0.525 and 1.751 μg mL(-1), respectively. The method was validated by determining soluble C60 fullerene in spiked river water. One added value of the paper is the fact that it can be ascribed to the "Third Way in Analytical Nanoscience and Nanotechnology".

  20. Formation of mixed and patterned self-assembled films of alkylphosphonates on commercially pure titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rudzka, Katarzyna; Sanchez Treviño, Alda Y.; Rodríguez-Valverde, Miguel A., E-mail: marodri@ugr.es; Cabrerizo-Vílchez, Miguel A.

    2016-12-15

    Highlights: • Chemically-tailored titanium surfaces were prepared by self-assembly of alkylphosphonates. • Mixed self-assembled films were prepared with aqueous mixtures of two alkylphosphonates. • Single self-assembled films were altered by laser abrasion. • Mixed and patterned self-assembled films on titanium may guide the bone-like formation. - Abstract: Titanium is extensively employed in biomedical devices, in particular as implant. The self-assembly of alkylphosphonates on titanium surfaces enable the specific adsorption of biomolecules to adapt the implant response against external stimuli. In this work, chemically-tailored cpTi surfaces were prepared by self-assembly of alkylphosphonate molecules. By bringing together attributes of two grafting molecules, aqueous mixtures of two alkylphosphonates were used to obtain mixed self-assembled films. Single self-assembled films were also altered by laser abrasion to produce chemically patterned cpTi surfaces. Both mixed and patterned self-assembled films were confirmed by AFM, ESEM and X-ray photoelectron spectroscopy. Water contact angle measurements also revealed the composition of the self-assembly films. Chemical functionalization with two grafting phosphonate molecules and laser surface engineering may be combined to guide the bone-like formation on cpTi, and the future biological response in the host.

  1. Oil-in-Water Self-Assembled Synthesis of Ag@AgCl Nano-Particles on Flower-like Bi2O2CO3 with Enhanced Visible-Light-Driven Photocatalytic Activity

    OpenAIRE

    Shuanglong Lin; Li Liu; Yinghua Liang; Wenquan Cui; Zisheng Zhang

    2016-01-01

    In this work, a series of novel flower-like Ag@AgCl/Bi2O2CO3 were prepared by simple and feasible oil-in-water self-assembly processes. The phase structures of as-prepared samples were examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), X-ray fluorescence spectrometer (XRF), etc. The characterization results indicated that the presence of Ag@AgCl did not affect the crystal structure, bu...

  2. Direct imaging by atomic force microscopy of surface-localized self-assembled monolayers on a cuprate superconductor and surface X-ray scattering analysis of analogous monolayers on the surface of water

    DEFF Research Database (Denmark)

    Schougaard, Steen B.; Reitzel, Niels; Bjørnholm, Thomas

    2007-01-01

    A self-assembled monolayer of CF3(CF2)(3)(CH2)(11)NH2 atop the (001) surface of the high-temperature superconductor YBa2Cu3O7-x was imaged by atomic force microscopy (AFM). The AFM images provide direct 2D-structural evidence for the epitaxial 5.5 angstrom square root 2 x root 2R45 degrees unit...... was studied by grazing-incidence X-ray diffraction and specular X-ray reflectivity. Structural differences and similarities between the water-supported and superconductor-localized monolayers are discussed....

  3. In silico properties characterization of water-soluble γ-cyclodextrin bi-capped C60 complex

    DEFF Research Database (Denmark)

    Cao, Ruyin; Wu, Shanshan

    2015-01-01

    Cyclodextrin-related host-guest encapsulation is pivotal to modulate the solubility of C60, thereby promoting its potential therapeutic applications. Here we present a computational study on γ-cyclodextrin bi-capped C60 complex, probing characteristics for all the possible stoichiometry in aqueou...... and computational results. PMF partitioning indicates that intermolecular van der Waals dispersion forces are essential for molecular recognition and self-assembly, and the hydrogen-bonding interactions play a key role in dissolving the complex in water....

  4. Amphiphilic perylene-calix[4]arene hybrids: synthesis and tunable self-assembly.

    Science.gov (United States)

    Rodler, Fabian; Schade, Boris; Jäger, Christof M; Backes, Susanne; Hampel, Frank; Böttcher, Christoph; Clark, Timothy; Hirsch, Andreas

    2015-03-11

    The first highly water-soluble perylene-calix[4]arene hybrid with the calixarene scaffold acting as a structure-determining central platform is presented. In this tetrahedrally shaped amphiphilic architecture the hydrophilic and hydrophobic subunits are oriented at the opposite side of the calixarene platform. The hydrophobic part contains the two perylene diimide moieties, which enable strong π-π interactions in self-assembly processes. Two hydrophilic Newkome-type dendrons provide sufficient water solubility at slightly basic conditions. The tetrahedrally shaped amphiphile displays an unprecedented aggregation behavior down to concentrations as low as 10(-7) mol L(-1). The intriguing self-assembly process of the compound in water as well as under changed polarity conditions, achieved by addition of THF, could be monitored by the complemented use of cryogenic transmission electron microscopy (cryo-TEM), UV-vis spectroscopy, and fluorescence spectroscopy. Molecular-dynamics and molecular modeling simulations helped in understanding the interplay of supramolecular and optical behavior.

  5. 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

  6. Self-assembled nanostructured metamaterials

    Science.gov (United States)

    Ponsinet, Virginie; Baron, Alexandre; Pouget, Emilie; Okazaki, Yutaka; Oda, Reiko; Barois, Philippe

    2017-07-01

    The concept of metamaterials emerged in the years 2000 with the achievement of artificial structures enabling nonconventional propagation of electromagnetic waves, such as negative phase velocity or negative refraction. The electromagnetic response of metamaterials is generally based on the presence of optically resonant elements —or meta-atoms— of sub-wavelength size and well-designed morphology so as to provide the desired electric and magnetic optical properties. Top-down technologies based on lithography techniques have been intensively used to fabricate a variety of efficient electric and magnetic resonators operating from microwave to visible light frequencies. However, the technological limits of the top-down approach are reached in visible light where a huge number of nanometre-sized elements is required. We show here that the bottom-up fabrication route based on the combination of nanochemistry and the self-assembly methods of colloidal physics provide an excellent alternative for the large-scale synthesis of complex meta-atoms, as well as for the fabrication of 2D and 3D samples exhibiting meta-properties in visible light. Contribution to the Focus Issue Self-assemblies of Inorganic and Organic Nanomaterials edited by Marie-Paule Pileni.

  7. Prodrugs as self-assembled hydrogels: a new paradigm for biomaterials.

    Science.gov (United States)

    Vemula, Praveen Kumar; Wiradharma, Nikken; Ankrum, James A; Miranda, Oscar R; John, George; Karp, Jeffrey M

    2013-12-01

    Prodrug-based self-assembled hydrogels represent a new class of active biomaterials that can be harnessed for medical applications, in particular the design of stimuli responsive drug delivery devices. In this approach, a promoiety is chemically conjugated to a known-drug to generate an amphiphilic prodrug that is capable of forming self-assembled hydrogels. Prodrug-based self-assembled hydrogels are advantageous as they alter the solubility of the drug, enhance drug loading, and eliminate the use of harmful excipients. In addition, self-assembled prodrug hydrogels can be designed to undergo controlled drug release or tailored degradation in response to biological cues. Herein we review the development of prodrug-based self-assembled hydrogels as an emerging class of biomaterials that overcome several common limitations encountered in conventional drug delivery. Published by Elsevier Ltd.

  8. Self-assembly of various Au nanocrystals on functionalized water-stable PVA/PEI nanofibers: a highly efficient surface-enhanced Raman scattering substrates with high density of "hot" spots.

    Science.gov (United States)

    Zhu, Han; Du, MingLiang; Zhang, Ming; Wang, Pan; Bao, ShiYong; Zou, Meiling; Fu, YaQin; Yao, JuMing

    2014-04-15

    We have demonstrated a facile approach for the fabrication of flexible and reliable sulfydryl functionalized PVA/PEI nanofibers with excellent water stability for the self-assembly of Au nanocrystals, such as Au nanoparticles (AuNPs), Au nanoflowers (AuNFs) and Au nanorods (AuNRs), used as the highly efficient surface-enhanced Raman scattering (SERS) substrates for the detection of rhodamine B (RhB). Various methods were employed to cross-link the PVA nanofibers with better morphology and porous structures after immersing in water for desired times. Various SERS-active Au nanocrystals, such as AuNPs, AuNFs, and AuNRs have been successfully synthesized. After the grafting of MPTES on the cross-linked PVA/PEI nanofibers, the Au nanocrystals can easily be self-assembled on the surfaces of the nanofibers because of the strong interactions of the Au-S chemical bondings. The Au nanocrystals self-assembled throughout the PVA/PEI nanofibers used as SERS substrates all exhibit enhanced SERS signals of RhB compared with their individual nanocrystals. It is mainly due to the close interparticle distance, mutual orientation and high density of "hot" spots, that can strongly affect the overall optical response and the SERS enhancement. By changing the amounts of the self-assembled AuNFs on the nanofibers, we can control the density of the "hot" spots. With the increased amounts of the AuNFs throughout the nanofibers, the SERS substrates show enhanced Raman signals of the RhB, indicating that the increased density of "hot" spots can directly lead to the SERS enhancement. The AuNFs/(PVA/PEI) SERS substrates show good sensitivity, reliability and low detection limit (10(-9) M). The presented approach can be broadly applicable to the assembly of different types of plasmonic nanostructures and these novel materials with strong SERS enhancement can be applied in bioanalysis and biosensors. © 2013 Published by Elsevier B.V.

  9. Multivalent Protein Assembly Using Monovalent Self-Assembling Building Blocks

    Directory of Open Access Journals (Sweden)

    Katja Petkau-Milroy

    2013-10-01

    Full Text Available Discotic molecules, which self-assemble in water into columnar supramolecular polymers, emerged as an alternative platform for the organization of proteins. Here, a monovalent discotic decorated with one single biotin was synthesized to study the self-assembling multivalency of this system in regard to streptavidin. Next to tetravalent streptavidin, monovalent streptavidin was used to study the protein assembly along the supramolecular polymer in detail without the interference of cross-linking. Upon self-assembly of the monovalent biotinylated discotics, multivalent proteins can be assembled along the supramolecular polymer. The concentration of discotics, which influences the length of the final polymers at the same time dictates the amount of assembled proteins.

  10. Characterization of Soluble Organics in Produced Water

    Energy Technology Data Exchange (ETDEWEB)

    Bostick, D.T.

    2002-01-16

    Soluble organics in produced water and refinery effluents represent treatment problems for the petroleum industry. Neither the chemistry involved in the production of soluble organics nor the impact of these chemicals on total effluent toxicity is well understood. The U.S. Department of Energy provides funding for Oak Ridge National Laboratory (ORNL) to support a collaborative project with Shell, Chevron, Phillips, and Statoil entitled ''Petroleum and Environmental Research Forum project (PERF 9844: Manage Water-Soluble Organics in Produced Water''). The goal of this project, which involves characterization and evaluation of these water-soluble compounds, is aimed at reducing the future production of such contaminants. To determine the effect that various drilling conditions might have on water-soluble organics (WSO) content in produced water, a simulated brine water containing the principal inorganic components normally found in Gulf of Mexico (GOM) brine sources was prepared. The GOM simulant was then contacted with as-received crude oil from a deep well site to study the effects of water cut, produced-water pH, salinity, pressure, temperature, and crude oil sources on the type and content of the WSO in produced water. The identities of individual semivolatile organic compounds (SVOCs) were determined in all as-received crude and actual produced water samples using standard USEPA Method (8270C) protocol. These analyses were supplemented with the more general measurements of total petroleum hydrocarbon (TPH) content in the gas (C{sub 6}-C{sub 10}), diesel (C{sub 10}-C{sub 20}), and oil (C{sub 20}-C{sub 28}) carbon ranges as determined by both gas chromatographic (GC) and infrared (IR) analyses. An open liquid chromatographic procedure was also used to differentiate the saturated hydrocarbon, aromatic hydrocarbon, and polar components within the extractable TPH. Inorganic constituents in the produced water were analyzed by ion

  11. Au nanorods modulated NIR fluorescence and singlet oxygen generation of water soluble dendritic zinc phthalocyanine.

    Science.gov (United States)

    Zhou, Xuefei; He, Xiaohong; Wei, Shiliang; Jia, Kun; Liu, Xiaobo

    2016-11-15

    A novel cyano-terminated zinc phthalocyanine (ZnPc-CN) exhibiting visible near infrared (vis-NIR) emitting around 690nm in N,N-dimethylformamide (DMF) solvent has been synthesized. Furthermore, the peripheral cyano groups of newly synthesized zinc phthalocyanine were hydrolyzed in strong basic solution, leading to water soluble carboxylated zinc phthalocyanine (ZnPc-COOH) with completely quenched fluorescence in aqueous solution. Interestingly, we found that the NIR fluorescence of aqueous ZnPc-COOH was dramatically recovered in the presence of gold nanorods (Au NR), which was due to the alternation of ZnPc-COOH molecules self-assembling via electrostatic interaction between cetyltrimethylammonium bromide (CTAB) on the surface of Au NR and peripheral carboxyl of ZnPc-COOH. In addition, ZnPc-COOH/Au NR conjugates demonstrated an improved singlet oxygen generation, which could be served as potential bioimaging probe and photosensitizer for photodynamic therapy. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. A dual-responsive supra-amphiphilic polypseudorotaxane constructed from a water-soluble pillar[7]arene and an azobenzene-containing random copolymer.

    Science.gov (United States)

    Chi, Xiaodong; Ji, Xiaofan; Xia, Danyu; Huang, Feihe

    2015-02-04

    Macromolecular supra-amphiphiles refer to a kind of macromolecular amphiphiles whose hydrophlic and hydrophobic parts are connected by noncovalent forces. They have applications in various fields, such as drug delivery, sensor systems, and biomedical materials. Here we report a novel molecular recognition motif between a new thermoresponsive water-soluble pillar[7]arene (WP7) and an azobenzene derivative. Furthermore, we utilized this recognition motif to construct the first pillararene-based supra-amphiphilic polypseudorotaxane which can self-assemble to form vesicles in water. Due to the dual-responsiveness of the molecular recognition motif (the thermoresponsiveness of WP7 and photoresponsiveness of azobenzene), the reversible transformations between solid nanospheres based on the self-assembly of the polymer backbone and vesicles based on the self-assembly of the supra-amphiphilic polypseudorotaxane were achieved by adjusting the solution temperature or UV-visible light irradiation. These dual-responsive aggregation behaviors were further used in the controlled release of water-soluble dye calcein molecules.

  13. The use of nano polymeric self-assemblies based on novel amphiphilic polymers for oral hydrophobic drug delivery.

    Science.gov (United States)

    Clare, Hoskins; Lin, Paul Kong Thoo; Tetley, Laurence; Cheng, Woei Ping

    2012-03-01

    To investigate the use of nano self-assemblies formed by polyallylamine (PAA) modified with 5 or 10% mole fluorenylmethoxy carbonyl (Fmoc(5)/(10)), dimethylamino-1-naphthalenesulfonyl (Dansyl(5)/(10)) and 5% mole cholesteryl group (Ch(5)) for oral hydrophobic drug delivery. Propofol, griseofulvin and prednisolone were loaded into amphiphilic PAAs. Particle size and morphology of drug-loaded self-assemblies were determined using photon correlation spectroscopy and transmission electron microscopy. Solubilising capacity, in vitro drug release and formulation stability were analysed by HPLC, and in vitro biocompatibility studies (haemolysis and cytotoxicity) were carried out on bovine erythrocytes and Caco-2 cells, respectively. Dansyl(10) and Ch(5) griseofulvin formulations were administered intra-gastrically to rats, and drug plasma levels were analysed by HPLC. Drug-encapsulated self-assemblies typically have hydrodynamic size of 300-400 nm. Dansyl(10) exhibited universal drug solubiliser property and had significantly improved prednisolone, griseofulvin and propofol solubility by 145, 557 and 224-fold, respectively. Fmoc polymers resulted in modest drug solubility improvement. These polymers were non-haemolytic, did not enhance cytotoxicity compared to unmodified PAA, and demonstrated significant increase in griseofulvin plasma concentration compared to griseofulvin in water after oral administration. Ch(5) and Dansyl(10) showed promising potential as nano-carriers for oral hydrophobic drug delivery.

  14. Self-Assembled Microwires of Terephthalic Acid and Melamine

    Directory of Open Access Journals (Sweden)

    Hong Wang

    2017-07-01

    Full Text Available Self-assembled microwires of terephthalic acid (TPA and melamine are prepared through the evaporation of water in a solution mixture of TPA and melamine. The microwires were characterized by using scanning electron microscope (SEM, attenuated total reflection infrared (ATR-IR spectra, and cross-polarized optical microscopy (CPOM. The TPA•M microwires showed semi-conductive properties.

  15. Biochemical synthesis of water soluble conducting polymers

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, Ferdinando F., E-mail: Ferdinando-Bruno@uml.edu [US Army Natick Soldier Research, Development and Engineering Center, Natick, MA 01760 (United States); Bernabei, Manuele [ITAF, Test Flight Centre, Chemistry Dept. Pratica di Mare AFB, 00071 Pomezia (Rome), Italy (UE) (Italy)

    2016-05-18

    An efficient biomimetic route for the synthesis of conducting polymers/copolymers complexed with lignin sulfonate and sodium (polystyrenesulfonate) (SPS) will be presented. This polyelectrolyte assisted PEG-hematin or horseradish peroxidase catalyzed polymerization of pyrrole (PYR), 3,4 ethyldioxithiophene (EDOT) and aniline has provided a route to synthesize water-soluble conducting polymers/copolymers under acidic conditions. The UV-vis, FTIR, conductivity and cyclic voltammetry studies for the polymers/copolymer complex indicated the presence of a thermally stable and electroactive polymers. Moreover, the use of water-soluble templates, used as well as dopants, provided a unique combination of properties such as high electronic conductivity, and processability. These polymers/copolymers are nowadays tested/evaluated for antirust features on airplanes and helicopters. However, other electronic applications, such as photovoltaics, for transparent conductive polyaniline, actuators, for polypyrrole, and antistatic films, for polyEDOT, will be proposed.

  16. Pillar[5]arene-based amphiphilic supramolecular brush copolymer: fabrication, controllable self-assembly and application in self-imaging targeted drug delivery†

    OpenAIRE

    Yu, Guocan; Zhao, Run; Wu, Dan; Zhang,Fuwu; Shao, Li; Zhou, Jiong; Yang, Jie; Tang, Guping; Chen, Xiaoyuan; Huang, Feihe

    2016-01-01

    Supramolecular brush copolymers have attracted continuing interest due to their unusual architectures, fascinating properties, and potential applications in many fields involving smart stimuli-responsive drug delivery systems. Herein, the first pillararene-based amphiphilic supramolecular brush copolymer (P5-PEG-Biotin⊃PTPE) was constructed on the basis of the host–guest molecular recognition between a water-soluble pillar[5]arene (P5) and a viologen salt (M). P5-PEG-Biotin⊃PTPE self-assemble...

  17. Water soluble azido polyisocyanides as functional beta-sheet mimics

    NARCIS (Netherlands)

    Schwartz, Erik; Schwartz, E.; Koepf, Matthieu; Kitto, Heather J.; Espelt, Mónica; Nebot-Carda, Vicent J.; de Gelder, Rene; Nolte, Roeland J.M.; Cornelissen, Jeroen Johannes Lambertus Maria; Rowan, Alan E.

    2009-01-01

    The design and synthesis of functional biomimetic water soluble polymers with a defined secondary structure has been developed using β-sheet polyisocyanopeptide scaffolds. Water soluble isocyanopolymers were prepared by random copolymerisation of the azido functionalized isocyanopeptides with

  18. Design principles for nonequilibrium self-assembly.

    Science.gov (United States)

    Nguyen, Michael; Vaikuntanathan, Suriyanarayanan

    2016-12-13

    We consider an important class of self-assembly problems, and using the formalism of stochastic thermodynamics, we derive a set of design principles for growing controlled assemblies far from equilibrium. The design principles constrain the set of configurations that can be obtained under nonequilibrium conditions. Our central result provides intuition for how equilibrium self-assembly landscapes are modified under finite nonequilibrium drive.

  19. Molecular self-assembly advances and applications

    CERN Document Server

    Dequan, Alex Li

    2012-01-01

    In the past several decades, molecular self-assembly has emerged as one of the main themes in chemistry, biology, and materials science. This book compiles and details cutting-edge research in molecular assemblies ranging from self-organized peptide nanostructures and DNA-chromophore foldamers to supramolecular systems and metal-directed assemblies, even to nanocrystal superparticles and self-assembled microdevices

  20. Self-assembled nanomaterials for photoacoustic imaging.

    Science.gov (United States)

    Wang, Lei; Yang, Pei-Pei; Zhao, Xiao-Xiao; Wang, Hao

    2016-02-07

    In recent years, extensive endeavors have been paid to construct functional self-assembled nanomaterials for various applications such as catalysis, separation, energy and biomedicines. To date, different strategies have been developed for preparing nanomaterials with diversified structures and functionalities via fine tuning of self-assembled building blocks. In terms of biomedical applications, bioimaging technologies are urgently calling for high-efficient probes/contrast agents for high-performance bioimaging. Photoacoustic (PA) imaging is an emerging whole-body imaging modality offering high spatial resolution, deep penetration and high contrast in vivo. The self-assembled nanomaterials show high stability in vivo, specific tolerance to sterilization and prolonged half-life stability and desirable targeting properties, which is a kind of promising PA contrast agents for biomedical imaging. Herein, we focus on summarizing recent advances in smart self-assembled nanomaterials with NIR absorption as PA contrast agents for biomedical imaging. According to the preparation strategy of the contrast agents, the self-assembled nanomaterials are categorized into two groups, i.e., the ex situ and in situ self-assembled nanomaterials. The driving forces, assembly modes and regulation of PA properties of self-assembled nanomaterials and their applications for long-term imaging, enzyme activity detection and aggregation-induced retention (AIR) effect for diagnosis and therapy are emphasized. Finally, we conclude with an outlook towards future developments of self-assembled nanomaterials for PA imaging.

  1. Water-soluble titanium alkoxide material

    Science.gov (United States)

    Boyle, Timothy J.

    2010-06-22

    A water soluble, water stable, titanium alkoxide composition represented by the chemical formula (OC.sub.6H.sub.6N).sub.2Ti(OC.sub.6H.sub.2(CH.sub.2N(CH.sub.3).sub.2).sub- .3-2,4,6).sub.2 with a theoretical molecular weight of 792.8 and an elemental composition of 63.6% C, 8.1% H, 14.1% N, 8.1% O and 6.0% Ti.

  2. An ultrasonic atomization assisted synthesis of self-assembled manganese oxide octahedral molecular sieve nanostructures and their application in catalysis and water treatment.

    Science.gov (United States)

    Iyer, Aparna; Kuo, Chung-Hao; Dharmarathna, Saminda; Luo, Zhu; Rathnayake, Dinithi; He, Junkai; Suib, Steven L

    2017-04-13

    Manganese oxides of octahedral molecular sieve (OMS-2) type have important applications in oxidation catalysis, adsorption, and as battery materials. The synthesis methods employed determine their morphology and textural properties which markedly affect their catalytic activity. In this work, a room temperature ultrasonic atomization assisted synthesis of OMS-2 type materials is demonstrated. This synthesis differs from previously reported methods in that it is a simple, no-heat application that leads to a striking morphological characteristic of uniformly sized OMS-2 fibers and their self-assembly into dense as well as hollow spheres. Control of various parameters in the ultrasonic atomization assisted synthesis led to OMS-2 with high surface areas (between 136-160 m(2) g(-1)) and mesoporosity. Catalytically these materials have higher activities in the oxidation of hydroxymethylfurfural (HMF), a bio-based chemical, (65% conversion of HMF vs. 14% with conventional OMS-2 catalyst) and a higher adsorption of lead from aqueous solutions (70% vs. 12% in conventional OMS-2 materials).

  3. Self-assembly models for lipid mixtures

    Science.gov (United States)

    Singh, Divya; Porcar, Lionel; Butler, Paul; Perez-Salas, Ursula

    2006-03-01

    Solutions of mixed long and short (detergent-like) phospholipids referred to as ``bicelle'' mixtures in the literature, are known to form a variety of different morphologies based on their total lipid composition and temperature in a complex phase diagram. Some of these morphologies have been found to orient in a magnetic field, and consequently bicelle mixtures are widely used to study the structure of soluble as well as membrane embedded proteins using NMR. In this work, we report on the low temperature phase of the DMPC and DHPC bicelle mixture, where there is agreement on the discoid structures but where molecular packing models are still being contested. The most widely accepted packing arrangement, first proposed by Vold and Prosser had the lipids completely segregated in the disk: DHPC in the rim and DMPC in the disk. Using data from small angle neutron scattering (SANS) experiments, we show how radius of the planar domain of the disks is governed by the effective molar ratio qeff of lipids in aggregate and not the molar ratio q (q = [DMPC]/[DHPC] ) as has been understood previously. We propose a new quantitative (packing) model and show that in this self assembly scheme, qeff is the real determinant of disk sizes. Based on qeff , a master equation can then scale the radii of disks from mixtures with varying q and total lipid concentration.

  4. Thermo-reversible morphology and conductivity of a conjugated polymer network embedded in polymeric self-assembly

    Science.gov (United States)

    Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe; Li, Yunchao; Hong, Kunlun; Sumpter, Bobby G.; Ohl, Michael; Paranthaman, Mariappan Parans; Smith, Gregory S.; Do, Changwoo

    Self-assembly of block copolymers provides opportunities to create nano hybrid materials, utilizing self-assembled micro-domains with a variety of morphology and periodic architectures as templates for functional nano-fillers. Here we report new progress towards the fabrication of a thermally responsive conducting polymer self-assembly made from a water-soluble poly(thiophene) derivative with short PEO side chains and Pluronic L62 solution in water. The structural and electrical properties of conjugated polymer-embedded nanostructures were investigated by combining SANS, SAXS, CGMD simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporating them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellar-to-lamellar phase transition defines the embedded conjugated polymer network. The conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. The research was sponsored by the Scientific User Facilities Division, Office of BES, U.S. DOE and Laboratory Directed Research and Development Program of ORNL, managed by UT-Battelle, LLC.

  5. Indomethacin solubility in propylene glycol + water mixtures according to the extended hildebrand solubility approach

    OpenAIRE

    Holguín, Andrés R.; Delgado, Daniel R.; Martínez, Fleming

    2012-01-01

    In this work the Extended Hildebrand Solubility Approach (EHSA) was applied to evaluate the solubility of the analgesic drug indomethacin in propylene glycol + water mixtures at 298.15 K. An acceptable correlative capacity of EHSA was found using a regular polynomial model in order four (overall deviation lower than 2.2 %), when the W interaction parameter is related to the solubility parameter of the mixtures. Nevertheless, the deviations obtained in the estimated solubility with respect to ...

  6. Extreme Activity of Drug Nanocrystals Coated with A Layer of Non-Covalent Polymers from Self-Assembled Boric Acid

    Science.gov (United States)

    Zhan, Honglei; Liang, Jun F.

    2016-12-01

    Non-covalent polymers have remarkable advantages over synthetic polymers for wide biomedical applications. In this study, non-covalent polymers from self-assembled boric acid were used as the capping reagent to replace synthetic polymers in drug crystallization. Under acidic pH, boric acid self-assembled on the surface of drug nanocrystals to form polymers with network-like structures held together by hydrogen bonds. Coating driven by boric acid self-assembly had negligible effects on drug crystallinity and structure but resulted in drug nanocrystals with excellent dispersion properties that aided in the formation of a more stable suspension. Boric acid coating improved drug stability dramatically by preventing drug molecules from undergoing water hydrolysis in a neutral environment. More importantly, the specific reactivity of orthoboric groups to diols in cell glycocalyx facilitated a rapid cross-membrane translocation of drug nanocrystals, leading to efficient intracellular drug delivery, especially on cancer cells with highly expressed sialic acids. Boric acid coated nanocrystals of camptothecin, an anticancer drug with poor aqueous solubility and stability, demonstrated extreme cytotoxic activity (IC50 boric acid will have wide biomedical applications especially in biomaterials and drug delivery field.

  7. Directed Self-Assembly of Nanodispersions

    Energy Technology Data Exchange (ETDEWEB)

    Furst, Eric M [University of Delaware

    2013-11-15

    Directed self-assembly promises to be the technologically and economically optimal approach to industrial-scale nanotechnology, and will enable the realization of inexpensive, reproducible and active nanostructured materials with tailored photonic, transport and mechanical properties. These new nanomaterials will play a critical role in meeting the 21st century grand challenges of the US, including energy diversity and sustainability, national security and economic competitiveness. The goal of this work was to develop and fundamentally validate methods of directed selfassembly of nanomaterials and nanodispersion processing. The specific aims were: 1. Nanocolloid self-assembly and interactions in AC electric fields. In an effort to reduce the particle sizes used in AC electric field self-assembly to lengthscales, we propose detailed characterizations of field-driven structures and studies of the fundamental underlying particle interactions. We will utilize microscopy and light scattering to assess order-disorder transitions and self-assembled structures under a variety of field and physicochemical conditions. Optical trapping will be used to measure particle interactions. These experiments will be synergetic with calculations of the particle polarizability, enabling us to both validate interactions and predict the order-disorder transition for nanocolloids. 2. Assembly of anisotropic nanocolloids. Particle shape has profound effects on structure and flow behavior of dispersions, and greatly complicates their processing and self-assembly. The methods developed to study the self-assembled structures and underlying particle interactions for dispersions of isotropic nanocolloids will be extended to systems composed of anisotropic particles. This report reviews several key advances that have been made during this project, including, (1) advances in the measurement of particle polarization mechanisms underlying field-directed self-assembly, and (2) progress in the

  8. Biocatalytic Self-Assembly on Magnetic Nanoparticles.

    Science.gov (United States)

    Conte, Maria P; Sahoo, Jugal Kishore; Abul-Haija, Yousef M; Lau, K H Aaron; Ulijn, Rein V

    2018-01-24

    Combining (bio)catalysis and molecular self-assembly provides an effective approach for the production and processing of self-assembled materials by exploiting catalysis to direct the assembly kinetics and hence controlling the formation of ordered nanostructures. Applications of (bio)catalytic self-assembly in biologically interfacing systems and in nanofabrication have recently been reported. Inspired by self-assembly in biological cells, efforts to confine catalysts on flat or patterned surfaces to exert spatial control over molecular gelator generation and nanostructure self-assembly have also emerged. Building on our previous work in the area, we demonstrate in this report the use of enzymes immobilized onto magnetic nanoparticles (NPs) to spatially localize the initiation of peptide self-assembly into nanofibers around NPs. The concept is generalized for both an equilibrium biocatalytic system that forms stable hydrogels and a nonequilibrium system that normally has a preset lifetime. Characterization of the hydrogels shows that self-assembly occurs at the site of enzyme immobilization on the NPs to give rise to gels with a "hub-and-spoke" morphology, where the nanofibers are linked through the enzyme-NP conjugates. This NP-controlled arrangement of self-assembled nanofibers enables both remarkable enhancements in the shear strength of hydrogel systems and a dramatic extension of the hydrogel stability in the nonequilibrium system. We are also able to show that the use of magnetic NPs enables the external control of both the formation of the hydrogel and its overall structure by application of an external magnetic field. We anticipate that the enhanced properties and stimuli-responsiveness of our NP-enzyme system will have applications ranging from nanomaterial fabrication to biomaterials and biosensing.

  9. Syntheses and Self-assembling Behaviors of Pentagonal Conjugates of Tryptophane Zipper-Forming Peptide

    Directory of Open Access Journals (Sweden)

    Nobuo Kimizuka

    2011-08-01

    Full Text Available Pentagonal conjugates of tryptophane zipper-forming peptide (CKTWTWTE with a pentaazacyclopentadecane core (Pentagonal-Gly-Trpzip and Pentagonal-Ala-Trpzip were synthesized and their self-assembling behaviors were investigated in water. Pentagonal-Gly-Trpzip self-assembled into nanofibers with the width of about 5 nm in neutral water (pH 7 via formation of tryptophane zipper, which irreversibly converted to nanoribbons by heating. In contrast, Pentagonal-Ala-Trpzip formed irregular aggregates in water.

  10. Mechanical Self-Assembly Science and Applications

    CERN Document Server

    2013-01-01

    Mechanical Self-Assembly: Science and Applications introduces a novel category of self-assembly driven by mechanical forces. This book discusses self-assembly in various types of small material structures including thin films, surfaces, and micro- and nano-wires, as well as the practice's potential application in micro and nanoelectronics, MEMS/NEMS, and biomedical engineering. The mechanical self-assembly process is inherently quick, simple, and cost-effective, as well as accessible to a large number of materials, such as curved surfaces for forming three-dimensional small structures. Mechanical self-assembly is complementary to, and sometimes offer advantages over, the traditional micro- and nano-fabrication. This book also: Presents a highly original aspect of the science of self-assembly Describes the novel methods of mechanical assembly used to fabricate a variety of new three-dimensional material structures in simple and cost-effective ways Provides simple insights to a number of biological systems and ...

  11. Self-assembly of nanoparticles into biomimetic capsid-like nanoshells

    Science.gov (United States)

    Yang, Ming; Chan, Henry; Zhao, Gongpu; Bahng, Joong Hwan; Zhang, Peijun; Král, Petr; Kotov, Nicholas A.

    2017-03-01

    Nanoscale compartments are one of the foundational elements of living systems. Capsids, carboxysomes, exosomes, vacuoles and other nanoshells easily self-assemble from biomolecules such as lipids or proteins, but not from inorganic nanomaterials because of difficulties with the replication of spherical tiling. Here we show that stabilizer-free polydispersed inorganic nanoparticles (NPs) can spontaneously organize into porous nanoshells. The association of water-soluble CdS NPs into self-limited spherical capsules is the result of scale-modified electrostatic, dispersion and other colloidal forces. They cannot be accurately described by the Derjaguin-Landau-Vervey-Overbeek theory, whereas molecular-dynamics simulations with combined atomistic and coarse-grained description of NPs reveal the emergence of nanoshells and some of their stabilization mechanisms. Morphology of the simulated assemblies formed under different conditions matched nearly perfectly the transmission electron microscopy tomography data. This study bridges the gap between biological and inorganic self-assembling nanosystems and conceptualizes a new pathway to spontaneous compartmentalization for a wide range of inorganic NPs including those existing on prebiotic Earth.

  12. Self-assembled polyelectrolyte complexes films as efficient compression coating layers for controlled-releasing tablets.

    Science.gov (United States)

    Li, Wenyan; Huo, Mengmeng; Sen Chaudhuri, Arka; Yang, Chen; Cao, Dazhong; Wu, Zhenghong; Qi, Xiaole

    2017-05-01

    Currently, polysaccharide-based hydrogels are widely studied macromolecular networks to modify drug dissolution from controlled-releasing matrix tablets. Among them, polyelectrolyte complexes (PEC) films consisted of chitosan (CS) and sodium alginate (SA) could be obtained via spontaneously assembling under physiological gastrointestinal environment. Here, we utilized these self-assembled PEC films as an efficient coating materials to develop controlled-released matrix tablets through compression coating process, with paracetamol (APAP) as model drug. The constitutive and morphology characteristic studies on these PEC films illustrated that the mixture of CS and SA with the weight ratio of 1:1 would be an promising outer layer for compression-coating tablets. In addition, the in vitro drug releasing behavior experiments demonstrated that the optimized compression coating tablets displayed satisfied zero-order drug releasing profits. Furthermore, the in vivo pharmacokinetic studies of these APAP loaded compression-coated tablets in New Zealand rabbits gave that the T max (12.32 ± 1.05 h) was significantly prolonged (p tablets (Jinfuning ® ) after oral administration. These studies suggest that the compression-coated tablets with self-assembled PEC film as coating outer layer may be a promising strategy for peroral controlled release delivery system of water soluble drugs.

  13. Light-Activated Hydrogel Formation via the Triggered Folding and Self-Assembly of a Designed Peptide

    Science.gov (United States)

    Haines, Lisa A.; Rajagopal, Karthikan; Ozbas, Bulent; Salick, Daphne A.; Pochan, Darrin J.; Schneider, Joel P.

    2009-01-01

    Photopolymerization can be used to construct materials with precise temporal and spatial resolution. Applications such as tissue engineering, drug delivery, the fabrication of microfluidic devices and the preparation of high-density cell arrays employ hydrogel materials that are often prepared by this technique. Current photopolymerization strategies used to prepare hydrogels employ photoinitiators, many of which are cytotoxic and require large macromolecular precursors that need to be functionalized with moieties capable of undergoing radical cross-linking reactions. We have developed a simple light-activated hydrogelation system that employs a designed peptide whose ability to self-assemble into hydrogel material is dependent on its intramolecular folded conformational state. An iterative design strategy afforded MAX7CNB, a photocaged peptide that, when dissolved in aqueous medium, remains unfolded and unable to self-assemble; a 2 wt % solution of freely soluble unfolded peptide is stable to ambient light and has the viscosity of water. Irradiation of the solution (260 < λ < 360 nm) releases the photocage and triggers peptide folding to produce amphiphilic β-hairpins that self-assemble into viscoelastic hydrogel material. Circular dichroic (CD) spectroscopy supports this folding and self-assembly mechanism, and oscillatory rheology shows that the resulting hydrogel is mechanically rigid ( G′ = 1000 Pa). Laser scanning confocal microscopy imaging of NIH 3T3 fibroblasts seeded onto the gel indicates that the gel surface is noncytotoxic, conducive to cell adhesion, and allows cell migration. Lastly, thymidine incorporation assays show that cells seeded onto decaged hydrogel proliferate at a rate equivalent to cells seeded onto a tissue culture-treated polystyrene control surface. PMID:16316249

  14. Self-Assembly at the Colloidal Scale

    Science.gov (United States)

    Zhong, Xiao

    The existence of self-assembly, the phenomenon of spontaneous structural formation from building blocks, transcends many orders of magnitude, ranging from molecular to cosmic. It is arguably the most common, important, and complex question in science. This thesis aims for understanding a spectrum of self-assembly-self assembly at the colloidal scale. Of the whole spectrum of self-assembly, the colloidal scale is of particular interest and importance to researchers, for not only comprehensive tools for colloidal scale studies have been well established, but also the various promising applications colloidal self-assembly can facilitate. In this thesis, a high throughput technique-Polymer Pen Lithography (PPL) is modified and its potential for creating corrals for colloidal assembly is evaluated. Then two different approaches of assembling colloids are explored in depth. One of them is by using a phenomenon called dielectrophoresis (DEP) as driving force to manipulate colloidal nucleation and crystal growth. And the other takes advantage of the Pt-catalyzed H2O 2 redox reaction to drive micrometer-scaled, rod-shaped colloids to swim and assemble. Lastly, an optical method called Holographic Video Microscopy (HVM) is used to monitor and characterize "bad" self-assembly of proteins, that is their aggregations. The four studies discussed in this thesis represent advancements in the colloidal scale from different aspects. The PPL technique enriched the toolbox for colloidal self-assembly. The DEP driven colloidal nucleation and crystal growth shed light on deeper understanding the mechanism of crystallization. And the swimming and assembly of micro-scale rods leads to kinetics reminiscent of bacterial run-and-tumble motion. Finally, the HVM technique for monitoring and understanding protein aggregation could potentially lead to better quality assurance for therapeutic proteins and could be a powerful tool for assessing their shelf lives.

  15. Electrostatic self-assembly of biomolecules

    Science.gov (United States)

    Olvera de La Cruz, Monica

    2015-03-01

    Charged filaments and membranes are natural structures abundant in cell media. In this talk we discuss the assembly of amphiphiles into biocompatible fibers, ribbons and membranes. We describe one- and two-dimensional assemblies that undergo re-entrant transitions in crystalline packing in response to changes in the solution pH and/or salt concentration resulting in different mesoscale morphologies and properties. In the case of one-dimensional structures, we discuss self-assembled amphiphiles into highly charged nanofibers in water that order into two-dimensional crystals. These fibers of about 6 nm cross-sectional diameter form crystalline arrays with inter-fiber spacings of up to 130 nm. Solution concentration and temperature can be adjusted to control the inter-fiber spacings. The addition of salt destroys crystal packing, indicating that electrostatic repulsions are necessary for the observed ordering. We describe the crystallization of bundles of filament networks interacting via long-range repulsions in confinement by a phenomenological model. Two distinct crystallization mechanisms in the short and large screening length regimes are discussed and the phase diagram is obtained. Simulation of large bundles predicts the existence of topological defects among bundled filaments. Crystallization processes driven by electrostatic attractions are also discussed. Funded by Center for Bio-Inspired Energy Science (CBES), which is an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0000989.

  16. Self-assembled biomimetic superhydrophobic hierarchical arrays.

    Science.gov (United States)

    Yang, Hongta; Dou, Xuan; Fang, Yin; Jiang, Peng

    2013-09-01

    Here, we report a simple and inexpensive bottom-up technology for fabricating superhydrophobic coatings with hierarchical micro-/nano-structures, which are inspired by the binary periodic structure found on the superhydrophobic compound eyes of some insects (e.g., mosquitoes and moths). Binary colloidal arrays consisting of exemplary large (4 and 30 μm) and small (300 nm) silica spheres are first assembled by a scalable Langmuir-Blodgett (LB) technology in a layer-by-layer manner. After surface modification with fluorosilanes, the self-assembled hierarchical particle arrays become superhydrophobic with an apparent water contact angle (CA) larger than 150°. The throughput of the resulting superhydrophobic coatings with hierarchical structures can be significantly improved by templating the binary periodic structures of the LB-assembled colloidal arrays into UV-curable fluoropolymers by a soft lithography approach. Superhydrophobic perfluoroether acrylate hierarchical arrays with large CAs and small CA hysteresis can be faithfully replicated onto various substrates. Both experiments and theoretical calculations based on the Cassie's dewetting model demonstrate the importance of the hierarchical structure in achieving the final superhydrophobic surface states. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Self-assembling graphene-anthraquinone-2-sulphonate supramolecular nanostructures with enhanced energy density for supercapacitors

    Science.gov (United States)

    Gao, Lifang; Gan, Shiyu; Li, Hongyan; Han, Dongxue; Li, Fenghua; Bao, Yu; Niu, Li

    2017-07-01

    Boosting the energy density of capacitive energy storage devices remains a crucial issue for facilitating applications. Herein, we report a graphene-anthraquinone supramolecular nanostructure by self-assembly for supercapacitors. The sulfonated anthraquinone exhibits high water solubility, a π-conjugated structure and redox active features, which not only serve as a spacer to interact with and stabilize graphene but also introduce extra pseudocapacitance contributions. The formed nest-like three-dimensional (3D) nanostructure with further hydrothermal treatment enhances the accessibility of ion transfer and exposes the redox-active quinone groups in the electrolytes. A fabricated all-solid-state flexible symmetric device delivers a high specific capacitance of 398.5 F g-1 at 1 A g-1 (1.5 times higher than graphene), superior energy density (52.24 Wh kg-1 at about 1 kW kg-1) and good stability (82% capacitance retention after 10 000 cycles).

  18. Self-assembly of glutamic acid linked paclitaxel dimers into nanoparticles for chemotherapy.

    Science.gov (United States)

    Wang, Zhanfeng; Zhuang, Miao; Sun, Tingting; Wang, Xin; Xie, Zhigang

    2017-06-01

    In this work, a glutamic acid linked paclitaxel (PTX) dimer (Glu-PTX2) with high PTX content of 88.9wt% was designed and synthesized. Glu-PTX2 could self-assemble into nanoparticles (Glu-PTX2 NPs) in aqueous solution to increase the water solubility of PTX. Glu-PTX2 NPs were characterized by electron microscopy and dynamic light scattering, exhibiting spherical morphology and favorable structural stability in aqueous media. Glu-PTX2 NPs could be internalized by cancer cells as revealed by confocal laser scanning microscopy and exert potent cytotoxicity. It is envisaged that Glu-PTX2 NPs would be an alternative formulation for PTX, and such amino acid linked drug dimers could also be applied to other therapeutic agents. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Lipid Self-Assemblies and Nanostructured Emulsions for Cosmetic Formulations

    Directory of Open Access Journals (Sweden)

    Chandrashekhar V. Kulkarni

    2016-10-01

    Full Text Available A majority of cosmetic products that we encounter on daily basis contain lipid constituents in solubilized or insolubilized forms. Due to their amphiphilic nature, the lipid molecules spontaneously self-assemble into a remarkable range of nanostructures when mixed with water. This review illustrates the formation and finely tunable properties of self-assembled lipid nanostructures and their hierarchically organized derivatives, as well as their relevance to the development of cosmetic formulations. These lipid systems can be modulated into various physical forms suitable for topical administration including fluids, gels, creams, pastes and dehydrated films. Moreover, they are capable of encapsulating hydrophilic, hydrophobic as well as amphiphilic active ingredients owing to their special morphological characters. Nano-hybrid materials with more elegant properties can be designed by combining nanostructured lipid systems with other nanomaterials including a hydrogelator, silica nanoparticles, clays and carbon nanomaterials. The smart materials reviewed here may well be the future of innovative cosmetic applications.

  20. 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.

  1. Self-assembly of nanocomposite materials

    Science.gov (United States)

    Brinker, C. Jeffrey; Sellinger, Alan; Lu, Yunfeng

    2001-01-01

    A method of making a nanocomposite self-assembly is provided where at least one hydrophilic compound, at least one hydrophobic compound, and at least one amphiphilic surfactant are mixed in an aqueous solvent with the solvent subsequently evaporated to form a self-assembled liquid crystalline mesophase material. Upon polymerization of the hydrophilic and hydrophobic compounds, a robust nanocomposite self-assembled material is formed. Importantly, in the reaction mixture, the amphiphilic surfactant has an initial concentration below the critical micelle concentration to allow formation of the liquid-phase micellar mesophase material. A variety of nanocomposite structures can be formed, depending upon the solvent evaporazation process, including layered mesophases, tubular mesophases, and a hierarchical composite coating composed of an isotropic worm-like micellar overlayer bonded to an oriented, nanolaminated underlayer.

  2. Self-Assembly Modularity and Physical Complexity

    Science.gov (United States)

    Ahnert, S. E.

    2012-12-01

    Self-assembly is ubiquitous in physics, chemistry and biology, and has many applications in materials science and engineering. Here we present a general approach for finding the simplest set of building blocks that will assemble into a given physical structure. Our procedure can be adapted to any given geometry, and thus to any given type of physical system. The amount of information required to describe this simplest set of building blocks provides a quantitative measure of the structure's physical complexity, which is capable of detecting any symmetry or modularity in the underlying structure.We also introduce the notions of joint, mutual and conditional complexity for self-assembling structures. We illustrate our approach using self-assembling polyominoes, and demonstrate the breadth of its potential applications by using it to quantify the physical complexity of protein complexes.

  3. S-Layer Protein Self-Assembly

    Science.gov (United States)

    Pum, Dietmar; Toca-Herrera, Jose Luis; Sleytr, Uwe B.

    2013-01-01

    Crystalline S(urface)-layers are the most commonly observed cell surface structures in prokaryotic organisms (bacteria and archaea). S-layers are highly porous protein meshworks with unit cell sizes in the range of 3 to 30 nm, and thicknesses of ~10 nm. One of the key features of S-layer proteins is their intrinsic capability to form self-assembled mono- or double layers in solution, and at interfaces. Basic research on S-layer proteins laid foundation to make use of the unique self-assembly properties of native and, in particular, genetically functionalized S-layer protein lattices, in a broad range of applications in the life and non-life sciences. This contribution briefly summarizes the knowledge about structure, genetics, chemistry, morphogenesis, and function of S-layer proteins and pays particular attention to the self-assembly in solution, and at differently functionalized solid supports. PMID:23354479

  4. Thermodynamics of sulfanilamide solubility in propylene glycol + water mixtures

    OpenAIRE

    Martínez, Fleming; Romdhani, Asma; Delgado, Daniel R.

    2011-01-01

    The solubility of sulfanilamide (SA) in propylene glycol + water cosolvent mixtures was determined at temperatures from 293.15 to 313.15 K. The thermodynamic functions: Gibbs energy, enthalpy, and entropy of solution and mixing were obtained from these solubility data by using the van’t Hoff and Gibbs equations. The solubility was maximal in propylene glycol and very low in water at all the temperatures. A non linear enthalpy–entropy relationship was observed from a plot of enthal...

  5. A Self-assembled Fluoride-Water Cyclic Cluster of $[F(H_2O)]_4^{4-}$ in a Molecular Box

    CERN Document Server

    Hossain, Md Alamgir; Pramanik, Avijit; Wong, Bryan M; Haque, Syed A; Powell, Douglas R

    2013-01-01

    We present an unprecedented fluoride-water cyclic cluster of $[F(H_2O)]_4^{4-}$ assembled in a cuboid-shaped molecular box formed by two large macrocycles. Structural characterization reveals that the $[F(H_2O)]_4^{4-}$ is assembled by strong H-bonding interactions (OH...F = 2.684(3) to 2.724(3) {\\AA}), where a fluoride anion plays the topological role of a water molecule in the classical cyclic water octamer. The interaction of fluoride was further confirmed by $^{19}$F NMR and $^1$H NMR spectroscopies, indicating the encapsulation of the anionic species within the cavity in solution. High level DFT calculations and Bader topological analyses fully support the crystallographic results, demonstrating that the bonding arrangement in the fluoride-water cluster arises from the unique geometry of the host.

  6. Nondeterministic self-assembly with asymmetric interactions

    Science.gov (United States)

    Tesoro, S.; Göpfrich, K.; Kartanas, T.; Keyser, U. F.; Ahnert, S. E.

    2016-08-01

    We investigate general properties of nondeterministic self-assembly with asymmetric interactions, using a computational model and DNA tile assembly experiments. By contrasting symmetric and asymmetric interactions we show that the latter can lead to self-limiting cluster growth. Furthermore, by adjusting the relative abundance of self-assembly particles in a two-particle mixture, we are able to tune the final sizes of these clusters. We show that this is a fundamental property of asymmetric interactions, which has potential applications in bioengineering, and provides insights into the study of diseases caused by protein aggregation.

  7. Self-assembling segmented coiled tubing

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, David W.

    2016-09-27

    Self-assembling segmented coiled tubing is a concept that allows the strength of thick-wall rigid pipe, and the flexibility of thin-wall tubing, to be realized in a single design. The primary use is for a drillstring tubular, but it has potential for other applications requiring transmission of mechanical loads (forces and torques) through an initially coiled tubular. The concept uses a spring-loaded spherical `ball-and-socket` type joint to interconnect two or more short, rigid segments of pipe. Use of an optional snap ring allows the joint to be permanently made, in a `self-assembling` manner.

  8. Bioconcentration of Water Soluble Fraction (WSF) of crude oil in ...

    African Journals Online (AJOL)

    Bioconcentration of water soluble fraction of Australian crude oil in 50 fingerlings of Oreochromis niloticus was conducted under laboratory conditions for 28 days. An initial acute toxicity test was carried out using different concentrations (25ml/L, 50ml/L, 75ml/L, 100ml/L and a control) of the water soluble fraction (WSF) of ...

  9. Formation of Mesostructured Nanoparticles through Self-Assembly and Aerosol Process

    Energy Technology Data Exchange (ETDEWEB)

    Brinker, C. Jeffrey; Fan, Hongyou; Lu, Yunfeng; Rieker, Thomas; Stump, Arron; Ward, Timothy L.

    1999-05-07

    Silica nanoparticles exhibiting hexagonal, cubic, and vesicular mesostructures have been prepared using aerosol assisted, self-assembled process. This process begins with homogennous aerosol droplets containing silica source, water, ethanol, and surfactant, in which surfactant concentration is far below the critical micelle concentration (cmc). Solvent evaporation enriches silica and surfactant inducing interfacial self-assembly confined to a spherical aerosol droplet and results in formation of completely solid, ordered spherical particles with stable hexagonal, cubic, or vesicular mesostructures.

  10. Novel nanosized water soluble fluorescent micelles with embedded perylene diimide fluorophores for potential biomedical applications: cell permeability, localization and cytotoxicity.

    Science.gov (United States)

    Bryaskova, Rayna; Georgiev, Nikolai I; Dimov, Stefan M; Tzoneva, Rumiana; Detrembleur, Christophe; Asiri, Abdullah M; Alamry, Khalid A; Bojinov, Vladimir B

    2015-06-01

    Novel biocompatible water-soluble fluorescent micelles with embedded perylene diimides (PDI) for intracellular applications have been prepared by self assembling of amphiphilic poly(vinyl alcohol)-b-poly(acrylonitrile) (PVA-b-PAN) copolymers in the presence of synthesized fluorophores. Amphiphilic PVA-b-PAN copolymers were obtained by selective hydrolysis of well-defined poly(vinyl acetate)-b-poly(acrylonitrile) (PVAc-b-PAN) copolymer. The preparation of the novel fluorescence micelles consisting of PVA hydrophilic shell and PAN hydrophobic core with incorporated PDI fluorophores has been confirmed by DLS and TEM analysis. The cytotoxicity of the water-soluble fluorophores and their internalization into living cells depending on the micellar concentration have been tested. It was shown that they could successfully enter in living cells without destroying their morphology. The results obtained indicate that the novel water-soluble fluorescent micelles with embedded PDI fluorophores would be suitable for potential intracellular biomedical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Stabilization of Self-Assembled Alumina Mesophases

    NARCIS (Netherlands)

    Perez, Lidia Lopez; Perdriau, Sebastien; ten Brink, Gert; Kooi, Bart J.; Heeres, Hero Jan; Melian-Cabrera, Ignacio

    2013-01-01

    An efficient route to stabilize alumina mesophases derived from evaporation-induced self-assembly is reported after investigating various aspects in-depth: influence of the solvent (EtOH, s-BuOH, and t-BuOH) on the textural and structural properties of the mesophases based on aluminum

  12. Self-assembly of hyperbranched spheres

    NARCIS (Netherlands)

    Huck, W.T.S.; Huck, Wilhelm T.S.; van Veggel, F.C.J.M.; Reinhoudt, David

    1997-01-01

    A new type of building block with two coordinatively unsaturated palladium centres has been described that self-assembles in nitromethane solution and disassembles when acetonitrile is added. The resulting hyperbranched, organopalladium spheres have a remarkably narrow size distribution as was

  13. 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 self...

  14. Designing thiophene-based azomethine oligomers with tailored properties: Self-assembly and charge carrier mobility

    DEFF Research Database (Denmark)

    Kiriy, N.; Bocharova, V.; Kiriy, A.

    2004-01-01

    This paper describes synthesis and characterization of two thiophene-based azomethines designed to optimize solubility, self-assembly, and charge carrier mobility. We found that incorporation of azomethine and amide moieties in the alpha,omega-position, and hexyl chains in the beta-position of th...... with the mobilities of the best organic semiconductors. All these significant differences in properties of related compounds can be attributed to the hydrogen bonding between QT-amide molecules responsible for the observed self-assembly....

  15. Water-soluble dietary fibers and cardiovascular disease.

    Science.gov (United States)

    Theuwissen, Elke; Mensink, Ronald P

    2008-05-23

    One well-established way to reduce the risk of developing cardiovascular disease (CVD) is to lower serum LDL cholesterol levels by reducing saturated fat intake. However, the importance of other dietary approaches, such as increasing the intake of water-soluble dietary fibers is increasingly recognized. Well-controlled intervention studies have now shown that four major water-soluble fiber types-beta-glucan, psyllium, pectin and guar gum-effectively lower serum LDL cholesterol concentrations, without affecting HDL cholesterol or triacylglycerol concentrations. It is estimated that for each additional gram of water-soluble fiber in the diet serum total and LDL cholesterol concentrations decrease by -0.028 mmol/L and -0.029 mmol/L, respectively. Despite large differences in molecular structure, no major differences existed between the different types of water-soluble fiber, suggesting a common underlying mechanism. In this respect, it is most likely that water-soluble fibers lower the (re)absorption of in particular bile acids. As a result hepatic conversion of cholesterol into bile acids increases, which will ultimately lead to increased LDL uptake by the liver. Additionally, epidemiological studies suggest that a diet high in water-soluble fiber is inversely associated with the risk of CVD. These findings underlie current dietary recommendations to increase water-soluble fiber intake.

  16. Spontaneous self-assembly of SC3 hydrophobins into nanorods in aqueous solution.

    Science.gov (United States)

    Zykwinska, Agata; Guillemette, Thomas; Bouchara, Jean-Philippe; Cuenot, Stéphane

    2014-07-01

    Hydrophobins are small surface active proteins secreted by filamentous fungi. Because of their ability to self-assemble at hydrophilic-hydrophobic interfaces, hydrophobins play a key role in fungal growth and development. In the present work, the organization in aqueous solution of SC3 hydrophobins from the fungus Schizophyllum commune was assessed using Dynamic Light Scattering, Atomic Force Microscopy and fluorescence spectroscopy. These complementary approaches have demonstrated that SC3 hydrophobins are able not only to spontaneously self-assemble at the air-water interface but also in pure water. AFM experiments evidenced that hydrophobins self-assemble in solution into nanorods. Fluorescence assays with thioflavin T allowed establishing that the mechanism governing SC3 hydrophobin self-assembly into nanorods involves β-sheet stacking. SC3 assembly was shown to be strongly influenced by ionic strength and solution pH. The presence of a very low ionic strength significantly favoured the protein self-assembly but a further increase of ions in solution disrupted the protein assembly. It was assessed that solution pH had a significant effect on the SC3 hydrophobins organization. In peculiar, the self-assembly process was considerably reduced at acidic pH. Our findings demonstrate that the self-assembly of SC3 hydrophobins into nanorods of well-defined length can be directly controlled in solution. Such control allows opening the way for the development of new smart self-assembled structures for targeted applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. A combined experimental and theoretical study of the supramolecular self-assembly of Cu(II) malonate complex assisted by various weak forces and water dimer

    Science.gov (United States)

    Manna, Prankrishna; Ray Choudhury, Somnath; Mitra, Monojit; Kumar Seth, Saikat; Helliwell, Madeleine; Bauzá, Antonio; Frontera, Antonio; Mukhopadhyay, Subrata

    2014-12-01

    A Cu(II) malonate complex with formula [Cu(C3H2O4)(C6H8N2)(H2O)]2·4H2O (1) [C6H8N2=2-picolylamine, C3H2O42-=malonate dianion] has been synthesized by mixing the reactants in their stoichiometric proportion and its crystal structure has been determined by single-crystal X-ray diffraction. In 1, monomeric neutral metal malonate units [Cu(C3H2O4)(C6H8N2)(H2O)] are interlinked with each other through hydrogen bonds, weak lone pair⋯π and cuprophilic interactions to generate supramolecular dimers, which in turn further associated through hydrogen bonding to form infinite 1D chains. Water dimers, through series of hydrogen bonds and weak π-stacking forces are found to be responsible for interconnection of 1D chains, which resulted in a 3D network. A density functional (DFT) study of the energetic features of several noncovalent interactions observed in the solid state have been analyzed and characterized using Bader's theory of “atoms-in-molecules”. We also present here Hirshfeld surface analysis to investigate the close intermolecular contacts.

  18. Hematite photoanode co-functionalized with self-assembling melanin and C-phycocyanin for solar water splitting at neutral pH

    Energy Technology Data Exchange (ETDEWEB)

    Schrantz, Krisztina; Wyss, Pradeep P.; Ihssen, Julian; Toth, Rita; Bora, Debajeet K.; Vitol, Elina A.; Rozhkova, Elena A.; Pieles, Uwe; Thöny-Meyer, Linda; Braun, Artur

    2017-04-01

    tNature provides functional units which can be integrated in inorganic solar cell materials, such as lightharvesting antenna proteins and photosynthetic molecular machineries, and thus help in advancing artifi-cial photosynthesis. Their integration needs to address mechanical adhesion, light capture, charge transferand corrosion resistance. We showed recently how enzymatic polymerization of melanin can immobi-lize the cyanobacterial light harvesting protein C-phycocyanin on the surface of hematite, a prospectivemetal oxide photoanode for solar hydrogen production by water splitting in photoelectrochemical cells.After the optimization of the functionalization procedure, in this work we show reproducible hydrogenproduction, measured parallel to the photocurrent on this bio-hybrid electrode in benign neutral pHphosphate. Over 90% increase compared to the photocurrent of the pristine hematite could be achieved.The hydrogen evolution was monitored during the photoelectrochemical measurement in an improvedphotoelectrochemical cell. The C-phycocyanin-melanin coating on the hematite was shown to exhibit acomb-like fractal pattern. Raman spectroscopy supported the presence of the protein on the hematiteanode surface. The stability of the protein coating is demonstrated during the 2 h GC measurement andthe 24 h operando current density measurement

  19. Molecular self-assembly into one-dimensional nanostructures.

    Science.gov (United States)

    Palmer, Liam C; Stupp, Samuel I

    2008-12-01

    Self-assembly of small molecules into one-dimensional nanostructures offers many potential applications in electronically and biologically active materials. The recent advances discussed in this Account demonstrate how researchers can use the fundamental principles of supramolecular chemistry to craft the size, shape, and internal structure of nanoscale objects. In each system described here, we used atomic force microscopy (AFM) and transmission electron microscopy (TEM) to study the assembly morphology. Circular dichroism, nuclear magnetic resonance, infrared, and optical spectroscopy provided additional information about the self-assembly behavior in solution at the molecular level. Dendron rod-coil molecules self-assemble into flat or helical ribbons. They can incorporate electronically conductive groups and can be mineralized with inorganic semiconductors. To understand the relative importance of each segment in forming the supramolecular structure, we synthetically modified the dendron, rod, and coil portions. The self-assembly depended on the generation number of the dendron, the number of hydrogen-bonding functions, and the length of the rod and coil segments. We formed chiral helices using a dendron-rod-coil molecule prepared from an enantiomerically enriched coil. Because helical nanostructures are important targets for use in biomaterials, nonlinear optics, and stereoselective catalysis, researchers would like to precisely control their shape and size. Tripeptide-containing peptide lipid molecules assemble into straight or twisted nanofibers in organic solvents. As seen by AFM, the sterics of bulky end groups can tune the helical pitch of these peptide lipid nanofibers in organic solvents. Furthermore, we demonstrated the potential for pitch control using trans-to-cis photoisomerization of a terminal azobenzene group. Other molecules called peptide amphiphiles (PAs) are known to assemble in water into cylindrical nanostructures that appear as nanofiber

  20. A combined experimental and theoretical study of the supramolecular self-assembly of Cu(II) malonate complex assisted by various weak forces and water dimer

    Energy Technology Data Exchange (ETDEWEB)

    Manna, Prankrishna [Department of Chemistry, Jadavpur University, Kolkata 700 032 (India); Ray Choudhury, Somnath [Central Chemical Laboratory, Geological Survey of India, 15 A and B Kyd Street, Kolkata 700 016 (India); Mitra, Monojit [Department of Chemistry, Jadavpur University, Kolkata 700 032 (India); Kumar Seth, Saikat [Department of Physics, M. G. Mahavidyalaya, Bhupatinagar, Purba Medinipur, West Bengal 721 425 (India); Helliwell, Madeleine [School of Chemistry, The University of Manchester, Brunswick Street, Manchester M13 9PL (United Kingdom); Bauzá, Antonio [Departament de Química, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma (Baleares) (Spain); Frontera, Antonio, E-mail: toni.frontera@uib.es [Departament de Química, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma (Baleares) (Spain); Mukhopadhyay, Subrata, E-mail: smukhopadhyay@chemistry.jdvu.ac.in [Department of Chemistry, Jadavpur University, Kolkata 700 032 (India)

    2014-12-15

    A Cu(II) malonate complex with formula [Cu(C{sub 3}H{sub 2}O{sub 4})(C{sub 6}H{sub 8}N{sub 2})(H{sub 2}O)]{sub 2}·4H{sub 2}O (1) [C{sub 6}H{sub 8}N{sub 2}=2-picolylamine, C{sub 3}H{sub 2}O{sub 4}{sup 2−}=malonate dianion] has been synthesized by mixing the reactants in their stoichiometric proportion and its crystal structure has been determined by single-crystal X-ray diffraction. In 1, monomeric neutral metal malonate units [Cu(C{sub 3}H{sub 2}O{sub 4})(C{sub 6}H{sub 8}N{sub 2})(H{sub 2}O)] are interlinked with each other through hydrogen bonds, weak lone pair⋯π and cuprophilic interactions to generate supramolecular dimers, which in turn further associated through hydrogen bonding to form infinite 1D chains. Water dimers, through series of hydrogen bonds and weak π–stacking forces are found to be responsible for interconnection of 1D chains, which resulted in a 3D network. A density functional (DFT) study of the energetic features of several noncovalent interactions observed in the solid state have been analyzed and characterized using Bader's theory of “atoms-in-molecules”. We also present here Hirshfeld surface analysis to investigate the close intermolecular contacts. - Graphical Abstract: Interplay of weak forces like hydrogen bonding, lone pair⋯π, Cu⋯Cu and π–stacking interactions leading to the formation of supramolecular network in [Cu(C{sub 3}H{sub 2}O{sub 4})(C{sub 6}H{sub 8}N{sub 2})(H{sub 2}O)]{sub 2}·4H{sub 2}O complex. - Highlights: • A complex of Cu(II) with malonate and 2-picolylamine is synthesized and X-ray characterized. • We report a density functional study of the energetic features of several noncovalent interactions • We perform Hirshfeld surface analysis to investigate the close intermolecular contacts.

  1. Use of Hoy's solubility parameters to predict water sorption/solubility of experimental primers and adhesives.

    Science.gov (United States)

    Nishitani, Yoshihiro; Yoshiyama, Masahiro; Hosaka, Keiichi; Tagami, Junji; Donnelly, Adam; Carrilho, Marcela; Tay, Franklin R; Pashley, David H

    2007-02-01

    Self-etching primers and adhesives contain very hydrophilic acidic monomers that result in high water sorption/solubilities of their polymers. However, the chemical composition of these products varies widely. The purpose of this work was to vary the chemical composition of experimental self-etching primers and adhesives to determine if the water sorption/solubility of the polymers were affected in a predictable manner. The Hoy's solubility parameters of these mixtures were calculated to permit ranking of the degree of hydrophilicity of the polymers. Water sorption/solubility was measured according to ISO 4049. The results showed highly significant (R(2) = 0.86, P solubility parameter for polar forces (delta(p)) of the polymers. Similar correlations were obtained between polymer solubility and delta(p). When these results were compared with previously published results obtained with more hydrophobic resins, excellent correlations were obtained, indicating that Hoy's delta(p) values may be used to predict the water sorption behavior of methylmethacrylate polymers.

  2. Synthesis of water soluble chitosan stabilized gold nanoparticles and determination of uric acid

    Science.gov (United States)

    Lanh Le, Thi; Khieu Dinh, Quang; Hoa Tran, Thai; Nguyen, Hai Phong; Le Hien Hoang, Thi; Hien Nguyen, Quoc

    2014-06-01

    Gold nanoparticles (Au-NPs) have been successfully synthesized by utilizing water soluble chitosan as reducing and stabilizing agent. The colloidal Au-NPs were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). The results showed that the colloidal Au-NPs had a plasmon absorption band with maximum wavelength in the range of 520-526 nm and the diameters were about 8-15 nm. In addition, a new Au-NPs-modified electrode was fabricated by self-assembling Au-NPs to the surface of the L-cysteine-modified glassy carbon electrode (Au-NPs/L-Cys/GCE). The Au-NPs-modified electrode showed an excellent character for electro-catalytic oxidization of uric acid (UA) in 0.1 mol L-1 phosphate buffer solution (pH 3.2). Using differential pulse anodic stripping voltammetry (DP-ASV), a high selectivity for determination of UA has been explored for the Au-NPs-modified electrode. DP-ASV peak currents of UA increased linearly with their concentration at the range of 2.0 × 10-6 to 4.0 × 10-5 mol L-1 with the detection limit of 2.7 × 10-6 mol L-1 for UA. The proposed method was applied for the detection of UA in human urine and serum samples with satisfactory results.

  3. Self-assembly between biomacromolecules and lipids

    Science.gov (United States)

    Liang, Hongjun

    Anionic DNA and cationic lipsomes can self-assemble into a multi-lamellar structure where two-dimensional (2-D) lipid sheets confine a periodic one-dimensional (1-D) lattice of parallel DNA chains, between which Cd2+ ions can condense, and be subsequently reacted with H 2S to template CdS nanorods with crystallographic control analogous to biomineralization. The strong electrostatic interactions align the templated CdS (002) polar planes parallel to the negatively charged sugar-phosphate DNA backbone, which indicates that molecular details of the DNA molecule are imprinted onto the inorganic crystal structure. The resultant nanorods have (002) planes tilted by ˜60° with respect to the rod axis, in contrast to all known II-VI semiconductor nanorods. Rational design of the biopolymer-membrane templates is possible, as demonstrated by the self-assembly between anionic M13 virus and cationic membrane. The filamentous virus has diameter ˜3x larger but similar surface charge density as DNA, the self-assembled complexes maintain the multi-lamellar structure, but pore sizes are ˜10x larger in area, which can be used to package and organize large functional molecules. Not only the counter-charged objects can self-assemble, the like-charged biopolymer and membrane can also self-assemble with the help of multivalent ions. We have investigated anionic lipid-DNA complexes induced by a range of divalent ions to show how different ion-mediated interactions are expressed in the self-assembled structures, which include two distinct lamellar phases and an inverted hexagonal phase. DNA can be selectively organized into or expelled out of the lamellar phases depending on membrane charge density and counterion concentration. For a subset of ion (Zn2+ etc.) at high enough concentration, 2-D inverted hexagonal phase can be formed where DNA strands are coated with anionic lipid tubes via interaction with Zn2+ ions. We suggest that the effect of ion binding on lipid's spontaneous

  4. Tribological characteristics of self-assembled nanometer film ...

    Indian Academy of Sciences (India)

    APTES) self-assembled mono- layer (SAM) were prepared on the hydroxylated silicon substrate by a self-assembling process from specially for- mulated solution. Chemical compositions of the films and chemical state of the elements were ...

  5. A Novel Strategy for Synthesis of Gold Nanoparticle Self Assemblies

    NARCIS (Netherlands)

    Verma, Jyoti; Lal, Sumit; van Veen, Henk A.; van Noorden, Cornelis J. F.

    2014-01-01

    Gold nanoparticle self assemblies are one-dimensional structures of gold nanoparticles. Gold nanoparticle self assemblies exhibit unique physical properties and find applications in the development of biosensors. Methodologies currently available for lab-scale and commercial synthesis of gold

  6. Self-Assembly of Double Hydrophilic Poly(2-ethyl-2-oxazoline-b-poly(N-vinylpyrrolidone Block Copolymers in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Jochen Willersinn

    2017-07-01

    Full Text Available The self-assembly of a novel combination of hydrophilic blocks in water is presented, namely poly(2-ethyl-2-oxazoline-b-poly(N-vinylpyrrolidone (PEtOx-b-PVP. The completely water-soluble double hydrophilic block copolymer (DHBC is formed via copper-catalyzed polymer conjugation, whereas the molecular weight of the PVP is varied in order to study the effect of block ratio on the self-assembly process. Studies via dynamic light scattering, static light scattering as well as microscopy techniques, e.g., cryo scanning electron microscopy or laser scanning confocal microscopy, show the formation of spherical particles in an aqueous solution with sizes between 300 and 400 nm. Particles of the DHBCs are formed without the influence of external stimuli. Moreover, the efficiency of self-assembly formation relies significantly on the molar ratio of the utilized blocks. The nature of the formed structures relies further on the concentration, and indications of particular and vesicular structures are found.

  7. Coccidioides immitis Vaccine: Potential of an Alkali-Soluble, Water-Soluble Cell Wall Antigen

    Science.gov (United States)

    Lecara, Grace; Cox, Rebecca A.; Simpson, Russell B.

    1983-01-01

    C-ASWS-M, the alkali-soluble, water-soluble cell wall antigen of Coccidioides immitis mycelia, was evaluated for its vaccine potential in mice. Vaccination with 0.5-, 1.5-, or 3-mg doses of C-ASWS-M in complete Freund adjuvant provided a significant level of protection against intraperitoneal challenge with 1,500 arthroconidia (P 0.05). PMID:6822433

  8. Versatile Self-Assembly and Biosensing Applications of DNA and Carbon Quantum Dots Coordinated Cerium Ions.

    Science.gov (United States)

    Wang, Ling; Wang, Yitong; Sun, Xiaofeng; Zhang, Geping; Dong, Shuli; Hao, Jingcheng

    2017-08-01

    Self-assembly exploits noncovalent interactions to offer a facile and effective method for the construction of soft materials with multifunctionalities and diversity. In this work, fluorescence carbon quantum dots coordinated by Ce3+ ions (CQDCe) have been synthesized and exploited as building blocks to generate a series of hierarchical structures through the ionic self-assembly of CQDCe and biomolecules, namely DNA, myoglobin (Mb), and hyaluronic acid (HA). In particular, vesicles can be constructed by the simple mixing of oppositely charged CQDCe and DNA in water. The formation of unusual vesicles can be explained by the self-assembly of CQDCe with a rearranged structure and the rigid DNA biomolecular scaffolds. This facile noncovalent self-assembly method has inspired the innovative use of virgin DNA as a building block to construct vesicles rather than resorting to a sophisticated synthesis. The self-assembly of CQDCe-biopolymers was accompanied by aggregation-induced photoluminescence (PL) quenching. The biosensing platform was designed to detect polypeptides and deoxyribonuclease I through competitive binding of CQDCe and enzymatic hydrolysis of the DNA backbone, respectively. We believe that the integrative self-assembly of CQDCe and DNA will enrich the theoretical study of vesicle formation by DNA molecules and extend the application of fluorescence carbon quantum dots in the biological field. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Thiolate ligands for synthesis of water-soluble gold clusters.

    Science.gov (United States)

    Ackerson, Christopher J; Jadzinsky, Pablo D; Kornberg, Roger D

    2005-05-11

    Water-soluble monolayer-protected gold clusters (MPCs) have been an object of investigation by many research groups since their first syntheses were reported in 1998 and 1999. The basic requirements for a ligand to form a monolayer protecting a gold cluster were established some time ago for alkanethiolate MPCs, but there has been no such information published for water-soluble MPCs. We identify 6 new ligands capable of forming water-soluble MPCs, as well as 22 water-soluble ligands that fail to form MPCs. Our findings contribute not only to the definition of the requirements for MPC formation but also to the variety of MPCs available for applications in chemistry and biology.

  10. Water-soluble dopamine-based polymers for photoacoustic imaging

    NARCIS (Netherlands)

    Repenko, T.; Fokong, S.; De Laporte, L.; Go, D.; Kiessling, F.; Lammers, Twan Gerardus Gertudis Maria; Kuehne, A.

    2015-01-01

    Here we present a facile synthetic method yielding a linear form of polydopamine via Kumada-coupling, which can be converted into water-soluble melanin, generating high contrast in photoacoustic imaging.

  11. Programming protein self assembly with coiled coils

    Energy Technology Data Exchange (ETDEWEB)

    Dietz, Hendrik; Bornschloegl, Thomas; Heym, Roland; Koenig, Frauke; Rief, Matthias [Physik Department E22, Technische Universitaet Muenchen, James-Franck-Strasse 1, 85748 Garching (Germany)

    2007-11-15

    The controlled assembly of protein domains into supramolecular structures will be an important prerequisite for the use of functional proteins in future nanotechnology applications. Coiled coils are multimerization motifs whose dimerization properties can be programmed by amino acid sequence. Here, we report programmed supramolecular self-assembly of protein molecules using coiled coils and directly demonstrate its potential on the single molecule level by AFM force spectroscopy. We flanked two different model proteins, Ig27 from human cardiac titin and green fluorescent protein (GFP), by coiled coil binding partners and studied the capability of these elementary building blocks to self-assemble into linear chains. Simple sterical constraints are shown to control the assembly process, providing evidence that many proteins can be assembled with this method. An application for this technique is the design of polyproteins for single molecule force spectroscopy with an integrated force-calibration standard.

  12. Self-assembling membranes and related methods thereof

    Science.gov (United States)

    Capito, Ramille M; Azevedo, Helena S; Stupp, Samuel L

    2013-08-20

    The present invention relates to self-assembling membranes. In particular, the present invention provides self-assembling membranes configured for securing and/or delivering bioactive agents. In some embodiments, the self-assembling membranes are used in the treatment of diseases, and related methods (e.g., diagnostic methods, research methods, drug screening).

  13. Aromatic Cross-Strand Ladders Control the Structure and Stability of [beta]-Rich Peptide Self-Assembly Mimics

    Energy Technology Data Exchange (ETDEWEB)

    Biancalana, Matthew; Makabe, Koki; Koide, Akiko; Koide, Shohei (UC)

    2009-09-02

    Though {beta}-rich self-assemblies comprise a major structural class of polypeptides, a detailed understanding of the determinants of their structure and stability is lacking. In particular, the roles of repetitive stretches of side chains running the long axis of these {beta}-sheets, termed 'cross-strand ladders,' remain poorly characterized due to the inherently insoluble and heterogeneous nature of self-assemblies. To overcome these experimental challenges, we have established a complementary experimental system termed 'peptide self-assembly mimics' (PSAMs). The PSAMs capture a defined number of self-assembly-like peptide repeats within a soluble {beta}-rich protein, making structural and energetic studies possible. In this work, we investigated the role of cross-strand ladders containing aromatic residues, which are prominent in self-assembling peptides. A combination of solution data and high-resolution crystal structures revealed that a single cross-strand ladder consisting solely of Tyr significantly stabilized, rigidified, and flattened the PSAM {beta}-sheet. These characteristics would stabilize each {beta}-sheet layer of a self-assembly and direct sheet conformations compatible with lamination. Our results therefore provide a rationale for the abundance of aromatic amino acids in fibril-forming peptides and establish important roles of cross-strand Tyr ladders in the structure and stability of {beta}-rich peptide self-assemblies.

  14. Biological Nanoplatforms for Self-Assembled Electronics

    Science.gov (United States)

    2015-03-24

    AFRL-RV-PS- AFRL-RV-PS- TR-2015-0024 TR-2015-0024 BIOLOGICAL NANOPLATFORMS FOR SELF- ASSEMBLED ELECTRONICS Stephen Jett University of New Mexico 1...University of New Mexico Albuquerque, NM 87131-0001 24 Mar 2015 Final Report APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. AIR FORCE...RESEARCH LABORATORY Space Vehicles Directorate 3550 Aberdeen Ave SE AIR FORCE MATERIEL COMMAND KIRTLAND AIR FORCE BASE, NM 87117-5776 NOTICE AND

  15. SUPPORTING INFORMATION Gold nanodots self-assembled ...

    Indian Academy of Sciences (India)

    VICHU

    Figure S1. Catalytic test reactions carried out for different AuNDs catalysts. Figure S2. Catalytic test reactions carried out for AuNDs prepared using different Au concentrations. Figure S3. AFM images of self-assembled AuNDs and bare PADA films. Figure S4. Recycle study of catalytic plate. Figure S5-S16. 1H and 13C NMR ...

  16. Smart Self-Assembled Hybrid Hydrogel Biomaterials

    OpenAIRE

    Kopeček, Jindřich; Yang, Jiyuan

    2012-01-01

    Hybrid biomaterials are systems created from components of at least two distinct classes of molecules, for example, synthetic macromolecules and proteins or peptide domains. The synergistic combination of two types of structures may produce new materials that possess unprecedented levels of structural organization and novel properties. This Review focuses on biorecognition-driven self-assembly of hybrid macromolecules into functional hydrogel biomaterials. First, basic rules that govern the s...

  17. Self-assembled monolayers in organic electronics.

    Science.gov (United States)

    Casalini, Stefano; Bortolotti, Carlo Augusto; Leonardi, Francesca; Biscarini, Fabio

    2017-01-03

    Self-assembly is possibly the most effective and versatile strategy for surface functionalization. Self-assembled monolayers (SAMs) can be formed on (semi-)conductor and dielectric surfaces, and have been used in a variety of technological applications. This work aims to review the strategy behind the design and use of self-assembled monolayers in organic electronics, discuss the mechanism of interaction of SAMs in a microscopic device, and highlight the applications emerging from the integration of SAMs in an organic device. The possibility of performing surface chemistry tailoring with SAMs constitutes a versatile approach towards the tuning of the electronic and morphological properties of the interfaces relevant to the response of an organic electronic device. Functionalisation with SAMs is important not only for imparting stability to the device or enhancing its performance, as sought at the early stages of development of this field. SAM-functionalised organic devices give rise to completely new types of behavior that open unprecedented applications, such as ultra-sensitive label-free biosensors and SAM/organic transistors that can be used as robust experimental gauges for studying charge tunneling across SAMs.

  18. Water sorption and solubility of polyamide denture base materials.

    Science.gov (United States)

    Nguyen, Long G; Kopperud, Hilde M; Øilo, Marit

    2017-01-01

    Purpose: Some patients experience adverse reactions to poly(methyl methacrylate)-based (PMMA) dentures. Polyamide (PA) as an alternative to PMMA has, however, not been well documented with regard to water sorption and water solubility. The aim of this in vitro study was to measure water sorption and water solubility of two PA materials compared with PMMA, and to evaluate the major components released from the PA materials and the effect on hardness of the materials. Methods: Ten discs (40.0 mm diameter, 2.0 mm thick) of each material (PA: Valplast and Breflex; PMMA: SR Ivocap HIP) were prepared according to manufacturers' recommendations. The specimens were tested for water sorption and water solubility, according to a modification of ISO 20795-1:2008. Released substances were analysed by gas chromatography/mass spectrometry (GC/MS). Results: There were statistically significant differences among the materials regarding water sorption, water solubility and time to water saturation. Breflex had the highest water sorption (30.4 μg/mm(3)), followed by PMMA-material (25.8 μg/mm(3)) and Valplast (13.6 μg/mm(3)). Both PA materials had statistically significant lower water solubility than the PMMA. Both PA had a net increase in weight. Analysis by GC/MS identified release of the compound 12-aminododecanolactam from the material Valplast. No release was found from the Breflex material. Conclusions: The PA denture materials show differences in water sorption and solubility, but within the limits of the standard requirements. The PA showed a net increase in weight after long-term water sorption. The clinical implications of the findings are not elucidated.

  19. Bioremediation prospects of fungi isolated from water soluble ...

    African Journals Online (AJOL)

    Bioremediation prospects of fungi isolated from water soluble fraction of crude oil samples. ... the level of pH, EC and TDS. The ability of the fungi to adapt to these conditions indicates their potential as a tool for bioremediation of crude oil polluted water. Keywords: Bioremediation, Crude Oil, Fungi, Polluted Water, Potential.

  20. Smart Self-Assembled Nanosystem Based on Water-Soluble Pillararene and Rare-Earth-Doped Upconversion Nanoparticles for pH-Responsive Drug Delivery.

    Science.gov (United States)

    Li, Haihong; Wei, Ruoyan; Yan, Gui-Hua; Sun, Ji; Li, Chunju; Wang, Haifang; Shi, Liyi; Capobianco, John A; Sun, Lining

    2018-01-24

    Exploring novel drug delivery systems with good stability and new structure to integrate pillararene and upconversion nanoparticles (UCNPs) into one system continues to be an important challenge. Herein, we report a novel preparation of a supramolecular upconversion nanosystem via the host-guest complexation based on carboxylate-based pillar[5]arene (WP5) and 15-carboxy-N,N,N-trialkylpentadecan-1-ammonium bromide (1)-functionalized UCNPs to produce WP5⊃1-UCNPs that can be loaded with the chemotherapeutic drug doxorubicin (DOX). Importantly, the WP5 on the surface of the drug-loaded nanosystem can be efficiently protonated under acidic conditions, resulting in the collapse of the nanosystem and drug release. Moreover, cellular uptake confirms that the nanosystem can enter human cervical cancer (HeLa) cells, resulting in drug accumulation in the cells. More importantly, cytotoxicity experiments demonstrated the excellent biocompatibility of WP5⊃1-UCNPs without loading DOX and that the nanosystem DOX-WP5⊃1-UCNPs exhibited an ability of killing HeLa cells effectively. We also investigated magnetic resonance imaging and upconversion luminescence imaging, which may be employed as visual imaging agents in cancer diagnosis and treatment. Thus, in the present work, we show a simple yet powerful strategy to combine UCNPs and pillar[5]arene to produce a unified nanosystem for dual-mode bioimaging-guided therapeutic applications.

  1. Electrochemical characterization of mixed self-assembled films of water-soluble single-walled carbon nanotube-poly(m-aminobenzene sulfonic acid) and Iron(II) tetrasulfophthalocyanine

    CSIR Research Space (South Africa)

    Agboola, BO

    2010-09-01

    Full Text Available . Immobilization of FeTSPc and SWCNT-PABS on gold electrode.? Before the experiments, the gold electrode was first cleaned using slurries of aluminum oxide nanopowder �Sigma- Aldrich�, mirror-finished on a Buehler felt pad, and then subjected to ultrasonic... vibration in ethanol to remove residual alumina nanopo- wder at the surface. The gold electrodes were then treated with the ?Piranha? solution �1:3 �v/v� 30% H2O2 and concentrated H2SO4� for �2 min; this step was necessary to remove organic contami...

  2. Self-Assembly of Large Amyloid Fibers

    Science.gov (United States)

    Ridgley, Devin M.

    Functional amyloids found throughout nature have demonstrated that amyloid fibers are potential industrial biomaterials. This work introduces a new "template plus adder" cooperative mechanism for the spontaneous self-assembly of micrometer sized amyloid fibers. A short hydrophobic template peptide induces a conformation change within a highly alpha-helical adder protein to form beta-sheets that continue to assemble into micrometer sized amyloid fibers. This study utilizes a variety of proteins that have template or adder characteristics which suggests that this mechanism may be employed throughout nature. Depending on the amino acid composition of the proteins used the mixtures form amyloid fibers of a cylindrical ( 10 mum diameter, 2 GPa Young's modulus) or tape (5- 10 mum height, 10-20 mum width and 100-200 MPa Young's modulus) morphology. Processing conditions are altered to manipulate the morphology and structural characteristics of the fibers. Spectroscopy is utilized to identify certain amino acid groups that contribute to the self-assembly process. Aliphatic amino acids (A, I, V and L) are responsible for initiating conformation change of the adder proteins to assemble into amyloid tapes. Additional polyglutamine segments (Q-blocks) within the protein mixtures will form Q hydrogen bonds to reinforce the amyloid structure and form a cylindrical fiber of higher modulus. Atomic force microscopy is utilized to delineate the self-assembly of amyloid tapes and cylindrical fibers from protofibrils (15-30 nm width) to fibers (10-20 mum width) spanning three orders of magnitude. The aliphatic amino acid content of the adder proteins' alpha-helices is a good predictor of high density beta-sheet formation within the protein mixture. Thus, it is possible to predict the propensity of a protein to undergo conformation change into amyloid structures. Finally, Escherichia coli is genetically engineered to express a template protein which self-assembles into large amyloid

  3. PCPP-Adjuvanted Respiratory Syncytial Virus (RSV) sF Subunit Vaccine: Self-Assembled Supramolecular Complexes Enable Enhanced Immunogenicity and Protection.

    Science.gov (United States)

    Cayatte, Corinne; Marin, Alexander; Rajani, Gaurav Manohar; Schneider-Ohrum, Kirsten; Snell Bennett, Angie; Marshall, Jason D; Andrianov, Alexander K

    2017-07-03

    PCPP, a well-defined polyphosphazene macromolecule, has been studied as an immunoadjuvant for a soluble form of the postfusion glycoprotein of respiratory syncytial virus (RSV sF), which is an attractive vaccine candidate for inducing RSV-specific immunity in mice and humans. We demonstrate that RSV sF-PCPP formulations induce high neutralization titers to RSV comparable to alum formulations even at a low PCPP dose and protect animals against viral challenge both in the lung and in the upper respiratory tract. PCPP formulations were also characterized by Th1-biased responses, compared to Th2-biased responses that are more typical for RSV sF alone or RSV sF-alum formulations, suggesting an inherent immunostimulating activity of the polyphosphazene adjuvant. We defined these immunologically active RSV sF-PCPP formulations as self-assembled water-soluble protein-polymer complexes with distinct physicochemical parameters. The secondary structure and antigenicity of the protein in the complex were fully preserved during the spontaneous aqueous self-assembly process. These findings further advance the concept of polyphosphazene immunoadjuvants as unique dual-functionality adjuvants integrating delivery and immunostimulating modalities in one water-soluble molecule.

  4. Self assembly of DNA nanoparticles with polycations for the delivery of genetic materials into cells.

    Science.gov (United States)

    Hosseinkhani, Hossein; Tabata, Yasuhiko

    2006-08-01

    Increasing attention has been paid to technology used for the delivery of genetic materials into cells for gene therapy and the generation of genetically engineered cells. So far, viral vectors have been mainly used because of their inherently high transfection efficiency of gene. However, there are some problems to be resolved for the clinical applications, such as the pathogenicity and immunogenicity of viral vectors themselves. Therefore, many research trials with non-viral vectors have been performed to enhance their efficiency to a level comparable to the viral vector. Two directions of these trials exist: Material improvement of non-viral vectors and their combination with various external physical stimuli. In this study gelatin was selected as a non-viral carrier for DNA. To give a positive charge to gelatin, different extents introduction of ethylenediamine (Ed), spermidine (Sd), and spermine (Sm) were reacted with gelatin in the presence of a water-soluble carbodiimide. When positively charged gelatin derivatives (Ed, Sd, and Sm) were mixed with negatively charged DNA, a self assembly of DNA nanoparticle (complex) was formed within few minutes through electrostatic interaction. Irrespective of the type of gelatin derivatives, the apparent molecular size of DNA was reduced by increasing the gelatin/DNA mixing ratio to attain a saturated value of about 150 nm. The condensed gelatin/DNA complexes showed the zeta potential of 10-15 mV. The amount of DNA internalized into the cells was significantly increased by the complexation with every gelatin derivative. The cells incubated with the gelatin/DNA complexes exhibited significantly stronger luciferase activities than naked plasmid DNA. This study clearly demonstrates and self-assembled DNA complexes has potential as a gene delivery vechile and are stable to transfer genetic materials to cells.

  5. Self-assembled biomimetic nanoreactors I: Polymeric template

    Science.gov (United States)

    McTaggart, Matt; Malardier-Jugroot, Cecile; Jugroot, Manish

    2015-09-01

    The variety of nanoarchitectures made feasible by the self-assembly of alternating copolymers opens new avenues for biomimicry. Indeed, self-assembled structures allow the development of nanoreactors which combine the efficiency of high surface area metal active centres to the effect of confinement due to the very small cavities generated by the self-assembly process. A novel self-assembly of high molecular weight alternating copolymers is characterized in the present study. The self-assembly is shown to organize into nanosheets, providing a 2 nm hydrophobic cavity with a 1D confinement.

  6. Novel electrosprayed nanospherules for enhanced aqueous solubility and oral bioavailability of poorly water-soluble fenofibrate.

    Science.gov (United States)

    Yousaf, Abid Mehmood; Mustapha, Omer; Kim, Dong Wuk; Kim, Dong Shik; Kim, Kyeong Soo; Jin, Sung Giu; Yong, Chul Soon; Youn, Yu Seok; Oh, Yu-Kyoung; Kim, Jong Oh; Choi, Han-Gon

    2016-01-01

    The purpose of the present research was to develop a novel electrosprayed nanospherule providing the most optimized aqueous solubility and oral bioavailability for poorly water-soluble fenofibrate. Numerous fenofibrate-loaded electrosprayed nanospherules were prepared with polyvinylpyrrolidone (PVP) and Labrafil(®) M 2125 as carriers using the electrospray technique, and the effect of the carriers on drug solubility and solvation was assessed. The solid state characterization of an optimized formulation was conducted by scanning electron microscopy, powder X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopic analyses. Oral bioavailability in rats was also evaluated for the formulation of an optimized nanospherule in comparison with free drug and a conventional fenofibrate-loaded solid dispersion. All of the electrosprayed nanospherule formulations had remarkably enhanced aqueous solubility and dissolution compared with free drug. Moreover, Labrafil M 2125, a surfactant, had a positive influence on the solubility and dissolution of the drug in the electrosprayed nanospherule. Increases were observed as the PVP/drug ratio increased to 4:1, but higher ratios gave no significant increases. In particular, an electrosprayed nanospherule composed of fenofibrate, PVP, and Labrafil M 2125 at the weight ratio of 1:4:0.5 resulted in a particle size of state. It demonstrated the highest solubility (32.51±2.41 μg/mL), an excellent dissolution (~85% in 10 minutes), and an oral bioavailability ~2.5-fold better than that of the free drug. It showed similar oral bioavailability compared to the conventional solid dispersion. Electrosprayed nanospherules, which provide improved solubility and bioavailability, are promising drug delivery tools for oral administration of poorly water-soluble fenofibrate.

  7. Monitoring the hydration of DNA self-assembled monolayers using an extensional nanomechanical resonator

    DEFF Research Database (Denmark)

    Cagliani, Alberto; Kosaka, Priscila; Tamayo, Javier

    2012-01-01

    We have fabricated an ultrasensitive nanomechanical resonator based on the extensional vibration mode to weigh the adsorbed water on self-assembled monolayers of DNA as a function of the relative humidity. The water adsorption isotherms provide the number of adsorbed water molecules per nucleotid...

  8. Synthesis and self-assembling of responsive polysaccharide-based copolymers in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Nivia do N.; Balaban, Rosangela de C. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Halila, Sami; Borsali, Redouane, E-mail: borsali@cermav.cnrs.fr, E-mail: halila@cermav.cnrs.fr [Centre de Recherche sur les Macromolecules Vegetales (CERMAV), Grenoble (France)

    2015-07-01

    This work reports the synthesis and the thermoresponsive self-assembly behavior of carboxymethylcellulose-g-JeffamineM2070 and carboxymethylcellulose-g-JeffamineM600 copolymers in aqueous media. They were prepared through the grafting of two different types of amino-terminated poly(ethylene oxide-co-propylene oxide) chains onto the carboxylate groups of carboxymethylcellulose, by using water-soluble carbodiimide derivative and N-hydroxysuccinimide as coupling reagents. The grafting efficiency was confirmed by infrared and the degree of substitution by {sup 1}H NMR integrations. The salt effect on cloud point temperature was evaluated into different solvents (Milli-Q water, 0.5M NaCl, synthetic sea water (SSW) and 0.5M K{sub 2}CO{sub 3}) by UV-Vis and dynamic light scattering (DLS) measurements. Both copolymers showed lower cloud point temperature in 0.5M K2CO3 than in 0.5M NaCl and in SSW, which was attributed to the higher ionic strength for K{sub 2}CO{sub 3} combined to the ability of CO{sub 3}{sup 2-} to decrease polymer-water interactions. Copolymers chains displayed higher hydrodynamic radii than CMC precursor at 25 and 60 °C in saline solutions, and self-associations changed as a function of the environment and copolymer composition. (author)

  9. The levels of water-soluble and triton-soluble Aβ are increased in Alzheimer's disease brain

    Science.gov (United States)

    Mc Donald, Jessica M.; Cairns, Nigel J.; Taylor-Reinwald, Lisa; Holtzman, David; Walsh, Dominic M.

    2012-01-01

    Although plaques composed of the amyloid β-protein (Aβ) are considered a defining feature of Alzheimer's disease (AD), they are also found in cognitively normal individuals and extensive evidence suggests that non-plaque, water-soluble forms of Aβ may play a role in AD pathogenesis. However, the relationship between the levels of water-soluble Aβ and the clinical severity of disease has never been investigated. Here, we present results of a pilot study designed to examine the levels of water-soluble forms of Aβ in brains of individuals who died at clinically distinct stages of AD. Using a serial extraction method, we also investigated the levels of triton-soluble and formic acid-soluble Aβ. We found that water-soluble and detergent-soluble Aβ monomer and SDS-stable dimer were elevated in AD and that the levels of water soluble Aβ did not increase with plaque pathology. These results support the notion that both water- and detergent-soluble Aβ are important in AD and are not simply released from plaques by mechanical disruption. Moreover, the fact that the levels of water- and triton-soluble Aβ were similar in very mild/mild AD and moderate/severe AD suggests that once a certain level of these species is attained, further accumulation is not necessary for the disease to progress. Consequently, therapeutic targeting of water-soluble Aβ should best benefit individuals in earliest phases of the disease process. PMID:22440675

  10. Self-assembly of conjugated polymer-Ag@SiO2 hybrid fluorescent nanoparticles for application to cellular imaging.

    Science.gov (United States)

    Tang, Fu; He, Fang; Cheng, Huicong; Li, Lidong

    2010-07-20

    A novel fluorescent nanoparticle was prepared via a simple self-assembly technique based on water-soluble conjugated polymers (CPs) and Ag@SiO(2) core-shell nanoparticles. Core-shell nanoparticles with silver NPs core show a unique property referred to as metal-enhanced fluorescence (MEF). In the present work, the cationic conjugated polymer poly[9,9'-bis(6''-(N,N,N-trimethylammonium)-hexyl) fluorene-2,7-ylenevinylene-co-alt-1,4-phenylene dibromide] (PFV) was hybridized with Ag@SiO(2) NPs via simple self-assembly procedure, and given high stability, monodispersity. The fluorescence intensity of PFV after assembling on Ag@SiO(2) core-shell NPs is enhanced 1.3-fold compared with the fluorescence intensity of PFV assembled on silica NPs without silver cores for the MEF property of the Ag@SiO(2) nanostructure. Nanocomposite with bright fluorescence was obtained. Moreover, the nanocomposition exhibits good monodispersity and low cytotoxicity, which promote their application in cellular imaging. Furthermore, fluorescent nanoparticles with amendable peripheral surfaces can also be potentially obtained because of the easy modification property of CPs and give potential application in selective biological sensing and imaging.

  11. The solubilities of benzene polycarboxylic acids in water

    Energy Technology Data Exchange (ETDEWEB)

    Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel)]. E-mail: apelblat@bgu.ac.il; Manzurola, Emanuel [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel); Abo Balal, Nazmia [Negev Academic College of Engineering, Beer Sheva (Israel)

    2006-05-15

    The solubilities in water of all benzene polycarboxylic acids are discussed, using data determined in this work (benzoic, terephthalic, trimellitic, trimesic, and pyromellitic acids) and available from the literature (benzoic, phthalic, isophthalic, terephthalic, hemimellitic, trimelitic, trimesic, mellophanic, prehnitic, pyromellitic, benzene-pentacarboxylic and mellitic acids). The apparent molar enthalpies of solution at the saturation point for these benzene polycarboxylic acids were determined from the temperature dependence of the solubilities.

  12. Self-assembled nanostructures on vicinal surfaces

    Science.gov (United States)

    Petrovykh, Dmitri Yourievich

    2000-10-01

    One of the first methods for visualizing crystal planes and atomic steps has been step decoration with gold on alkali-halide surfaces. An impressive body of work has been conducted since then on the role of steps in controlling surface diffusion and adsorption rates, catalytic and chemical activity, and other physical and chemical surface properties. Due to these special characteristics, vicinal surfaces offer an approach for creating self-assembled structures with one or more dimensions on nanometer scale. The storage and communications industries have been revolutionized by applications of two-dimensional electron gas confined in thin films, so an interest in one and zero-dimensional systems is not surprising. This work demonstrates how macroscopic amounts of low-dimensional structures can be produced by self-assembly using stepped surfaces as nanometer-scale templates. High-quality templates of step arrays can be prepared on vicinal Si(111) surfaces. Sub-monolayer CaF2/Si(111) heteroepitaxial growth is examined in a series of experiments. A new growth mode is observed in addition to the ones typical in three dimensions. With increasing coverage, the growth front changes from rough to smooth geometry, driven by the elastic interactions between the multiple growth fronts and the surface steps. The mechanism is thus unique to the two-dimensional growth on stepped surfaces. The possible arrangements of the CaF2 self-assembled nanostructures are arrays of stripes or islands, both interesting as potential masks for silicon nanolithography. Anisotropic surface reconstructions, such as Ca and Au induced 3 x 1 and 5 x 2 on Si(111), are effectively self-assembled one-dimensional atomic chains. Reconstructions are single-domain on vicinal surfaces and with odd electron count a metallic one-dimensional state is expected in both the above examples. However in angular-resolved photoemission both appear as semiconductors, and Au-Si(111)5 x 2 exhibits a continuous one

  13. Nanoscale spirals by directed self-assembly

    Science.gov (United States)

    Choi, Hong Kyoon; Chang, Jae-Byum; Hannon, Adam F.; Yang, Joel K. W.; Berggren, Karl K.; Alexander-Katz, Alfredo; Ross, Caroline A.

    2017-06-01

    Archimedean spiral patterns are formed by the directed self-assembly of diblock copolymer thin films within a circular template. The presence of a notch in the template promotes the formation of a spiral compared to concentric rings, and the notch shape determines the chirality of the spiral. Double spirals occur when the notch width is increased or when there are two notches. The spiral followed an Archimedean form with exponent ≈0.9. Self-consistent field theory reproduces the experimentally observed morphologies and demonstrates the templating of spirals in cylindrical-morphology block copolymer films.

  14. Self-assembly of colloidal surfactants

    Science.gov (United States)

    Kegel, Willem

    2012-02-01

    We developed colloidal dumbbells with a rough and a smooth part, based on a method reported in Ref. [1]. Specific attraction between the smooth parts occurs upon addition of non-adsorbing polymers of appropriate size. We present the first results in terms of the assemblies that emerge in these systems. [4pt] [1] D.J. Kraft, W.S. Vlug, C.M. van Kats, A. van Blaaderen, A. Imhof and W.K. Kegel, Self-assembly of colloids with liquid protrusions, J. Am. Chem. Soc. 131, 1182, (2009)

  15. Surfaces wettability and morphology modulation in a fluorene derivative self-assembly system

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xinhua, E-mail: caoxhchem@163.com; Gao, Aiping; Zhao, Na; Yuan, Fangyuan; Liu, Chenxi; Li, Ruru

    2016-04-15

    Graphical abstract: - Highlights: • The different structures could be obtained in this self-assembly system. • A water-drop could freely roll on the xerogel film with the sliding angle of 15.0. • The superhydrophobic surface can be obtained via supramolecular self-assembly. - Abstract: A new organogelator based on fluorene derivative (gelator 1) was designed and synthesized. Organogels could be obtained via the self-assembly of the derivative in acetone, toluene, ethyl acetate, hexane, DMSO and petroleum ether. The self-assembly process was thoroughly characterized using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV–vis, FT-IR and the contact angle. Surfaces with different morphologies and wetting properties were formed via the self-assembly of gelator 1 in the six different solvents. Interestingly, a superhydrophobic surface with a contact angle of 150° was obtained from organogel 1 in DMSO and exhibited the lotus-effect. The sliding angle necessary for a water droplet to move on the glass was only 15°. Hydrogen bonding and van der Waals forces were attributed as the main driving forces for gel formation.

  16. Oil-in-Water Self-Assembled Synthesis of Ag@AgCl Nano-Particles on Flower-like Bi2O2CO3 with Enhanced Visible-Light-Driven Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Shuanglong Lin

    2016-06-01

    Full Text Available In this work, a series of novel flower-like Ag@AgCl/Bi2O2CO3 were prepared by simple and feasible oil-in-water self-assembly processes. The phase structures of as-prepared samples were examined by X-ray diffraction (XRD, Scanning electron microscopy (SEM, Transmission electron microscopy (TEM, UV-vis diffuse reflectance spectroscopy (DRS, X-ray fluorescence spectrometer (XRF, etc. The characterization results indicated that the presence of Ag@AgCl did not affect the crystal structure, but exerted a great influence on the photocatalytic activity of Bi2O2CO3 and enhanced the absorption band of pure Bi2O2CO3. The photocatalytic activities of the Ag@AgCl/Bi2O2CO3 samples were determined by photocatalytic degradation of methylene blue (MB under visible light irradiation. The Ag@AgCl (10 wt %/Bi2O2CO3 composite showed the highest photocatalytic activity, degrading 97.9% MB after irradiation for 20 min, which is over 1.64 and 3.66 times faster than that of pure Ag@AgCl (calculated based on the equivalent Ag@AgCl content in Ag@AgCl (10 wt %/Bi2O2CO3 and pure Bi2O2CO3, respectively. Bisphenol A (BPA was also degraded to further prove the degradation ability of Ag@AgCl/Bi2O2CO3. Photocurrent studies indicated that the recombination of photo-generated electron–hole pairs was decreased effectively due to the formation of heterojunctions between flower-like Bi2O2CO3 and Ag@AgCl nanoparticles. Trapping experiments indicated that O2−, h+ and Cl° acted as the main reactive species for MB degradation in the present photocatalytic system. Furthermore, the cycling experiments revealed the good stability of Ag@AgCl/Bi2O2CO3 composites. Based on the above, a photocatalytic mechanism for the degradation of organic compounds over Ag@AgCl/Bi2O2CO3 was proposed.

  17. Oil-in-Water Self-Assembled Synthesis of Ag@AgCl Nano-Particles on Flower-like Bi2O2CO3 with Enhanced Visible-Light-Driven Photocatalytic Activity

    Science.gov (United States)

    Lin, Shuanglong; Liu, Li; Liang, Yinghua; Cui, Wenquan; Zhang, Zisheng

    2016-01-01

    In this work, a series of novel flower-like Ag@AgCl/Bi2O2CO3 were prepared by simple and feasible oil-in-water self-assembly processes. The phase structures of as-prepared samples were examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), X-ray fluorescence spectrometer (XRF), etc. The characterization results indicated that the presence of Ag@AgCl did not affect the crystal structure, but exerted a great influence on the photocatalytic activity of Bi2O2CO3 and enhanced the absorption band of pure Bi2O2CO3. The photocatalytic activities of the Ag@AgCl/Bi2O2CO3 samples were determined by photocatalytic degradation of methylene blue (MB) under visible light irradiation. The Ag@AgCl (10 wt %)/Bi2O2CO3 composite showed the highest photocatalytic activity, degrading 97.9% MB after irradiation for 20 min, which is over 1.64 and 3.66 times faster than that of pure Ag@AgCl (calculated based on the equivalent Ag@AgCl content in Ag@AgCl (10 wt %)/Bi2O2CO3) and pure Bi2O2CO3, respectively. Bisphenol A (BPA) was also degraded to further prove the degradation ability of Ag@AgCl/Bi2O2CO3. Photocurrent studies indicated that the recombination of photo-generated electron–hole pairs was decreased effectively due to the formation of heterojunctions between flower-like Bi2O2CO3 and Ag@AgCl nanoparticles. Trapping experiments indicated that O2−, h+ and Cl° acted as the main reactive species for MB degradation in the present photocatalytic system. Furthermore, the cycling experiments revealed the good stability of Ag@AgCl/Bi2O2CO3 composites. Based on the above, a photocatalytic mechanism for the degradation of organic compounds over Ag@AgCl/Bi2O2CO3 was proposed. PMID:28773607

  18. 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.

  19. Interlaboratory validation of small-scale solubility and dissolution measurements of poorly water-soluble drugs

    DEFF Research Database (Denmark)

    Andersson, Sara B. E.; Alvebratt, Caroline; Bevernage, Jan

    2016-01-01

    The purpose of this study was to investigate the interlaboratory variability in determination of apparent solubility (Sapp) and intrinsic dissolution rate (IDR) using a miniaturized dissolution instrument. Three poorly water-soluble compounds were selected as reference compounds and measured...... at multiple laboratories using the same experimental protocol. Dissolution was studied in fasted-state simulated intestinal fluid and phosphate buffer (pH 6.5). An additional 6 compounds were used for the development of an IDR measurement guide, which was then validated with 5 compounds. The results clearly...

  20. Water sorption and solubility of core build-up materials.

    Science.gov (United States)

    Zankuli, M A; Devlin, H; Silikas, N

    2014-12-01

    To investigate the variation in water sorption and solubility across a range of different core build-up materials. Five materials were tested, four of which are resin-based materials (Grandio Core, Core.X Flow, Bright Flow Core, Speedee) and one resin-modified glass ionomer (Fuji II LC). All specimens (n=10) were immersed in 10ml distilled water in individual glass containers and weighed at one week, 14 and 28 days. After a total immersion time of 28 days, 7 specimens were dried to a constant mass, in a desiccator for 28 days. Three samples of each material were not dried, but were left in distilled water for 1 year, to determine the long-term water sorption properties. Specimens were weighed at monthly intervals until 6 months and then at the 9th and 12th months. Each specimen was measured using a digital electronic caliper (Mitutoyo Corporation, Japan). After 28 days immersion, the change in water sorption and solubility of the materials ranged from 12.9 to 67.1μg/mm(3) (P<0.001) and 0.9-6.4μg/mm(3) respectively (P<0.001). Except for Fuji II LC, an independent T-test showed significantly higher water sorption and solubility for the other materials after 1-year total immersion in water compared to 1 month (P<0.05). Using repeated measures ANOVA, all materials showed mass changes over time (1 month) (P<0.001). Grandio Core had the lowest water sorption and solubility among the tested materials. According to the ISO 4049 standards, all the tested materials showed acceptable water sorption and solubility, apart from the water sorption behavior of Fuji II LC. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. Controllable synthesis of self-assembly Co3O4 nanoflake microspheres for electrochemical performance

    Science.gov (United States)

    Liu, Fangyan; Zhang, Binbin; Su, Hai; Zhang, Haitao; Zhang, Lei; Yang, Weiqing

    2016-09-01

    Tuning the ratios of ethanol to water, self-assembling microspheres composed of Co3O4 nanoflakes are synthesized by the hydrothermal method. The scanning electron microscopy (SEM) images of as-grown samples obviously show that the dispersive multilayered structures gradually change into micro/nanobelts and cubic blocks structures, and then into the desired self-assembled microspheres with increasing ratios of ethanol to water. Also, all the x-ray diffraction (XRD) patterns evidently demonstrate that all obtained Co3O4 has cubic crystal structure. The corresponding synthesis mechanism is discussed in detail. More importantly, the unique self-assembling Co3O4 nanoflake microspheres have excellent electrochemical performance with large specific capacitance, good rate capability and excellent cycling performance, evidently presenting a potential capability of Co3O4 nanoflake microspheres to act as electrode materials for supercapacitors in sustainable power sources.

  2. Self-Assembled Asymmetric Block Copolymer Membranes: Bridging the Gap from Ultra- to Nanofiltration

    KAUST Repository

    Yu, Haizhou

    2015-09-21

    The self-assembly of block copolymers is an emerging strategy to produce isoporous ultrafiltration membranes. However, thus far, it has not been possible to bridge the gap from ultra- to nanofiltration and decrease the pore size of self-assembled block copolymer membranes to below 5 nm without post-treatment. It is now reported that the self-assembly of blends of two chemically interacting copolymers can lead to highly porous membranes with pore diameters as small as 1.5 nm. The membrane containing an ultraporous, 60 nm thin separation layer can fully reject solutes with molecular weights of 600 g mol−1 in aqueous solutions with a water flux that is more than one order of magnitude higher than the permeance of commercial nanofiltration membranes. Simulations of the membrane formation process by dissipative particle dynamics (DPD) were used to explain the dramatic observed pore size reduction combined with an increase in water flux.

  3. Single-mode lasing from colloidal water-soluble CdSe/CdS quantum dot-in-rods.

    Science.gov (United States)

    Di Stasio, Francesco; Grim, Joel Q; Lesnyak, Vladimir; Rastogi, Prachi; Manna, Liberato; Moreels, Iwan; Krahne, Roman

    2015-03-18

    Core-shell CdSe/CdS nanocrystals are a very promising material for light emitting applications. Their solution-phase synthesis is based on surface-stabilizing ligands that make them soluble in organic solvents, like toluene or chloroform. However, solubility of these materials in water provides many advantages, such as additional process routes and easier handling. So far, solubilization of CdSe/CdS nanocrystals in water that avoids detrimental effects on the luminescent properties poses a major challenge. This work demonstrates how core-shell CdSe/CdS quantum dot-in-rods can be transferred into water using a ligand exchange method employing mercaptopropionic acid (MPA). Key to maintaining the light-emitting properties is an enlarged CdS rod diameter, which prevents potential surface defects formed during the ligand exchange from affecting the photophysics of the dot-in-rods. Films made from water-soluble dot-in-rods show amplified spontaneous emission (ASE) with a similar threshold (130 μJ/cm(2)) as the pristine material (115 μJ/cm(2)). To demonstrate feasibility for lasing applications, self-assembled microlasers are fabricated via the "coffee-ring effect" that display single-mode operation and a very low threshold of ∼10 μJ/cm(2). The performance of these microlasers is enhanced by the small size of MPA ligands, enabling a high packing density of the dot-in-rods. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Self-assembled nanogaps via seed-mediated growth of end-to-end linked gold nanorods

    DEFF Research Database (Denmark)

    Jain, Titoo; Westerlund, Axel Rune Fredrik; Johnson, Erik

    2009-01-01

    on the nanoscale. We here present a new way to end-to-end link AuNRs with a single or few linker molecules. Whereas methods reported in the literature so far rely on modification of the AuNRs after the synthesis, we here dimerize gold nanoparticle seeds with a water-soluble dithiol-functionalized polyethylene......Gold nanorods (AuNRs) are of interest for a wide range of applications, ranging from imaging to molecular electronics, and they have been studied extensively for the past decade. An important issue in AuNR applications is the ability to self-assemble the rods in predictable structures...... that a large fraction of the rods are flexible around the hinging molecule in solution, as expected for a molecularly linked nanogap. By using excess of gold nanoparticles relative to the linking dithiol molecule, this method can provide a high probability that a single molecule is connecting the two rods...

  5. Electrostatic Force Microscopy of Self Assembled Peptide Structures

    DEFF Research Database (Denmark)

    Clausen, Casper Hyttel; Dimaki, Maria; Pantagos, Spyros P.

    2011-01-01

    In this report electrostatic force microscopy (EFM) is used to study different peptide self-assembled structures, such as tubes and particles. It is shown that not only geometrical information can be obtained using EFM, but also information about the composition of different structures. In partic...... compared to the radius of the AFM tip used. Finally, an agreement between the detected signal and the structure of the hollow peptide tubes is demonstrated.......In this report electrostatic force microscopy (EFM) is used to study different peptide self-assembled structures, such as tubes and particles. It is shown that not only geometrical information can be obtained using EFM, but also information about the composition of different structures....... In particular we use EFM to investigate the structures of diphenylalanine peptide tubes, particles, and CSGAITIG peptide particles placed on pre-fabricated SiO2 surfaces with a backgate. We show that the cavity in the peptide tubes could be to the presence of water residues. Additionally we show that self...

  6. Silver nanoprisms self-assembly on differently functionalized silica surface

    Science.gov (United States)

    Pilipavicius, J.; Chodosovskaja, A.; Beganskiene, A.; Kareiva, A.

    2015-03-01

    In this work colloidal silica/silver nanoprisms (NPRs) composite coatings were made. Firstly colloidal silica sols were synthesized by sol-gel method and produced coatings on glass by dip-coating technique. Next coatings were silanized by (3-Aminopropyl)triethoxysilane (APTES), N-[3-(Trimethoxysilyl)propyl]ethylenediamine (AEAPTMS), (3- Mercaptopropyl)trimethoxysilane (MPTMS). Silver NPRs where synthesized via seed-mediated method and high yield of 94±15 nm average edge length silver NPRs were obtained with surface plasmon resonance peak at 921 nm. Silica-Silver NPRs composite coatings obtained by selfassembly on silica coated-functionalized surface. In order to find the most appropriate silanization way for Silver NPRs self-assembly, the composite coatings were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), water contact angle (CA) and surface free energy (SFE) methods. Results have showed that surface functionalization is necessary to achieve self-assembled Ag NPRs layer. MPTMS silanized coatings resulted sparse distribution of Ag NPRs. Most homogeneous, even distribution composite coatings obtained on APTES functionalized silica coatings, while AEAPTMS induced strong aggregation of Silver NPRs.

  7. Anisotropic Self-Assembly from Isotropic Colloidal Building Blocks.

    Science.gov (United States)

    Rey, Marcel; Law, Adam D; Buzza, D Martin A; Vogel, Nicolas

    2017-12-06

    Spherical colloidal particles generally self-assemble into hexagonal lattices in two dimensions. However, more complex, non-hexagonal phases have been predicted theoretically for isotropic particles with a soft repulsive shoulder but have not been experimentally realized. We study the phase behavior of microspheres in the presence of poly(N-isopropylacrylamide) (PNiPAm) microgels at the air/water interface. We observe a complex phase diagram, including phases with chain and square arrangements, which exclusively form in the presence of the microgels. Our experimental data suggests that the microgels form a corona around the microspheres and induce a soft repulsive shoulder that governs the self-assembly in this system. The observed structures are fully reproduced by both minimum energy calculations and finite temperature Monte Carlo simulations of hard core-soft shoulder particles with experimentally realistic interaction parameters. Our results demonstrate how complex, anisotropic assembly patterns can be realized from entirely isotropic building blocks by control of the interaction potential.

  8. Controllable self-assembly of RNA dendrimers.

    Science.gov (United States)

    Sharma, Ashwani; Haque, Farzin; Pi, Fengmei; Shlyakhtenko, Lyudmila S; Evers, B Mark; Guo, Peixuan

    2016-04-01

    We report programmable self-assembly of branched, 3D globular, monodisperse and nanoscale sized dendrimers using RNA as building blocks. The central core and repeating units of the RNA dendrimer are derivatives of the ultrastable three-way junction (3WJ) motif from the bacteriophage phi29 motor pRNA. RNA dendrimers were constructed by step-wise self-assembly of modular 3WJ building blocks initiating with a single 3WJ core (Generation-0) with overhanging sticky end and proceeding in a radial manner in layers up to Generation-4. The final constructs were generated under control without any structural defects in high yield and purity, as demonstrated by gel electrophoresis and AFM imaging. Upon incorporation of folate on the peripheral branches of the RNA dendrimers, the resulting constructs showed high binding and internalization into cancer cells. RNA dendrimers are envisioned to have a major impact in targeting, disease therapy, molecular diagnostics and bioelectronics in the near future. Dendrimers are gaining importance as a carrier platform for diagnosis and therapeutics. The authors here reported building of their dendrimer molecules using RNA as building blocks. The addition of folate also allowed recognition and subsequent binding to tumor cells. This new construct may prove to be useful in many clinical settings. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Oral formulation strategies to improve solubility of poorly water-soluble drugs.

    Science.gov (United States)

    Singh, Abhishek; Worku, Zelalem Ayenew; Van den Mooter, Guy

    2011-10-01

    In the past two decades, there has been a spiraling increase in the complexity and specificity of drug-receptor targets. It is possible to design drugs for these diverse targets with advances in combinatorial chemistry and high throughput screening. Unfortunately, but not entirely unexpectedly, these advances have been accompanied by an increase in the structural complexity and a decrease in the solubility of the active pharmaceutical ingredient. Therefore, the importance of formulation strategies to improve the solubility of poorly water-soluble drugs is inevitable, thus making it crucial to understand and explore the recent trends. Drug delivery systems (DDS), such as solid dispersions, soluble complexes, self-emulsifying drug delivery systems (SEDDS), nanocrystals and mesoporous inorganic carriers, are discussed briefly in this review, along with examples of marketed products. This article provides the reader with a concise overview of currently relevant formulation strategies and proposes anticipated future trends. Today, the pharmaceutical industry has at its disposal a series of reliable and scalable formulation strategies for poorly soluble drugs. However, due to a lack of understanding of the basic physical chemistry behind these strategies, formulation development is still driven by trial and error.

  10. Peptide Self-Assembled Nanostructures for Drug Delivery Applications

    Directory of Open Access Journals (Sweden)

    Taotao Fan

    2017-01-01

    Full Text Available Peptide self-assembled nanostructures are very popular in many biomedical applications. Drug delivery is one of the most promising applications among them. The tremendous advantages for peptide self-assembled nanostructures include good biocompatibility, low cost, tunable bioactivity, high drug loading capacities, chemical diversity, specific targeting, and stimuli responsive drug delivery at disease sites. Peptide self-assembled nanostructures such as nanoparticles, nanotubes, nanofibers, and hydrogels have been investigated by many researchers for drug delivery applications. In this review, the underlying mechanisms for the self-assembled nanostructures based on peptides with different types and structures are introduced and discussed. Peptide self-assembled nanostructures associated promising drug delivery applications such as anticancer drug and gene drug delivery are highlighted. Furthermore, peptide self-assembled nanostructures for targeted and stimuli responsive drug delivery applications are also reviewed and discussed.

  11. Self-Assembly of Human Serum Albumin: A Simplex Phenomenon

    Science.gov (United States)

    Thakur, Garima; Prashanthi, Kovur; Jiang, Keren; Thundat, Thomas

    2017-01-01

    Spontaneous self-assemblies of biomolecules can generate geometrical patterns. Our findings provide an insight into the mechanism of self-assembled ring pattern generation by human serum albumin (HSA). The self-assembly is a process guided by kinetic and thermodynamic parameters. The generated protein ring patterns display a behavior which is geometrically related to a n-simplex model and is explained through thermodynamics and chemical kinetics. PMID:28930179

  12. Grooved nanowires from self-assembling hairpin molecules for solar cells.

    Science.gov (United States)

    Tevis, Ian D; Tsai, Wei-Wen; Palmer, Liam C; Aytun, Taner; Stupp, Samuel I

    2012-03-27

    One of the challenges facing bulk heterojunction organic solar cells is obtaining organized films during the phase separation of intimately mixed donor and acceptor components. We report here on the use of hairpin-shaped sexithiophene molecules to generate by self-assembly grooved nanowires as the donor component in bulk heterojunction solar cells. Photovoltaic devices were fabricated via spin-casting to produce by solvent evaporation a percolating network of self-assembled nanowires and fullerene acceptors. Thermal annealing was found to increase power conversion efficiencies by promoting domain growth while still maintaining this percolating network of nanostructures. The benefits of self-assembly and grooved nanowires were examined by building devices from a soluble sexithiophene derivative that does not form one-dimensional structures. In these systems, excessive phase separation caused by thermal annealing leads to the formation of defects and lower device efficiencies. We propose that the unique hairpin shape of the self-assembling molecules allows the nanowires as they form to interact well with the fullerenes in receptor-ligand type configurations at the heterojunction of the two domains, thus enhancing device efficiencies by 23%. © 2012 American Chemical Society

  13. Molecular design and synthesis of self-assembling camptothecin drug amphiphiles.

    Science.gov (United States)

    Cheetham, Andrew G; Lin, Yi-An; Lin, Ran; Cui, Honggang

    2017-06-01

    The conjugation of small molecular hydrophobic anticancer drugs onto a short peptide with overall hydrophilicity to create self-assembling drug amphiphiles offers a new prodrug strategy, producing well-defined, discrete nanostructures with a high and quantitative drug loading. Here we show the detailed synthesis procedure and how the molecular structure can influence the synthesis of the self-assembling prodrugs and the physicochemical properties of their assemblies. A series of camptothecin-based drug amphiphiles were synthesized via combined solid- and solution-phase synthetic techniques, and the physicochemical properties of their self-assembled nanostructures were probed using a number of imaging and spectroscopic techniques. We found that the number of incorporated drug molecules strongly influences the rate at which the drug amphiphiles are formed, exerting a steric hindrance toward any additional drugs to be conjugated and necessitating extended reaction time. The choice of peptide sequence was found to affect the solubility of the conjugates and, by extension, the critical aggregation concentration and contour length of the filamentous nanostructures formed. In the design of self-assembling drug amphiphiles, the number of conjugated drug molecules and the choice of peptide sequence have significant effects on the nanostructures formed. These observations may allow the fine-tuning of the physicochemical properties for specific drug delivery applications, ie systemic vs local delivery.

  14. The nature of protein interactions governing globular protein-polymer block copolymer self-assembly.

    Science.gov (United States)

    Lam, Christopher N; Kim, Minkyu; Thomas, Carla S; Chang, Dongsook; Sanoja, Gabriel E; Okwara, Chimdimma U; Olsen, Bradley D

    2014-04-14

    The effects of protein surface potential on the self-assembly of protein-polymer block copolymers are investigated in globular proteins with controlled shape through two approaches: comparison of self-assembly of mCherry-poly(N-isopropylacrylamide) (PNIPAM) bioconjugates with structurally homologous enhanced green fluorescent protein (EGFP)-PNIPAM bioconjugates, and mutants of mCherry with altered electrostatic patchiness. Despite large changes in amino acid sequence, the temperature-concentration phase diagrams of EGFP-PNIPAM and mCherry-PNIPAM conjugates have similar phase transition concentrations. Both materials form identical phases at two different coil fractions below the PNIPAM thermal transition temperature and in the bulk. However, at temperatures above the thermoresponsive transition, mCherry conjugates form hexagonal phases at high concentrations while EGFP conjugates form a disordered micellar phase. At lower concentration, mCherry shows a two-phase region while EGFP forms homogeneous disordered micellar structures, reflecting the effect of changes in micellar stability. Conjugates of four mCherry variants with changes to their electrostatic surface patchiness also showed minimal change in phase behavior, suggesting that surface patchiness has only a small effect on the self-assembly process. Measurements of protein/polymer miscibility, second virial coefficients, and zeta potential show that these coarse-grained interactions are similar between mCherry and EGFP, indicating that coarse-grained interactions largely capture the relevant physics for soluble, monomeric globular protein-polymer conjugate self-assembly.

  15. A piezoelectric immunosensor using hybrid self-assembled monolayers for detection of Schistosoma japonicum.

    Directory of Open Access Journals (Sweden)

    Shiping Wang

    Full Text Available BACKGROUND: The parasite Schistosoma japonicum causes schistosomiasis disease, which threatens human life and hampers economic and social development in some Asian countries. An important lesson learned from efforts to reduce the occurrence of schistosomiasis is that the diagnostic approach must be altered as further progress is made towards the control and ultimate elimination of the disease. METHODOLOGY/PRINCIPAL FINDINGS: Using mixed self-assembled monolayer membrane (mixed SAM technology, a mixture of mercaptopropionic acid (MPA and mercaptoethanol (ME was self-assembled on the surface of quartz crystals by gold-sulphur-bonds. Soluble egg antigens (SEA of S. japonicum were then cross-linked to the quartz crystal using a special coupling agent. As compared with the traditional single self-assembled monolayer immobilization method, S. japonicum antigen (SjAg immobilization using mixed self-assembled monolayers exhibits much greater immunoreactivity. Under optimal experimental conditions, the detection range is 1:1500 to 1:60 (infected rabbit serum dilution ratios. We measured several infected rabbit serum samples with varying S. japonicum antibody (SjAb concentrations using both immunosensor and ELISA techniques and then produced a correlation analysis. The correlation coefficients reached 0.973. CONCLUSIONS/SIGNIFICANCE: We have developed a new, simple, sensitive, and reusable piezoelectric immunosensor that directly detects SjAb in the serum. This method may represent an alternative to the current diagnostic methods for S. japonicum infection in the clinical laboratory or for analysis outside the laboratory.

  16. Magnetic self-assembly of small parts

    Science.gov (United States)

    Shetye, Sheetal B.

    Modern society's propensity for miniaturized end-user products is compelling electronic manufacturers to assemble and package different micro-scale, multi-technology components in more efficient and cost-effective manners. As the size of the components gets smaller, issues such as part sticking and alignment precision create challenges that slow the throughput of conventional robotic pick-n-place systems. As an alternative, various self-assembly approaches have been proposed to manipulate micro to millimeter scale components in a parallel fashion without human or robotic intervention. In this dissertation, magnetic self-assembly (MSA) is demonstrated as a highly efficient, completely parallel process for assembly of millimeter scale components. MSA is achieved by integrating permanent micromagnets onto component bonding surfaces using wafer-level microfabrication processes. Embedded bonded powder methods are used for fabrication of the magnets. The magnets are then magnetized using pulse magnetization methods, and the wafers are then singulated to form individual components. When the components are randomly mixed together, self-assembly occurs when the intermagnetic forces overcome the mixing forces. Analytical and finite element methods (FEM) are used to study the force interactions between the micromagnets. The multifunctional aspects of MSA are presented through demonstration of part-to-part and part-to-substrate assembly of 1 mm x 1mm x 0.5 mm silicon components. Part-to-part assembly is demonstrated by batch assembly of free-floating parts in a liquid environment with the assembly yield of different magnetic patterns varying from 88% to 90% in 20 s. Part-to-substrate assembly is demonstrated by assembling an ordered array onto a fixed substrate in a dry environment with the assembly yield varying from 86% to 99%. In both cases, diverse magnetic shapes/patterns are used to control the alignment and angular orientation of the components. A mathematical model is

  17. Surfaces wettability and morphology modulation in a fluorene derivative self-assembly system

    Science.gov (United States)

    Cao, Xinhua; Gao, Aiping; Zhao, Na; Yuan, Fangyuan; Liu, Chenxi; Li, Ruru

    2016-04-01

    A new organogelator based on fluorene derivative (gelator 1) was designed and synthesized. Organogels could be obtained via the self-assembly of the derivative in acetone, toluene, ethyl acetate, hexane, DMSO and petroleum ether. The self-assembly process was thoroughly characterized using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-vis, FT-IR and the contact angle. Surfaces with different morphologies and wetting properties were formed via the self-assembly of gelator 1 in the six different solvents. Interestingly, a superhydrophobic surface with a contact angle of 150° was obtained from organogel 1 in DMSO and exhibited the lotus-effect. The sliding angle necessary for a water droplet to move on the glass was only 15°. Hydrogen bonding and van der Waals forces were attributed as the main driving forces for gel formation.

  18. Self-assembled software and method of overriding software execution

    Science.gov (United States)

    Bouchard, Ann M.; Osbourn, Gordon C.

    2013-01-08

    A computer-implemented software self-assembled system and method for providing an external override and monitoring capability to dynamically self-assembling software containing machines that self-assemble execution sequences and data structures. The method provides an external override machine that can be introduced into a system of self-assembling machines while the machines are executing such that the functionality of the executing software can be changed or paused without stopping the code execution and modifying the existing code. Additionally, a monitoring machine can be introduced without stopping code execution that can monitor specified code execution functions by designated machines and communicate the status to an output device.

  19. Study of pH-dependent drugs solubility in water

    Directory of Open Access Journals (Sweden)

    Pobudkowska A.

    2014-01-01

    Full Text Available The solubilities of five sparingly soluble drug-compounds in water have been measured at constant temperatures (298.1K and 310.1K by the classical saturation shake-flask method. All substances presented in this work are derivatives of anthranilic acid: flufenamic acid, (FLU, mefenamic acid, (MEF, niflumic acid, (NIF, diclofenac sodium, (DIC, and meclofenamic sodium, (MEC. All of them have anti-inflammatory action. Since the aqueous solubility of the ionized drug is significantly higher than the unionized, the experimental conditions that affect equilibrium solubility values such as composition of aqueous buffer have been examined. The Henderson-Hasselbalch (HH relationship has been used to predict the pH-dependent solubility profiles of chosen drugs at two temperatures. For this purpose the pKa values of the investigated drugs have been determined with Bates-Schwarzenbach spectrophotometric method at temperature 310.1 K. At temperature 298.1K these values were reported earlier. Similar values of pKa were obtained from the solubility measurements.

  20. 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.

  1. Self-assembled monolayers on silicon oxide

    Energy Technology Data Exchange (ETDEWEB)

    Belgardt, Christian; Graaf, Harald; Baumgaertel, Thomas; Borczyskowski, Christian von [Center for Nanostructured Materials and Analytics, Institute of Physics, Chemnitz University of Technology, Reichenhainer Str. 70, 09107 Chemnitz (Germany)

    2010-02-15

    We evaluated the wet-chemical formation of octa-decyltrichlorosilane (OTS) self-assembled monolayers on silicon substrates with a silicon oxide layer. Our investigations were focussed on the influence of the reaction time on the surface energy. The surface energy was thereby calculated by measuring the static contact angle of two probe liquids on the surface. We found that only high reaction times of several hundred minutes yield a high quality monolayer with a minimal surface energy. A clear increase of the dispersive part of the surface energy for short reaction times is found. This can be explained by a high ratio of gauche-conformation within the alkyl chains accompanied by a rather slow rearrangement of the chains inside the monolayer to form a densely packed all-trans conformation. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Self-Assembling Brush Polymers Bearing Multisaccharides.

    Science.gov (United States)

    Lee, Jongchan; Kim, Jin Chul; Lee, Hoyeol; Song, Sungjin; Kim, Heesoo; Ree, Moonhor

    2017-06-01

    Three different series of brush polymers bearing glucosyl, maltosyl, or maltotriosyl moiety at the bristle end are successfully prepared by using cationic ring-opening polymerization and two sequential postmodification reactions. All brush polymers, except for the polymer containing 100 mol% maltotriosyl moiety, demonstrate the formation of multibilayer structure in films, always providing saccharide-enriched surface. These self-assembling features are remarkable, regarding the bulkiness of saccharide moieties and the kink in the bristle due to the triazole linker. The saccharide-enriched film surfaces reveal exceptionally high specific binding affinity to concanavalin A but suppress nonspecific binding of plasma proteins severely. Overall, the brush polymers bearing saccharide moieties of various kinds in this study are highly suitable materials for biomedical applications including biosensors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Self-assembling multimeric nucleic acid constructs

    Science.gov (United States)

    Cantor, C.R.; Niemeyer, C.M.; Smith, C.L.; Sano, Takeshi; Hnatowich, D.J.; Rusckowski, M.

    1996-10-01

    The invention is directed to constructs and compositions containing multimeric forms of nucleic acid. Multimeric nucleic acids comprise single-stranded nucleic acids attached via biotin to streptavidin and bound with a functional group. These constructs can be utilized in vivo to treat or identify diseased tissue or cells. Repeated administrations of multimeric nucleic acid compositions produce a rapid and specific amplification of nucleic acid constructs and their attached functional groups. For treatment purposes, functional groups may be toxins, radioisotopes, genes or enzymes. Diagnostically, labeled multimeric constructs may be used to identify specific targets in vivo or in vitro. Multimeric nucleic acids may also be used in nanotechnology and to create self-assembling polymeric aggregates such as membranes of defined porosity, microcircuits and many other products. 5 figs.

  4. Smart self-assembled hybrid hydrogel biomaterials.

    Science.gov (United States)

    Kopeček, Jindřich; Yang, Jiyuan

    2012-07-23

    Hybrid biomaterials are systems created from components of at least two distinct classes of molecules, for example, synthetic macromolecules and proteins or peptide domains. The synergistic combination of two types of structures may produce new materials that possess unprecedented levels of structural organization and novel properties. This Review focuses on biorecognition-driven self-assembly of hybrid macromolecules into functional hydrogel biomaterials. First, basic rules that govern the secondary structure of peptides are discussed, and then approaches to the specific design of hybrid systems with tailor-made properties are evaluated, followed by a discussion on the similarity of design principles of biomaterials and macromolecular therapeutics. Finally, the future of the field is briefly outlined. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Plasma concentrations of water.soluble vitamins in metabolic ...

    African Journals Online (AJOL)

    Context: Vitamins B1 (thiamine), B3 (niacin), B6 (pyridoxine), and C (ascorbic acid) are vital for energy, carbohydrate, lipid, and amino acid metabolism and in the regulation of the cellular redox state. Some studies have associated low levels of water.soluble vitamins with metabolic syndrome and its various components.

  6. Water-Soluble Gold Nanoparticles Protected by Fluorinated Amphiphilic Thiolates

    NARCIS (Netherlands)

    Gentilini, Cristina; Evangelista, Fabrizio; Rudolf, Petra; Franchi, Paola; Lucarini, Marco; Pasquato, Lucia

    2008-01-01

    The preparation and the properties of gold nanoparticles (Au NPs) protected by perfluorinated amphiphiles are described. The thiols were devised to form a perfluorinated region close to the gold surface and to have a hydrophilic portion in contact with the bulk solvent to impart solubility in water.

  7. Plasma concentrations of water-soluble vitamins in metabolic ...

    African Journals Online (AJOL)

    2012-01-21

    Jan 21, 2012 ... levels of water-soluble vitamins with metabolic syndrome and its various components. Aims: This study aims to determine the plasma concentrations of vitamins B1, B3, B6, and C in Nigerians with metabolic syndrome and in healthy controls. Settings and Design: One-hundred subjects with metabolic ...

  8. Synthesis and characterization of water-soluble carbon nanotubes ...

    Indian Academy of Sciences (India)

    Carbon nanotubes (CNT) has been synthesized by pyrolysing mustard oil using an oil lamp. It was made water-soluble (wsCNT) through oxidative treatment by dilute nitric acid and was characterized by SEM, AFM, XRD, Raman and FTIR spectroscopy. The synthesized wsCNT showed the presence of several junctions and ...

  9. Highly Active Water-Soluble Olefin Metathesis Catalyst

    OpenAIRE

    Hong, Soon Hyeok; Grubbs, Robert H

    2006-01-01

    A novel water-soluble ruthenium olefin metathesis catalyst supported by a poly(ethylene glycol) conjugated saturated 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene ligand is reported. The catalyst displays improved activity in ring-opening metathesis polymerization, ring-closing metathesis, and cross-metathesis reactions in aqueous media.

  10. Water-soluble diphosphadiazacyclooctanes as ligands for aqueous organometallic catalysis

    KAUST Repository

    Boulanger, Jérôme

    2012-12-01

    Two new water-soluble diphosphacyclooctanes been synthesized and characterized by NMR and surface tension measurements. Both phosphanes proved to coordinate rhodium in a very selective way as well-defined bidentates were obtained. When used in Rh-catalyzed hydroformylation of terminal alkenes, both ligands positively impacted the reaction chemoselectivity. © 2012 Elsevier B.V.

  11. Seasonal and genotypic variation of water-soluble polysaccharide ...

    African Journals Online (AJOL)

    Cyclocarya paliurus (Batal) Iljinskaja is an important medicinal woody plant due to numerous bioactive natural products in its leaves. As an important bioactive natural product, water-soluble polysaccharides (WSP) in leaves of C. paliurus possess diverse biological activities, such as hypoglycemic, anticancer and ...

  12. SYNTHESIS AND PROPERTIES OF STERICALLY HINDERED WATER SOLUBLE PORPHYRINE

    Directory of Open Access Journals (Sweden)

    Yu. V. Ishkov

    2014-12-01

    Full Text Available 5,10,15,20-(2-methoxy-3-quinolinylporphyrine, which was a mixture of atropisomers, was obtained by condensation of 2-methoxyquinoline-3-carbaldehyde with pyrrole in propionic acid. Quaternization of nitrogen atoms of peripheric substituents in this compound lead to water soluble sterically hindered porphyrine.

  13. Synthesis and characterization of water-soluble carbon nanotubes ...

    Indian Academy of Sciences (India)

    Abstract. Carbon nanotubes (CNT) has been synthesized by pyrolysing mustard oil using an oil lamp. It was made water-soluble (wsCNT) through oxidative treatment by dilute nitric acid and was characterized by SEM, AFM, XRD, Raman and FTIR spec- troscopy. The synthesized wsCNT showed the presence of several ...

  14. Compositional analysis of water-soluble materials in switchgrass.

    Science.gov (United States)

    Chen, Shou-Feng; Mowery, Richard A; Sevcik, Richard S; Scarlata, Christopher J; Chambliss, C Kevin

    2010-03-24

    Any valuation of a potential feedstock for bioprocessing is inherently dependent upon detailed knowledge of its chemical composition. Accepted analytical procedures for compositional analysis of biomass water-soluble extracts currently enable near-quantitative mass closure on a dry weight basis. Techniques developed in conjunction with a previous analytical assessment of corn stover have been applied to assess the composition of water-soluble materials in four representative switchgrass samples. To date, analytical characterization of water-soluble material in switchgrass has resulted in >78% mass closures for all four switchgrass samples, three of which have a mass closure of >85%. Over 30 previously unknown constituents in aqueous extracts of switchgrass were identified and quantified using a variety of chromatographic techniques. Carbohydrates (primarily sucrose, glucose, and fructose) were found to be the predominant water-soluble components of switchgrass, accounting for 18-27% of the dry weight of extractives. Total glycans (monomeric and oligomeric sugars) contributed 25-32% to the dry weight of extractives. Additional constituents contributing to the mass balance for extractives included various alditols (2-3%), organic acids (10-13%), inorganic ions (11-13%), and a distribution of oligomers presumed to represent a diverse mixture of lignin-carbohydrate complexes (30-35%). Switchgrass results are compared with previous analyses of corn stover extracts and presented in the context of their potential impact on biomass processing, feedstock storage, and future analyses of feedstock composition.

  15. Short Communication Relationships between the water solubility of ...

    African Journals Online (AJOL)

    132. Short Communication. Relationships between the water solubility of roughage dry matter and certain chemical characteristics. J.W. Cilliers- and H.J. Cilliers. North West Agricultural Development lnstitute, Private. Bag X804, Potchefstroom, 2520 Republic of South Africa. Received 17 May 1995; accepted 8 August 1995.

  16. The coagulation characteristics of humic acid by using acid-soluble chitosan, water-soluble chitosan, and chitosan coagulant mixtures.

    Science.gov (United States)

    Chen, Chih-Yu; Wu, Chung-Yu; Chung, Ying-Chien

    2015-01-01

    Chitosan is a potential substitute for traditional aluminium salts in water treatment systems. This study compared the characteristics of humic acid (HA) removal by using acid-soluble chitosan, water-soluble chitosan, and coagulant mixtures of chitosan with aluminium sulphate (alum) or polyaluminium chloride (PACl). In addition, we evaluated their respective coagulation efficiencies at various coagulant concentrations, pH values, turbidities, and hardness levels. Furthermore, we determined the size and settling velocity of flocs formed by these coagulants to identify the major factors affecting HA coagulation. The coagulation efficiency of acid- and water-soluble chitosan for 15 mg/l of HA was 74.4% and 87.5%, respectively. The optimal coagulation range of water-soluble chitosan (9-20 mg/l) was broader than that of acid-soluble chitosan (4-8 mg/l). Notably, acid-soluble chitosan/PACl and water-soluble chitosan/alum coagulant mixtures exhibited a higher coagulation efficiency for HA than for PACl or alum alone. Furthermore, these coagulant mixtures yielded an acceptable floc settling velocity and savings in both installation and operational expenses. Based on these results, we confidently assert that coagulant mixtures with a 1:1 mass ratio of acid-soluble chitosan/PACl and water-soluble chitosan/alum provide a substantially more cost-effective alternative to using chitosan alone for removing HA from water.

  17. Self assembled structures for 3D integration

    Science.gov (United States)

    Rao, Madhav

    Three dimensional (3D) micro-scale structures attached to a silicon substrate have various applications in microelectronics. However, formation of 3D structures using conventional micro-fabrication techniques are not efficient and require precise control of processing parameters. Self assembly is a method for creating 3D structures that takes advantage of surface area minimization phenomena. Solder based self assembly (SBSA), the subject of this dissertation, uses solder as a facilitator in the formation of 3D structures from 2D patterns. Etching a sacrificial layer underneath a portion of the 2D pattern allows the solder reflow step to pull those areas out of the substrate plane resulting in a folded 3D structure. Initial studies using the SBSA method demonstrated low yields in the formation of five different polyhedra. The failures in folding were primarily attributed to nonuniform solder deposition on the underlying metal pads. The dip soldering method was analyzed and subsequently refined. A modified dip soldering process provided improved yield among the polyhedra. Solder bridging referred as joining of solder deposited on different metal patterns in an entity influenced the folding mechanism. In general, design parameters such as small gap-spacings and thick metal pads were found to favor solder bridging for all patterns studied. Two types of soldering: face and edge soldering were analyzed. Face soldering refers to the application of solder on the entire metal face. Edge soldering indicates application of solder only on the edges of the metal face. Mechanical grinding showed that face soldered SBSA structures were void free and robust in nature. In addition, the face soldered 3D structures provide a consistent heat resistant solder standoff height that serve as attachments in the integration of dissimilar electronic technologies. Face soldered 3D structures were developed on the underlying conducting channel to determine the thermo-electric reliability of

  18. Self-assembly of granular crystals

    Science.gov (United States)

    Shattuck, Mark

    2015-03-01

    Acoustic meta-materials are engineered materials with the ability to control, direct, and manipulate sound waves. Since the 1990s, several groups have developed acoustic meta-materials with novel capabilities including negative index materials for acoustic super-lenses, phononic crystals with acoustic band gaps for wave guides and mirrors, and acoustic cloaking device. Most previous work on acoustic meta-materials has focused on continuum solids and fluids. In contrast, we report on coordinated computational and experimental studies to use macro-self-assembly of granular materials to produce acoustic meta-materials. The advantages of granular acoustic materials are three-fold: 1) Microscopic control: The discrete nature of granular media allows us to optimize acoustic properties on both the grain and network scales. 2) Tunability: The speed of sound in granular media depends strongly on pressure due to non-linear contact interactions and contact breaking. 3) Direct visualization: The macro-scale size of the grains enables visualization of the structure and stress propagation within granular assemblies. We report simulations and experiments of vibrated particles that form a variety of self-assembled ordered structures in two- and three-dimensions. In the simplest case of mono-disperse spheres, using a combination of pressure and vibration we produce crystals with long-range order on the scale of 100's of particles. Using special particle shapes that form ``lock and key'' structures we are able to make binary crystals with prescribed stoichiometries. We discuss the mechanical properties of these structures and methods to create more complicated structures.

  19. Shape Restoration by Active Self-Assembly

    Directory of Open Access Journals (Sweden)

    D. Arbuckle

    2005-01-01

    Full Text Available Shape restoration is defined as the problem of constructing a desired, or goal, solid shape Sg by growing an initial solid Si, which is a subset of the goal but is otherwise unknown. This definition attempts to capture abstractly a situation that often arises in the physical world when a solid object loses its desired shape due to wear and tear, corrosion or other phenomena. For example, if the top of the femur becomes distorted, the hip joint no longer functions properly and may have to be replaced surgically. Growing it in place back to its original shape would be an attractive alternative to replacement. This paper presents a solution to the shape restoration problem by using autonomous assembly agents (robots that self-assemble to fill the volume between Sg and Si. If the robots have very small dimension (micro or nano, the desired shape is approximated with high accuracy. The assembly agents initially execute a random walk. When two robots meet, they may exchange a small number of messages. The robot behavior is controlled by a finite state machine with a small number of states. Communication contact models chemical communication, which is likely to be the medium of choice for robots at the nanoscale, while small state and small messages are limitations that also are expected of nanorobots. Simulations presented here show that swarms of such robots organize themselves to achieve shape restoration by using distributed algorithms. This is one more example of an interesting geometric problem that can be solved by the Active Self-Assembly paradigm introduced in previous papers by the authors.

  20. Morphological Analysis and Solubility of Lead Particles: Effect of Phosphates and Implications to Drinking Water (Presentation)

    Science.gov (United States)

    Describe lead synthesis experiments conduced to model the impact of water quality on lead particles and solubility Develop a model system that can be used for lead solubility studies Understand how phosphates impact morphology and solubility transformations with time

  1. Synthesis of Water-Soluble Deep-Cavity Cavitands.

    Science.gov (United States)

    Hillyer, Matthew B; Gibb, Corinne L D; Sokkalingam, Punidha; Jordan, Jacobs H; Ioup, Sarah E; Gibb, Bruce C

    2016-08-19

    An efficient, four-step synthesis of a range of water-soluble, deep-cavity cavitands is presented. Key to this approach are octahalide derivatives (4, X = Cl or Br) that allow a range of water-solubilizing groups to be added to the outer surface of the core host structure. In many cases, the conversion of the starting dodecol (1) resorcinarene to the different cavitands avoids any chromatographic procedures.

  2. Effect of Concentration on the Supramolecular Polymerization Mechanism via Implicit-Solvent Coarse-Grained Simulations of Water-Soluble 1,3,5-Benzenetricarboxamide.

    Science.gov (United States)

    Bochicchio, Davide; Pavan, Giovanni M

    2017-08-17

    We report an implicit-solvent coarse-grained (CG) model for a water-soluble 1,3,5-benzenetricarboxamide (BTA) supramolecular polymer. The technical advances guaranteed by this CG model allow simulation of the self-assembly of 1000 BTA monomers and easy variation of the BTA concentration into the system down to experimental dilute conditions. In this way, we can monitor the mechanism of supramolecular polymerization as a function of the concentration at submolecular resolution exceeding the microsecond time scale. While increasing the concentration produces rapid formation of large disordered clusters that are then converted into BTA fibers, moving to very dilute concentrations favors early ordering of the oligomers in solution even at small sizes. Interestingly, we observe that below a certain concentration the oligomers that dynamically grow in solution during the self-assembly present the same level (and amplification) of order of prestacked equilibrated oligomers of the same size, meaning that concentration-dependent kinetic effects have disappeared from the polymerization mechanism.

  3. Low-voltage organic transistors based on solution processed semiconductors and self-assembled monolayer gate dielectrics

    NARCIS (Netherlands)

    Woebkenberg, Paul H.; Ball, James; Kooistra, Floris B.; Hummelen, Jan C.; de Leeuw, Dago M.; Bradley, Donal D. C.; Anthopoulos, Thomas D.

    2008-01-01

    Reduction in the operating voltage of organic transistors is of high importance for successful implementation in low-power electronic applications. Here we report on low-voltage n-channel transistors fabricated employing a combination of soluble organic semiconductors and a self-assembled gate

  4. Alignment and Use of Self-Assembled Peptide Nanotubes as Dry-Etching Mask

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Castillo, Jaime; Bakmand, Tanya

    2012-01-01

    Self-assembled diphenylalanine peptide nanotubes provide a means of achieving nanostructured materials in a very simple and fast way. Recent discoveries have shown that this unique material, in addition to remaining stable under dry conditions, rapidly dissolves in water making it a promising can...

  5. Chaplins of Streptomyces coelicolor self-assemble into two distinct functional amyloids

    NARCIS (Netherlands)

    Bokhove, Marcel; Claessen, Dennis; de Jong, Wouter; Dijkhuizen, Lubbert; Boekema, Egbert J.; Oostergetel, Gert T.

    2013-01-01

    Chaplins are small, secreted proteins of streptomycetes that play instrumental roles in the formation of aerial hyphae and attachment of hyphae to surfaces. Here we show that the purified proteins self-assemble at a water/air interface into an asymmetric and amphipathic protein membrane that has an

  6. Water-soluble pentagonal-prismatic titanium-oxo clusters

    OpenAIRE

    Zhang, Guanyun; Liu, Caiyun; Long, De-Liang; Cronin, Leroy; Tung, Chen-Ho; Wang, Yifeng

    2016-01-01

    By using solubility control to crystallize the prenucleation clusters of hydrosol, a family of titanium-oxo clusters possessing the {Ti18O27} core in which the 18 Ti(IV)-ions are uniquely connected with μ-oxo ligands into a triple-decked pentagonal prism was obtained. The cluster cores are wrapped by external sulfate and aqua ligands, showing good solubilities and stabilities in a variety of solvents including acetonitrile and water and allowing their solution chemistry being studied by means...

  7. Self assembled silicon nanowire Schottky junction assisted by collagen

    Science.gov (United States)

    Stievenard, Didier; Sahli, Billel; Coffinier, Yannick; Boukherroub, Rabah; Melnyk, Oleg

    2008-03-01

    We present results on self assembled silicon nanowire Schottky junction assisted by collagen fibrous. The collagen is the principle protein of connective human tissues. It presents the double interest to be a low cost biological material with the possibility to be combed as the DNA molecule. First, the collagen was combed on OTS modified surface with gold electrodes. Second, silicon nanowires were grown on silicon substrate by CVD of silane gas (SiH4) at high temperature (500 C) using a vapor-liquid-solid (VLS) process and gold particles as catalysts. In order to increase electrostatic interaction between the collagen and the nanowires, these latters were chemically modified by mercaptopropylmethoxysilane (MPTS), then chemically oxidized. Therefore, the nanowires were transferred from their substrate into water and a drop of it deposited on the surface. Nanowires are only bound to collagen and in particular, in electrode gaps. The formation of spontaneous Schotkty junction is demonstrated by current-voltage characteristics.

  8. Phase Diagrams of Electrostatically Self-Assembled Amphiplexes

    Energy Technology Data Exchange (ETDEWEB)

    V Stanic; M Mancuso; W Wong; E DiMasi; H Strey

    2011-12-31

    We present the phase diagrams of electrostatically self-assembled amphiplexes (ESA) comprised of poly(acrylic acid) (PAA), cetyltrimethylammonium chloride (CTACl), dodecane, pentanol, and water at three different NaCl salt concentrations: 100, 300, and 500 mM. This is the first report of phase diagrams for these quinary complexes. Adding a cosurfactant, we were able to swell the unit cell size of all long-range ordered phases (lamellar, hexagonal, Pm3n, Ia3d) by almost a factor of 2. The added advantage of tuning the unit cell size makes such complexes (especially the bicontinuous phases) attractive for applications in bioseparation, drug delivery, and possibly in oil recovery.

  9. [Effects of snow cover on water soluble and organic solvent soluble components during foliar litter decomposition in an alpine forest].

    Science.gov (United States)

    Xu, Li-Ya; Yang, Wan-Qin; Li, Han; Ni, Xiang-Yin; He, Jie; Wu, Fu-Zhong

    2014-11-01

    Seasonal snow cover may change the characteristics of freezing, leaching and freeze-thaw cycles in the scenario of climate change, and then play important roles in the dynamics of water soluble and organic solvent soluble components during foliar litter decomposition in the alpine forest. Therefore, a field litterbag experiment was conducted in an alpine forest in western Sichuan, China. The foliar litterbags of typical tree species (birch, cypress, larch and fir) and shrub species (willow and azalea) were placed on the forest floor under different snow cover thickness (deep snow, medium snow, thin snow and no snow). The litterbags were sampled at snow formation stage, snow cover stage and snow melting stage in winter. The results showed that the content of water soluble components from six foliar litters decreased at snow formation stage and snow melting stage, but increased at snow cover stage as litter decomposition proceeded in the winter. Besides the content of organic solvent soluble components from azalea foliar litter increased at snow cover stage, the content of organic solvent soluble components from the other five foliar litters kept a continue decreasing tendency in the winter. Compared with the content of organic solvent soluble components, the content of water soluble components was affected more strongly by snow cover thickness, especially at snow formation stage and snow cover stage. Compared with the thicker snow covers, the thin snow cover promoted the decrease of water soluble component contents from willow and azalea foliar litter and restrain the decrease of water soluble component content from cypress foliar litter. Few changes in the content of water soluble components from birch, fir and larch foliar litter were observed under the different thicknesses of snow cover. The results suggested that the effects of snow cover on the contents of water soluble and organic solvent soluble components during litter decomposition would be controlled by

  10. Formulation of a Novel Nanoemulsion System for Enhanced Solubility of a Sparingly Water Soluble Antibiotic, Clarithromycin

    Directory of Open Access Journals (Sweden)

    Stuti Vatsraj

    2014-01-01

    Full Text Available The sparingly water soluble property of majority of medicinally significant drugs acts as a potential barrier towards its utilization for therapeutic purpose. The present study was thus aimed at development of a novel oil-in-water (o/w nanoemulsion (NE system having ability to function as carrier for poorly soluble drugs with clarithromycin as a model antibiotic. The therapeutically effective concentration of clarithromycin, 5 mg/mL, was achieved using polysorbate 80 combined with olive oil as lipophilic counterion. A three-level three-factorial central composite experimental design was utilized to conduct the experiments. The effects of selected variables, polysorbate 80 and olive oil content and concentration of polyvinyl alcohol, were investigated. The particle size of clarithromycin for the optimized formulation was observed to be 30 nm. The morphology of the nanoemulsion was explored using transmission electron microscopy (TEM. The emulsions prepared with the optimized formula demonstrated good physical stability during storage at room temperature. Antibacterial activity was conducted with the optimized nanoemulsion NESH 01 and compared with free clarithromycin. Zone of inhibition was larger for NESH 01 as compared to that with free clarithromycin. This implies that the solubility and hence the bioavailability of clarithromycin has increased in the formulated nanoemulsion system.

  11. Hydrocarbon molar water solubility predicts NMDA vs. GABAA receptor modulation.

    Science.gov (United States)

    Brosnan, Robert J; Pham, Trung L

    2014-11-19

    Many anesthetics modulate 3-transmembrane (such as NMDA) and 4-transmembrane (such as GABAA) receptors. Clinical and experimental anesthetics exhibiting receptor family specificity often have low water solubility. We hypothesized that the molar water solubility of a hydrocarbon could be used to predict receptor modulation in vitro. GABAA (α1β2γ2s) or NMDA (NR1/NR2A) receptors were expressed in oocytes and studied using standard two-electrode voltage clamp techniques. Hydrocarbons from 14 different organic functional groups were studied at saturated concentrations, and compounds within each group differed only by the carbon number at the ω-position or within a saturated ring. An effect on GABAA or NMDA receptors was defined as a 10% or greater reversible current change from baseline that was statistically different from zero. Hydrocarbon moieties potentiated GABAA and inhibited NMDA receptor currents with at least some members from each functional group modulating both receptor types. A water solubility cut-off for NMDA receptors occurred at 1.1 mM with a 95% CI = 0.45 to 2.8 mM. NMDA receptor cut-off effects were not well correlated with hydrocarbon chain length or molecular volume. No cut-off was observed for GABAA receptors within the solubility range of hydrocarbons studied. Hydrocarbon modulation of NMDA receptor function exhibits a molar water solubility cut-off. Differences between unrelated receptor cut-off values suggest that the number, affinity, or efficacy of protein-hydrocarbon interactions at these sites likely differ.

  12. Side-chain-controlled self-assembly of polystyrene-polypeptide miktoarm star copolymers

    KAUST Repository

    Junnila, Susanna

    2012-03-27

    We show how the self-assembly of miktoarm star copolymers can be controlled by modifying the side chains of their polypeptide arms, using A 2B and A 2B 2 type polymer/polypeptide hybrids (macromolecular chimeras). Initially synthesized PS 2PBLL and PS 2PBLL 2 (PS, polystyrene; PBLL, poly(ε-tert-butyloxycarbonyl-l-lysine) ) miktoarms were first deprotected to PS 2PLLHCl and PS 2PLLHCl 2 miktoarms (PLLHCl, poly(l-lysine hydrochloride)) and then complexed ionically with sodium dodecyl sulfonate (DS) to give the supramolecular complexes PS 2PLL(DS) and PS 2(PLL(DS)) 2. The solid-state self-assemblies of these six miktoarm systems were studied by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and small- and wide-angle X-ray scattering (SAXS, WAXS). The side chains of the polypeptide arms were observed to have a large effect on the solubility, polypeptide conformation, and self-assembly of the miktoarms. Three main categories were observed: (i) lamellar self-assemblies at the block copolymer length scale with packed layers of α-helices in PS 2PBLL and PS 2PBLL 2; (ii) charge-clustered polypeptide micelles with less-defined conformations in a nonordered lattice within a PS matrix in PS 2PLLHCl and PS 2PLLHCl 2; (iii) lamellar polypeptide-surfactant self-assemblies with β-sheet conformation in PS 2PLL(DS) and PS 2(PLL(DS)) 2 which dominate over the formation of block copolymer scale structures. Differences between the 3- and 4-arm systems illustrate how packing frustration between the coil-like PS arms and rigid polypeptide conformations can be relieved by the right number of arms, leading to differences in the extent of order. © 2012 American Chemical Society.

  13. Self-assembled Nanomaterials for Hybrid Electronic and Photonic Systems

    Science.gov (United States)

    2015-05-15

    Self-assembled Nanomaterials for Hybrid Electronic and Photonic Systems This grant studied DNA nanostructures and their applications in a variety of...Number of Papers published in non peer-reviewed journals: Final Report: Self-assembled Nanomaterials for Hybrid Electronic and Photonic Systems Report

  14. Combinatoric and mean field analysis of heterogeneous self assembly

    Science.gov (United States)

    2013-08-01

    REPORT Combinatoric and mean-field analysis of heterogeneous self-assembly 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: We present a stochastic analysis... Combinatoric and mean-field analysis of heterogeneous self-assembly Report Title ABSTRACT We present a stochastic analysis of heterogeneous

  15. Mechanisms of formation of self-assembled nanostructures in heteroepitaxy

    NARCIS (Netherlands)

    Kotrla, M.; Much, F.; Volkmann, T.; Biehl, M.; Sandera, P.

    2003-01-01

    We briefly review the recent results on formation of self-assembled nanostructures during heteroepitaxy of immiscible metals. The methods of microscopic modelling of multicomponent growth are described. Results of simulation of self-assembled structures with alternating strips using both lattice and

  16. Scalable Directed Self-Assembly Using Ultrasound Waves

    Science.gov (United States)

    2015-09-04

    at Aberdeen Proving Grounds (APG), to discuss a possible collaboration. The idea is to integrate the ultrasound directed self- assembly technique ...difference between the ultrasound technology studied in this project, and other directed self-assembly techniques is its scalability and...deliverable: A scientific tool to predict particle organization, pattern, and orientation, based on the operating and design parameters of the ultrasound

  17. Self-Assembly of Magnetic Colloids in Soft Confinement

    NARCIS (Netherlands)

    Liu, P.

    2016-01-01

    The central theme in this thesis is the effect of the soft confinements consisting of molecular microtubes and fluid interfaces, on the self-assembly of colloids. We have specially focused on the synthesis of magnetic colloids and the magnetic responses of self-assembled structures including

  18. Self-assembly of hydrolysed α-lactalbumin into nanotubes

    NARCIS (Netherlands)

    Graveland-Bikker, Johanna Frederike

    2005-01-01

    Self-assembly of proteins, peptides and DNA is a powerful approach for fabricating novel supramolecular architectures. Via this "bottom-up" approach many new nanomaterials have been and will be produced. Building blocks that self-assemble into fibrous materials are of special interest, because

  19. Different carboxylic acid homodimers in self-assemblies of adducts ...

    Indian Academy of Sciences (India)

    H2cpa) observed inthe self-assemblies of salts or cocrystals of H2cpa with nitrogen containing compounds are discussed. Pyridiniumsalt of the H2cpa is a self-assembly of Hcpa with the pyridinium cation. The assembly is a combinationof ...

  20. RNA self-assembly and RNA nanotechnology.

    Science.gov (United States)

    Grabow, Wade W; Jaeger, Luc

    2014-06-17

    CONSPECTUS: Nanotechnology's central goal involves the direct control of matter at the molecular nanometer scale to build nanofactories, nanomachines, and other devices for potential applications including electronics, alternative fuels, and medicine. In this regard, the nascent use of nucleic acids as a material to coordinate the precise arrangements of specific molecules marked an important milestone in the relatively recent history of nanotechnology. While DNA served as the pioneer building material in nucleic acid nanotechnology, RNA continues to emerge as viable alternative material with its own distinct advantages for nanoconstruction. Several complementary assembly strategies have been used to build a diverse set of RNA nanostructures having unique structural attributes and the ability to self-assemble in a highly programmable and controlled manner. Of the different strategies, the architectonics approach uniquely endeavors to understand integrated structural RNA architectures through the arrangement of their characteristic structural building blocks. Viewed through this lens, it becomes apparent that nature routinely uses thermodynamically stable, recurrent modular motifs from natural RNA molecules to generate unique and more complex programmable structures. With the design principles found in natural structures, a number of synthetic RNAs have been constructed. The synthetic nanostructures constructed to date have provided, in addition to affording essential insights into RNA design, important platforms to characterize and validate the structural self-folding and assembly properties of RNA modules or building blocks. Furthermore, RNA nanoparticles have shown great promise for applications in nanomedicine and RNA-based therapeutics. Nevertheless, the synthetic RNA architectures achieved thus far consist largely of static, rigid particles that are still far from matching the structural and functional complexity of natural responsive structural elements such

  1. Solvent mediated self-assembly of solids

    Energy Technology Data Exchange (ETDEWEB)

    De Yoreo, J.; Wilson, W.D.; Palmore, T.

    1997-12-12

    Solvent-mediated crystallization represents a robust approach to self-assembly of nanostructures and microstructures. In organic systems, the relative ease with which the structure of hydrogen- bonded molecules can be manipulated allows for generation of a wide variety of nanoscale crystal structures. In living organisms, control over the micron-to-millimeter form of inorganic crystals is achieved through introduction of bio-organic molecules. The purpose of this proposal is to understand the interplay between solution chemistry, molecular structure, surface chemistry, and the processes of nucleation and crystal growth in solvent-mediated systems, with the goal of developing the atomic and molecular basis of a solvent-mediated self-assembly technology. We will achieve this purpose by: (1) utilizing an atomic force microscopy (AFM) approach that provides in situ, real time imaging during growth from solutions, (2) by modifying kinetic Monte Carlo (KMC) models to include solution-surface kinetics, (3) by introducing quantum chemistry (QC) calculations of the potentials of the relevant chemical species and the near-surface structure of the solution, and (4) by utilizing molecular dynamics (MD) simulations to identify the minimum energy pathways to the solid state. Our work will focus on two systems chosen to address both the manometer and micron-to-millimeter length scales of assembly, the family of 2,5- diketopiperazines (X-DKPs) and the system of CaCO{sub 3} with amino acids. Using AFM, we will record the evolution of surface morphology, critical lengths, step speeds, and step-step interactions as a function of supersaturation and temperature. In the case of the X-DKPs, these measurements will be repeated as the molecular structure of the growth unit is varied. In the case of CaCO{sub 3}, they will be performed as a function of solution chemistry including pH, ionic strength, and amino acid content. In addition, we will measure nucleation rates and orientations of

  2. Cationic xylan adsorption onto self-assembled monolayers and model cellulose surfaces

    Science.gov (United States)

    Esker, Alan; Kaya, Abdulaziz; Drazenovich, Daniel; Glasser, Wolfgang; Schwikal, Katrin; Heinze, Thomas

    2009-03-01

    Self-assembly of cationic hydroxypropyltrimethylammonium xylans (HPMAs) with different degrees of substitution (DS) onto self-assembled monolayers (SAMs) and model cellulose surfaces has been investigated by surface plasmon resonance (SPR). Maximal adsorption of HPMAs onto COOH-terminated SAMs occurs at an intermediate DS=0.10. Ionic strength effects on adsorbed amount follow different trends at low and high DS values which qualitatively agree with predictions of scaling theory for polyelectrolyte adsorption. For adsorption onto model cellulose surfaces and OH-terminated SAMs, surface excess values are relatively low compared to COOH-terminated SAMs. For adsorption onto CH3-terminated SAMs, solubility of the HPMAs plays an important role as HPMA adsorption decreases with increasing DS values.

  3. Water-soluble conjugated polymers for fluorescent-enzyme assays.

    Science.gov (United States)

    Feng, Fude; Liu, Libing; Yang, Qiong; Wang, Shu

    2010-08-17

    Enzyme assays are receiving more and more research and application interest because of the rapidly increasing demands of clinical diagnosis, environmental analysis, drug discovery, and molecular biology. Water-soluble light-harvesting conjugated polymers (CPs) coordinate the action of a large number of absorbing units to afford an amplified fluorescence signal, which makes them useful as optical platforms in highly sensitive chemical and biological sensors. This Feature Article highlights recent developments of water-soluble CPs for fluorescent assays of enzymes. Different signal transduction mechanisms, such as electron transfer, fluorescence resonance energy transfer (FRET), and aggregation or conformation changes of CPs, are employed in these assays according to the dissimilar nature of enzymes. Potential challenges and future research directions in these approaches based on CPs are also discussed. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Initial condition of stochastic self-assembly.

    Science.gov (United States)

    Davis, Jason K; Sindi, Suzanne S

    2016-02-01

    The formation of a stable protein aggregate is regarded as the rate limiting step in the establishment of prion diseases. In these systems, once aggregates reach a critical size the growth process accelerates and thus the waiting time until the appearance of the first critically sized aggregate is a key determinant of disease onset. In addition to prion diseases, aggregation and nucleation is a central step of many physical, chemical, and biological process. Previous studies have examined the first-arrival time at a critical nucleus size during homogeneous self-assembly under the assumption that at time t=0 the system was in the all-monomer state. However, in order to compare to in vivo biological experiments where protein constituents inherited by a newly born cell likely contain intermediate aggregates, other possibilities must be considered. We consider one such possibility by conditioning the unique ergodic size distribution on subcritical aggregate sizes; this least-informed distribution is then used as an initial condition. We make the claim that this initial condition carries fewer assumptions than an all-monomer one and verify that it can yield significantly different averaged waiting times relative to the all-monomer condition under various models of assembly.

  5. Functional Self-Assembled Nanofibers by Electrospinning

    Science.gov (United States)

    Greiner, A.; Wendorff, J. H.

    Electrospinning constitutes a unique technique for the production of nanofibers with diameters down to the range of a few nanometers. In strong contrast to conventional fiber producing techniques, it relies on self-assembly processes driven by the Coulomb interactions between charged elements of the fluids to be spun to nanofibers. The transition from a macroscopic fluid object such as a droplet emerging from a die to solid nanofibers is controlled by a set of complex physical instability processes. They give rise to extremely high extensional deformations and strain rates during fiber formation causing among others a high orientational order in the nanofibers as well as enhanced mechanical properties. Electrospinning is predominantly applied to polymer based materials including natural and synthetic polymers, but, more recently, its use has been extended towards the production of metal, ceramic and glass nanofibers exploiting precursor routes. The nanofibers can be functionalized during electrospinning by introducing pores, fractal surfaces, by incorporating functional elements such as catalysts, quantum dots, drugs, enzymes or even bacteria. The production of individual fibers, random nonwovens, or orientationally highly ordered nonwovens is achieved by an appropriate selection of electrode configurations. Broad areas of application exist in Material and Life Sciences for such nanofibers, including not only optoelectronics, sensorics, catalysis, textiles, high efficiency filters, fiber reinforcement but also tissue engineering, drug delivery, and wound healing. The basic electrospinning process has more recently been extended towards compound co-electrospinning and precision deposition electrospinning to further broaden accessible fiber architectures and potential areas of application.

  6. What promotes derected self assembly (DSA)?

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, S.T.

    2016-09-01

    A low-energy electron beam (EB) can create self-interstitial atoms (SIA) in a solid and can cause directed self-assembly (DSA), e.g. {3 1 1}{sub SIA} platelets in c-Si. The crystalline structure of this planar defect is known from experiment to be made up of SIAs that form well aligned 〈1 1 0〉 atomic rows on each (3 1 1) plane. To simulate the experiment we distributed Frenkel pairs (FP) randomly in bulk c-Si. Then making use of a molecular dynamic (MD) simulation, we have reproduced the experimental result, where SIAs are trapped at metastable sites in bulk. With increasing pre-doped FP concentration, the number of SIAs that participate in DSA tends to be increased but soon slightly supressed. On the other hand, when the FP concentration is less than 3%, a cooperative motion of target atoms was characterized from the long-range-order (LRO) parameter. Here we investigated the correlation between DSA and that cooperative motion, by adding a case of intrinsic c-Si. We confirmed that the cooperative motion slightly promote DSA by assisting migration of SIAs toward metastable sites as long as the FP concentration is less than 3%, however, it is essentially independent of DSA.

  7. Self-assembly programming of DNA polyominoes.

    Science.gov (United States)

    Ong, Hui San; Syafiq-Rahim, Mohd; Kasim, Noor Hayaty Abu; Firdaus-Raih, Mohd; Ramlan, Effirul Ikhwan

    2016-10-20

    Fabrication of functional DNA nanostructures operating at a cellular level has been accomplished through molecular programming techniques such as DNA origami and single-stranded tiles (SST). During implementation, restrictive and constraint dependent designs are enforced to ensure conformity is attainable. We propose a concept of DNA polyominoes that promotes flexibility in molecular programming. The fabrication of complex structures is achieved through self-assembly of distinct heterogeneous shapes (i.e., self-organised optimisation among competing DNA basic shapes) with total flexibility during the design and assembly phases. In this study, the plausibility of the approach is validated using the formation of multiple 3×4 DNA network fabricated from five basic DNA shapes with distinct configurations (monomino, tromino and tetrominoes). Computational tools to aid the design of compatible DNA shapes and the structure assembly assessment are presented. The formations of the desired structures were validated using Atomic Force Microscopy (AFM) imagery. Five 3×4 DNA networks were successfully constructed using combinatorics of these five distinct DNA heterogeneous shapes. Our findings revealed that the construction of DNA supra-structures could be achieved using a more natural-like orchestration as compared to the rigid and restrictive conventional approaches adopted previously. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Optical orientation in self assembled quantum dots

    CERN Document Server

    Stevens, G C

    2002-01-01

    We examined Zeeman splitting in a series of ln sub x Ga sub ( sub 1 sub - sub x sub ) As/GaAs self assembled quantum dots (SAQD's) with different pump polarisations. All these measurements were made in very low external magnetic fields where direct determination of the Zeeman splitting energy is impossible due to its small value in comparison to the photoluminescence linewidths. The use of a technique developed by M. J. Snelling allowed us to obtain the Zeeman splitting and hence the excitonic g-factors indirectly. We observed a linear low field splitting, becoming increasingly non-linear at higher fields. We attribute this non-linearity to field induced level mixing. It is believed these are the first low field measurements in these structures. A number of apparent nuclear effects in the Zeeman splitting measurements led us onto the examination of nuclear effects in these structures. The transverse and oblique Hanie effects then allowed us to obtain the sign of the electronic g-factors in two of our samples,...

  9. Size-Controlled Water-Soluble Ag Nanoparticles

    OpenAIRE

    Dominguez-Vera, J. M.; Galvez, N.; Sanchez, P; A. J. Mota; Trasobares Llorente, Susana; Hernandez, J.C.; Calvino Gámez, José Juan

    2007-01-01

    Ag nanoparticles of two different sizes (1 and 4 nm) were prepared within an apoferritin cavity by using an Ag+-loaded apoferritin as a nanoconfined environment for their construction. The initial amount of Ag' ions injected in the apoferritin cavity dictates the size of the final Ag particles. The protein shell prevents bulk aggregation of the metal particles, which renders them water soluble and extremely stable.

  10. Water sorption, solubility and surface roughness of resin surface sealants

    OpenAIRE

    Biazuz,Jaqueline; Zardo,Patrícia; Rodrigues-Junior,Sinval Adalberto

    2015-01-01

    Surface sealants have been suggested as final glaze of the surface of composite restorations. However, little is known about bulk and surface properties of these materials aiming the long-term preservation of the surface integrity of these restorations. AIM: To evaluate the water sorption, solubility and surface roughness of commercial surface sealants for restorations. METHODS: Five disc-shaped specimens 15 mm diameter X 1 mm high were made from the surface sealants Natural Glaze DFL and Per...

  11. Fabrication of bioinspired nanostructured materials via colloidal self-assembly

    Science.gov (United States)

    Huang, Wei-Han

    Through millions of years of evolution, nature creates unique structures and materials that exhibit remarkable performance on mechanicals, opticals, and physical properties. For instance, nacre (mother of pearl), bone and tooth show excellent combination of strong minerals and elastic proteins as reinforced materials. Structured butterfly's wing and moth's eye can selectively reflect light or absorb light without dyes. Lotus leaf and cicada's wing are superhydrophobic to prevent water accumulation. The principles of particular biological capabilities, attributed to the highly sophisticated structures with complex hierarchical designs, have been extensively studied. Recently, a large variety of novel materials have been enabled by natural-inspired designs and nanotechnologies. These advanced materials will have huge impact on practical applications. We have utilized bottom-up approaches to fabricate nacre-like nanocomposites with "brick and mortar" structures. First, we used self-assembly processes, including convective self-assembly, dip-coating, and electrophoretic deposition to form well oriented layer structure of synthesized gibbsite (aluminum hydroxide) nanoplatelets. Low viscous monomer was permeated into layered nanoplatelets and followed by photo-curing. Gibbsite-polymer composite displays 2 times higher tensile strength and 3 times higher modulus when compared with pure polymer. More improvement occurred when surface-modified gibbsite platelets were cross-linked with the polymer matrix. We observed ˜4 times higher strength and nearly 1 order of magnitude higher modulus than pure polymer. To further improve the mechanical strength and toughness of inorganicorganic nanocomposites, we exploited ultrastrong graphene oxide (GO), a single atom thick hexagonal carbon sheet with pendant oxidation groups. GO nanocomposite is made by co-filtrating GO/polyvinyl alcohol suspension on 0.2 im pore-sized membrane. It shows ˜2 times higher strength and ˜15 times higher

  12. Polyelectrolyte microcapsules for sustained delivery of water-soluble drugs

    Energy Technology Data Exchange (ETDEWEB)

    Anandhakumar, S.; Debapriya, M. [Department of Materials Engineering, Indian Institute of Science, Bangalore, 560012 (India); Nagaraja, V. [Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012 (India); Raichur, Ashok M., E-mail: amr@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science, Bangalore, 560012 (India)

    2011-03-12

    Polyelectrolyte capsules composed of weak polyelectrolytes are introduced as a simple and efficient system for spontaneous encapsulation of low molecular weight water-soluble drugs. Polyelectrolyte capsules were prepared by layer-by-layer (LbL) assembling of weak polyelectrolytes, poly(allylamine hydrochloride) (PAH) and poly(methacrylic acid) (PMA) on polystyrene sulfonate (PSS) doped CaCO{sub 3} particles followed by core removal with ethylene-diaminetetraacetic acid (EDTA). The loading process was observed by confocal laser scanning microscopy (CLSM) using tetramethylrhodamineisothiocyanate labeled dextran (TRITC-dextran) as a fluorescent probe. The intensity of fluorescent probe inside the capsule decreased with increase in cross-linking time. Ciprofloxacin hydrochloride (a model water-soluble drug) was spontaneously deposited into PAH/PMA capsules and their morphological changes were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The quantitative study of drug loading was also elucidated which showed that drug loading increased with initial drug concentration, but decreased with increase in pH. The loaded drug was released in a sustained manner for 6 h, which could be further extended by cross-linking the capsule wall. The released drug showed significant antibacterial activity against E. coli. These findings indicate that such capsules can be potential carriers for water-soluble drugs in sustained/controlled drug delivery applications.

  13. Hybrid solar cells from water-soluble polymers

    Directory of Open Access Journals (Sweden)

    James T. McLeskey

    2006-01-01

    Full Text Available We report on the use of a water-soluble, light-absorbing polythiophene polymer to fabricate novel photovoltaic devices. The polymer is a water-soluble thiophene known as sodium poly[2-(3-thienyl-ethoxy-4-butylsulfonate] or PTEBS. The intention is to take advantage of the properties of conjugated polymers (flexible, tunable, and easy to process and incorporate the additional benefits of water solubility (easily controlled evaporation rates and environmentally friendly. The PTEBS polythiophene has shown significant photovoltaic response and has been found to be effective for making solar cells. To date, solar cells in three different configurations have been produced: titanium dioxide (TiO2 bilayer cells, TiO2 bulk heterojunction solar cells, and carbon nanotubes (CNTs in bulk heterojunctions. The best performance thus far has been achieved with TiO2 bilayer devices. These devices have an open circuit voltage (Voc of 0.84V, a short circuit current (Jsc of 0.15 mA/cm2, a fill factor (ff of 0.91, and an efficiency (η of 0.15 %.

  14. Preparation and Characterization of Water-Soluble Xylan Ethers

    Directory of Open Access Journals (Sweden)

    Kay Hettrich

    2017-03-01

    Full Text Available Xylan is a predominant hemicellulose component that is found in plants and in some algae. This polysaccharide is made from units of xylose (a pentose sugar. One promising source of xylan is oat spelt. This feedstock was used for the synthesis of two xylan ethers. To achieve water soluble products, we prepared dihydroxypropyl xylan as a non-ionic ether on the one hand, and carboxymethyl xylan as an ionic derivative on the other hand. Different preparation methods like heterogeneous, pseudo-homogeneous, and homogeneous syntheses were compared. In the case of dihydroxypropyl xylan, the synthesis method did not significantly affect the degree of substitution (DS. In contrast, in the case of carboxymethyl xylan, clear differences of the DS values were found in dependence on the synthesis method. Xylan ethers with DS values of >1 could be obtained, which mostly show good water solubility. The synthesized ionic, as well as non-ionic, xylan ethers were soluble in water, even though the aqueous solutions showed slight turbidity. Nevertheless, stable, transparent, and stainable films could be prepared from aqueous solutions from carboxymethyl xylans.

  15. Enzyme-assisted self-assembly under thermodynamic control.

    Science.gov (United States)

    Williams, Richard J; Smith, Andrew M; Collins, Richard; Hodson, Nigel; Das, Apurba K; Ulijn, Rein V

    2009-01-01

    The production of functional molecular architectures through self-assembly is commonplace in biology, but despite advances, it is still a major challenge to achieve similar complexity in the laboratory. Self-assembled structures that are reproducible and virtually defect free are of interest for applications in three-dimensional cell culture, templating, biosensing and supramolecular electronics. Here, we report the use of reversible enzyme-catalysed reactions to drive self-assembly. In this approach, the self-assembly of aromatic short peptide derivatives provides a driving force that enables a protease enzyme to produce building blocks in a reversible and spatially confined manner. We demonstrate that this system combines three features: (i) self-correction--fully reversible self-assembly under thermodynamic control; (ii) component-selection--the ability to amplify the most stable molecular self-assembly structures in dynamic combinatorial libraries; and (iii) spatiotemporal confinement of nucleation and structure growth. Enzyme-assisted self-assembly therefore provides control in bottom-up fabrication of nanomaterials that could ultimately lead to functional nanostructures with enhanced complexities and fewer defects.

  16. Effect of water and salt content on protein solubility and water retention of meat preblends.

    Science.gov (United States)

    Kenney, P B; Hunt, M C

    1990-01-01

    Different preblend water contents at a constant ionic strength were investigated to determine if increasing water availability would increase protein solubility and water retention in meat preblends. Four salt levels (0, 2, 4 and 8%) and four water levels (0, 20, 40 and 80% formulation water) were used with ground bovine semimembranosus muscle that had been frozen once. Ground muscle was mixed with either NaCl alone (0% formulation water) or NaCl and brine (20, 40 and 80% formulation water) for the 2, 4 and 8% NaCl treatments. Distilled water was used for the 0% NaCl treatment. The mixtures were stored at 5°C for 12 h. Following storage, the water/brine content was standardized, and protein solubility and water retention were measured. Elevating the water content of preblends, in which the salt concentration had been standardized, increased the water retained during centrifugation (P water retention. Copyright © 1990. Published by Elsevier Ltd.

  17. Fibrin self-assembly is adapted to oxidation.

    Science.gov (United States)

    Rosenfeld, Mark A; Bychkova, Anna V; Shchegolikhin, Alexander N; Leonova, Vera B; Kostanova, Elizaveta A; Biryukova, Marina I; Sultimova, Natalia B; Konstantinova, Marina L

    2016-06-01

    Fibrinogen is extremely susceptible to attack by reactive oxygen species (ROS). Having been suffered an oxidative modification, the fibrinogen molecules, now with altered spatial structure and function of fibrin network, affect hemostasis differently. However, the potential effects of the oxidative stress on the early stages of the fibrin self-assembly process remain unexplored. To clarify the damaging influence of ROS on the knob 'A': hole 'a' and the D:D interactions, the both are operating on the early stages of the fibrin polymerization, we have used a novel approach based on exploration of FXIIIa-mediated self-assembly of the cross-linked fibrin oligomers dissolved in the moderately concentrated urea solutions. The oligomers were composed of monomeric desA fibrin molecules created by cleaving the fibrinopeptides A off the fibrinogen molecules with a thrombin-like enzyme, reptilase. According to the UV-absorbance and fluorescence measurements data, the employed low ozone/fibrinogen ratios have induced only a slight fibrinogen oxidative modification that was accompanied by modest chemical transformations of the aromatic amino acid residues of the protein. Else, a slight consumption of the accessible tyrosine residues has been observed due to intermolecular dityrosine cross-links formation. The set of experimental data gathered with the aid of electrophoresis, elastic light scattering and analytical centrifugation has clearly witnessed that the oxidation can serve as an effective promoter for the observed enhanced self-assembly of the covalently cross-linked oligomers. At urea concentration of 1.20M, the pristine and oxidized fibrin oligomers were found to comprise a heterogeneous set of the double-stranded protofibrils that are cross-linked only by γ-γ dimers and the fibers consisting on average of four strands that are additionally linked by α polymers. The amounts of the oxidized protofibrils and the fibers accumulated in the system were higher than those

  18. Magnetic manipulation of self-assembled colloidal asters.

    Energy Technology Data Exchange (ETDEWEB)

    Snezhko, A.; Aranson, I. S. (Materials Science Division)

    2011-09-01

    Self-assembled materials must actively consume energy and remain out of equilibrium to support structural complexity and functional diversity. Here we show that a magnetic colloidal suspension confined at the interface between two immiscible liquids and energized by an alternating magnetic field dynamically self-assembles into localized asters and arrays of asters, which exhibit locomotion and shape change. By controlling a small external magnetic field applied parallel to the interface, we show that asters can capture, transport, and position target microparticles. The ability to manipulate colloidal structures is crucial for the further development of self-assembled microrobots

  19. Functional self-assembled lipidic systems derived from renewable resources.

    Science.gov (United States)

    Silverman, Julian R; Samateh, Malick; John, George

    2016-01-01

    Self-assembled lipidic amphiphile systems can create a variety of multi-functional soft materials with value-added properties. When employing natural reagents and following biocatalytic syntheses, self-assembling monomers may be inherently designed for degradation, making them potential alternatives to conventional and persistent polymers. By using non-covalent forces, self-assembled amphiphiles can form nanotubes, fibers, and other stimuli responsive architectures prime for further applied research and incorporation into commercial products. By viewing these lipid derivatives under a lens of green principles, there is the hope that in developing a structure-function relationship and functional smart materials that research may remain safe, economic, and efficient.

  20. Physicochemical characterization of cellulose nanocrystal and nanoporous self-assembled CNC membrane derived from Ceiba pentandra.

    Science.gov (United States)

    Mohamed, Mohamad Azuwa; W Salleh, W N; Jaafar, Juhana; Ismail, A F; Abd Mutalib, Muhazri; Mohamad, Abu Bakar; M Zain, M F; Awang, Nor Asikin; Mohd Hir, Zul Adlan

    2017-02-10

    This research involves the rare utilisation of the kapok fibre (Ceiba pentandra) as a raw material for the fabrication of cellulose nanocrystal (CNC) and self-assembled CNC membranes. The isolation of CNC from Ceiba pentandra began with the extraction of cellulose via the chemical alkali extraction by using 5wt% NaOH, followed by the typical acidified bleaching method and, finally, the CNC production through acid hydrolysis with 60wt% H2SO4 at the optimum time of 60min. The prepared CNC was then employed for the preparation of self-assembled membrane through the water suspension casting evaporation technique. The obtained CNC membrane was characterised in terms of its composition, crystallinity, thermal stability, as well as, structural and morphological features with the use of several techniques including FTIR, XRD, AFM, TEM, FESEM, and TGA. The FESEM and AFM analyses had illustrated the achievement of a self-assembled CNC membrane with a smooth surface and a well-distributed nano-porous structure, with the porosity of 52.82±7.79%. In addition, the findings proved that the self-assembled CNC membrane displayed good adsorption capability indicated by the recorded efficiency of 79% and 85% for 10mg/L and 5mg/L of methylene blue in an aqueous solution, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Functionalized fullerenes in self-assembled monolayers.

    Science.gov (United States)

    Gimenez-Lopez, Maria del Carmen; Räisänen, Minna T; Chamberlain, Thomas W; Weber, Uli; Lebedeva, Maria; Rance, Graham A; Briggs, G Andrew D; Pettifor, David; Burlakov, Victor; Buck, Manfred; Khlobystov, Andrei N

    2011-09-06

    Anisotropy of intermolecular and molecule-substrate interactions holds the key to controlling the arrangement of fullerenes into 2D self-assembled monolayers (SAMs). The chemical reactivity of fullerenes allows functionalization of the carbon cages with sulfur-containing groups, thiols and thioethers, which facilitates the reliable adsorption of these molecules on gold substrates. A series of structurally related molecules, eight of which are new fullerene compounds, allows systematic investigation of the structural and functional parameters defining the geometry of fullerene SAMs. Scanning tunnelling microscopy (STM) measurements reveal that the chemical nature of the anchoring group appears to be crucial for the long-range order in fullerenes: the assembly of thiol-functionalized fullerenes is governed by strong molecule-surface interactions, which prohibit formation of ordered molecular arrays, while thioether-functionalized fullerenes, which have a weaker interaction with the surface than the thiols, form a variety of ordered 2D molecular arrays owing to noncovalent intermolecular interactions. A linear row of fullerene molecules is a recurring structural feature of the ordered SAMs, but the relative alignment and the spacing between the fullerene rows is strongly dependent on the size and shape of the spacer group linking the fullerene cage and the anchoring group. Careful control of the chemical functionality on the carbon cages enables positioning of fullerenes into at least four different packing arrangements, none of which have been observed before. Our new strategy for the controlled arrangement of fullerenes on surfaces at the molecular level will advance the development of practical applications for these nanomaterials. © 2011 American Chemical Society

  2. Water-soluble fullerene derivatives for drug discovery.

    Science.gov (United States)

    Nakamura, Shigeo; Mashino, Tadahiko

    2012-01-01

    Fullerenes (represented by buckminsterfullerene, C(60)) are a new kind of organic compound with a cage-like structure. A great deal of attention has been focused on their unique properties. From the viewpoint of drug discovery, fullerenes could be novel lead compounds for drug discovery. However, fullerenes are poorly soluble in aqueous media. Incorporation of water-soluble groups into the fullerene core enables investigation of its biological activities. Certain fullerene derivatives show inhibitory activity against human immunodeficiency virus reverse transcriptase. Hepatitis C virus RNA polymerase is also inhibited by fullerene derivatives. Therefore, fullerene derivatives are candidate antiviral agents. In addition, fullerene derivatives exhibit antiproliferative activity by inducing apoptosis related to the generation of reactive oxygen species. Fullerene derivatives also have the potential to be anticancer drugs.

  3. Mechanisms for oral absorption of poorly water-soluble compounds

    DEFF Research Database (Denmark)

    Lind, Marianne Ladegaard

    viability and monolayer integrity were developed. The effect of simulated intestinal fluids on the absorption of the poorly water-soluble drug substances, estradiol and diazepam, was studied. The flux of both drug substances across the Caco-2 cells was decreased when simulated intestinal fluids containing...... micelles were applied in the apical compartment. The flux of diazepam was further decreased when pharmaceutical surfactants (Labrafil, fatty acid ester of polyethylene glycol, Cremophor RH40, polysorbate 80 and Pluronic L81) were added to the medium. This was most likely caused by partial incorporation...... of the drug substances in the micelles, and accordingly the drug substances need to be released from the micelles before being absorbed. However, the solubility of estradiol and diazepam was higher in the simulated intestinal fluids, indicating that the presence of bile salts, phospholipids and lipolysis...

  4. Novel water-soluble polyurethane nanomicelles for cancer chemotherapy: physicochemical characterization and cellular activities

    Directory of Open Access Journals (Sweden)

    Khosroushahi Ahmad

    2012-01-01

    Full Text Available Abstract Background Efficient delivery of anticancer chemotherapies such as paclitaxel (PTX can improve treatment strategy in a variety of tumors such as breast and ovarian cancers. Accordingly, researches on polymeric nanomicelles continue to find suitable delivery systems. However, due to biocompatibility concerns, a few micellar nanoformulations have exquisitely been translated into clinical uses. Here, we report the synthesis of novel water-soluble nanomicelles using bioactive polyurethane (PU polymer and efficient delivery of PTX in the human breast cancer MCF-7 cells. Results The amphiphilic polyurethane was prepared through formation of urethane bounds between hydroxyl groups in poly (tetramethylene ether glycol (PTMEG and dimethylol propionic acid with isocyanate groups in toluene diisocyanate (TDI. The free isocyanate groups were blocked with phenol, while the free carboxyl groups of dimethylol propionic acid were reacted with triethylamine to attain ionic centers in the polymer backbone. These hydrophobic PTMEG blocks displayed self-assembly forming polymeric nanomicelles in water. The PTX loaded PU nanomicelles showed suitable physical stability, negative zeta potential charge (-43 and high loading efficiency (80% with low level of critical micelle concentration (CMC. In vitro drug release profile showed a faster rate of drug liberation at pH 5.4 as compared to that of pH 7.4, implying involvement of a pH-sensitive mechanism for drug release from the nanomicelles. The kinetic of release exquisitely obeyed the Higuchi model, confirming involvement of diffusion and somewhat erosion at pH 5.4. These nanomicelles significantly inhibited the growth and proliferation of the human breast cancer MCF-7 cells, leading them to apoptosis. The real time RT-PCR analysis confirmed the activation of apoptosis as result of liberation of cytochrome c in the cells treated with the PTX loaded PU nanomicelles. The comet assay analysis showed somewhat DNA

  5. Synthesis and anticancer properties of water-soluble zinc ionophores.

    Science.gov (United States)

    Magda, Darren; Lecane, Philip; Wang, Zhong; Hu, Weilin; Thiemann, Patricia; Ma, Xuan; Dranchak, Patricia K; Wang, Xiaoming; Lynch, Vincent; Wei, Wenhao; Csokai, Viktor; Hacia, Joseph G; Sessler, Jonathan L

    2008-07-01

    Several water-solubilized versions of the zinc ionophore 1-hydroxypyridine-2-thione (ZnHPT), synthesized as part of the present study, have been found both to increase the intracellular concentrations of free zinc and to produce an antiproliferative activity in exponential phase A549 human lung cancer cultures. Gene expression profiles of A549 cultures treated with one of these water-soluble zinc ionophores, PCI-5002, reveal the activation of stress response pathways under the control of metal-responsive transcription factor 1 (MTF-1), hypoxia-inducible transcription factor 1 (HIF-1), and heat shock transcription factors. Additional oxidative stress response and apoptotic pathways were activated in cultures grown in zinc-supplemented media. We also show that these water-soluble zinc ionophores can be given to mice at 100 micromol/kg (300 micromol/m(2)) with no observable toxicity and inhibit the growth of A549 lung and PC3 prostate cancer cells grown in xenograft models. Gene expression profiles of tumor specimens harvested from mice 4 h after treatment confirmed the in vivo activation of MTF-1-responsive genes. Overall, we propose that water-solubilized zinc ionophores represent a potential new class of anticancer agents.

  6. Water sorption and water solubility of self-etching and self-adhesive resin cements.

    Science.gov (United States)

    Petropoulou, Aikaterini; Vrochari, Areti D; Hellwig, Elmar; Stampf, Susanne; Polydorou, Olga

    2015-11-01

    The long-term success of indirect restorations depends on the clinical behavior of luting cements. In the oral environment, properties such as water sorption and solubility negatively affect the cements' clinical performance over time, jeopardizing the restoration's longevity. The purpose of this in vitro study was to compare the water sorption and solubility characteristics of self-etching, self-adhesive, and conventional resin cements. One conventional (Calibra), 1 self-etching (Panavia F), and 2 self-adhesive (Clearfil SA, G-Cem Automix) dual-polymerized resin cements were used. Fourteen disks of each material were prepared. Water sorption and solubility were calculated according to International Organization for Standards (ISO) specification 4049:2009. According to the water sorption test, all materials were found to interact with water. No statistically significant differences were found between the water sorption of Panavia F and Clearfil SA (P=.911). These cements exhibited higher water sorption values than the other materials (Psolubility (Psolubility values than the other materials. G-Cem Automix and Calibra exhibited negative solubility. However, all water sorption and solubility values were below the threshold values proposed by the ISO standard. Within the limitations of the present in vitro study, the interaction of resin cements with water is not type-related (conventional, self-etching, or self-adhesive). Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  7. Self-Assembling Wireless Autonomous Reconfigurable Modules (SWARM) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Payload Systems Inc. and the MIT Space Systems Laboratory propose Self-assembling, Wireless, Autonomous, Reconfigurable Modules (SWARM) as an innovative approach to...

  8. DNA Self-assembly Catalyzed by Artificial Agents.

    Science.gov (United States)

    Shi, Chao; Wang, Yifan; Zhang, Menghua; Ma, Cuiping

    2017-07-28

    Nucleic acids have been shown to be versatile molecules and engineered to produce various nanostructures. However, the poor rate of these uncatalyzed nucleic acid reactions has restricted the development and applications. Herein, we reported a novel finding that DNA self-assembly could be nonenzymatically catalyzed by artificial agents with an increasing dissociation rate constant K2. The catalytic role of several artificial agents in DNA self-assembly was verified by real-time fluorescent detection or agarose gel electrophoresis. We found that 20% PEG 200 could significantly catalyze DNA self-assembly and increase the reaction efficiency, such as linear hybridization chain reaction (HCR) and exponential hairpin assembly (EHA). Therefore, we foresee that a fast and efficient DNA self-assembly in structural DNA nanotechnology will be desirable.

  9. A review on self-assembly in microfluidic devices

    Science.gov (United States)

    Dou, Yingying; Wang, Bingsheng; Jin, Mingliang; Yu, Ying; Zhou, Guofu; Shui, Lingling

    2017-11-01

    Self-assembly is a process that operates over a vast range of length and time scales. Microfluidic technology has been proven to be a powerful tool to manipulate micro- and nano-scale substrates with precise control over size and speed using various fluidic materials and properties. In this review, we discuss the current status of microfluidic technology in manipulating fluid dynamics and interfacial phenomena which influence self-assembly process and resulted structures. The self-assembled materials/structures were summarized and discussed as the sequence of the objective size at the micro-, nano- and molecular scale. Overall, microfluidics is becoming a useful tool to manipulate various fluids regarding to physical and chemical properties, being inherently suitable for self-assembly process control.

  10. Enzymatic self-assembly of nanostructures for theranostics.

    Science.gov (United States)

    Chen, Yue; Liang, Gaolin

    2012-01-01

    Self-assembly of small molecules or macromolecules through non-covalent or covalent bonds to build up supramolecular nanostructures is a prevalent and important process in nature. While most chemists use small molecules to assemble nanostructures with physical or chemical perturbations, nature adopts enzymes to catalyze the reaction to assemble biological, functional nanostructures with high efficiency and specificity. Although enzymatic self-assembly of nanostructures has been remained challenging for chemists, there are still a few examples of using important enzymes to initiate the self-assembly of nanostructures for diagnosis or therapy of certain diseases because down-regulation or overexpression of certain enzymes always associates with abnormalities of tissues/organs or diseases in living body. Herein, we introduce the concept of enzymatic self-assembly and illustrate the design and application of enzyme-catalyzed or -regulated formation of nanostructures for theranostics.

  11. Self-assembling Venturi-like peptide nanotubes.

    Science.gov (United States)

    Fuertes, Alberto; Ozores, Haxel Lionel; Amorín, Manuel; Granja, Juan R

    2017-01-05

    We describe the design and synthesis of self-assembling peptide nanotubes that have an internal filter area and whose length and internal diameters, at the entrance and in the constricted area, are precisely controlled.

  12. Urethane tetrathiafulvalene derivatives: synthesis, self-assembly and electrochemical properties

    Directory of Open Access Journals (Sweden)

    Xiang Sun

    2015-11-01

    Full Text Available This paper reports the self-assembly of two new tetrathiafulvalene (TTF derivatives that contain one or two urethane groups. The formation of nanoribbons was evidenced by scanning electron microscopy (SEM and X-ray diffraction (XRD, which showed that the self-assembly ability of T1 was better than that of T2. The results revealed that more urethane groups in a molecule did not necessarily instigate self-assembly. UV–vis and FTIR spectra were measured to explore noncovalent interactions. The driving forces for self-assembly of TTF derivatives were mainly hydrogen bond interactions and π–π stacking interactions. The electronic conductivity of the T1 and T2 films was tested by a four-probe method.

  13. Multiresponsive self-assembled liquid crystals with azobenzene groups.

    Science.gov (United States)

    Xu, Miao; Chen, Liqin; Zhou, Yifeng; Yi, Tao; Li, Fuyou; Huang, Chunhui

    2008-10-15

    An optical and electric field-responsive self-assembled complex containing nitril azobenzene groups and 1,3,5-triazine-2,4-diamine was obtained and characterized. Both the azobenzene precursor and the complex form a liquid-crystalline phase in a certain temperature range. The transition temperature from crystalline phase to liquid-crystalline mesophase was obviously decreased in the complex by the self-assembling. The self-assembled liquid crystals revealed good response to both stimuli of light irradiation and electric field, and the induced molecular orientation could be held even after the removal of the stimuli. The structural and mechanical investigation proved that the formation of hydrogen bonds and assembly-induced molecular dipolar change contributed to the multiresponding action. This kind of self-assembled complex thus has potential applications in imaging and data storage.

  14. Self-Assembled Nanostructured Health Monitoring Sensors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the proposed NASA SBIR program is to design, fabricate and evaluate the performance of self-assembled nanostructured sensors for the health...

  15. Noncanonical Self-Assembly of Highly Asymmetric Genetically Encoded Polypeptide Amphiphiles into Cylindrical Micelles

    Science.gov (United States)

    2015-01-01

    Elastin-like polypeptides (ELPs) are a class of biopolymers consisting of the pentameric repeat (VPGαG)n based on the sequence of mammalian tropoelastin that display a thermally induced soluble-to-insoluble phase transition in aqueous solution. We have discovered a remarkably simple approach to driving the spontaneous self-assembly of high molecular weight ELPs into nanostructures by genetically fusing a short 1.5 kDa (XGy)z assembly domain to one end of the ELP. Classical theories of self-assembly based on the geometric mass balance of hydrophilic and hydrophobic block copolymers suggest that these highly asymmetric polypeptides should form spherical micelles. Surprisingly, when sufficiently hydrophobic amino acids (X) are presented in a periodic sequence such as (FGG)8 or (YG)8, these highly asymmetric polypeptides self-assemble into cylindrical micelles whose length can be tuned by the sequence of the morphogenic tag. These nanostructures were characterized by light scattering, tunable resistive pulse sensing, fluorescence spectrophotometry, and thermal turbidimetry, as well as by cryogenic transmission electron microscopy (cryo-TEM) and small-angle neutron scattering (SANS). These short assembly domains provide a facile strategy to control the size, shape, and stability of stimuli responsive polypeptide nanostructures. PMID:25268037

  16. Region-selective self-assembly of functionalized carbon allotropes from solution.

    Science.gov (United States)

    Wang, Zhenxing; Mohammadzadeh, Saeideh; Schmaltz, Thomas; Kirschner, Johannes; Khassanov, Artoem; Eigler, Siegfried; Mundloch, Udo; Backes, Claudia; Steinrück, Hans-Georg; Magerl, Andreas; Hauke, Frank; Hirsch, Andreas; Halik, Marcus

    2013-12-23

    Approaches for the selective self-assembly of functionalized carbon allotropes from solution are developed and validated for 0D-fullerenes, 1D-carbon nanotubes and 2D-graphene. By choosing the right molecular interaction of self-assembled monolayers (serving the surface) with the functionalization features of carbon materials, which provide the solubility but also serve the driving force for assembly, we demonstrate a region-selective and self-terminating assembly of the materials. Active layers of the carbon allotropes can be selectively deposited in the channel region of thin-film transistor (TFT) devices by this approach. As an example for a 0D system, molecules of C60 functionalized octadecylphosphonic acids are used to realize self-assembled monolayer field-effect transistors (SAMFETs) based on a selective molecular exchange reaction of stearic acid in the channel region. For noncovalently functionalized single-walled carbon nanotubes (SWCNTs) and graphene oxide (GO) flakes, the electrostatic Coulomb interactions between the functional groups of the carbon allotropes and the charged head groups of a SAM dielectric layer are utilized to implement the selective deposition.

  17. 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....

  18. Mesoscopic Self-Assembly: A Shift to Complexity

    Directory of Open Access Journals (Sweden)

    Massimo eMastrangeli

    2015-06-01

    Full Text Available By focusing on the construction of thermodynamically stable structures, the self-assembly of mesoscopic systems has proven capable of formidable achievements in the bottom-up engineering of micro- and nanosystems. Yet, inspired by an analogous evolution in supramolecular chemistry, synthetic mesoscopic self-assembly may have a lot more ahead, within reach of a shift toward fully three-dimensional architectures, collective interactions of building blocks and kinetic control. All over these challenging fronts, complexity holds the key.

  19. Self-assembly of graphene nanostructures on nanotubes.

    Science.gov (United States)

    Patra, Niladri; Song, Yuanbo; Král, Petr

    2011-03-22

    We demonstrate by molecular dynamics simulations that carbon nanotubes can activate and guide on their surfaces and in their interiors the self-assembly of planar graphene nanostructures of various sizes and shapes. Nanotubes can induce bending, folding, sliding, and rolling of the nanostructures in vacuum and in the presence of solvent, leading to stable graphene rings, helices, and knots. We investigate the self-assembly conditions and analyze the stability of the formed nanosystems, with numerous possible applications.

  20. Enzymatic Self-Assembly of Nanostructures for Theranostics

    OpenAIRE

    Yue Chen, Gaolin Liang

    2012-01-01

    Self-assembly of small molecules or macromolecules through non-covalent or covalent bonds to build up supramolecular nanostructures is a prevalent and important process in nature. While most chemists use small molecules to assemble nanostructures with physical or chemical perturbations, nature adopts enzymes to catalyze the reaction to assemble biological, functional nanostructures with high efficiency and specificity. Although enzymatic self-assembly of nanostructures has been remained chall...

  1. Optimal control of electrostatic self-assembly of binary monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Shestopalov, N V; Henkelman, G; Powell, C T; Rodin, G J [Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX 78712 (United States)], E-mail: nikolay@ices.utexas.edu

    2009-05-15

    A simple macroscopic model is used to determine an optimal annealing schedule for self-assembly of binary monolayers of spherical particles. The model assumes that a single rate-controlling mechanism is responsible for the formation of spatially ordered structures and that its rate follows an Arrhenius form. The optimal schedule is derived in an analytical form using classical optimization methods. Molecular dynamics simulations of the self-assembly demonstrate that the proposed schedule outperforms other schedules commonly used for simulated annealing.

  2. Self-assembled tunable networks of sticky colloidal particles

    Energy Technology Data Exchange (ETDEWEB)

    Demortiere, Arnaud; Snezhko, Oleksiy Alexey; Sapozhnikov, Maksim; Becker, Nicholas G.; Proslier, Thomas; Aronson, Igor S.

    2017-07-18

    Self-assembled tunable networks of microscopic polymer fibers ranging from wavy colloidal "fur" to highly interconnected networks are created from polymer systems and an applied electric field. The networks emerge via dynamic self-assembly in an alternating (ac) electric field from a non-aqueous suspension of "sticky" polymeric colloidal particles with a controlled degree of polymerization. The resulting architectures are tuned by the frequency and amplitude of the electric field and surface properties of the particles.

  3. Preparation and characterisation of novel chlorothiazide potassium solid-state salt forms: Intermolecular self assembly suprastructures.

    Science.gov (United States)

    Paluch, Krzysztof J; Tajber, Lidia; McCabe, Thomas; O'Brien, John E; Corrigan, Owen I; Healy, Anne Marie

    2011-02-14

    Chlorothiazide (CTZ) is a poorly soluble diuretic agent. The aim of the present work was to produce and characterise a potassium salt form of chlorothiazide which has the potential advantages of improved aqueous solubility and potassium supplementation. A number of novel potassium salt forms of CTZ (CTZK) were prepared: CTZK monohydrate (form I), CTZK dihydrate (form II), anhydrous CTZK (form III), CTZK monohydrate hemiethanolate (form IV) and a desolvate of CTZK monohydrate hemiethanolate (form V). These salt forms were characterised by thermal analysis, PXRD, NMR, elemental analysis, FTIR, Karl Fisher titrimetry, ICP-MS and GC-MS. The ethanol-free CTZK forms were also characterised by dynamic vapour sorption analysis (DVS). CTZK form I was stable (in the DVS) over the range 0-60% RH. The dihydrate form of the salt was stable (in the DVS) over a broader range of relative humidities, 10-90% RH at 25°C. CTZK form II was less hygroscopic at high humidities (70-90% RH) than the previously reported CTZNa dihydrate. Single crystal X-ray analysis indicated that chlorothiazide potassium, crystallised from water or water/acetone mixture, formed a dihydrated polymeric-like intermolecular self-assembly (ISA) suprastructure. The ISA coordination was determined to be: (CTZ)(3)·K·(H(2)O)(2)(CTZ)(2)·(H(2)O)(2)·K·(CTZ)(3) (monoclinic, space group: C2/c, single crystal cell parameters: a=18.328(4)Å, b=7.3662(16)Å, c=19.993(5)Å, α=90°, β=99.729(3)°, γ=90°). When CTZK was crystallised from ethanol, a monohydrate hemiethanolate ISA was formed, described as (CTZ)(3)·K·CTZ·(H(2)O)(2)·CTZ·K·(CTZ)(2) (triclinic, space group: P-1, single crystal cell parameters: a=7.078(3)Å, b=9.842(5)Å, c=21.994(11)Å, α=87.522(13)°, β=84.064(14)°, γ=78.822(12)°). The aqueous solubility of CTZK dihydrate, was determined to be 78.71±1.82mg/ml, approximately 400-fold higher than chlorothiazide, indicating a biopharmaceutical advantage associated with the potassium salt form

  4. Solubilities of selected organic electronic materials in pressurized hot water and estimations of aqueous solubilities at 298.15 K.

    Science.gov (United States)

    Karásek, Pavel; Hohnová, Barbora; Planeta, Josef; Št'avíková, Lenka; Roth, Michal

    2013-02-01

    Increasing production and disposal of organic light-emitting diode (OLED) displays for smartphones and tablets may have impact on the environment depending on the aqueous solubility of the pertinent chemicals. Here, aqueous solubilities are presented for several compounds, mostly aromatic amines, used as hole transport materials in the OLED displays. Solute selection includes 1,4-bis(diphenylamino)benzene, tetra-N-phenylbenzidine, 4,4'-bis(N-carbazolyl)-1,1'-biphenyl, 1,3,5-tris(diphenylamino)benzene, and 9,10-bis(phenylethynyl)anthracene. The solubilities are those in pressurized hot water (PHW), i.e., measured at elevated temperature (up to 260 °C) and pressure. The semi-quantitative estimates of room-temperature solubilities of the solutes have been obtained from extrapolations of the solubilities in PHW. For the compounds studied, the estimated aqueous solubilities at room temperature do not exceed 2×10(-11) g of the solute per 1 kg of water. Aqueous solubilities of triphenylamine have also been measured and used to upgrade a recent group-contribution model of aqueous solubilities of organic nonelectrolytes with the parameters for the nitrogen atom in aromatic amines. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Anandamide and analogous endocannabinoids: a lipid self-assembly study

    Energy Technology Data Exchange (ETDEWEB)

    Sagnella, Sharon M.; Conn, Charlotte E.; Krodkiewska, Irena; Mulet, Xavier; Drummond, Calum J.

    2014-09-24

    Anandamide, the endogenous agonist of the cannabinoid receptors, has been widely studied for its interesting biological and medicinal properties and is recognized as a highly significant lipid signaling molecule within the nervous system. Few studies have, however, examined the effect of the physical conformation of anandamide on its function. The study presented herein has focused on characterizing the self-assembly behaviour of anandamide and four other endocannabinoid analogues of anandamide, viz., 2-arachidonyl glycerol, arachidonyl dopamine, 2-arachidonyl glycerol ether (noladin ether), and o-arachidonyl ethanolamide (virodhamine). Molecular modeling of the five endocannabinoid lipids indicates that the highly unsaturated arachidonyl chain has a preference for a U or J shaped conformation. Thermal phase studies of the neat amphiphiles showed that a glass transition was observed for all of the endocannabinoids at {approx} -110 C with the exception of anandamide, with a second glass transition occurring for 2-arachidonyl glycerol, 2-arachidonyl glycerol ether, and virodhamine (-86 C, -95 C, -46 C respectively). Both anandamide and arachidonyl dopamine displayed a crystal-isotropic melting point (-4.8 and -20.4 C respectively), while a liquid crystal-isotropic melting transition was seen for 2-arachidonyl glycerol (-40.7 C) and 2-arachidonyl glycerol ether (-71.2 C). No additional transitions were observed for virodhamine. Small angle X-ray scattering and cross polarized optical microscopy studies as a function of temperature indicated that in the presence of excess water, both 2-arachidonyl glycerol and anandamide form co-existing Q{sub II}{sup G} (gyroid) and Q{sub II}{sup D} (diamond) bicontinuous cubic phases from 0 C to 20 C, which are kinetically stable over a period of weeks but may not represent true thermodynamic equilibrium. Similarly, 2-arachidonyl glycerol ether acquired an inverse hexagonal (HII) phase in excess water from 0 C to 40 C, while

  6. Solubility of acetaminophen in polyethylene glycol 400 + water mixtures according to the extended hildebrand solubility approach

    OpenAIRE

    Edgar Ahumada; Daniel Delgado; Fleming Martínez

    2014-01-01

    The Extended Hildebrand Solubility Approach(EHSA) was applied in the presentwork to evaluate the solubility of theanalgesic drug acetaminophen (paracetamol)in polyethylene glycol 400 + watermixtures at 298.15 K. An acceptablecorrelative capacity of EHSA was foundusing a regular polynomial model in orderfour (overall deviation below 0.7%),when the W interaction parameter is relatedto the solubility parameter of themixtures. Thus, the deviations obtainedin the estimated solubility with respect ...

  7. Application of various water soluble polymers in gas hydrate inhibition

    DEFF Research Database (Denmark)

    Kamal, Muhammad Shahzad; Hussein, Ibnelwaleed A.; Sultan, Abdullah S.

    2016-01-01

    . This review presents the various types of water soluble polymers used for hydrate inhibition, including conventional and novel polymeric inhibitors along with their limitations. The review covers the relevant properties of vinyl lactam, amide, dendrimeric, fluorinated, and natural biodegradable polymers....... The factors affecting the performance of these polymers and the structure-property relationships are reviewed. A comprehensive review of the techniques used to evaluate the performance of the polymeric inhibitors is given. This review also addresses recent developments, current and future challenges......, and field applications of a range of polymeric kinetic hydrate inhibitors....

  8. Preliminary evaluation of a water soluble chlorin photosensitizer

    Science.gov (United States)

    Zou, Jian; Huang, Qiuyan; Li, Weijun; Zou, Shulin; Han, Zhen; Huang, Zheng

    2017-07-01

    Some of the key optical properties of a new water soluble chlorine (YLG-1) were evaluated. The sensitizer has a strong absorption at 398 nm and 655 nm in DMSO. A strong red fluorescence is detected under the excitation of 398 nm. The fluorescence life time is approximately 5 ns and fluorescence quantum yield 20%. The sensitizer does not accumulate in normal skin after topical use or IV injection. Preliminary in vivo results suggest that this novel chlorine causes little cutaneous phototoxicity. Its potentials in photodynamic therapy (PDT) deserve further study.

  9. Determination of Carboxylic Acids and Water-soluble Inorganic Ions ...

    African Journals Online (AJOL)

    The results showed that mean mass concentration of PM2.5 and PM10 were 13 ± 3.5 μg m–3 and 16 ± 2.3 μg m–3, respectively. Mean concentrations of the total carboxylates were 23.7±6.5 ngm–3 in PM2.5 and 36.4 ± 12 ngm–3 in PM10 whereas total water-soluble inorganic ions were 448±88 ngm–3 and 646± 214 ...

  10. Water-soluble magnetic nanoparticles with biologically active stabilizers

    Science.gov (United States)

    Zablotskaya, Alla; Segal, Izolda; Lukevics, Edmunds; Maiorov, Mikhail; Zablotsky, Dmitry; Blums, Elmars; Shestakova, Irina; Domracheva, Ilona

    2009-05-01

    We present the results of the interaction of iron oxide nanoparticles with some biologically active surfactants, namely, oleic acid and cytotoxic alkanolamine derivatives. Physico-chemical properties, as magnetization, magnetite concentration and particle diameter, of the prepared magnetic samples were studied. The nanoparticle size of 11 nm for toluene magnetic fluid determined by TEM is in good agreement with the data obtained by the method of magnetogranulometry. In vitro cytotoxic effect of water-soluble nanoparticles with different iron oxide:oleic acid molar ratio were revealed against human fibrosarcoma and mouse hepatoma cells. In vivo results using a sarcoma mouse model showed observable antitumor action.

  11. Water-soluble magnetic nanoparticles with biologically active stabilizers

    Energy Technology Data Exchange (ETDEWEB)

    Zablotskaya, Alla [Latvian Institute of Organic Synthesis, 21 Aizkraukles Street, Riga LV-1006 (Latvia)], E-mail: aez@osi.lv; Segal, Izolda; Lukevics, Edmunds [Latvian Institute of Organic Synthesis, 21 Aizkraukles Street, Riga LV-1006 (Latvia); Maiorov, Mikhail; Zablotsky, Dmitry; Blums, Elmars [Institute of Physics, University of Latvia, 32 Miera, Salaspils LV-2169 (Latvia); Shestakova, Irina; Domracheva, Ilona [Latvian Institute of Organic Synthesis, 21 Aizkraukles Street, Riga LV-1006 (Latvia)

    2009-05-15

    We present the results of the interaction of iron oxide nanoparticles with some biologically active surfactants, namely, oleic acid and cytotoxic alkanolamine derivatives. Physico-chemical properties, as magnetization, magnetite concentration and particle diameter, of the prepared magnetic samples were studied. The nanoparticle size of 11 nm for toluene magnetic fluid determined by TEM is in good agreement with the data obtained by the method of magnetogranulometry. In vitro cytotoxic effect of water-soluble nanoparticles with different iron oxide:oleic acid molar ratio were revealed against human fibrosarcoma and mouse hepatoma cells. In vivo results using a sarcoma mouse model showed observable antitumor action.

  12. [Antibacterial activity of water soluble fraction from Scolopendra subspinipes mutilans].

    Science.gov (United States)

    Ren, Wen-hua; Zhang, Shuang-quan; Song, Da-xiang; Zhou, Kai-ya

    2007-01-01

    The water soluble fraction (SWSF) of centipede Scolopendra subspinipes mautilans, injected with Escherichia coli K12 D31 for 3-4 days showed broad-spectrum antimicrobial activity against Gram-positive, Gram-negative bacteria and fungi. It showed strong antibacterial activity against E. coli K12D31 at different temperatures, pH and ionic strengths. It did not show any hemolytic and agglutination activities at the concentration below 600 microg/ml. After E. coli K12 D31 treated with SWSF, the ultrastructure showed that its outer cell wall was broken, surface collapsed and intracellular substances leaked out.

  13. Solubility of paroxetine hydrochloride hemi-hydrate in (water + acetone)

    Energy Technology Data Exchange (ETDEWEB)

    Ren Guobin [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)]. E-mail: renguobin2557@sohu.com; Wang Jingkang [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Li Guizhi [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2005-08-15

    Using a laser monitoring observation technique, the solubilities of paroxetine hydrochloride hemi-hydrate in (water + acetone) were determined by the synthetic method from (294.45 to 323.20) K, respectively. Results of these measurements were correlated by the three variants of the combined nearly ideal binary solvent/Redlich-Kister (CNIBS/R-K) model. For the seven group data studied, three variants of the (CNIBS/R-K) equation were found to provide accurate mathematical representations of the experimental data and variant 2 is the best of the three variants.

  14. Antibacterial Characteristics and Activity of Water-Soluble Chitosan Derivatives Prepared by the Maillard Reaction

    Directory of Open Access Journals (Sweden)

    Ying-Chien Chung

    2011-10-01

    Full Text Available The antibacterial activity of water-soluble chitosan derivatives prepared by Maillard reactions against Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Escherichia coli, Shigella dysenteriae, and Salmonella typhimurium was examined. Relatively high antibacterial activity against various microorganisms was noted for the chitosan-glucosamine derivative as compared to the acid-soluble chitosan. In addition, it was found that the susceptibility of the test organisms to the water-soluble chitosan derivative was higher in deionized water than in saline solution. Metal ions were also found to reduce the antibacterial activity of the water-soluble chitosan derivative on S. aureus. The marked increase in glucose level, protein content and lactate dehydrogenase (LDH activity was observed in the cell supernatant of S. aureus exposed to the water-soluble chitosan derivative in deionized water. The results suggest that the water-soluble chitosan produced by Maillard reaction may be a promising commercial substitute for acid-soluble chitosan.

  15. Self-Assembled Biosensors on a Solid Interface for Rapid Detection and Growth Monitoring of Bacteria

    CERN Document Server

    Kinnunen, Paivo; Craig, Elizabeth; Brahmasandra, Sundu; McNaughton, Brandon H

    2012-01-01

    Developing rapid methods for pathogen detection and growth monitoring at low cell and analyte concentrations is an important goal, which numerous technologies are working towards solving. Rapid biosensors have already made a dramatic impact on improving patient outcomes and with continued development, these technologies may also help limit the emergence of antimicrobial resistance and reduce the ever expanding risk of foodborne illnesses. One technology that is being developed with these goals in mind is asynchronous magnetic bead rotation (AMBR) biosensors. Self-assembled AMBR biosensors have been demonstrated at water/air and water/oil interfaces, and here, for the first time, we report on self-assembled AMBR biosensors used at a solid interface. The solid interface configuration was used to measure the growth of Escherichia coli with two distinct phenomena at low cell concentrations: firstly, the AMBR rotational period decreased and secondly, the rotational period increased after several division times. Ta...

  16. Therapeutic Effects of Water Soluble Danshen Extracts on Atherosclerosis

    Directory of Open Access Journals (Sweden)

    Yoon Hee Cho

    2013-01-01

    Full Text Available Danshen is a traditional Chinese medicine with many beneficial effects on cardiovascular diseases. The aim of this study was to evaluate the mechanisms responsible for the antiatherogenic effect of water soluble Danshen extracts (DEs. Rat vascular smooth muscle cells (VSMCs and human umbilical vein endothelial cells (HUVECs were treated with DE. To evaluate the effects of DE in vivo, carotid balloon injury and tail vein thrombosis were induced in Sprague-Dawley (SD rats and iliac artery stent was induced in New Zealand white rabbits. The inhibitory action of DE on platelet aggregation was confirmed with an impedance aggregometer. DE inhibited the production of reactive oxygen species, and the migration and proliferation of platelet-derived growth factor-BB stimulated VSMCs. Furthermore, DE prevented inflammation and apoptosis in HUVECs. Both effects of DE were reconfirmed in both rat models. DE treatment attenuated platelet aggregation in both in vivo and ex vivo conditions. Pretreatment with DE prevented tail vein thrombosis, which is normally induced by κ-carrageenan injection. Lastly, DE-treated rabbits showed decreased in-stent restenosis of stented iliac arteries. These results suggest that water soluble DE modulates key atherogenic events in VSMCs, endothelial cells, and platelets in both in vitro and in vivo conditions.

  17. Biological properties of water-soluble phosphorhydrazone dendrimers

    Directory of Open Access Journals (Sweden)

    Anne-Marie Caminade

    2013-01-01

    Full Text Available Dendrimers are hyperbranched and perfectly defined macromolecules, constituted of branches emanating from a central core in an iterative fashion. Phosphorhydrazone dendrimers constitute a special family of dendrimers, possessing one phosphorus atom at each branching point. The internal structure of these dendrimers is hydrophobic, but hydrophilic terminal groups can induce the solubility of the whole structure in water. Indeed, the properties of these compounds are mainly driven by the type of terminal groups their bear; this is especially true for the biological properties. For instance, positively charged terminal groups are efficient for transfection experiments, as drug carriers, as anti-prion agents, and as inhibitor of the aggregation of Alzheimer's peptides, whereas negatively charged dendrimers have anti-HIV properties and can influence the human immune system, leading to anti-inflammatory properties usable against rheumatoid arthritis. This review will give the most representative examples of the biological properties of water-soluble phosphorhydrazone dendrimers, organized depending on the type of terminal groups they bear.

  18. Interactions of main chain in folding and self assembly of unfolded protein structure: Enquiries with a serine solubilized nonapeptide

    Directory of Open Access Journals (Sweden)

    Kinshuk Raj Srivastava

    2014-06-01

    Full Text Available Interactions of the protein main chain are probed for their role in folding and self-assembly. The interactions are assessed with serine nonapeptide Ac-(Ser-Ala4-Ser-NH2 in poly-L and alternating-L,D structure variations. Being a neutral molecule, Serine nonapeptide has been found to display not only folding-unfolding equilibrium, but also association-dissociation equilibrium as a function of solvent and concentration. Thus scrutiny of intra- and inter-molecular interactions have been undertaken in water, methanol, and DMSO solvents. In water, poly-L peptide displays a PPII-helix conformation which unfolds to extended β-conformation with increase of temperature, apparently in a two-state equilibrium. Poly-L peptide at high concentration and on transfer to the low polarity solvent, methanol, displays ordering as a β-hairpin. This implies folding of the peptide by self assembly. Self assembly and ordering possibly as double-stranded β-helix is also evidence for alternating-L,D peptide. Both isomers were observed to be unfolded in high polarity solvent DMSO. Dynamic light scattering suggests that assembly in both isomers may involve large size aggregates. The results have established that folding and self-assembly can be coupled equilibria dependent upon solute structure, concentration, and solvent. The interactions of the protein main chain involved in folding and self assembly of unfolded structure are illuminated and have been discussed.

  19. Solubility of zinc ferrite in high-temperature oxygenated water

    Science.gov (United States)

    Hanzawa, Yukiko; Hiroishi, Daisuke; Matsuura, Chihiro; Ishigure, Kenkichi

    1998-02-01

    The solubility of zinc ferrite was measured at 423 K, 473 K, and 523 K in an oxygenated water system, which is rather similar to the chemical condition of boiling water reactors. Thermodynamic analysis was performed by a procedure minimizing standard Gibbs free energy of the system at the final state. From both the analysis and the experimental results it was concluded that the dissolution process of ZnFe 2O 4 in conditions where no redox reaction occurs is described by combination of ZnFe 2O 4 dissolution and Fe 2O 3 precipitation equilibria. By fitting to the experimental results, thermodynamic data of ZnFe 2O 4 are re-analyzed at 423 K, 473 K, and 523 K.

  20. Photophysical characterization of layer-by-layer self-assembled ...

    Indian Academy of Sciences (India)

    for the fabrication of films of water soluble molecules. This method provides a means to build ... in water in order to remove off the surplus cations attached to surface and then in the solution of DNA for 15 min .... increase in length of the dipole moment vector [11] and the absorption intensity increases thereby. Figure 5 is the ...

  1. Self-assembled poly(2-ethyl-2-oxazoline) fibers in aqueous solutions

    OpenAIRE

    Güner, Pınar Tatar; Miko, Annamaria; Schweinberger, Florian F.; Demirel, A. Levent

    2012-01-01

    Poly(2-ethyl-2-oxazoline) (PEOX) formed self-assembled fibers in aqueous solutions above the cloud point temperature (T-c) through a slow crystallization process. The fiber formation above T-c happened both in pure water and in the presence of salting-in (SCN-) and salting-out (CH3COO-) ions. The crystal structure and the melting temperature of the PEOX fibers were determined.

  2. Fluorescent nanoparticles based on self-assembled pi-conjugated systems.

    Science.gov (United States)

    Kaeser, Adrien; Schenning, Albertus P H J

    2010-07-27

    pi-Conjugated molecules are interesting components to prepare fluorescent nanoparticles. From the use of polymer chains that form small aggregates in water to the self-assembly of small chromophoric segments into highly ordered structures, the preparation of these materials allows to develop systems with applications as sensors or biolabels. The potential functionalization of the nanoparticles can lead to specific probing. This progress report describes the recent advances in the preparation of such emittive organic nanoparticles.

  3. Synthesis and solution self-assembly of side-chain cobaltocenium-containing block copolymers.

    Science.gov (United States)

    Ren, Lixia; Hardy, Christopher G; Tang, Chuanbing

    2010-07-07

    The synthesis of side-chain cobaltocenium-containing block copolymers and their self-assembly in solution was studied. Highly pure monocarboxycobaltocenium was prepared and subsequently attached to side chains of poly(tert-butyl acrylate)-block-poly(2-hydroxyethyl acrylate), yielding poly(tert-butyl acrylate)-block-poly(2-acryloyloxyethyl cobaltoceniumcarboxylate). The cobaltocenium block copolymers exhibited vesicle morphology in the mixture of acetone and water, while micelles of nanotubes were formed in the mixture of acetone and chloroform.

  4. 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.

  5. Membrane-targeted self-assembling cyclic peptide nanotubes.

    Science.gov (United States)

    Rodríguez-Vázquez, Nuria; Ozores, H Lionel; Guerra, Arcadio; González-Freire, Eva; Fuertes, Alberto; Panciera, Michele; Priegue, Juan M; Outeiral, Juan; Montenegro, Javier; Garcia-Fandino, Rebeca; Amorin, Manuel; Granja, Juan R

    2014-01-01

    Peptide nanotubes are novel supramolecular nanobiomaterials that have a tubular structure. The stacking of cyclic components is one of the most promising strategies amongst the methods described in recent years for the preparation of nanotubes. This strategy allows precise control of the nanotube surface properties and the dimensions of the tube diameter. In addition, the incorporation of 3- aminocycloalkanecarboxylic acid residues in the nanotube-forming peptides allows control of the internal properties of the supramolecular tube. The research aimed at the application of membrane-interacting self-assembled cyclic peptide nanotubes (SCPNs) is summarized in this review. The cyclic peptides are designed to interact with phospholipid bilayers to induce nanotube formation. The properties and orientation of the nanotube can be tuned by tailoring the peptide sequence. Hydrophobic peptides form transmembrane pores with a hydrophilic orifice, the nature of which has been exploited to transport ions and small molecules efficiently. These synthetic ion channels are selective for alkali metal ions (Na(+), K(+) or Cs(+)) over divalent cations (Ca(2+)) or anions (Cl(-)). Unfortunately, selectivity was not achieved within the series of alkali metal ions, for which ion transport rates followed the diffusion rates in water. Amphipathic peptides form nanotubes that lie parallel to the membrane. Interestingly, nanotube formation takes place preferentially on the surface of bacterial membranes, thus making these materials suitable for the development of new antimicrobial agents.

  6. Highly water-soluble multi-walled carbon nanotubes amine-functionalized by supercritical water oxidation.

    Science.gov (United States)

    Chun, Kyoung-Yong; Moon, In-Kyu; Han, Joo-Hee; Do, Seung-Hoe; Lee, Jin-Seo; Jeon, Seong-Yun

    2013-11-07

    Multi-walled carbon nanotubes (MWNTs) have been amine-functionalized by eco-friendly supercritical water oxidation. The facilely functionalized MWNTs have high solubility (~84 mg L(-1)) in water and 78% transmittance at 30-fold dilution. The Tyndall effect is also shown for several liquids.

  7. Evaluation of ISO 4049: water sorption and water solubility of resin cements.

    Science.gov (United States)

    Müller, Johannes A; Rohr, Nadja; Fischer, Jens

    2017-04-01

    The aim of this study was to evaluate the water sorption and solubility test design of ISO 4049 for resin cements. Sorption and solubility of six dual-curing resin cements [RelyX Unicem 2 Automix (RUN), Multilink Speed CEM (MLS), Panavia SA Plus (PSA), RelyX Ultimate (RUL), Multilink Automix (MLA), and Panavia V5 (PV5)] were analyzed by storage in distilled water after dual-curing. In addition, sorption and solubility during thermal cycling were assessed with self-cured and dual-cured specimens. After water storage, all cements revealed sorption in the range of 30 μg mm(-3) except for PV5, for which sorption was markedly lower (mean ± SD = 20.8 ± 0.4 μg mm(-3) ). Solubility values were negative for RUN and RUL (-2.1 ± 0.08 μg mm(-3) and -1.9 ± 0.13 μg mm(-3) , respectively). All other cements attained positive values in the range of 0.4-0.8 μg mm(-3) . Thermal cycling effects were more pronounced. The assessment of water sorption according to ISO 4049 provides reliable results. Solubility results must be interpreted with care because absorbed water may distort the values. © 2017 Eur J Oral Sci.

  8. Layer-By-Layer Self-Assembly of Polyelectrolytic Block Copolymer Worms on a Planar Substrate.

    Science.gov (United States)

    Penfold, Nicholas J W; Parnell, Andrew J; Molina, Marta; Verstraete, Pierre; Smets, Johan; Armes, Steven P

    2017-12-08

    Cationic and anionic block copolymer worms are prepared by polymerization-induced self-assembly via reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion copolymerization of 2-hydroxypropyl methacrylate and glycidyl methacrylate (GlyMA), using a binary mixture of a nonionic poly(ethylene oxide) macromolecular RAFT agent and either a cationic poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride) or an anionic poly(potassium 3-sulfopropyl methacrylate) macromolecular RAFT agent. In each case, covalent stabilization of the worm cores was achieved via reaction of the epoxide groups on the GlyMA repeat units with 3-mercaptopropyltriethoxysilane. Aqueous electrophoresis studies indicated a pH-independent mean zeta potential of +40 mV and -39 mV for the cationic and anionic copolymer worms, respectively. These worms are expected to mimic the rigid rod behavior of water-soluble polyelectrolyte chains in the absence of added salt. The kinetics of adsorption of the cationic worms onto a planar anionic silicon wafer was examined at pH 5 and was found to be extremely fast at 1.0 w/w % copolymer concentration in the absence of added salt. Scanning electron microscopy (SEM) analysis indicated that a relatively constant worm surface coverage of 16% was achieved at 20 °C for adsorption times ranging from just 2 s up to 2 min. Furthermore, the successive layer-by-layer deposition of cationic and anionic copolymer worms onto planar surfaces was investigated using SEM, ellipsometry, and surface zeta potential measurements. These techniques confirmed that the deposition of oppositely charged worms resulted in a monotonic increase in the mean layer thickness, with a concomitant surface charge reversal occurring on addition of each new worm layer. Unexpectedly, two distinct linear regimes were observed when plotting the mean layer thickness against the total number of adsorbed worm layers, with a steeper gradient (corresponding to thicker layers) being

  9. Fluid-Mediated Stochastic Self-Assembly at Centimetric and Sub-Millimetric Scales: Design, Modeling, and Control

    Directory of Open Access Journals (Sweden)

    Bahar Haghighat

    2016-08-01

    Full Text Available Stochastic self-assembly provides promising means for building micro-/nano-structures with a variety of properties and functionalities. Numerous studies have been conducted on the control and modeling of the process in engineered self-assembling systems constituted of modules with varied capabilities ranging from completely reactive nano-/micro-particles to intelligent miniaturized robots. Depending on the capabilities of the constituting modules, different approaches have been utilized for controlling and modeling these systems. In the quest of a unifying control and modeling framework and within the broader perspective of investigating how stochastic control strategies can be adapted from the centimeter-scale down to the (sub-millimeter-scale, as well as from mechatronic to MEMS-based technology, this work presents the outcomes of our research on self-assembly during the past few years. As the first step, we leverage an experimental platform to study self-assembly of water-floating passive modules at the centimeter scale. A dedicated computational framework is developed for real-time tracking, modeling and control of the formation of specific structures. Using a similar approach, we then demonstrate controlled self-assembly of microparticles into clusters of a preset dimension in a microfluidic chamber, where the control loop is closed again through real-time tracking customized for a much faster system dynamics. Finally, with the aim of distributing the intelligence and realizing programmable self-assembly, we present a novel experimental system for fluid-mediated programmable stochastic self-assembly of active modules at the centimeter scale. The system is built around the water-floating 3-cm-sized Lily robots specifically designed to be operative in large swarms and allows for exploring the whole range of fully-centralized to fully-distributed control strategies. The outcomes of our research efforts extend the state-of-the-art methodologies

  10. 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

  11. A self-assembling nanomedicine of conjugated linoleic acid-paclitaxel conjugate (CLA-PTX) with higher drug loading and carrier-free characteristic

    Science.gov (United States)

    Zhong, Ting; Yao, Xin; Zhang, Shuang; Guo, Yang; Duan, Xiao-Chuan; Ren, Wei; Dan Huang; Yin, Yi-Fan; Zhang, Xuan

    2016-11-01

    The main objective of this study was to demonstrate the proof-of-principle for the hypothesis that conjugated linoleic acid-paclitaxel conjugate (CLA-PTX), a novel fatty acid modified anti-cancer drug conjugate, could self-assemble forming nanoparticles. The results indicated that a novel self-assembling nanomedicine, CLA-PTX@PEG NPs (about 105 nm), with Cremophor EL (CrEL)-free and organic solvent-free characteristics, was prepared by a simple precipitation method. Being the ratio of CLA-PTX:DSPE-PEG was only 1:0.1 (w/w), the higher drug loading CLA-PTX@PEG NPs (about 90%) possessed carrier-free characteristic. The stability results indicated that CLA-PTX@PEG NPs could be stored for at least 9 months. The safety of CLA-PTX@PEG NPs was demonstrated by the MTD results. The anti-tumor activity and cellular uptake were also confirmed in the in vitro experiments. The lower crystallinity, polarity and solubility of CLA-PTX compared with that of paclitaxel (PTX) might be the possible reason for CLA-PTX self-assembling forming nanoparticles, indicating a relationship between PTX modification and nanoparticles self-assembly. Overall, the data presented here confirm that this drug self-delivery strategy based on self-assembly of a CLA-PTX conjugate may offer a new way to prepare nanomedicine products for cancer therapy involving the relationship between anticancer drug modification and self-assembly into nanoparticles.

  12. Signatures of self-assembly in size distributions of wood members in dam structures of Castor canadensis

    Directory of Open Access Journals (Sweden)

    David M. Blersch

    2014-12-01

    Full Text Available Beavers (Castor canadensis construct dams on rivers throughout most of their historical range in North America, and their impact on water patterns in the landscape is considerable. Dam formation by beavers involves two processes: (1 intentional construction through the selection and placement of wood and sediment, which facilitates (2 the passive capture and accretion of suspended wood and sediment. The second process is a self-assembly mechanism that the beavers leverage by utilizing energy subsidies of watershed transport processes. The relative proportion of beaver activity to self-assembly processes in dam construction, however, is unknown. Here we show that lotic self-assembly processes account for a substantial portion of the work expended in beaver dam construction. We found through comprehensive measurement of the stick dimensions that the distributions for diameter, length, and volume are log-normal. By noting evidence of teeth markings, we determined that size distributions skewed significantly larger for wood handled by beavers compared to those that were not. Subsequent mass calculations suggest that beavers perform 50%–70% of the work of wood member placement for dam assembly, with riparian self-assembly processes contributing the remainder. Additionally, our results establish a benchmark for assessing the proportion of self-assembly work in similar riparian structures.

  13. Unfolding a molecular trefoil derived from a zwitterionic metallopeptide to form self-assembled nanostructures

    KAUST Repository

    Zhang, Ye

    2015-02-19

    While used extensively by nature to control the geometry of protein structures, and dynamics of proteins, such as self-organization, hydration forces and ionic interactions received less attention for controlling the behaviour of small molecules. Here we describe the synthesis and characterization of a novel zwitterionic metallopeptide consisting of a cationic core and three distal anionic groups linked by self-assembling peptide motifs. 2D NMR spectra, total correlated spectroscopy and nuclear Overhauser effect spectroscopy, show that the molecule exhibits a three-fold rotational symmetry and adopts a folded conformation in dimethyl sulfoxide due to Coulombic forces. When hydrated in water, the molecule unfolds to act as a self-assembling building block of supramolecular nanostructures. By combining ionic interactions with the unique geometry from metal complex and hydrophobic interactions from simple peptides, we demonstrate a new and effective way to design molecules for smart materials through mimicking a sophisticated biofunctional system using a conformational switch.

  14. Fabrication of cellulose self-assemblies and high-strength ordered cellulose films.

    Science.gov (United States)

    Yuan, Zaiwu; Zhang, Jingjing; Jiang, Anning; Lv, Wenting; Wang, Yuewen; Geng, Hongjuan; Wang, Jin; Qin, Menghua

    2015-03-06

    Based on the formation of cellulose hydrogels in NaOH/urea aqueous solvent media, cellulose self-assembly precursor is acquired. It is proved that the water uptake capability of the cellulose hydrogels depends highly on the cross-link degree (CLD) of cellulose. With varying CLD and concentration of cellulose, a variety of morphologies of cellulose self-assemblies, including sheets with perfect morphology, high-aspect-ratio fibers, and disorganized segments and network, are formed through evaporation. Furthermore, cellulose films are fabricated by diecasting and evaporating the cellulose hydrogels, resulting in a 3D-ordered structure of closely stacking of cellulose sheets. The mechanical test indicates both tensile strength and flexibility of the cellulose films are greatly improved, which is attributed to the formation of the orderly stacking of cellulose sheets. The study is expected to lay an important foundation on the preparation of ordered and high-strength cellulose materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Unfolding a molecular trefoil derived from a zwitterionic metallopeptide to form self-assembled nanostructures

    Science.gov (United States)

    Zhang, Ye; Zhou, Ning; Shi, Junfeng; Pochapsky, Susan Sondej; Pochapsky, Thomas C.; Zhang, Bei; Zhang, Xixiang; Xu, Bing

    2015-02-01

    While used extensively by nature to control the geometry of protein structures, and dynamics of proteins, such as self-organization, hydration forces and ionic interactions received less attention for controlling the behaviour of small molecules. Here we describe the synthesis and characterization of a novel zwitterionic metallopeptide consisting of a cationic core and three distal anionic groups linked by self-assembling peptide motifs. 2D NMR spectra, total correlated spectroscopy and nuclear Overhauser effect spectroscopy, show that the molecule exhibits a three-fold rotational symmetry and adopts a folded conformation in dimethyl sulfoxide due to Coulombic forces. When hydrated in water, the molecule unfolds to act as a self-assembling building block of supramolecular nanostructures. By combining ionic interactions with the unique geometry from metal complex and hydrophobic interactions from simple peptides, we demonstrate a new and effective way to design molecules for smart materials through mimicking a sophisticated biofunctional system using a conformational switch.

  16. Aqueous dispersion polymerization: a new paradigm for in situ block copolymer self-assembly in concentrated solution.

    Science.gov (United States)

    Sugihara, Shinji; Blanazs, Adam; Armes, Steven P; Ryan, Anthony J; Lewis, Andrew L

    2011-10-05

    Reversible addition-fragmentation chain transfer polymerization has been utilized to polymerize 2-hydroxypropyl methacrylate (HPMA) using a water-soluble macromolecular chain transfer agent based on poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC). A detailed phase diagram has been elucidated for this aqueous dispersion polymerization formulation that reliably predicts the precise block compositions associated with well-defined particle morphologies (i.e., pure phases). Unlike the ad hoc approaches described in the literature, this strategy enables the facile, efficient, and reproducible preparation of diblock copolymer spheres, worms, or vesicles directly in concentrated aqueous solution. Chain extension of the highly hydrated zwitterionic PMPC block with HPMA in water at 70 °C produces a hydrophobic poly(2-hydroxypropyl methacrylate) (PHPMA) block, which drives in situ self-assembly to form well-defined diblock copolymer spheres, worms, or vesicles. The final particle morphology obtained at full monomer conversion is dictated by (i) the target degree of polymerization of the PHPMA block and (ii) the total solids concentration at which the HPMA polymerization is conducted. Moreover, if the targeted diblock copolymer composition corresponds to vesicle phase space at full monomer conversion, the in situ particle morphology evolves from spheres to worms to vesicles during the in situ polymerization of HPMA. In the case of PMPC(25)-PHPMA(400) particles, this systematic approach allows the direct, reproducible, and highly efficient preparation of either block copolymer vesicles at up to 25% solids or well-defined worms at 16-25% solids in aqueous solution.

  17. Self-Assembled Asymmetric Block Copolymer Membranes: Bridging the Gap from Ultra- to Nanofiltration.

    Science.gov (United States)

    Yu, Haizhou; Qiu, Xiaoyan; Moreno, Nicolas; Ma, Zengwei; Calo, Victor Manuel; Nunes, Suzana P; Peinemann, Klaus-Viktor

    2015-11-16

    The self-assembly of block copolymers is an emerging strategy to produce isoporous ultrafiltration membranes. However, thus far, it has not been possible to bridge the gap from ultra- to nanofiltration and decrease the pore size of self-assembled block copolymer membranes to below 5 nm without post-treatment. It is now reported that the self-assembly of blends of two chemically interacting copolymers can lead to highly porous membranes with pore diameters as small as 1.5 nm. The membrane containing an ultraporous, 60 nm thin separation layer can fully reject solutes with molecular weights of 600 g mol(-1) in aqueous solutions with a water flux that is more than one order of magnitude higher than the permeance of commercial nanofiltration membranes. Simulations of the membrane formation process by dissipative particle dynamics (DPD) were used to explain the dramatic observed pore size reduction combined with an increase in water flux. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. An efficient strategy to assemble water soluble histidine-perylene diimide and graphene oxide for the detection of PPi in physiological conditions and in vitro.

    Science.gov (United States)

    Muthuraj, B; Mukherjee, Sudip; Chowdhury, Sayan Roy; Patra, Chitta Ranjan; Iyer, Parameswar K

    2017-03-15

    A strategy to develop water soluble, biocompatible nanocomposite probe for the detection of pyrophosphate (PPi) in physiological conditions and in in vitro live melanoma cancer cells (B16F10) is reported. The self-assembled nanocomposite probe comprised of amino acid (histidine) functionalized perylenediimide (PDI-HIS), copper ion and graphene oxide (GO) and that could be utilized as a highly effective sensing platform in biological conditions and cellular environment via fluorescence "turn-on" for PPi detection. This controlled fabrication of metal organic self-assembled spheres along with GO proved very valuable for the detection of PPi in unprecedented sensitivity over other competing ions. The PDI-HIS-Cu-GO (PCG) nanocomposite sensor provides a unique platform for the fluorogenic detection of PPi having a very low limit of detection (LOD) of 0.60×10 -7 M based on the strong affinity (1.0×10 6 M -1 ) between the copper complex of PDI-HIS receptor and PPi. The intracellular detection of PPi using PCG also carried out in B16F10 cells where >10 times observed as compared to the PDI-HIS+Cu 2+ complex. Thus early cancer detection via PPi recognition in physiological conditions and in live cells was possible using PCG. Furthermore, the fabrication of PDI-HIS and PCG with PVA hydrogel films and on thin layer chromatography plates demonstrated the practical utility for the detection of PPi anions by "off-on" response rapidly in a label free manner. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Reactivity of Metal Ions Bound to Water-Soluble Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Sauer, N.N.; Watkins, J.G.; Lin, M.; Birnbaum, E.R.; Robison, T.W.; Smith, B.F.; Gohdes, J.W.; McDonald, J.G.

    1999-06-29

    The intent of this work is to determine the effectiveness of catalysts covalently bound to polymers and to understand the consequences of supporting the catalysts on catalyst efficiency and selectivity. Rhodium phosphine complexes with functional groups for coupling to polymers were prepared. These catalyst precursors were characterized using standard techniques including IR, NMR, and elemental analysis. Studies on the modified catalysts showed that they were still active hydrogenation catalysts. However, tethering of the catalysts to polyamines gave systems with low hydrogenation activity. Analogous biphasic systems were also explored. Phosphine ligands with a surfactant-like structure have been synthesized and used to prepare catalytically active complexes of palladium. The palladium complexes were utilized in Heck-type coupling reactions (e.g. coupling of iodobenzene and ethyl acrylate to produce ethyl cinnamate) under vigorously stirred biphasic reaction conditions, and were found to offer superior performance over a standard water-soluble palladium catalyst under analogous conditions.

  20. Biodegradable fibre scaffolds incorporating water-soluble drugs and proteins.

    Science.gov (United States)

    Ma, J; Meng, J; Simonet, M; Stingelin, N; Peijs, T; Sukhorukov, G B

    2015-07-01

    A new type of biodegradable drug-loaded fibre scaffold has been successfully produced for the benefit of water-soluble drugs and proteins. Model drug loaded calcium carbonate (CaCO3) microparticles incorporated into poly(lactic acid-co-glycolic acid) (PLGA) fibres were manufactured by co-precipitation of CaCO3 and the drug molecules, followed by electrospinning of a suspension of such drug-loaded microparticles in a PLGA solution. Rhodamine 6G and bovine serum albumin were used as model drugs for our release study, representing small bioactive molecules and protein, respectively. A bead and string structure of fibres was achieved. The drug release was investigated with different drug loadings and in different pH release mediums. Results showed that a slow and sustained drug release was achieved in 40 days and the CaCO3 microparticles used as the second barrier restrained the initial burst release.

  1. Monolayer Silane-Coated, Water-Soluble Quantum Dots.

    Science.gov (United States)

    Zhang, Xi; Shamirian, Armen; Jawaid, Ali M; Tyrakowski, Christina M; Page, Leah E; Das, Adita; Chen, Ou; Isovic, Adela; Hassan, Asra; Snee, Preston T

    2015-12-02

    A one-step method to produce ≈12 nm hydrodynamic diameter water-soluble CdSe/ZnS quantum dots (QDs), as well as CdS/ZnS, ZnSe/ZnMnS/ZnS, AgInS2 /ZnS, and CuInS2 /ZnS QDs, by ligand exchange with a near-monolayer of organosilane caps is reported. The method cross-links the surface-bound silane ligands such that the samples are stable on the order of months under ambient conditions. Furthermore, the samples may retain a high quantum yield (60%) over this time. Several methods to functionalize aqueous QD dispersions with proteins and fluorescent dyes have been developed with reaction yields as high as 97%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Hydrodynamic Self-Assembly of Topographical Patterns on Soft Materials

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Satish [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-01-06

    The objective of this project is to use theoretical tools to explore fundamentally new ways of creating and controlling surface topography on soft materials (e.g., polymeric liquids, gels, colloidal suspensions) that make use of principles from hydrodynamics and self-assembly. Surface topography is known to have a significant impact on the optical, adhesive, and wetting properties of materials, so improved fundamental understanding of how to create and control it will help enable the tailoring of these properties to desired specifications. Self-assembly is the spontaneous organization of an ordered structure, and hydrodynamics often plays an important role in the self-assembly of soft materials. This research supported through this project has led to the discovery of a number of novel phenomena that are described in published journal articles. In this way, the research significantly adds to the fundamental understanding of the topics investigated.

  3. Regulating DNA Self-assembly by DNA-Surface Interactions.

    Science.gov (United States)

    Liu, Longfei; Li, Yulin; Wang, Yong; Zheng, Jianwei; Mao, Chengde

    2017-12-14

    DNA self-assembly provides a powerful approach for preparation of nanostructures. It is often studied in bulk solution and involves only DNA-DNA interactions. When confined to surfaces, DNA-surface interactions become an additional, important factor to DNA self-assembly. However, the way in which DNA-surface interactions influence DNA self-assembly is not well studied. In this study, we showed that weak DNA-DNA interactions could be stabilized by DNA-surface interactions to allow large DNA nanostructures to form. In addition, the assembly can be conducted isothermally at room temperature in as little as 5 seconds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Associative Pattern Recognition Through Macro-molecular Self-Assembly

    Science.gov (United States)

    Zhong, Weishun; Schwab, David J.; Murugan, Arvind

    2017-05-01

    We show that macro-molecular self-assembly can recognize and classify high-dimensional patterns in the concentrations of N distinct molecular species. Similar to associative neural networks, the recognition here leverages dynamical attractors to recognize and reconstruct partially corrupted patterns. Traditional parameters of pattern recognition theory, such as sparsity, fidelity, and capacity are related to physical parameters, such as nucleation barriers, interaction range, and non-equilibrium assembly forces. Notably, we find that self-assembly bears greater similarity to continuous attractor neural networks, such as place cell networks that store spatial memories, rather than discrete memory networks. This relationship suggests that features and trade-offs seen here are not tied to details of self-assembly or neural network models but are instead intrinsic to associative pattern recognition carried out through short-ranged interactions.

  5. Self-Assembly in Biosilicification and Biotemplated Silica Materials

    Directory of Open Access Journals (Sweden)

    Francisco M. Fernandes

    2014-09-01

    Full Text Available During evolution, living organisms have learned to design biomolecules exhibiting self-assembly properties to build-up materials with complex organizations. This is particularly evidenced by the delicate siliceous structures of diatoms and sponges. These structures have been considered as inspiration sources for the preparation of nanoscale and nanostructured silica-based materials templated by the self-assembled natural or biomimetic molecules. These templates range from short peptides to large viruses, leading to biohybrid objects with a wide variety of dimensions, shapes and organization. A more recent strategy based on the integration of biological self-assembly as the driving force of silica nanoparticles organization offers new perspectives to elaborate highly-tunable, biofunctional nanocomposites.

  6. Self-Assembly in Biosilicification and Biotemplated Silica Materials.

    Science.gov (United States)

    Fernandes, Francisco M; Coradin, Thibaud; Aimé, Carole

    2014-09-04

    During evolution, living organisms have learned to design biomolecules exhibiting self-assembly properties to build-up materials with complex organizations. This is particularly evidenced by the delicate siliceous structures of diatoms and sponges. These structures have been considered as inspiration sources for the preparation of nanoscale and nanostructured silica-based materials templated by the self-assembled natural or biomimetic molecules. These templates range from short peptides to large viruses, leading to biohybrid objects with a wide variety of dimensions, shapes and organization. A more recent strategy based on the integration of biological self-assembly as the driving force of silica nanoparticles organization offers new perspectives to elaborate highly-tunable, biofunctional nanocomposites.

  7. Self-assembly of hydrofluorinated Janus graphene monolayer

    DEFF Research Database (Denmark)

    Jin, Yakang; Xue, Qingzhong; Zhu, Lei

    2016-01-01

    der Waals (vdW) interaction and the coupling of C-H/π/C-F interaction and π/π interaction are proven to offer the continuous driving force of self-assembly of J-GN. The results show that J-GN can self-assemble into various J-NSs structures, including arcs, multi-wall J-NS and arm-chair-like J...... driving force of the self-assembly. Finally, we studied the hydrogen sorption over the formed J-NS with a considerable interlayer spacing, which reaches the US DOE target, indicating that J-NS is a promising candidate for hydrogen storage by controlling the temperature of system. Our theoretical results...

  8. Scratch Drive Actuator Driven Self-assembled Variable Optical Attenuator

    Science.gov (United States)

    Lee, Chengkuo; Lai, Yen-Jyh; Wu, Chia-Yu; Lin, Yu-Shen; Tasi, Ming Hung; Huang, Ruey-Shing; Lin, Min-Shyong

    2004-06-01

    This paper describes the new concept and design for a self-assembled variable optical attenuator (VOA) derived by using surface micromachining technology. A residual stress-induced flexure curved beam with corrugated trench anchors can lift up the reflective mirror shutter. This self-assembled reflective shutter can be driven by a set of scratch drive actuator (SDA), then slides into the spacing between input and output fiber ends. The attenuation range of proposed microelectromechanical systems (MEMS) VOA is determined by the vertical position of self-assembled pop-up polysilicon reflective shutter in which it is controlled by the value of applied dc voltage. This new VOA demonstrates continuous attenuation capability and wide attenuation range based on using an electrostatic actuator that is a new residual stress-induced flexure curved beam with corrugated-trench anchors. This device exhibits attenuation range of 70 dB and insertion loss less than 1 dB.

  9. Self-assembly of model proteins into virus capsids

    Science.gov (United States)

    Wołek, Karol; Cieplak, Marek

    2017-11-01

    We consider self-assembly of proteins into a virus capsid by the methods of molecular dynamics. The capsid corresponds either to SPMV or CCMV and is studied with and without the RNA molecule inside. The proteins are flexible and described by the structure-based coarse-grained model augmented by electrostatic interactions. Previous studies of the capsid self-assembly involved solid objects of a supramolecular scale, e.g. corresponding to capsomeres, with engineered couplings and stochastic movements. In our approach, a single capsid is dissociated by an application of a high temperature for a variable period and then the system is cooled down to allow for self-assembly. The restoration of the capsid proceeds to various extent, depending on the nature of the dissociated state, but is rarely complete because some proteins depart too far unless the process takes place in a confined space.

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

    Science.gov (United States)

    Liu, Jianfeng; Liu, Jinjian; Xu, Hongyan; Zhang, Yumin; Chu, Liping; Liu, Qingfen; Song, Naling; Yang, Cuihong

    2014-01-01

    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.

  11. Water uptake by fresh Indonesian peat burning particles is limited by water-soluble organic matter

    Science.gov (United States)

    Chen, Jing; Hapsari Budisulistiorini, Sri; Itoh, Masayuki; Lee, Wen-Chien; Miyakawa, Takuma; Komazaki, Yuichi; Qing Yang, Liu Dong; Kuwata, Mikinori

    2017-09-01

    The relationship between hygroscopic properties and chemical characteristics of Indonesian biomass burning (BB) particles, which are dominantly generated from peatland fires, was investigated using a humidified tandem differential mobility analyzer. In addition to peat, acacia (a popular species at plantation) and fern (a pioneering species after disturbance by fire) were used for experiments. Fresh Indonesian peat burning particles are almost non-hygroscopic (mean hygroscopicity parameter, κ dry diameter = 100 nm, hereinafter) for Riau peat burning particles, while that for Central Kalimantan ranges from 0.05 to 0.06. Fern combustion particles are more hygroscopic (κ = 0. 08), whereas the acacia burning particles have a mediate κ value (0.04). These results suggest that κ is significantly dependent on biomass types. This variance in κ is partially determined by fractions of water-soluble organic carbon (WSOC), as demonstrated by a correlation analysis (R = 0.65). κ of water-soluble organic matter is also quantified, incorporating the 1-octanol-water partitioning method. κ values for the water extracts are high, especially for peat burning particles (A0 (a whole part of the water-soluble fraction): κ = 0.18, A1 (highly water-soluble fraction): κ = 0.30). This result stresses the importance of both the WSOC fraction and κ of the water-soluble fraction in determining the hygroscopicity of organic aerosol particles. Values of κ correlate positively (R = 0.89) with the fraction of m/z 44 ion signal quantified using a mass spectrometric technique, demonstrating the importance of highly oxygenated organic compounds to the water uptake by Indonesian BB particles. These results provide an experimentally validated reference for hygroscopicity of organics-dominated particles, thus contributing to more accurate estimation of environmental and climatic impacts driven by Indonesian BB particles on both regional and global scales.

  12. Morphological Analysis and Solubility of Lead Particles: Effect of Phosphates and Implications to Drinking Water Distribution

    Science.gov (United States)

    Objective • Describe lead synthesis experiments conduced to model the impact of water quality on lead particles and solubility • Develop a model system that can be used for lead solubility studies • Understand the how phosphates impact the morphology and solubility transfo...

  13. Self-Assembling Ability Determines the Activity of Enzyme-Instructed Self-Assembly for Inhibiting Cancer Cells.

    Science.gov (United States)

    Feng, Zhaoqianqi; Wang, Huaimin; Chen, Xiaoyi; Xu, Bing

    2017-11-01

    Enzyme-instructed self-assembly (EISA) represents a dynamic continuum of supramolecular nanostructures that selectively inhibits cancer cells via simultaneously targeting multiple hallmark capabilities of cancer, but how to design the small molecules for EISA from the vast molecular space remains an unanswered question. Here we show that the self-assembling ability of small molecules controls the anticancer activity of EISA. Examining the EISA precursor analogues consisting of an N-capped d-tetrapeptide, a phosphotyrosine residue, and a diester or a diamide group, we find that, regardless of the stereochemistry and the regiochemistry of their tetrapeptidic backbones, the anticancer activities of these precursors largely match their self-assembling abilities. Additional mechanistic studies confirm that the assemblies of the small peptide derivatives result in cell death, accompanying significant rearrangement of cytoskeletal proteins and plasma membranes. These results imply that the diester or diamide derivatives of the d-tetrapeptides self-assemble pericellularly, as well as intracellularly, to result in cell death. As the first case to correlate thermodynamic properties (e.g., self-assembling ability) of small molecules with the efficacy of a molecule process against cancer cells, this work provides an important insight for developing a molecular dynamic continuum for potential cancer therapy, as well as understanding the cytotoxicity of pathogenic assemblies.

  14. Self-Assembly of Cellulose Oligomers into Nanoribbon Network Structures Based on Kinetic Control of Enzymatic Oligomerization.

    Science.gov (United States)

    Serizawa, Takeshi; Fukaya, Yuka; Sawada, Toshiki

    2017-10-27

    The ability to chemically synthesize desired molecules followed by their in situ self-assembly in reaction solution has attracted much attention as a simple and environmentally friendly method to produce self-assembled nanostructures. In this study, α-D-glucose 1-phosphate monomers and cellobiose primers were subjected to cellodextrin phosphorylase-catalyzed reverse phosphorolysis reactions in aqueous solution in order to synthesize cellulose oligomers, which were then in situ self-assembled into crystalline nanoribbon network structures. The average degree-of-polymerization (DP) values of the cellulose oligomers were estimated to be approximately 7-8 with a certain degree of DP distribution. The cellulose oligomers crystallized with the cellulose II allomorph appeared to align perpendicularly to the base plane of the nanoribbons in an anti-parallel manner. Detailed analyses of reaction time dependence suggested that the production of nanoribbon network structures was kinetically controlled by the amount of water-insoluble cellulose oligomers produced.

  15. Phosphorylation Modulates Ameloblastin Self-assembly and Ca2+ Binding

    Directory of Open Access Journals (Sweden)

    Øystein Stakkestad

    2017-07-01

    Full Text Available Ameloblastin (AMBN, an important component of the self-assembled enamel extra cellular matrix, contains several in silico predicted phosphorylation sites. However, to what extent these sites actually are phosphorylated and the possible effects of such post-translational modifications are still largely unknown. Here we report on in vitro experiments aimed at investigating what sites in AMBN are phosphorylated by casein kinase 2 (CK2 and protein kinase A (PKA and the impact such phosphorylation has on self-assembly and calcium binding. All predicted sites in AMBN can be phosphorylated by CK2 and/or PKA. The experiments show that phosphorylation, especially in the exon 5 derived part of the molecule, is inversely correlated with AMBN self-assembly. These results support earlier findings suggesting that AMBN self-assembly is mostly dependent on the exon 5 encoded region of the AMBN gene. Phosphorylation was significantly more efficient when the AMBN molecules were in solution and not present as supramolecular assemblies, suggesting that post-translational modification of AMBN must take place before the enamel matrix molecules self-assemble inside the ameloblast cell. Moreover, phosphorylation of exon 5, and the consequent reduction in self-assembly, seem to reduce the calcium binding capacity of AMBN suggesting that post-translational modification of AMBN also can be involved in control of free Ca2+ during enamel extra cellular matrix biomineralization. Finally, it is speculated that phosphorylation can provide a functional crossroad for AMBN either to be phosphorylated and act as monomeric signal molecule during early odontogenesis and bone formation, or escape phosphorylation to be subsequently secreted as supramolecular assemblies that partake in enamel matrix structure and mineralization.

  16. Hydrazine-mediated construction of nanocrystal self-assembly materials.

    Science.gov (United States)

    Zhou, Ding; Liu, Min; Lin, Min; Bu, Xinyuan; Luo, Xintao; Zhang, Hao; Yang, Bai

    2014-10-28

    Self-assembly is the basic feature of supramolecular chemistry, which permits to integrate and enhance the functionalities of nano-objects. However, the conversion of self-assembled structures to practical materials is still laborious. In this work, on the basis of studying one-pot synthesis, spontaneous assembly, and in situ polymerization of aqueous semiconductor nanocrystals (NCs), NC self-assembly materials are produced and applied to design high performance white light-emitting diode (WLED). In producing self-assembly materials, the additive hydrazine (N2H4) is curial, which acts as the promoter to achieve room-temperature synthesis of aqueous NCs by favoring a reaction-controlled growth, as the polyelectrolyte to weaken inter-NC electrostatic repulsion and therewith facilitate the one-dimensional self-assembly, and in particular as the bifunctional monomers to polymerize with mercapto carboxylic acid-modified NCs via in situ amidation reaction. This strategy is versatile for mercapto carboxylic acid-modified aqueous NCs, for example CdS, CdSe, CdTe, CdSe(x)Te(1-x), and Cd(y)Hg(1-y)Te. Because of the multisite modification with carboxyl, the NCs act as macromonomers, thus producing cross-linked self-assembly materials with excellent thermal, solvent, and photostability. The assembled NCs preserve strong luminescence and avoid unpredictable fluorescent resonance energy transfer, the main problem in design WLED from multiple NC components. These advantages allow the fabrication of NC-based WLED with high color rendering index (86), high luminous efficacy (41 lm/W), and controllable color temperature.

  17. Ceramic membrane ozonator for soluble organics removal from produced water

    Science.gov (United States)

    Siagian, U. W. R.; Dwipramana, A. S.; Perwira, S. B.; Khoiruddin; Wenten, I. G.

    2018-01-01

    In this work, the performance of ozonation for degradation of soluble organic compounds in produced water was investigated. Tubular ceramic membrane diffuser (with and without a static mixer in the lumen side) was used to facilitate contact between ozone and produced water. The ozonation was conducted at ozone flow rate of 8 L.min-1, ozone concentration of 0.4 ppm, original pH of the solution, and pressure of 1.2 bar, while the flow rates of the produced water were varied (192, 378 and 830 mL.min-1). It was found that the reduction of benzene, toluene, ethylbenzene, and xylene were 85%, 99%, 85%, and 95%, respectively. A lower liquid flow rate in a laminar state showed a better component reduction due to the longer contacting time between the liquid and the gas phase. The introduction of the static mixer in the lumen side of the membrane as a turbulence promoter provided a positive effect on the performance of the membrane diffuser. The twisted static mixer exhibited the better removal rate than the spiral static mixer.

  18. Leveraging symmetry to predict self-assembly of multiple polymers

    Science.gov (United States)

    Lin, Milo M.

    2017-09-01

    Protein self-assembly is fundamental to biological function and disease. Experimentally, the atomic-level structure is difficult to obtain and the assembly mechanism is poorly understood. The large number of possible states accessible to such systems limits computational prediction. Here, I introduce a new computational approach that enforces conformational symmetry, whereby all chains in the system adopt the same conformation. Using this approach on a 2D lattice, a designed multi-chain conformation is found more than four orders of magnitude faster than existing approaches. Furthermore, the free energy landscape can be efficiently computed, showing potential for enabling atomistic prediction of protein self-assembly.

  19. 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.

  20. Structural simulations of nanomaterials self-assembled from ionic macrocycles.

    Energy Technology Data Exchange (ETDEWEB)

    van Swol, Frank B.; Medforth, Craig John (University of New Mexico, Albuquerque, NM)

    2010-10-01

    Recent research at Sandia has discovered a new class of organic binary ionic solids with tunable optical, electronic, and photochemical properties. These nanomaterials, consisting of a novel class of organic binary ionic solids, are currently being developed at Sandia for applications in batteries, supercapacitors, and solar energy technologies. They are composed of self-assembled oligomeric arrays of very large anions and large cations, but their crucial internal arrangement is thus far unknown. This report describes (a) the development of a relevant model of nonconvex particles decorated with ions interacting through short-ranged Yukawa potentials, and (b) the results of initial Monte Carlo simulations of the self-assembly binary ionic solids.

  1. Self-assembly patterning of organic molecules on a surface

    Science.gov (United States)

    Pan, Minghu; Fuentes-Cabrera, Miguel; Maksymovych, Petro; Sumpter, Bobby G.; Li, Qing

    2017-04-04

    The embodiments disclosed herein include all-electron control over a chemical attachment and the subsequent self-assembly of an organic molecule into a well-ordered three-dimensional monolayer on a metal surface. The ordering or assembly of the organic molecule may be through electron excitation. Hot-electron and hot-hole excitation enables tethering of the organic molecule to a metal substrate, such as an alkyne group to a gold surface. All-electron reactions may allow a direct control over the size and shape of the self-assembly, defect structures and the reverse process of molecular disassembly from single molecular level to mesoscopic scale.

  2. Self-assembly of active amphiphilic Janus particles

    Science.gov (United States)

    Mallory, S. A.; Alarcon, F.; Cacciuto, A.; Valeriani, C.

    2017-12-01

    In this article, we study the phenomenology of a two dimensional dilute suspension of active amphiphilic Janus particles. We analyze how the morphology of the aggregates emerging from their self-assembly depends on the strength and the direction of the active forces. We systematically explore and contrast the phenomenologies resulting from particles with a range of attractive patch coverages. Finally, we illustrate how the geometry of the colloids and the directionality of their interactions can be used to control the physical properties of the assembled active aggregates and suggest possible strategies to exploit self-propulsion as a tunable driving force for self-assembly.

  3. Two dimensional self-assembly of inverse patchy colloids

    OpenAIRE

    K, Remya Ann Mathews; Mani, Ethayaraja

    2017-01-01

    We report on the self-assembly of inverse patchy colloids (IPC) using Monte Carlo simulations in two-dimensions. The IPC model considered in this work corresponds to either bipolar colloids or colloids decorated with complementary DNA on their surfaces, where only patch and non-patch parts attract. The patch coverage is found to be a dominant factor in deciding equilibrium self-assembled structures. In particular, both regular square and triangular crystals are found to be stable at 0.5 patch...

  4. Nano-engineering by optically directed self-assembly.

    Energy Technology Data Exchange (ETDEWEB)

    Furst, Eric (University of Delaware, Newark, DE); Dunn, Elissa (Yale University, New Haven, CT); Park, Jin-Gyu (Yale University, New Haven, CT); Brinker, C. Jeffrey; Sainis, Sunil (Yale University, New Haven, CT); Merrill, Jason (Yale University, New Haven, CT); Dufresne, Eric (Yale University, New Haven, CT); Reichert, Matthew D.; Brotherton, Christopher M.; Bogart, Katherine Huderle Andersen; Molecke, Ryan A.; Koehler, Timothy P.; Bell, Nelson Simmons; Grillet, Anne Mary; Gorby, Allen D.; Singh, John (University of Delaware, Newark, DE); Lele, Pushkar (University of Delaware, Newark, DE); Mittal, Manish (University of Delaware, Newark, DE)

    2009-09-01

    Lack of robust manufacturing capabilities have limited our ability to make tailored materials with useful optical and thermal properties. For example, traditional methods such as spontaneous self-assembly of spheres cannot generate the complex structures required to produce a full bandgap photonic crystals. The goal of this work was to develop and demonstrate novel methods of directed self-assembly of nanomaterials using optical and electric fields. To achieve this aim, our work employed laser tweezers, a technology that enables non-invasive optical manipulation of particles, from glass microspheres to gold nanoparticles. Laser tweezers were used to create ordered materials with either complex crystal structures or using aspherical building blocks.

  5. Self-Assembly of Charged Amphiphilic Diblock Copolymers with Insoluble Blocks of Decreasing Hydrophobicity: From Kinetically Frozen Colloids to Macrosurfactants

    Energy Technology Data Exchange (ETDEWEB)

    M Jacquin; P Muller; H Cottet; O Theodoly

    2011-12-31

    We have investigated the self-assembly properties in aqueous solution of amphiphilic diblock copolymers with insoluble blocks of different hydrophobicity and demonstrated that the condition to obtain dynamic micelles is to design samples with insoluble blocks of low enough hydrophobicity. We focus here on results with new water-soluble amphiphilic diblock copolymers poly(diethyleneglycol ethylether acrylate)-b-poly(acrylic acid), or PDEGA-b-PAA. The physical characteristics of PDEGA-b-PAA micelles at high ionization have been determined by small angle neutron scattering (SANS). We show that PDEGA-b-PAA samples form micelles at thermodynamic equilibrium. The critical micelle concentrations (CMCs) decrease strongly with ionic strength and temperature due to a solvent quality decrease for, respectively, the corona and the core. This behavior of reversible aggregation is remarkable as compared to the behavior of kinetically frozen aggregation that has been widely observed with samples of similar architecture and different hydrophobic blocks, for example, poly(styrene)-b-poly(acrylic acid), PS-b-PAA, and poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA. We have measured the interfacial tension between water and the homopolymers PDEGA and PBA at, respectively, 3 and 20 mN/m at room temperature, which permits one to estimate the energy cost to extract a unimer from a micelle. The results are consistent with a micelle association that is fast for PDEGA-b-PAA and kinetically frozen PBA-b-PAA. Hence, PDEGA-b-PAA samples form a new system of synthetic charged macrosurfactant with unique properties of fast dynamic association, tunable charge, and water solubility even at temperatures and NaCl concentrations as high as 65 C and 1 M.

  6. Study on Mixed Solvency Concept in Formulation Development of Aqueous Injection of Poorly Water Soluble Drug

    Directory of Open Access Journals (Sweden)

    Shailendra Singh Solanki

    2013-01-01

    Full Text Available In the present investigation, mixed-solvency approach has been applied for the enhancement of aqueous solubility of a poorly water- soluble drug, zaltoprofen (selected as a model drug, by making blends (keeping total concentrations 40% w/v, constant of selected water-soluble substances from among the hydrotropes (urea, sodium benzoate, sodium citrate, nicotinamide; water-soluble solids (PEG-4000, PEG-6000; and co-solvents (propylene glycol, glycerine, PEG-200, PEG-400, PEG-600. Aqueous solubility of drug in case of selected blends (12 blends ranged from 9.091 ± 0.011 mg/ml–43.055 ± 0.14 mg/ml (as compared to the solubility in distilled water 0.072 ± 0.012 mg/ml. The enhancement in the solubility of drug in a mixed solvent containing 10% sodium citrate, 5% sodium benzoate and 25 % S cosolvent (25% S cosolvent contains PEG200, PEG 400, PEG600, Glycerine and Propylene glycol was more than 600 fold. This proved a synergistic enhancement in solubility of a poorly water-soluble drug due to mixed cosolvent effect. Each solubilized product was characterized by ultraviolet and infrared techniques. Various properties of solution such as pH, viscosity, specific gravity and surface tension were studied. The developed formulation was studied for physical and chemical stability. This mixed solvency shall prove definitely a boon for pharmaceutical industries for the development of dosage form of poorly water soluble drugs.

  7. Ultrasmall Peptides Self-Assemble into Diverse Nanostructures: Morphological Evaluation and Potential Implications

    Directory of Open Access Journals (Sweden)

    Charlotte A.E. Hauser

    2011-09-01

    Full Text Available In this study, we perform a morphological evaluation of the diverse nanostructures formed by varying concentration and amino acid sequence of a unique class of ultrasmall self-assembling peptides. We modified these peptides by replacing the aliphatic amino acid at the C-aliphatic terminus with different aromatic amino acids. We tracked the effect of introducing aromatic residues on self-assembly and morphology of resulting nanostructures. Whereas aliphatic peptides formed long, helical fibers that entangle into meshes and entrap >99.9% water, the modified peptides contrastingly formed short, straight fibers with a flat morphology. No helical fibers were observed for the modified peptides. For the aliphatic peptides at low concentrations, different supramolecular assemblies such as hollow nanospheres and membrane blebs were found. Since the ultrasmall peptides are made of simple, aliphatic amino acids, considered to have existed in the primordial soup, study of these supramolecular assemblies could be relevant to understanding chemical evolution leading to the origin of life on Earth. In particular, we propose a variety of potential applications in bioengineering and nanotechnology for the diverse self-assembled nanostructures.

  8. A Self-Assembling Peptide Gel as a Vitreous Substitute: A Rabbit Study.

    Science.gov (United States)

    Uesugi, Koji; Sakaguchi, Hirokazu; Hayashida, Yasutaka; Hayashi, Ryuhei; Baba, Koichi; Suganuma, Yuya; Yokoi, Hidenori; Tsujikawa, Motokazu; Nishida, Kohji

    2017-08-01

    To evaluate a self-assembling peptide gel as a potential vitreous substitute. PanaceaGel SPG-178, a self-assembling peptide gel, was diluted with distilled water and a balanced salt solution to achieve a final peptide concentration of 0.1%. The gel's refractive index, visible light transmission rate, and rheologic properties were investigated. The gel's biocompatibility was evaluated by examining the cellular viability (live and dead staining) and proliferation rate (alamarBlue assay). A 25-G pars plana vitrectomy was performed on the right eye of 21 New Zealand white rabbits. The gel was then injected into the vitreous cavity of 15 eyes. Six eyes were injected with a balanced salt solution (BSS) and served as controls. Toxicity was examined using electroretinography and histologic analysis after the injection of the gel. The gel's physical properties closely resembled those of human vitreous. The gel showed no apparent toxicity. When the gel was injected into the vitreous cavity, fragmentation was not observed. Additionally, the gel remained transparent in the vitreous cavity and no complications were observed for 3 months after the injection. Electroretinography and histology confirmed the gel's biocompatibility. This diluted self-assembling peptide gel could be provide a promising vitreous substitute.

  9. Recombinant production of self-assembling β-structured peptides using SUMO as a fusion partner

    Directory of Open Access Journals (Sweden)

    Prakash Abhinav

    2012-07-01

    Full Text Available Abstract Background Self-assembling peptides that form nanostructured hydrogels are important biomaterials for tissue engineering scaffolds. The P11-family of peptides includes, P11-4 (QQRFEWEFEQQ and the complementary peptides P11-13 (EQEFEWEFEQE and P11-14 (QQOrnFOrnWOrnFOrnQQ. These form self-supporting hydrogels under physiological conditions (pH 7.4, 140 mM NaCl either alone (P11-4 or when mixed (P11-13 and P11-14. We report a SUMO-peptide expression strategy suitable for allowing release of native sequence peptide by SUMO protease cleavage. Results We have expressed SUMO-peptide fusion proteins from pET vectors by using autoinduction methods. Immobilised metal affinity chromatography was used to purify the fusion protein, followed by SUMO protease cleavage in water to release the peptides, which were recovered by reverse phase HPLC. The peptide samples were analysed by electrospray mass spectrometry and self-assembly was followed by circular dichroism and transmission electron microscopy. Conclusions The fusion proteins were produced in high yields and the β-structured peptides were efficiently released by SUMO protease resulting in peptides with no additional amino acid residues and with recoveries of 46% to 99%. The peptides behaved essentially the same as chemically synthesised and previously characterised recombinant peptides in self-assembly and biophysical assays.

  10. Controllable fabrication of lotus-leaf-like superhydrophobic surface on copper foil by self-assembly

    Science.gov (United States)

    Yuan, Zhiqing; Wang, Xian; Bin, Jiping; Wang, Menglei; Peng, Chaoyi; Xing, Suli; Xiao, Jiayu; Zeng, Jingcheng; Chen, Hong

    2014-09-01

    A novel approach was developed to fabricate a lotus-leaf-like superhydrophobic surface on a copper foil by simple self-assembly method with the assistance of the porous PDMS template which was used to adjust the oxidized parts of the copper foil surface before self-assembly. The results showed a series of beautiful flower-like microstructures resulting from the self-assembly of cupric stearate that were distributed at regular intervals on the as-prepared copper foil surface similar to the papillae of lotus leaf surface. The water contact angle of the as-prepared copper surface was up to 161° and its sliding angle was only 3°. Its great superhydrophobicity could be kept unchanged after 6 months in air. The formation mechanism of the lotus-leaf-like structure was discussed. This simple and low-cost method is expected to be applied to design and prepare complicated superhydrophobic surfaces with beautiful regular microstructures on different substrates such as stainless steel, zinc, and so on.

  11. INTERFACIAL SELF-ASSEMBLY OF A HYDROPHOBIN INTO AN AMPHIPATHIC PROTEIN MEMBRANE MEDIATES FUNGAL ATTACHMENT TO HYDROPHOBIC SURFACES

    NARCIS (Netherlands)

    WOSTEN, HAB; SCHUREN, FHJ; WESSELS, JGH

    1994-01-01

    The SC3p hydrophobin of Schizophyllum commune is a small hydrophobic protein (100-101 amino acids with eight cysteine residues) that self-assembles at a water/air interface and coats aerial hyphae with an SDS-insoluble protein membrane, at the outer side highly hydrophobic and with a typical rodlet

  12. New self-assembled nanocrystal micelles for biolabels and biosensors.

    Energy Technology Data Exchange (ETDEWEB)

    Tallant, David Robert; Wilson, Michael C. (University of New Mexico, Albuquerque, NM); Leve, Erik W. (University of New Mexico, Albuquerque, NM); Fan, Hongyou; Brinker, C. Jeffrey; Gabaldon, John (University of New Mexico, Albuquerque, NM); Scullin, Chessa (University of New Mexico, Albuquerque, NM)

    2005-12-01

    The ability of semiconductor nanocrystals (NCs) to display multiple (size-specific) colors simultaneously during a single, long term excitation holds great promise for their use in fluorescent bio-imaging. The main challenges of using nanocrystals as biolabels are achieving biocompatibility, low non-specific adsorption, and no aggregation. In addition, functional groups that can be used to further couple and conjugate with biospecies (proteins, DNAs, antibodies, etc.) are required. In this project, we invented a new route to the synthesis of water-soluble and biocompatible NCs. Our approach is to encapsulate as-synthesized, monosized, hydrophobic NCs within the hydrophobic cores of micelles composed of a mixture of surfactants and phospholipids containing head groups functionalized with polyethylene glycol (-PEG), -COOH, and NH{sub 2} groups. PEG provided biocompatibility and the other groups were used for further biofunctionalization. The resulting water-soluble metal and semiconductor NC-micelles preserve the optical properties of the original hydrophobic NCs. Semiconductor NCs emit the same color; they exhibit equal photoluminescence (PL) intensity under long-time laser irradiation (one week) ; and they exhibit the same PL lifetime (30-ns). The results from transmission electron microscopy and confocal fluorescent imaging indicate that water-soluble semiconductor NC-micelles are biocompatible and exhibit no aggregation in cells. We have extended the surfactant/lipid encapsulation techniques to synthesize water-soluble magnetic NC-micelles. Transmission electron microscopy results suggest that water-soluble magnetic NC-micelles exhibit no aggregation. The resulting NC-micelles preserve the magnetic properties of the original hydrophobic magnetic NCs. Viability studies conducted using yeast cells suggest that the magnetic nanocrystal-micelles are biocompatible. We have demonstrated, for the first time, that using external oscillating magnetic fields to manipulate

  13. Lubrication of polysilicon micromechanisms with self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, U.; Foster, J.D.; Habib, U.; Howe, R.T.; Maboudian, R. [Berkeley Sensor and Actuator Center, CA (United States); Senft, D.C.; Dugger, M.T. [Sandia National Labs., Albuquerque, NM (United States)

    1998-06-01

    Here, the authors report on the lubricating effects of self-assembled monolayers (SAMs) on MEMS by measuring static and dynamic friction with two polysilicon surface- micromachined devices. The first test structure is used to study friction between laterally sliding surfaces and with the second, friction between vertical sidewalls can be investigated. Both devices are SAM-coated following the sacrificial oxide etch and the microstructures emerge released and dry from the final water rinse. The coefficient of static friction, {mu}{sub s} was found to decrease from 2.1 {+-} 0.8 for the SiO{sub 2} coating to 0.11 {+-} 0.01 and 0.10 {+-} 0.01 for films derived from octadecyltrichloro-silane (OTS) and 1H,1H,2H,2H-perfluorodecyl-trichlorosilane (FDTS). Both OTS and FDTS SAM-coated structures exhibit dynamic coefficients of friction, {mu}{sub d} of 0.08 {+-} 0.01. These values were found to be independent of the apparent contact area, and remain unchanged after 1 million impacts at 5.6 {micro}N (17 kPa), indicating that these SAMs continue to act as boundary lubricants despite repeated impacts. Measurements during sliding friction from the sidewall friction testing structure give comparable initial {mu}{sub d} values of 0.02 at a contact pressure of 84 MPa. After 15 million wear cycles, {mu}{sub d} was found to rise to 0.27. Wear of the contacting surfaces was examined by SEM. Standard deviations in the {mu} data for SAM treatments indicate uniform coating coverage.

  14. [Emission Characteristics of Water-Soluble Ions in Fumes of Coal Fired Boilers in Beijing].

    Science.gov (United States)

    Hu, Yue-qi; Ma, Zhao-hui; Feng, Ya-jun; Wang, Chen; Chen, Yuan-yuan; He, Ming

    2015-06-01

    Selecting coal fired boilers with typical flue gas desulfurization and dust extraction systems in Beijing as the study objects, the issues and characteristics of the water-soluble ions in fumes of coal fired boilers and theirs influence factors were analyzed and evaluated. The maximum mass concentration of total water-soluble ions in fumes of coal fired boilers in Beijing was 51.240 mg x m(-3) in the benchmark fume oxygen content, the minimum was 7.186 mg x m(-3), and the issues of the water-soluble ions were uncorrelated with the fume moisture content. SO4(2-) was the primary characteristic water-soluble ion for desulfurization reaction, and the rate of contribution of SO4(2-) in total water-soluble ions ranged from 63.8% to 81.0%. F- was another characteristic water-soluble ion in fumes of thermal power plant, and the rate of contribution of F- in total water-soluble ions ranged from 22.2% to 32.5%. The fume purification technologies significantly influenced the issues and the emission characteristics of water-soluble ions in fumes of coal fired boilers. Na+ was a characteristic water-soluble ion for the desulfurizer NaOH, NH4+ and NO3+ were characteristic for the desulfurizer NH4HCO3, and Mg2+ was characteristic for the desulfurizer MgO, but the Ca2+ emission was not increased by addition of the desulfurizer CaO or CaCO3 The concentrations of NH4+ and NO3- in fumes of thermal power plant were lower than those in fumes of industrial or heating coal fired boilers. The form of water-soluble ions was significantly correlated with fume temperature. The most water-soluble ions were in superfine state at higher fume temperature and were not easily captured by the filter membrane.

  15. Host-guest complexation driven dynamic supramolecular self-assembly.

    Science.gov (United States)

    Zhang, Huacheng; Nguyen, Kim Truc; Ma, Xing; Yan, Hong; Guo, Junfei; Zhu, Liangliang; Zhao, Yanli

    2013-04-07

    Host-guest complexation between pillararene trimer 1 and biviologen 2 was used to fabricate the dynamic supramolecular self-assembly, which exhibits a reversible multidimensional transformation from 0D to 3D upon concentration changes. As a comparison, assemblies built by the complexation between 1,4-dimethoxypillar[5]arene and 2 only show spherical morphology under similar conditions.

  16. Photoinduced self-assembly of nanostructure in glass

    Directory of Open Access Journals (Sweden)

    Shimotsuma Y.

    2013-11-01

    Full Text Available Ultrashort-pulsed laser direct writing can be useful for a 3D material processing. Especially the localized form-birefringence originated from self-assembled nanostructure in isotropic material (i.e. SiO2 and GeO2 glass was demonstrated.

  17. Electronic functionalization of organic semiconductors with self-assembled monolayers

    Science.gov (United States)

    Podzorov, Vitaly

    2008-03-01

    Self-assembled monolayers (SAM) are widely used in a variety of emerging applications for surface modification of metals and oxides. Here, we demonstrate a new type of molecular self-assembly: the growth of organosilane SAMs at the surface of organic semiconductors. Remarkably, SAM growth results in a pronounced increase of surface conductivity of organic materials, which can be very large for SAMs with a strong electron withdrawing ability. For example, the conductivity induced by perfluorinated alkyl silanes in organic molecular crystals approaches 10̂-5 S per square, two orders of magnitude greater than the maximum conductivity typically achieved in organic field-effect transistors (OFETs). The observed large electronic effect opens new opportunities for nanoscale surface functionalization of organic semiconductors with molecular self-assembly. In particular, SAM-induced conductivity exhibits sensitivity to different molecular species present in the environment, which makes this system very attractive for chemical sensing applications [1]. [1]. M. F. Calhoun, J. Sanchez, D. Olaya, M. E. Gershenson and V. Podzorov, ``Electronic functionalization of the surface of organic semiconductors with self-assembled monolayers'', Nature Materials, Nov. 18, (2007).

  18. Self-assembling biomolecular catalysts for hydrogen production.

    Science.gov (United States)

    Jordan, Paul C; Patterson, Dustin P; Saboda, Kendall N; Edwards, Ethan J; Miettinen, Heini M; Basu, Gautam; Thielges, Megan C; Douglas, Trevor

    2016-02-01

    The chemistry of highly evolved protein-based compartments has inspired the design of new catalytically active materials that self-assemble from biological components. A frontier of this biodesign is the potential to contribute new catalytic systems for the production of sustainable fuels, such as hydrogen. Here, we show the encapsulation and protection of an active hydrogen-producing and oxygen-tolerant [NiFe]-hydrogenase, sequestered within the capsid of the bacteriophage P22 through directed self-assembly. We co-opted Escherichia coli for biomolecular synthesis and assembly of this nanomaterial by expressing and maturing the EcHyd-1 hydrogenase prior to expression of the P22 coat protein, which subsequently self assembles. By probing the infrared spectroscopic signatures and catalytic activity of the engineered material, we demonstrate that the capsid provides stability and protection to the hydrogenase cargo. These results illustrate how combining biological function with directed supramolecular self-assembly can be used to create new materials for sustainable catalysis.

  19. Tetrahymena dynamin related protein 6 self assembles independent ...

    Indian Academy of Sciences (India)

    eluted as small oligomeric forms. Absence of any peak in the void volume suggests that human dynamin 1 does not form self-assembled structure under high ionic strength condition. Supplementary figure 3: Size exclusion chromatography profile of Drp6-R414A. His6-Drp6-. R414A expressed and purified from bacteria ...

  20. Covalently stabilized self-assembled chlorophyll nanorods by olefin metathesis.

    Science.gov (United States)

    Sengupta, Sanchita; Würthner, Frank

    2012-06-11

    A new chlorophyll derivative with peripheral olefinic chains has been synthesised and its self-assembly properties have been studied, revealing formation of well-defined nanorods. These nanorods were stabilized and rigidified by olefin metathesis reaction as confirmed by spectroscopic and microscopic methods.

  1. Functional materials derived from block copolymer self-assembly

    DEFF Research Database (Denmark)

    Li, Tao

    The main objective of this project is to explore block copolymer self-assembly for generating functional materials with well-defined morphology on sub-20 nanometer length scale, which can be utilized in many important applications such as solar cells and nanolithography. One of the specific targe...

  2. Tailoring self-assembled monolayers at the electrochemical interface

    Indian Academy of Sciences (India)

    The main focus of this review is to illustrate the amenability of self-assembled monolayers (SAMs) for functionalisation with different receptors, catalytic materials, biomolecules, enzymes, antigen-antibody, etc for various applications. The review discusses initially about the preparation and characterization of SAMs and ...

  3. Electrostatic Self-Assembly of Polysaccharides into Nanofibers

    DEFF Research Database (Denmark)

    Mendes, Ana Carina Loureiro; Strohmenger, Timm; Goycoolea, Francisco

    2017-01-01

    In this study, the anionic polysaccharide Xanthan gum (X) was mixed with positively charged Chitosan oligomers (ChO), and used as building blocks, to generate novel nanofibers by electrostatic self-assembly in aqueous conditions. Different concentrations, ionic strength and order of mixing of both...

  4. Multiphonon capture processes in self-assembled quantum dots

    DEFF Research Database (Denmark)

    Magnúsdóttir, Ingibjörg; Uskov, A.; Bischoff, Svend

    2001-01-01

    We investigate capture of carriers from states in the continuous part of the energy spectrum into the discrete states of self-assembled InAs/GaAs QDs via emission of one or two phonons. We are not aware of any other investigations of two-phonon mediated capture processes in QDs, but we show that ...

  5. Complex Colloidal Structures by Self-assembly in Electric Fields

    NARCIS (Netherlands)

    Vutukuri, H.R.

    2012-01-01

    The central theme of this thesis is exploiting the directed self-assembly of both isotropic and anisotropic colloidal particles to achieve the fabrication of one-, two-, and three-dimensional complex colloidal structures using external electric fields and/or a simple in situ thermal annealing

  6. Synthesis, characterization and self-assembly of Co complexes ...

    Indian Academy of Sciences (India)

    (H-bonded) assemblies and afford inclusion complexes with solvents serving as the guest molecules.12 Self- assembly of phenolic compounds show that the ...... Board (SERB), Govt. of India for the generous financial support and CIF-USIC of this university for the instru- mental facilities. AA and DB thank University Grant.

  7. Reactivity within a confined self-assembled nanospace

    NARCIS (Netherlands)

    Koblenz, T.S.; Wassenaar, J.; Reek, J.N.H.

    2008-01-01

    Confined nanospaces in which reactions can take place, have been created by various approaches such as molecular capsules, zeolites and micelles. In this tutorial review we focus on the application of self-assembled nanocapsules with well-defined cavities as nanoreactors for organic and metal

  8. Critical Self-assembly Concentration of Bolaamphiphilic Peptides ...

    African Journals Online (AJOL)

    The study of the self-assembly properties of peptides and proteins is important for the understanding of molecular recognition processes and for the rational design of functional biomaterials. Novel bolaamphiphilic peptides and peptide hybrids incorporating non-natural aminoacids were designed around a model ...

  9. Tuning of metal work functions with self-assembled monolayers

    NARCIS (Netherlands)

    de Boer, B; Hadipour, A; Mandoc, MM; van Woudenbergh, T; Blom, PWM

    2005-01-01

    Work functions of gold and silver are varied by over 1.4 and 1.7 eV, respectively, by using self-assembled monolayers. Using these modified electrodes, the hole current in a poly(2-methoxy-5-(2'-ethylhexyloxy)- 1,4-phenylene vinylene) light-emitting diode is tuned by more than six orders of

  10. Tetrahymena dynamin-related protein 6 self-assembles ...

    Indian Academy of Sciences (India)

    Usha P Kar

    2017-12-30

    Dec 30, 2017 ... Self-assembly on target membranes is one of the important properties of all dynamin family proteins. Drp6, a dynamin- related protein in Tetrahymena, controls nuclear remodelling and undergoes cycles of assembly/disassembly on the nuclear envelope. To elucidate the mechanism of Drp6 function, we ...

  11. Polymer Self-Assembled Nanostructures as Innovative Drug Nanocarrier Platforms.

    Science.gov (United States)

    Pippa, Natassa; Pispas, Stergios; Demetzos, Costas

    2016-01-01

    Polymer self-assembled nanostructures are used in pharmaceutical sciences as bioactive molecules' delivery systems for therapeutic and diagnostic purposes. Micelles, polyelectrolyte complexes, polymersomes, polymeric nanoparticles, nanogels and polymer grafted liposomes represent delivery vehicles that are marketed and/or under clinical development, as drug formulations. In this mini-review, these, recently appeared in the literature, innovative polymer drug nanocarrier platforms are discussed, starting from their technological development in the laboratory to their potential clinical use, through studies of their biophysics, thermodynamics, physical behavior, morphology, bio-mimicry, therapeutic efficacy and safety. The properties of an ideal drug delivery system are the structural control over size and shape of drug or imaging agent cargo/domain, biocompatibility, nontoxic polymer/ pendant functionality and the precise, nanoscale container and/or scaffolding properties with high drug or imaging agent capacity features. Self-assembled polymer nanostructures exhibit all these properties and could be considered as ideal drug nanocarriers through control of their size, structure and morphology, with the aid of a large variety of parameters, in vitro and in vivo. These modern trends reside at the interface of soft matter self-assembly and pharmaceutical sciences and the technologies for health. Great advantages related to basic science and applications are expected by understanding the self-assembly behavior of these polymeric nanotechnological drug delivery systems, created through bio-inspiration and biomimicry and have potential utilization into clinical applications.

  12. Applications of self-assembled monolayers in materials chemistry

    Indian Academy of Sciences (India)

    Self-assembly provides a simple route to organise suitable organic molecules on noble metal and selected nanocluster surfaces by using monolayers of long chain organic molecules with various functionalities like -SH, -COOH, -NH2, silanes etc. These surfaces can be effectively used to build-up interesting nano level ...

  13. Long lived coherence in self-assembled quantum dots

    DEFF Research Database (Denmark)

    Birkedal, Dan; Leosson, Kristjan; Hvam, Jørn Märcher

    2001-01-01

    We report measurements of ultralong coherence in self-assembled quantum dots. Transient four-wave mixing experiments at 5 K show an average dephasing time of 372 ps, corresponding to a homogeneous linewidth of 3.5 mu eV, which is significantly smaller than the linewidth observed in single-dot lum...

  14. Self-Assemblies of Single-Walled Carbon Nanotubes through Tunable Tethering of Pyrenes by Dextrin for Rapidly Chiral Sensing

    Directory of Open Access Journals (Sweden)

    Wei-Li Wei

    2011-01-01

    Full Text Available Pyrene-modified dextrin (Py-Dex was synthesized via the Schiff base reaction between reducing end of dextrins and 1-aminopyrene, and then self-assemblies of single-walled carbon nanotubes (SWNTs were fabricated through the tunable tethering of pyrene to SWNTs by dextrin chains. The Py-Dex-SWNTs assemblies were found to be significantly water-soluble because of the synergistic effect of dextrin chains and pyrene moieties. Py-Dex and Py-Dex-SWNTs were adequately characterized by NMR, UV-vis, fluorescence spectroscopy, Raman spectroscopy, matrix-assisted laser desorption/ionization-time of flight mass spectroscopy, and transmission electron microscopy. The tethering effect of dextrin toward pyrene moieties was clearly revealed and was found to be tunable by adjusting the length of dextrin chains. The fluorescence of pyrene moieties was sufficiently quenched by SWNTs with the support of dextrin chains. Furthermore, the Py-Dex-SWNTs assemblies were used for chiral selective sensing by introducing cyclodextrins as chiral binding sites. The rapid chiral sensing was successfully tested for different enantiomers.

  15. Solubility of sodium chloride in superionic water ice

    Science.gov (United States)

    Hernandez, Jean-Alexis; Caracas, Razvan

    2017-04-01

    In icy planets, complex interactions are expected to occur at the interface between the rocky core and the icy mantle composed of mixtures based on water, methane, and ammonia [1, 2]. The hydration of the silicate layer produces salts (MgSO4, NaCl, KCl) that could mix with the ice, and change considerably its properties [3]. Here, we used first-principles molecular dynamics to investigate the stability and the properties of the binary system NaCl-H2O at the relevant thermodynamic conditions for planetary interiors up to ice giants. In these conditions, pure water ice undergoes several transitions that affect considerably its ionic conductivity and its elastic properties [4]. We calculated the Gibbs free energy of mixing along the NaCl-H2O binary by applying Boltzmann statistics to account for energy differences between configurations. We evaluated vibrational entropy from the vibrational spectra of the nuclei motion using the recently developed two phases thermodynamic memory function (2PT-MF) model for multicomponent systems [5, 6]. We show that the solubility of NaCl in water ice at 1600 K is less than 0.78 mol%. We find that salty ices present an extended superionic domain toward high pressures in comparison to pure water ice. Finally, we predict that the complete symmetrization of the hydrogen bonds (i.e. transition to ice X) occurs at higher pressure than in pure water ice, as observed in LiCl doped water ice at ambient temperature [7]. References: [1] M. R. Frank, C. E. Runge, H. P. Scott, S. J. Maglio, J. Olson, V. B. Prakapenka, G. Shen, PEPI 155 (2006) 152-162 [2] B. Journaux, I. Daniel, R. Caracas, G. Montagnac, H. Cardon, Icarus 226 (2013) 355-363 [3] S. Klotz, L. E. Bove, T. Strässle, T. C. Hansen, A. M. Saitta, Nature Materials 8 (2009) 405-409 [4] J. -A. Hernandez, R. Caracas, Phys. Rev. Lett. 117 (2016) 135503 [5] M. P. Desjarlais, Phys. Rev. E 88 (2013) 062145 [6] M. French, M. P. Desjarlais, R. Redmer, Phys. Rev. E 93 (2016) 022140 [7] L. E. Bove

  16. Simultaneous Rapid Determination of the Solubility and Diffusion Coefficients of a Poorly Water-Soluble Drug Based on a Novel UV Imaging System.

    Science.gov (United States)

    Lu, Yan; Li, Mingzhong

    2016-01-01

    The solubility and diffusion coefficient are two of the most important physicochemical properties of a drug compound. In practice, both have been measured separately, which is time consuming. This work utilizes a novel technique of UV imaging to determine the solubility and diffusion coefficients of poorly water-soluble drugs simultaneously. A 2-step optimal method is proposed to determine the solubility and diffusion coefficients of a poorly water-soluble pharmaceutical substance based on the Fick's second law of diffusion and UV imaging measurements. Experimental results demonstrate that the proposed method can be used to determine the solubility and diffusion coefficients of a drug with reasonable accuracy, indicating that UV imaging may provide a new opportunity to accurately measure the solubility and diffusion coefficients of a poorly water-soluble drug simultaneously and rapidly. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  17. Self-assembled arginine-rich peptides as effective antimicrobial agents.

    Science.gov (United States)

    Mi, Gujie; Shi, Di; Herchek, Whitney; Webster, Thomas J

    2017-04-01

    Bacteria can adapt to their ever-changing environment to develop a resistance to commonly used antibiotics. This escalating evolution of bacteria coupled with a diminished number of effective antibiotics has caused a global healthcare crisis. New antimicrobials and novel approaches to tackle this problem are urgently needed. Antimicrobial peptides are of particular interest in this endeavor due to their broad spectrum antimicrobial properties as well as ability to combat multi-drug resistant bacteria. Most peptides have both hydrophobic and hydrophilic regions that enable them to be soluble in an aqueous solution, yet can insert into and subsequently disintegrate lipid rich membranes through diverse mechanisms. In this study, a novel class of cationic nanoparticles (formed by the self-assembly of an amphiphilic peptide) were shown to have strong antimicrobial properties against gram-positive bacteria, specifically Staphylococcus aureus, Staphylococcus epidermidis, and methicillin-resistant Staphylococcus aureus (MRSA) with minimal toxicity to human dermal fibroblasts. The particular self-assembled structure tested here included an arginine rich nanoparticle (C17 H35 GR7RGDS or amphiphilic peptide nanoparticles, APNPs) which incorporated seven arginine residues (imparting a positive charge to improve membrane interactions), a hydrophobic block which drove the self-assembly process, and the presence of an amino acid quadruplet arginine-glycine-aspartic acid-serine (RGDS) which may render these nanoparticles capable of attracting healthy cells while competing bacterial adherence to fibronectin, an adhesive protein found on cell surfaces. As such, this in vitro study demonstrated that the presently formulated APNPs should be further studied for a wide range of antibacterial applications where antibiotics are no longer useful. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1046-1054, 2017. © 2017 Wiley Periodicals, Inc.

  18. Water-soluble fullerene materials for bioapplications: photoinduced reactive oxygen species generation

    Science.gov (United States)

    The photoinduced reactive oxygen species (ROS) generation from several water-soluble fullerenes was examined. Macromolecular or small molecular water-soluble fullerene complexes/derivatives were prepared and their 1O2 and O2•- generation abilities were evaluated by EPR spin-trapping methods. As a r...

  19. Process for the production of furfural from pentoses and/or water soluble pentosans

    NARCIS (Netherlands)

    De Jong, W.; Marcotullio, G.

    2012-01-01

    The invention is directed to a process for the production of furfural from pentoses and/or water soluble pentosans, said process comprising converting the said pentoses and/or water soluble pentosans in aqueous solution in a first step to furfural and in a second step feeding the aqueous solution

  20. 40 CFR 799.6786 - TSCA water solubility: Generator column method.

    Science.gov (United States)

    2010-07-01

    ...-366 (1981). (2) Hansch, C. et al., The linear free-energy relationship between partition coefficients... 40 Protection of Environment 31 2010-07-01 2010-07-01 true TSCA water solubility: Generator column... TESTING REQUIREMENTS Product Properties Test Guidelines § 799.6786 TSCA water solubility: Generator column...

  1. Synthesis, structure and reactivity of a water-soluble copper(I) complex

    Indian Academy of Sciences (India)

    Administrator

    Water-soluble phosphines and their complexes have attracted a great deal of interest because of their potential use in aqueous catalytic organometallic chemistry and biomedical applications. Tris(hydroxymethyl)phosphine (THP) is moderately air-stable and water-soluble. While the coordination chemistry of this ligand with ...

  2. Analyzing water soluble soil organics as Trifluoroacetyl derivatives by liquid state proton nuclear magnetic resonance

    Science.gov (United States)

    Felipe Garza Sanchez; Zakiya Holmes Leggett; Sabapathy Sankar

    2005-01-01

    In forested ecosystems, water soluble organics play an important role in soil processes including carbon and nutrient turnover, microbial activity and pedogenesis. The quantity and quality (i.e., chemistry) of these materials is sensitive to land management practices. Monitoring alterations in the chemistry of water soluble organics resulting from land management...

  3. Biomimetic polymers responsive to a biological signaling molecule: nitric oxide triggered reversible self-assembly of single macromolecular chains into nanoparticles.

    Science.gov (United States)

    Hu, Jinming; Whittaker, Michael R; Duong, Hien; Li, Yang; Boyer, Cyrille; Davis, Thomas P

    2014-07-21

    Novel nitric oxide (NO) responsive monomers (NAPMA and APUEMA) containing o-phenylenediamine functional groups have been polymerized to form NO-responsive macromolecular chains as truly biomimetic polymers. Upon exposure to NO--a ubiquitous cellular signaling molecule--the NAPMA- and APUEMA-labeled thermoresponsive copolymers exhibited substantial changes in solubility, clearly characterized by tuneable LCST behavior, thereby inducing self-assembly into nanoparticulate structures. Moreover, the NO-triggered self-assembly process in combination with environmentally sensitive fluorescence dyes could be employed to detect and image endogenous NO. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Antiradical activity of water soluble components in common diet vegetables.

    Science.gov (United States)

    Racchi, Marco; Daglia, Maria; Lanni, Cristina; Papetti, Adele; Govoni, Stefano; Gazzani, Gabriella

    2002-02-27

    The antiradical activity of water-soluble components contained in mushrooms (Psalliota campestris), onions (Allium cepa), white cabbage (Brassica oleracea var. alba), and yellow bell peppers (Capsicum annuum) against hydroxyl radicals was tested in a chemical and biological system. The vegetable juices were obtained by centrifugation of a vegetable homogenate processed at 2 degrees C or heated at 102 degrees C. The chemical system consisted of a buffered reaction mixture composed of Fe(III)-EDTA, 2-deoxy-D-ribose, ascorbic acid, and H(2)O(2) generating the hydroxyl radical. The antiradical activity was expressed as an inhibition of deoxyribose degradation. The biological system consisted of IMR32 neuroblastoma cells exposed to H(2)O(2) in the presence or absence of the vegetable juices. Cells were pretreated for either 24 h or 1 h with the vegetable juices, and reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was used as a cell viability assay. All vegetable juices inhibited the degradation of deoxyribose and increased the viability of H(2)O(2) treated cells. Raw mushroom juice proved to be the most active in both cases. Boiling significantly affected the activity of mushroom juice, but did not change significantly the effect on onions and yellow bell peppers, and partially increased the activity of white cabbage juice. Mushroom antiradical activity was also confirmed by a cytofluorimetric analysis.

  5. Water Soluble Polymers as Proton Exchange Membranes for Fuel Cells

    Directory of Open Access Journals (Sweden)

    Bing-Joe Hwang

    2012-03-01

    Full Text Available The relentless increase in the demand for useable power from energy-hungry economies continues to drive energy-material related research. Fuel cells, as a future potential power source that provide clean-at-the-point-of-use power offer many advantages such as high efficiency, high energy density, quiet operation, and environmental friendliness. Critical to the operation of the fuel cell is the proton exchange membrane (polymer electrolyte membrane responsible for internal proton transport from the anode to the cathode. PEMs have the following requirements: high protonic conductivity, low electronic conductivity, impermeability to fuel gas or liquid, good mechanical toughness in both the dry and hydrated states, and high oxidative and hydrolytic stability in the actual fuel cell environment. Water soluble polymers represent an immensely diverse class of polymers. In this comprehensive review the initial focus is on those members of this group that have attracted publication interest, principally: chitosan, poly (ethylene glycol, poly (vinyl alcohol, poly (vinylpyrrolidone, poly (2-acrylamido-2-methyl-1-propanesulfonic acid and poly (styrene sulfonic acid. The paper then considers in detail the relationship of structure to functionality in the context of polymer blends and polymer based networks together with the effects of membrane crosslinking on IPN and semi IPN architectures. This is followed by a review of pore-filling and other impregnation approaches. Throughout the paper detailed numerical results are given for comparison to today’s state-of-the-art Nafion® based materials.

  6. Hierarchical self-assembly: Self-organized nanostructures in a nematically ordered matrix of self-assembled polymeric chains

    Science.gov (United States)

    Mubeena, Shaikh; Chatterji, Apratim

    2015-03-01

    We report many different nanostructures which are formed when model nanoparticles of different sizes (diameter σn) are allowed to aggregate in a background matrix of semiflexible self-assembled polymeric wormlike micellar chains. The different nanostructures are formed by the dynamical arrest of phase-separating mixtures of micellar monomers and nanoparticles. The different morphologies obtained are the result of an interplay of the available free volume, the elastic energy of deformation of polymers, the density (chemical potential) of the nanoparticles in the polymer matrix, and, of course, the ratio of the size of self-assembling nanoparticles and self-avoidance diameter of polymeric chains. We have used a hybrid semi-grand-canonical Monte Carlo simulation scheme to obtain the (nonequilibrium) phase diagram of the self-assembled nanostructures. We observe rodlike structures of nanoparticles which get self-assembled in the gaps between the nematically ordered chains, as well as percolating gel-like network of conjoined nanotubes. We also find a totally unexpected interlocked crystalline phase of nanoparticles and monomers, in which each crystal plane of nanoparticles is separated by planes of perfectly organized polymer chains. We identified the condition which leads to such interlocked crystal structure. We suggest experimental possibilities of how the results presented in this paper could be used to obtain different nanostructures in the laboratory.

  7. Water-Soluble 2-Hydroxyisophthalamides for Sensitization of Lanthanide Luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Samuel, Amanda P. S.; Moore, Evan G.; Melchior, Marco; Xu, Jide; Raymond, Kenneth N.

    2008-02-20

    A series of octadentate ligands featuring the 2-hydroxyisophthalamide (IAM) antenna chromophore (to sensitize Tb(III) and Eu(III) luminescence) has been prepared and characterized. The length of the alkyl amine scaffold that links the four IAM moieties has been varied in order to investigate the effect of the ligand backbone on the stability and photophysical properties of the Ln(III) complexes. The amine backbones utilized in this study are N,N,N{prime},N{prime}-tetrakis-(2-aminoethyl)-ethane-1,2-diamine [H(2,2)-], N,N,N{prime},N{prime}-tetrakis-(2-aminoethyl)-propane-1,3-diamine [H(3,2)-] and N,N,N{prime},N{prime}-tetrakis-(2-aminoethyl)-butane-1,4-diamine [H(4,2)-]. These ligands also incorporate methoxyethylene [MOE] groups on each of the IAM chromophores to increase their water solubility. The aqueous ligand protonation constants and Tb(III) and Eu(III) formation constants were determined from solution thermodynamic studies. The resulting values indicate that at physiological pH, the Eu(III) and Tb(III) complexes of H(2,2)-IAM-MOE and H(4,2)-IAM-MOE are sufficiently stable to prevent dissociation at nanomolar concentrations. The photophysical measurements for the Tb(III) complexes gave overall quantum yield values of 0.56, 0.39, and 0.52 respectively for the complexes with H(2,2)-IAM-MOE, H(3,2)-IAM-MOE and H(4,2)-IAM-MOE, while the corresponding Eu(III) complexes displayed significantly weaker luminescence, with quantum yield values of 0.0014, 0.0015, and 0.0058, respectively. Analysis of the steady state Eu(III) emission spectra provides insight into the solution symmetries of the complexes. The combined solubility, stability and photophysical performance of the Tb(III) complexes in particular make them well suited to serve as the luminescent reporter group in high sensitivity time-resolved fluoroimmunoassays.

  8. Development of Soluble Manganese Sorptive Contactors for Enhancing Potable Water Treatment Practices

    OpenAIRE

    Zuravnsky, Lauren

    2006-01-01

    Without proper removal at a water treatment facility, the soluble manganese (Mn) concentration can reach and exceed the Secondary Maximum Contaminant Level (SMCL) of 0.05 mg/L in the water distribution system. At this level, soluble Mn can be oxidized to solid Mn-oxide particulates, leading to water discoloration events and resulting in numerous consumer complaints. Manganese-laden water can severely stain fixtures and laundry as well as increase turbidity and foul tastes. A major discolo...

  9. [Analysis on water-soluble components in roots of Changium smyrnioides among different populations by HPLC].

    Science.gov (United States)

    Wang, Changlin; Guo, Qiaosheng; Cheng, Boxing; Yang, Liwen; Zhou, Tinghui

    2010-12-01

    To analyze water-soluble components in the roots of Ch. smyrnioides among different populations that distributed in the main areas and give a reference for germplasm evaluation and quality control. Water-soluble components were extracted with the cold-soaking method and analyzed by HPLC, similarity coefficient was calculated by included angle cosine method according to relative content of major water-soluble components, and systematic relationships were constructed based on UPGMA method. There was significant difference in water-soluble components in root among population. Jiuhuashan population had the highest content of water-soluble extract. The content of water-soluble extract was below the pharmacopoeia standard in the root of Dalongshan population and Fushan population. There was significant difference in the HPLC chromatogram of water-soluble components in the root of Ch. smyrnioides from different populations, and the number of common peak was small. Similarity coefficient significantly ranged from 0.0306 to 0.9995 among 10 populations of Ch. smymrnioides. Water-soluble components in the root of Zijinshan population was the most unique, similarity coefficients were relatively small among Zijinshan population and the other seven populations except Hongshan population, and similarity coefficient was in a higher level of 0.9697 between Zijinshan population and Hongshan population. Water-soluble components were extremely similar in four populations that were Laoshan, Maoshan, Qinglongshan and Langyashan, and similarity coefficients among them were in a high level exceeded 0.99. 10 populations were divided into 3 groups according to clustering results. Water-soluble components show a high diversity in the roots of Ch. smyrnioides among different populations, and can be clearly divided into 3 types.

  10. Investigation of Self-Assembly Processes for Chitosan-Based Coagulant-Flocculant Systems: A Mini-Review

    Directory of Open Access Journals (Sweden)

    Savi Bhalkaran

    2016-09-01

    Full Text Available The presence of contaminants in wastewater poses significant challenges to water treatment processes and environmental remediation. The use of coagulation-flocculation represents a facile and efficient way of removing charged particles from water. The formation of stable colloidal flocs is necessary for floc aggregation and, hence, their subsequent removal. Aggregation occurs when these flocs form extended networks through the self-assembly of polyelectrolytes, such as the amine-based polysaccharide (chitosan, which form polymer “bridges” in a floc network. The aim of this overview is to evaluate how the self-assembly process of chitosan and its derivatives is influenced by factors related to the morphology of chitosan (flocculant and the role of the solution conditions in the flocculation properties of chitosan and its modified forms. Chitosan has been used alone or in conjunction with a salt, such as aluminum sulphate, as an aid for the removal of various waterborne contaminants. Modified chitosan relates to grafted anionic or cationic groups onto the C-6 hydroxyl group or the amine group at C-2 on the glucosamine monomer of chitosan. By varying the parameters, such as molecular weight and the degree of deacetylation of chitosan, pH, reaction and settling time, dosage and temperature, self-assembly can be further investigated. This mini-review places an emphasis on the molecular-level details of the flocculation and the self-assembly processes for the marine-based biopolymer, chitosan.

  11. Protein self-assembly following in situ expression in artificial and mammalian cells.

    Science.gov (United States)

    Migas, Urszula M; Quinn, Michelle K; McManus, Jennifer J

    2017-05-22

    The self-assembly of proteins has been widely studied in controlled in vitro conditions, and more recently in biological environments. The self-assembly of proteins in biology can be a feature of the pathogenesis of protein condensation disease, or can occur during normal physiological function, for example during the formation of intracellular non-membrane bound organelles. To determine the mechanisms for the assembly process fully, controlled in vitro experiments using purified protein solutions are often required. However, making direct connections between insights gathered from controlled experiments and those in complex biological environments remains a challenge. Using the P23T mutant of human γD-crystallin, a protein associated with congenital cataract, we have demonstrated that the equilibrium solubility boundary and solution behavior measured using phase diagrams of purified protein solutions is consistent with the assembly of the protein expressed in cell-free expression medium in artificial cells (without fluorescent labelling) and condensates formed in mammalian cells, thereby directly connecting in vitro measurements with those performed under physiological conditions.

  12. Click functionalization of phenyl-capped bithiophene on azide-terminated self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yijun; Cui, Jiaxi [Max Planck Institute for Polymer Research (MPIP), Ackermannweg 10, Mainz 55128 (Germany); Ikeda, Taichi, E-mail: IKEDA.Taichi@nims.go.jp [Max Planck Institute for Polymer Research (MPIP), Ackermannweg 10, Mainz 55128 (Germany); Polymer Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044 (Japan)

    2015-11-15

    Graphical abstract: - Highlights: • Electrochemically-active self-assembled monolayers with phenyl-capped bithiophene were prepared. • Post-functionalization method based on click chemistry solved the solubility issue of phenyl-capped thiophene alkanethiol. • The capture and release of the counter anions during the redox reaction were detectable by E-QCM. - Abstract: We immobilized tetra(ethylene glycol)-substituted phenyl-capped bithiophene with alkyne terminals (Ph2TPh-alkyne) on azide-terminated self-assembled monolayers (N{sub 3}-SAMs) by Cu-catalyzed azide-alkyne cycloaddition reaction. Ph2TPh-functionalized SAMs on a gold substrate showed reversible electrochemical response. The surface densities of the azide groups in N{sub 3}-SAMs and Ph2TPh units in Ph2TPh-functionalized SAMs were estimated to be 7.3 ± 0.3 × 10{sup −10} mol cm{sup −2} and 4.6 ± 0.3 × 10{sup −10} mol cm{sup −2}, respectively, by quartz crystal microbalance (QCM). Most of Ph2TPh-alkynes are considered to be anchored on N{sub 3}-SAMs via both terminal groups. Ph2TPh-functionalized SAMs exhibited reversible redox peaks in cyclic voltammetry (CV). In redox reaction, reversible capture and release of the counter anion could be monitored by electrochemical QCM (E-QCM).

  13. Formation of active inclusion bodies induced by hydrophobic self-assembling peptide GFIL8.

    Science.gov (United States)

    Wang, Xu; Zhou, Bihong; Hu, Weike; Zhao, Qing; Lin, Zhanglin

    2015-06-16

    In the last few decades, several groups have observed that proteins expressed as inclusion bodies (IBs) in bacteria could still be biologically active when terminally fused to an appropriate aggregation-prone partner such as pyruvate oxidase from Paenibacillus polymyxa (PoxB). More recently, we have demonstrated that three amphipathic self-assembling peptides, an alpha helical peptide 18A, a beta-strand peptide ELK16, and a surfactant-like peptide L6KD, have properties that induce target proteins into active IBs. We have developed an efficient protein expression and purification approach for these active IBs by introducing a self-cleavable intein molecule. In this study, the self-assembling peptide GFIL8 (GFILGFIL) with only hydrophobic residues was analyzed, and this peptide effectively induced the formation of cytoplasmic IBs in Escherichia coli when terminally attached to lipase A and amadoriase II. The protein aggregates in cells were confirmed by transmission electron microscopy analysis and retained ~50% of their specific activities relative to the native counterparts. We constructed an expression and separation coupled tag (ESCT) by incorporating an intein molecule, the Mxe GyrA intein. Soluble target proteins were successfully released from active IBs upon cleavage of the intein between the GFIL8 tag and the target protein, which was mediated by dithiothreitol. A variant of GFIL8, GFIL16 (GFILGFILGFILGFIL), improved the ESCT scheme by efficiently eliminating interference from the soluble intein-GFIL8 molecule. The yields of target proteins at the laboratory scale were 3.0-7.5 μg/mg wet cell pellet, which is comparable to the yields from similar ESCT constructs using 18A, ELK16, or the elastin-like peptide tag scheme. The all-hydrophobic self-assembling peptide GFIL8 induced the formation of active IBs in E. coli when terminally attached to target proteins. GFIL8 and its variant GFIL16 can act as a "pull-down" tag to produce purified soluble proteins with

  14. New water-soluble polyanionic dendrimers and binding to acetylcholine in water by means of contact ion-pairing interactions.

    Science.gov (United States)

    Ornelas, Cátia; Boisselier, Elodie; Martinez, Victor; Pianet, Isabelle; Ruiz Aranzaes, Jaime; Astruc, Didier

    2007-12-21

    A new water-soluble polyanionic dendrimer containing 81 benzoate termini (diameter: 11+/-1 nm from DOSY NMR spectroscopy) has been synthesized; it interacts with acetylcholine cations in water-soluble assemblies in which each carboxylate terminus reversibly forms contact ion pairs and aggregates at the tether termini, as shown by 1H NMR spectroscopy.

  15. Predicting supramolecular self-assembly on reconstructed metal surfaces

    Science.gov (United States)

    Roussel, Thomas J.; Barrena, Esther; Ocal, Carmen; Faraudo, Jordi

    2014-06-01

    The prediction of supramolecular self-assembly onto solid surfaces is still challenging in many situations of interest for nanoscience. In particular, no previous simulation approach has been capable to simulate large self-assembly patterns of organic molecules over reconstructed surfaces (which have periodicities over large distances) due to the large number of surface atoms and adsorbing molecules involved. Using a novel simulation technique, we report here large scale simulations of the self-assembly patterns of an organic molecule (DIP) over different reconstructions of the Au(111) surface. We show that on particular reconstructions, the molecule-molecule interactions are enhanced in a way that long-range order is promoted. Also, the presence of a distortion in a reconstructed surface pattern not only induces the presence of long-range order but also is able to drive the organization of DIP into two coexisting homochiral domains, in quantitative agreement with STM experiments. On the other hand, only short range order is obtained in other reconstructions of the Au(111) surface. The simulation strategy opens interesting perspectives to tune the supramolecular structure by simulation design and surface engineering if choosing the right molecular building blocks and stabilising the chosen reconstruction pattern.The prediction of supramolecular self-assembly onto solid surfaces is still challenging in many situations of interest for nanoscience. In particular, no previous simulation approach has been capable to simulate large self-assembly patterns of organic molecules over reconstructed surfaces (which have periodicities over large distances) due to the large number of surface atoms and adsorbing molecules involved. Using a novel simulation technique, we report here large scale simulations of the self-assembly patterns of an organic molecule (DIP) over different reconstructions of the Au(111) surface. We show that on particular reconstructions, the molecule

  16. A Case Study of the Likes and Dislikes of DNA and RNA in Self-Assembly.

    Science.gov (United States)

    Zuo, Hua; Wu, Siyu; Li, Mo; Li, Yulin; Jiang, Wen; Mao, Chengde

    2015-12-07

    Programmed self-assembly of nucleic acids (DNA and RNA) is an active research area as it promises a general approach for nanoconstruction. Whereas DNA self-assembly has been extensively studied, RNA self-assembly lags much behind. One strategy to boost RNA self-assembly is to adapt the methods of DNA self-assembly for RNA self-assembly because of the chemical and structural similarities of DNA and RNA. However, these two types of molecules are still significantly different. To enable the rational design of RNA self-assembly, a thorough examination of their likes and dislikes in programmed self-assembly is needed. The current work begins to address this task. It was found that similar, two-stranded motifs of RNA and DNA lead to similar, but clearly different nanostructures. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Self-assembled carboxylate complexes of zinc, nickel and copper

    Science.gov (United States)

    Deka, Kaustavmoni; Barooah, Nilotpal; Sarma, Rupam Jyoti; Baruah, Jubaraj B.

    2007-02-01

    A metallo-organic hybrid acid namely tetra-aquo bis-4-carboxy- N-phthaloylglycinato zinc(II) dihydrate is prepared and characterised. In this complex the hydrogen bonding by free carboxylic acid group and π-π interactions between the rings in crystal lattice contributes to the formation of self-assembled structure. A monomeric nickel complex from 2-carbomethoxy benzoic acid ( L2H) and pyridine [Ni( L2)(py) 3(H 2O) 2] L2 is prepared (where py = pyridine). This complex has ionic as well as monodentate carboxylates. It forms self-assembly by C-H⋯π as well as hydrogen-bonding interactions. The 2-carbomethoxy benzoic acid ( L2H) forms dimeric copper complex [Cu 2( L2) 4(H 2O) 2]2H 2O which has an extended chain structure through hydrogen-bond interactions.

  18. Self-Assembly and Hydrogelation of Peptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Wahyudi Priyono Suwarso

    2012-04-01

    Full Text Available Seven peptide amphiphiles were successfully synthesized using solid phase peptide synthesis method. Peptide amphiphiles were characterized using matrix assisted laser desorption/ionization (MALDI. Atomic force microscopy (AFM study showed that peptide amphiphiles having glycine, valine, or proline as linker, self-assembled into 100-200 nm nanofibers structure. According to our research, both peptide amphiphile with positive and negative charges bear similar self-assembly properties. Peptide amphiphile also showed its capability as low molecular weight gelator (LMWG. Peptide amphiphiles bearing C-16 and C-12 as alkyl showed better hydrogelation properties than C-8 alkyl. Five out of seven peptide amphiphiles have minimum gelation concentration (MGC lower than 1% (w/v.

  19. Dynamic covalent chemistry in aid of peptide self-assembly.

    Science.gov (United States)

    Sadownik, Jan W; Ulijn, Rein V

    2010-08-01

    Self-assembled peptide systems have been widely studied in the context of gaining understanding of the rules that govern biomolecular processes and increasingly as new bio-inspired nanomaterials. Such materials may be designed to be highly dynamic, displaying adaptive and self-healing properties. This review focuses on recent approaches, which exploit reversible covalent and noncovalent chemistry in combination with peptide-based self-assembly. Selected examples of recent advances include sulphur and nitrogen-based reversible reactions, metal-ligand coordination and enzyme-assisted transamidation that lead to structures such as catenanes, nanofibres, β-hairpins and coiled-coil assemblies. It is demonstrated that these structures give rise to nanomaterials with emergent properties that are highly sensitive and adaptive to external conditions and may allow for in vitro evolution of novel peptide nanostructures via templating or self-recognition. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Programmed self-assembly of a quadruplex DNA nanowire.

    Science.gov (United States)

    Hessari, Nason Ma'ani; Spindler, Lea; Troha, Tinkara; Lam, Wan-Chi; Drevenšek-Olenik, Irena; da Silva, Mateus Webba

    2014-03-24

    The ability to produce, reproducibly and systematically, well-defined quadruplex DNA nanowires through controlled rational design is poorly understood despite potential utility in structural nanotechnology. The programmed hierarchical self-assembly of a long four-stranded DNA nanowire through cohesive self-assembly of GpC and CpG "sticky" ends is reported. The encoding of bases within the quadruplex stem allows for an uninterrupted π-stacking system with rectilinear propagation for hundreds of nanometers in length. The wire is mechanically stable and features superior nuclease resistance to double-stranded DNA. The study indicates the feasibility for programmed assembly of uninterrupted quadruplex DNA nanowires. This is fundamental to the systematic investigation of well-defined DNA nanostructures for uses in optoelectronic and electronic devices as well as other structural nanotechnology applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Synthesis and Self-Assembly of Triangulenium Salts

    DEFF Research Database (Denmark)

    Shi, Dong

    This thesis describes the design and synthesis of asymmetrically substituted amphiphilic tis(dialkylamino)trioxiatriangulenium (ATOTA+) salts with different counter ions. Attention was focused on exploring the assembling properties of the ATOTA+ salts in aqueous media. A direct vortexing-processed...... in influencing the assembling process and morphology of the assembled nanostructures. Tailoring the ATOTA+ system with alkyl chains of different length showed large effect on the final morphology of assembled supramolecular structures. The first two chapters give a brief introduction to molecular self......, highly ordered, and free-floating bilayer nanosheets through prolonged vigorous shaking. In this study, a mechanism for the self-assembly process agitated by prolonged vigorous shaking is proposed. It is proposed that the self-assembly is realized via a intermediated monolayer formed at the dynamic air...

  2. Molecular Gels Materials with Self-Assembled Fibrillar Networks

    CERN Document Server

    Weiss, Richard G

    2006-01-01

    Molecular gels and fibrillar networks – a comprehensive guide to experiment and theory Molecular Gels: Materials with Self-Assembled Fibrillar Networks provides a comprehensive treatise on gelators, especially low molecular-mass gelators (LMOGs), and the properties of their gels. The structures and modes of formation of the self-assembled fibrillar networks (SAFINs) that immobilize the liquid components of the gels are discussed experimentally and theoretically. The spectroscopic, rheological, and structural features of the different classes of LMOGs are also presented. Many examples of the application of the principal analytical techniques for investigation of molecular gels (including SANS, SAXS, WAXS, UV-vis absorption, fluorescence and CD spectroscopies, scanning electron, transmission electron and optical microscopies, and molecular modeling) are presented didactically and in-depth, as are several of the theories of the stages of aggregation of individual LMOG molecules leading to SAFINs. Several actua...

  3. Optical nanoimaging for block copolymer self-assembly.

    Science.gov (United States)

    Yan, Jie; Zhao, Ling-Xi; Li, Chong; Hu, Zhe; Zhang, Guo-Feng; Chen, Ze-Qiang; Chen, Tao; Huang, Zhen-Li; Zhu, Jintao; Zhu, Ming-Qiang

    2015-02-25

    One approach toward optical nanoimaging involves sequential molecular localization of photoswitchable fluorophores to achieve high resolution beyond optical limit of diffraction. Block copolymer micelles assembled from polystryrene-block-poly(ethylene oxide) block copolymers (PSt-b-PEO) are visualized in optical nanoimaging by staining the polystyrene blocks with spiropyrans (SPs). SPs localized in hydrophobic phase of block copolymer micelles exhibit reversible fluorescence on-off switching at alternating irradiation of UV and visible light. Phase-selective distribution of SPs in block copolymer micelles enables optical nanoimaging of microphase structures of block copolymer self-assembly at 50-nm resolution. To date, this is the sturdiest realization of optical nanoimaging with subdiffraction resolution for solution self-assembly of block copolymers.

  4. Catalysis of Transesterification Reactions by a Self-Assembled Nanosystem

    Directory of Open Access Journals (Sweden)

    Davide Zaramella

    2013-01-01

    Full Text Available Histidine-containing peptides self-assemble on the surface of monolayer protected gold nanoparticles to form a catalytic system for transesterification reactions. Self-assembly is a prerequisite for catalysis, since the isolated peptides do not display catalytic activity by themselves. A series of catalytic peptides and substrates are studied in order to understand the structural parameters that are of relevance to the catalytic efficiency of the system. It is shown that the distance between the His-residue and the anionic tail does not affect the catalytic activity. On the other hand, the catalytic His-residue is sensitive to the chemical nature of the flanking amino acid residues. In particular, the presence of polar Ser-residues causes a significant increase in activity. Finally, kinetic studies of a series of substrates reveal that substrates with a hydrophobic component are very suitable for this catalytic system.

  5. Self-assembling enzymes and the origins of the cytoskeleton

    Science.gov (United States)

    Barry, Rachael; Gitai, Zemer

    2011-01-01

    The bacterial cytoskeleton is composed of a complex and diverse group of proteins that self-assemble into linear filaments. These filaments support and organize cellular architecture and provide a dynamic network controlling transport and localization within the cell. Here, we review recent discoveries related to a newly appreciated class of self-assembling proteins that expand our view of the bacterial cytoskeleton and provide potential explanations for its evolutionary origins. Specifically, several types of metabolic enzymes can form structures similar to established cytoskeletal filaments and, in some cases, these structures have been repurposed for structural uses independent of their normal role. The behaviors of these enzymes suggest that some modern cytoskeletal proteins may have evolved from dual-role proteins with catalytic and structural functions. PMID:22014508

  6. J-aggregation of cyanine dyes by self-assembly.

    Science.gov (United States)

    Steiger, Rolf; Pugin, Raphaël; Heier, Jakob

    2009-12-01

    The importance of highly ordered surfaces, containing adsorptive surface states, is discussed for J-aggregation by self-assembly. Such nucleating surfaces are nanometer-sized edges and corners of cubic AgBr microcrystals, or surface iodide-clusters located along edges and corners of AgBr:I microcrystals. Of particular interest are dendrimers, monoatomic steps on terraced silver halide microcrystals and fullerene derivatives as nucleating surfaces. Molecular organisation into J-aggregates by self-assembly was realized using aprotic, apolar solvents for fullerenes, and polar solvents for dendrimers and monoatomic surface steps. By using dendrimers as nucleating agents in mesopores of metal oxide nanoparticle coatings, size-controlled and stable J-aggregates with high optical densities and strong fluorescence were obtained reproducibly. Such films may be useful for sensors, opto-electronics, lighting and photovoltaics.

  7. Self-assembly of hyperbranched polymers and its biomedical applications.

    Science.gov (United States)

    Zhou, Yongfeng; Huang, Wei; Liu, Jinyao; Zhu, Xinyuan; Yan, Deyue

    2010-11-02

    Hyperbranched polymers (HBPs) are highly branched macromolecules with a three-dimensional dendritic architecture. Due to their unique topological structure and interesting physical/chemical properties, HBPs have attracted wide attention from both academia and industry. In this paper, the recent developments in HBP self-assembly and their biomedical applications have been comprehensively reviewed. Many delicate supramolecular structures from zero-dimension (0D) to three-dimension (3D), such as micelles, fibers, tubes, vesicles, membranes, large compound vesicles and physical gels, have been prepared through the solution or interfacial self-assembly of amphiphilic HBPs. In addition, these supramolecular structures have shown promising applications in the biomedical areas including drug delivery, protein purification/detection/delivery, gene transfection, antibacterial/antifouling materials and cytomimetic chemistry. Such developments promote the interdiscipline researches among surpramolecular chemistry, biomedical chemistry, nano-technology and functional materials.

  8. Water solubility of lead and cadmium compounds in flue ash purging residues

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, H.

    1984-07-01

    Water soluble compounds (Pb, Cd) in flue ash purging residues represents a danger for environment. By waste incineration may be emitted as rain soluble salts 200-300 kg Pb, 2000 kg Cd and 10,000-80,000 kg Zn per year and plant. Dumping the material without prior washing out and recycling of the soluble compounds seems not to be responsible to future generations.

  9. Self-Assembled Monolayers of CdSe Nanocrystals on Doped GaAs Substrates

    DEFF Research Database (Denmark)

    Marx, E.; Ginger, D.S.; Walzer, Karsten

    2002-01-01

    This letter reports the self-assembly and analysis of CdSe nanocrystal monolayers on both p- and a-doped GaAs substrates. The self-assembly was performed using a 1,6-hexanedithiol self-assembled monolayer (SAM) to link CdSe nanocrystals to GaAs substrates. Attenuated total reflection Fourier tran...

  10. STM visualisation of counterions and the effect of charges on self-assembled monolayers of macrocycles

    NARCIS (Netherlands)

    Kudernac, Tibor; Shabelina, Natalia; Mamdouh, Wael; Höger, Sigurd; De Feyter, Steven

    2011-01-01

    Despite their importance in self-assembly processes, the influence of charged counterions on the geometry of self-assembled organic monolayers and their direct localisation within the monolayers has been given little attention. Recently, various examples of self-assembled monolayers composed of

  11. Carbonate linkage bearing naphthalenediimides: self-assembly and photophysical properties.

    Science.gov (United States)

    Kulkarni, Chidambar; George, Subi J

    2014-04-14

    Self-assembly of carbonate linkage bearing naphthalene diimides (NDI) showed unusually red-shifted excimer emission at approximately 560 nm. On the other hand, the ether linkers showed usual excimers at around 520 nm, highlighting the role of the carbonate group in tuning the molecular organization and the resultant photophysical properties of NDI. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Coherence and dephasing in self-assembled quantum dots

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Leosson, K.; Birkedal, Dan

    2003-01-01

    We measured dephasing times in InGaAl/As self-assembled quantum dots at low temperature using degenerate four-wave mixing. At 0K, the coherence time of the quantum dots is lifetime limited, whereas at finite temperatures pure dephasing by exciton-phonon interactions governs the quantum dot...... coherence. The inferred homogeneous line widths are significantly smaller than the line widths usually observed in the photoluminescence from single quantum dots indicating an additional inhomogeneours broadening mechanism in the latter....

  13. Spin State As a Probe of Vesicle Self-Assembly

    OpenAIRE

    Kim, Sanghoon; Bellouard, Christine; Eastoe, Julian; Canilho, Nadia; Rogers, Sarah E; Ihiawakrim, Dris; Ersen, Ovidiu; Pasc, Andreea

    2016-01-01

    A novel system of paramagnetic vesicles was designed using ion pairs of iron-containing surfactants. Unilamellar vesicles (diameter ≈ 200 nm) formed spontaneously and were characterized by cryogenic transmission electron microscopy, nanoparticle tracking analysis, and light and small-angle neutron scattering. Moreover, for the first time, it is shown that magnetization measurements can be used to investigate self-assembly of such functionalized systems, giving information on the vesicle compo...

  14. Spin State As a Probe of Vesicle Self-Assembly.

    Science.gov (United States)

    Kim, Sanghoon; Bellouard, Christine; Eastoe, Julian; Canilho, Nadia; Rogers, Sarah E; Ihiawakrim, Dris; Ersen, Ovidiu; Pasc, Andreea

    2016-03-02

    A novel system of paramagnetic vesicles was designed using ion pairs of iron-containing surfactants. Unilamellar vesicles (diameter ≈ 200 nm) formed spontaneously and were characterized by cryogenic transmission electron microscopy, nanoparticle tracking analysis, and light and small-angle neutron scattering. Moreover, for the first time, it is shown that magnetization measurements can be used to investigate self-assembly of such functionalized systems, giving information on the vesicle compositions and distribution of surfactants between the bilayers and the aqueous bulk.

  15. Molecular Self-Assembly into One-Dimensional Nanostructures

    OpenAIRE

    Palmer, Liam C.; Stupp, Samuel I.

    2008-01-01

    Self-assembly of small molecules into one-dimensional nanostructures offers many potential applications in electronically and biologically active materials. The recent advances discussed in this Account demonstrate how researchers can use the fundamental principles of supramolecular chemistry to craft the size, shape, and internal structure of nanoscale objects. In each system described here, we used atomic force microscopy (AFM) and transmission electron microscopy (TEM) to study the assembl...

  16. Biocompatible and Biomimetic Self-Assembly of Functional Nanostructures

    Science.gov (United States)

    2010-02-28

    and C. J. Brinker, "Photoresponsive nanocomposite formed by self-assembly of an azobenzene -modified silane," Angew. Chem.-Int. Edit. 42 (15), 1731...Responsive Materials: Azobenzene Containing Polymers and Liquid Crystals,U Yue Zhao and Tomiki Ikeda, eds., John Wiley & Sons, Inc., Hoboken, NJ...phagocyte- derived oxidants: New role for the NADPH oxidase in host defense. Proc Natl Acad Sci U S A. 101, 13867-13872 (2004). xviii. Iler, R.K

  17. Microtubule dynamics. II. Kinetics of self-assembly

    DEFF Research Database (Denmark)

    Flyvbjerg, H.; Jobs, E.

    1997-01-01

    dependence on initial conditions-except it is known to be impossible for equilibrium reactions. This article presents a case study of a far-from-equilibrium reaction: it presents a systematic phenomenological analysis of experimental time series for the amount of final product, a biopolymer, formed from...... to analyze the self-assembly of microtubules from tubulin are general, and many other reactions and processes may be studied as inverse problems with these methods when enough experimental data are available....

  18. Low temperature self-assembled growth of rutile TiO2/manganese oxide nanocrystalline films

    Science.gov (United States)

    Sun, Zhenya; Zhou, Daokun; Du, Jianhua; Xie, Yuxing

    2017-10-01

    We report formation of rutile TiO2 nanocrystal at low temperature range in the presence of α-MnO2 which self-assembled onto sulfanyl radical activated silicon oxide substrate. SEM, HRTEM, XPS and Raman spectroscopy were used to study the morphology and oxidation state of synthesised crystals. The results showed that when the α-MnO2 was reduced to Mn3O4, it induced the formation of rutile instead of anatase phase in the TiCl4-HCl aqueous system. The finding will promote the understanding of phase transformation mechanism when manganese oxide and titanium oxide co-exist in soil and water environment.

  19. Use of self-assembled peptide nanostructures for the fabrication of silicon nanowires

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Castillo, Jaime; Bakmand, Tania

    2011-01-01

    1. INTRODUCTION Self-assembled diphenylalanine peptide nanotubes provide a means of achieving nanostructured materials in a very simple and fast way. Recent discoveries have shown that this unique material, in addition to remaining stable under dry conditions, rapidly dissolves in water making...... if an electrical contact could be established between the metal electrodes and the silicon nanowires and I-V curve was measured. Figure 4 displays the electrical characterization of the silicon nanowire. The fabricated silicon nanowire was also decorated with functional compounds in order to probe their potential...

  20. Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces

    Directory of Open Access Journals (Sweden)

    Loïc Pantaine

    2017-04-01

    Full Text Available Aniline-terminated self-assembled monolayers (SAMs on gold surfaces have successfully reacted with ArSO2NHOSO2Ar (Ar = 4-MeC6H4 or 4-FC6H4 resulting in monolayers with sulfamide moieties and different end groups. Moreover, the sulfamide groups on the SAMs can be hydrolyzed showing the partial regeneration of the aniline surface. SAMs were characterized by water contact angle (WCA measurements, Fourier-transform infrared reflection absorption spectroscopy (IRRAS and X-ray photoelectron spectroscopy (XPS.

  1. Self-Assembling Biological Springs Force Transducers on the Micron Nanoscale

    Energy Technology Data Exchange (ETDEWEB)

    Benedek, George [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Casparay, Alfred H. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2016-08-19

    In this project, we are developing a new system for measuring forces within and between nanoscale biological molecules based on mesoscopic springs made of cholesterol helical ribbons. These ribbons self-assemble in a wide variety of complex fluids containing sterol, a mixture of surfactants and water [1] and have spring constants in the range from 0.5 to 500 pN/nm [2-4]. By the end of this project, we have demonstrated that the cholesterol helical ribbons can be used for measuring forces between biological objects and for mapping the strain fields in hydrogels.

  2. Towards improved solubility of poorly water-soluble drugs: cryogenic co-grinding of piroxicam with carrier polymers.

    Science.gov (United States)

    Penkina, Anna; Semjonov, Kristian; Hakola, Maija; Vuorinen, Sirpa; Repo, Timo; Yliruusi, Jouko; Aruväli, Jaan; Kogermann, Karin; Veski, Peep; Heinämäki, Jyrki

    2016-01-01

    Amorphous solid dispersions (SDs) open up exciting opportunities in formulating poorly water-soluble active pharmaceutical ingredients (APIs). In the present study, novel catalytic pretreated softwood cellulose (CPSC) and polyvinylpyrrolidone (PVP) were investigated as carrier polymers for preparing and stabilizing cryogenic co-ground SDs of poorly water-soluble piroxicam (PRX). CPSC was isolated from pine wood (Pinus sylvestris). Raman and Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) were used for characterizing the solid-state changes and drug-polymer interactions. High-resolution scanning electron microscope (SEM) was used to analyze the particle size and surface morphology of starting materials and final cryogenic co-ground SDs. In addition, the molecular aspects of drug-polymer interactions and stabilization mechanisms are presented. The results showed that the carrier polymer influenced both the degree of amorphization of PRX and stabilization against crystallization. The cryogenic co-ground SDs prepared from PVP showed an enhanced dissolution rate of PRX, while the corresponding SDs prepared from CPSC exhibited a clear sustained release behavior. In conclusion, cryogenic co-grinding provides a versatile method for preparing amorphous SDs of poorly water-soluble APIs. The solid-state stability and dissolution behavior of such co-ground SDs are to a great extent dependent on the carrier polymer used.

  3. Facile synthesis of highly water-soluble fullerenes more than half-covered by hydroxyl groups.

    Science.gov (United States)

    Kokubo, Ken; Matsubayashi, Kenji; Tategaki, Hiroshi; Takada, Hiroya; Oshima, Takumi

    2008-02-01

    Using a novel hydrogen peroxide heating method, we synthesized milky white, water-soluble polyhydroxylated fullerenes (fullerenols) with 36-40 hydroxyl groups (estimated average) along with 8-9 secondary bound water molecules. The fullerenols exhibited high water solubility up to 58.9 mg/mL in a neutral (pH = 7) condition. Dynamic light scattering analysis showed a high dispersion property, to give a narrow particle size distribution within 0.7-2.0 nm.

  4. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity

    OpenAIRE

    Johannes Ranke; Alaa Othman; Ping Fan; Anja Müller

    2009-01-01

    The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by r...

  5. Algorithmic self-assembly of DNA Sierpinski triangles.

    Directory of Open Access Journals (Sweden)

    Paul W K Rothemund

    2004-12-01

    Full Text Available Algorithms and information, fundamental to technological and biological organization, are also an essential aspect of many elementary physical phenomena, such as molecular self-assembly. Here we report the molecular realization, using two-dimensional self-assembly of DNA tiles, of a cellular automaton whose update rule computes the binary function XOR and thus fabricates a fractal pattern--a Sierpinski triangle--as it grows. To achieve this, abstract tiles were translated into DNA tiles based on double-crossover motifs. Serving as input for the computation, long single-stranded DNA molecules were used to nucleate growth of tiles into algorithmic crystals. For both of two independent molecular realizations, atomic force microscopy revealed recognizable Sierpinski triangles containing 100-200 correct tiles. Error rates during assembly appear to range from 1% to 10%. Although imperfect, the growth of Sierpinski triangles demonstrates all the necessary mechanisms for the molecular implementation of arbitrary cellular automata. This shows that engineered DNA self-assembly can be treated as a Turing-universal biomolecular system, capable of implementing any desired algorithm for computation or construction tasks.

  6. Probabilistic inverse design for self-assembling materials

    Science.gov (United States)

    Jadrich, R. B.; Lindquist, B. A.; Truskett, T. M.

    2017-05-01

    One emerging approach for the fabrication of complex architectures on the nanoscale is to utilize particles customized to intrinsically self-assemble into a desired structure. Inverse methods of statistical mechanics have proven particularly effective for the discovery of interparticle interactions suitable for this aim. Here we evaluate the generality and robustness of a recently introduced inverse design strategy [B. A. Lindquist et al., J. Chem. Phys. 145, 111101 (2016)] by applying this simulation-based machine learning method to optimize for interparticle interactions that self-assemble particles into a variety of complex microstructures as follows: cluster fluids, porous mesophases, and crystalline lattices. Using the method, we discover isotropic pair interactions that lead to the self-assembly of each of the desired morphologies, including several types of potentials that were not previously understood to be capable of stabilizing such systems. One such pair potential led to the assembly of the highly asymmetric truncated trihexagonal lattice and another produced a fluid containing spherical voids, or pores, of designed size via purely repulsive interactions. Through these examples, we demonstrate several advantages inherent to this particular design approach including the use of a parametrized functional form for the optimized interparticle interactions, the ability to constrain the range of said parameters, and compatibility of the inverse design strategy with a variety of simulation protocols (e.g., positional restraints).

  7. 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.

  8. Molecular Effects on Coacervate-Driven Block Copolymer Self Assembly

    Science.gov (United States)

    Lytle, Tyer; Radhakrishna, Mithun; Sing, Charles

    Two oppositely charged polymers can undergo associative phase separation in a salt solution in a process known as \\x98complex coacervation. Recent work has used this as a motif to control the self-assembly behavior of a mixture of oppositely-charged block copolymers which form nanoscale structures. The materials formed from these complex coacervate-block copolymers (BCPs) have potential use as drug delivery systems, gels, and sensors. We have developed a hybrid Monte Carlo-Single Chain in a Mean Field (MC-SCMF) simulation method that is able to determine morphological phase diagrams for BCPs. This technique is an efficient way to calculate morphological phase diagrams and provides a clear link between molecular level features and self-assembly behaviors. Morphological phase diagrams showing the effects of polymer concentration, salt concentration, chain length, and charge-block fraction at large charge densities on self-assembly behavior have been determined. An unexpected phase transition from disorder to hexagonal packing at large salt concentrations has been observed for charge-block fractions equal to and larger than 0.5. This is attributed to the salt filling space stabilizing the morphology of the BCP.

  9. Evolutionary dynamics in a simple model of self-assembly

    Science.gov (United States)

    Johnston, Iain G.; Ahnert, Sebastian E.; Doye, Jonathan P. K.; Louis, Ard A.

    2011-06-01

    We investigate the evolutionary dynamics of an idealized model for the robust self-assembly of two-dimensional structures called polyominoes. The model includes rules that encode interactions between sets of square tiles that drive the self-assembly process. The relationship between the model’s rule set and its resulting self-assembled structure can be viewed as a genotype-phenotype map and incorporated into a genetic algorithm. The rule sets evolve under selection for specified target structures. The corresponding complex fitness landscape generates rich evolutionary dynamics as a function of parameters such as the population size, search space size, mutation rate, and method of recombination. Furthermore, these systems are simple enough that in some cases the associated model genome space can be completely characterized, shedding light on how the evolutionary dynamics depends on the detailed structure of the fitness landscape. Finally, we apply the model to study the emergence of the preference for dihedral over cyclic symmetry observed for homomeric protein tetramers.

  10. Molecular Motions in Functional Self-Assembled Nanostructures

    Directory of Open Access Journals (Sweden)

    Jean-Marc Saiter

    2013-01-01

    Full Text Available The construction of “smart” materials able to perform specific functions at the molecular scale through the application of various stimuli is highly attractive but still challenging. The most recent applications indicate that the outstanding flexibility of self-assembled architectures can be employed as a powerful tool for the development of innovative molecular devices, functional surfaces and smart nanomaterials. Structural flexibility of these materials is known to be conferred by weak intermolecular forces involved in self-assembly strategies. However, some fundamental mechanisms responsible for conformational lability remain unexplored. Furthermore, the role played by stronger bonds, such as coordination, ionic and covalent bonding, is sometimes neglected while they can be employed readily to produce mechanically robust but also chemically reversible structures. In this review, recent applications of structural flexibility and molecular motions in self-assembled nanostructures are discussed. Special focus is given to advanced materials exhibiting significant performance changes after an external stimulus is applied, such as light exposure, pH variation, heat treatment or electromagnetic field. The crucial role played by strong intra- and weak intermolecular interactions on structural lability and responsiveness is highlighted.

  11. Self-assembly of lipopolysaccharide layers on allantoin crystals.

    Science.gov (United States)

    Vagenende, Vincent; Ching, Tim-Jang; Chua, Rui-Jing; Jiang, Qiu Zhen; Gagnon, Pete

    2014-08-01

    Self-assembly of lipopolysaccharides (LPS) on solid surfaces is important for the study of bacterial membranes, but has not been possible due to technical difficulties and the lack of suitable solid supports. Recently we found that crystals of the natural compound allantoin selectively bind pure LPS with sub-nanomolar affinity. The physicochemical origins of this selectivity and the adsorption mode of LPS on allantoin crystals remain, however, unknown. In this study we present evidence that LPS adsorption on allantoin crystals is initiated through hydrogen-bond attachment of hydrophilic LPS regions. Hydrophobic interactions between alkyl chains of adjacently adsorbed LPS molecules subsequently promote self-assembly of LPS layers. The essential role of hydrogen-bond interactions is corroborated by our finding that allantoin crystals bind to practically any hydrophilic surface chemistry. Binding contributions of hydrophobic interactions between LPS alkyl chains are evidenced by the endothermic nature of the adsorption process and explain why the binding affinity for LPS is several orders of magnitude higher than for proteins (lysozyme, BSA and IgG) and polysaccharides. Self-assembly of LPS layers via hydrogen-bond attachment on allantoin crystals emerges as a novel binding mechanism and could be considered as a practical method for preparing biomimetic membranes on a solid support. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Polymer directed self-assembly of pH-responsive antioxidant nanoparticles.

    Science.gov (United States)

    Tang, Christina; Amin, Devang; Messersmith, Phillip B; Anthony, John E; Prud'homme, Robert K

    2015-03-31

    We have developed pH-responsive, multifunctional nanoparticles based on encapsulation of an antioxidant, tannic acid (TA), using flash nanoprecipitation, a polymer directed self-assembly method. Formation of insoluble coordination complexes of tannic acid and iron during mixing drives nanoparticle assembly. Tuning the core material to polymer ratio, the size of the nanoparticles can be readily tuned between 50 and 265 nm. The resulting nanoparticle is pH-responsive, i.e., stable at pH 7.4 and soluble under acidic conditions due to the nature of the coordination complex. Further, the coordination complex can be coprecipitated with other hydrophobic materials such as therapeutics or imaging agents. For example, coprecipitation with a hydrophobic fluorescent dye creates fluorescent nanoparticles. In vitro, the nanoparticles have low cytotoxicity and show antioxidant activity. Therefore, these particles may facilitate intracellular delivery of antioxidants.

  13. Gold(I) catalysis at extreme concentrations inside self-assembled nanospheres.

    Science.gov (United States)

    Gramage-Doria, Rafael; Hessels, Joeri; Leenders, Stefan H A M; Tröppner, Oliver; Dürr, Maximilian; Ivanović-Burmazović, Ivana; Reek, Joost N H

    2014-12-01

    Homogeneous transition-metal catalysis is a crucial technology for the sustainable preparation of valuable chemicals. The catalyst concentration is usually kept as low as possible, typically at mM or μM levels, and the effect of high catalyst concentration is hardly exploited because of solubility issues and the inherent unfavorable catalyst/substrate ratio. Herein, a self-assembly strategy is reported which leads to local catalyst concentrations ranging from 0.05 M to 1.1 M, inside well-defined nanospheres, whilst the overall catalyst concentration in solution remains at the conventional mM levels. We disclose that only at this high concentration, the gold(I) chloride is reactive and shows high selectivity in intramolecular CO and CC bond-forming cyclization reactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Rapid self-assembly of complex biomolecular architectures during mussel byssus biofabrication

    Science.gov (United States)

    Priemel, Tobias; Degtyar, Elena; Dean, Mason N.; Harrington, Matthew J.

    2017-03-01

    Protein-based biogenic materials provide important inspiration for the development of high-performance polymers. The fibrous mussel byssus, for instance, exhibits exceptional wet adhesion, abrasion resistance, toughness and self-healing capacity-properties that arise from an intricate hierarchical organization formed in minutes from a fluid secretion of over 10 different protein precursors. However, a poor understanding of this dynamic biofabrication process has hindered effective translation of byssus design principles into synthetic materials. Here, we explore mussel byssus assembly in Mytilus edulis using a synergistic combination of histological staining and confocal Raman microspectroscopy, enabling in situ tracking of specific proteins during induced thread formation from soluble precursors to solid fibres. Our findings reveal critical insights into this complex biological manufacturing process, showing that protein precursors spontaneously self-assemble into complex architectures, while maturation proceeds in subsequent regulated steps. Beyond their biological importance, these findings may guide development of advanced materials with biomedical and industrial relevance.

  15. Water-enhanced solubility of carboxylic acids in organic solvents and its applications to extraction processes

    Energy Technology Data Exchange (ETDEWEB)

    Starr, John N. [Univ. of California, Berkeley, CA (United States)

    1991-11-01

    The solubilities of carboxylic acids in certain organic solvents increase remarkably with an increasing amount of water in the organic phase. This phenomenon leads to a novel extract regeneration process in which the co-extracted water is selectively removed from an extract, and the carboxylic acid precipitates. This approach is potentially advantageous compared to other regeneration processes because it removes a minor component of the extract in order to achieve a large recovery of acid from the extract. Carboxylic acids of interest include adipic acid, fumaric acid, and succinic acid because of their low to moderate solubilities in organic solvents. Solvents were screened for an increase in acid solubility with increased water concentration in the organic phase. Most Lewis-base solvents were found to exhibit this increased solubility phenomena. Solvents that have a carbonyl functional group showed a very large increase in acid solubility. 71 refs., 52 figs., 38 tabs.

  16. Polymer-assisted synthesis of water-soluble PbSe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Melnig, V., E-mail: vmelnig@uaic.r [' Al. I. Cuza' University, Faculty of Physics (Romania); Apostu, M.-O. [' Al. I. Cuza' University, Faculty of Chemistry (Romania); Foca, N. [' Gh. Asachi' University, Faculty of Chemistry (Romania)

    2008-12-15

    Stable PbSe quantum dots were synthesised in water-based media using poly(amidehydroxyurethane) water-soluble polymer. The polymer acts like a precursor carrier, blocks the particles aggregation and assures their solubility. Atomic force microscopy data show that the particle radius is smaller than the Bohr radius of PbSe. Interactions studies, performed by Fourier transform IR spectroscopy, show that the quantum dots are capped with poly(amidehydroxyurethane). The proposed synthesis was realised in the absence of any organic solvent. As a result, the produced particles have good water solubility, stability and good arguments to be biologically compatible.

  17. The synthesis of a water-soluble derivative of rutin as an antiradical agent

    Energy Technology Data Exchange (ETDEWEB)

    Pedriali, Carla Aparecida; Fernandes, Adjaci Uchoa [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica. Dept. de Bioquimica]. E-mail: capedriali@hotmail.com; Bernusso, Leandra de Cassia; Polakiewicz, Bronislaw [Universidade de Sao Paulo (USP), SP (Brazil). Faculdade de Ciencias Farmaceuticas. Dept. de Tecnologia Bioquimico-Farmaceutica

    2008-07-01

    The purpose of this study was to synthesize a water-soluble derivative of rutin (compound 2) by introducing carboxylate groups on rutin's sugar moiety. The rutin derivative showed an almost 100-fold solubility increase in water. The antiradical capacity of compound 2 was evaluated using the luminol/AAPH system, and the derivative's activity was 1.5 times greater than that of Trolox. Despite the derivative's high solubility in water (log P = -1.13), lipid peroxidation of brain homogenate membranes was very efficiently inhibited (inhibition values were only 19% lower than the inhibition values of rutin). (author)

  18. Relationship between Side?Chain Polarity and the Self?Assembly Characteristics of Perylene Diimide Derivatives in Aqueous Solution

    OpenAIRE

    Schill, Jurgen; Milroy, Lech?Gustav; Lugger, Jody A. M.; Schenning, Albertus P. H. J.; Brunsveld, Luc

    2017-01-01

    Abstract Perylene?3,4,9,10?tetracarboxylic acid diimides (PDIs) have recently gained considerable interest for water?based biosensing applications. PDIs have been studied intensively in the bulk state, but their physical properties in aqueous solution in interplay with side?chain polarity are, however, poorly understood. Therefore, three perylene diimide based derivatives were synthesized to study the relationship between side?chain polarity and their self?assembly characteristics in water. T...

  19. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity

    Science.gov (United States)

    Ranke, Johannes; Othman, Alaa; Fan, Ping; Müller, Anja

    2009-01-01

    The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities. PMID:19399248

  20. Explaining ionic liquid water solubility in terms of cation and anion hydrophobicity.

    Science.gov (United States)

    Ranke, Johannes; Othman, Alaa; Fan, Ping; Müller, Anja

    2009-03-01

    The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities.

  1. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity

    Directory of Open Access Journals (Sweden)

    Johannes Ranke

    2009-03-01

    Full Text Available The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities.

  2. Rampant Exchange of the Structure and Function of Extramembrane Domains between Membrane and Water Soluble Proteins

    Science.gov (United States)

    Nam, Hyun-Jun; Han, Seong Kyu; Bowie, James U.; Kim, Sanguk

    2013-01-01

    Of the membrane proteins of known structure, we found that a remarkable 67% of the water soluble domains are structurally similar to water soluble proteins of known structure. Moreover, 41% of known water soluble protein structures share a domain with an already known membrane protein structure. We also found that functional residues are frequently conserved between extramembrane domains of membrane and soluble proteins that share structural similarity. These results suggest membrane and soluble proteins readily exchange domains and their attendant functionalities. The exchanges between membrane and soluble proteins are particularly frequent in eukaryotes, indicating that this is an important mechanism for increasing functional complexity. The high level of structural overlap between the two classes of proteins provides an opportunity to employ the extensive information on soluble proteins to illuminate membrane protein structure and function, for which much less is known. To this end, we employed structure guided sequence alignment to elucidate the functions of membrane proteins in the human genome. Our results bridge the gap of fold space between membrane and water soluble proteins and provide a resource for the prediction of membrane protein function. A database of predicted structural and functional relationships for proteins in the human genome is provided at sbi.postech.ac.kr/emdmp. PMID:23555228

  3. Self-Assembly of Plasmonic Nanoclusters for Optical Metauids

    Science.gov (United States)

    Schade, Nicholas Benjamin

    I discuss experimental progress towards developing a material with an isotropic, negative index of refraction at optical frequencies. The simplest way to make such a material is to create a metafluid, or a disordered collection of subwavelength, isotropic electromagnetic resonators. Small clusters of metal particles, such as tetrahedra, serve as these constituents. What is needed are methods for manufacturing these structures with high precision and in sufficient yield that their resonances are identical. Jonathan Fan et al. [Science, 328 (5982), 1135-1138, 2010] demonstrated that colloidal self-assembly is a means of preparing electromagnetic resonators from metal nanoparticles. However, the resonances are sensitive to the separation gaps between particles. Standard synthesis routes for metal nanoparticles yield crystals or nanoshells that are inadequate for metafluids due to polydispersity, faceting, and thermal instabilities. To ensure that the separation gaps and resonances are uniform, more monodisperse spherical particles are needed. An additional challenge is the self-assembly of tetrahedral clusters in high yield from these particles. In self-assembly approaches that others have examined previously, the yield of any particular type of cluster is low. In this dissertation I present solutions to several of these problems, developed in collaboration with my research group and others. We demonstrate that slow chemical etching can transform octahedral gold crystals into ultrasmooth, monodisperse nanospheres. The particles can serve as seeds for the growth of larger octahedra which can in turn be etched. The size of the gold nanospheres can therefore be adjusted as desired. We further show that in colloidal mixtures of two sphere species that strongly bind to one another, the sphere size ratio determines the size distribution of self-assembled clusters. At a critical size ratio, tetrahedral clusters assemble in high yield. We explain the experimentally observed

  4. Nanoscale click-reactive scaffolds from peptide self-assembly.

    Science.gov (United States)

    Guttenplan, Alexander P M; Young, Laurence J; Matak-Vinkovic, Dijana; Kaminski, Clemens F; Knowles, Tuomas P J; Itzhaki, Laura S

    2017-10-06

    Due to their natural tendency to self-assemble, proteins and peptides are important components for organic nanotechnology. One particular class of peptides of recent interest is those that form amyloid fibrils, as this self-assembly results in extremely strong, stable quasi-one-dimensional structures which can be used to organise a wide range of cargo species including proteins and oligonucleotides. However, assembly of peptides already conjugated to proteins is limited to cargo species that do not interfere sterically with the assembly process or misfold under the harsh conditions often used for assembly. Therefore, a general method is needed to conjugate proteins and other molecules to amyloid fibrils after the fibrils have self-assembled. Here we have designed an amyloidogenic peptide based on the TTR105-115 fragment of transthyretin to form fibrils that display an alkyne functionality, important for bioorthogonal chemical reactions, on their surface. The fibrils were formed and reacted both with an azide-containing amino acid and with an azide-functionalised dye by the Huisgen cycloaddition, one of the class of "click" reactions. Mass spectrometry and total internal reflection fluorescence optical microscopy were used to show that peptides incorporated into the fibrils reacted with the azide while maintaining the structure of the fibril. These click-functionalised amyloid fibrils have a variety of potential uses in materials and as scaffolds for bionanotechnology. Although previous studies have produced peptides that can both form amyloid fibrils and undergo "click"-type reactions, this is the first example of amyloid fibrils that can undergo such a reaction after they have been formed. Our approach has the advantage that self-assembly takes place before click functionalization rather than pre-functionalised building blocks self-assembling. Therefore, the molecules used to functionalise the fibril do not themselves have to be exposed to harsh, amyloid

  5. 21 CFR 201.319 - Water-soluble gums, hydrophilic gums, and hydrophilic mucilloids (including, but not limited to...

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Water-soluble gums, hydrophilic gums, and... Specific Labeling Requirements for Specific Drug Products § 201.319 Water-soluble gums, hydrophilic gums... been associated with the ingestion of water-soluble gums, hydrophilic gums, and hydrophilic mucilloids...

  6. A Theoretical and Experimental Study of DNA Self-assembly

    Science.gov (United States)

    Chandran, Harish

    The control of matter and phenomena at the nanoscale is fast becoming one of the most important challenges of the 21st century with wide-ranging applications from energy and health care to computing and material science. Conventional top-down approaches to nanotechnology, having served us well for long, are reaching their inherent limitations. Meanwhile, bottom-up methods such as self-assembly are emerging as viable alternatives for nanoscale fabrication and manipulation. A particularly successful bottom up technique is DNA self-assembly where a set of carefully designed DNA strands form a nanoscale object as a consequence of specific, local interactions among the different components, without external direction. The final product of the self-assembly process might be a static nanostructure or a dynamic nanodevice that performs a specific function. Over the past two decades, DNA self-assembly has produced stunning nanoscale objects such as 2D and 3D lattices, polyhedra and addressable arbitrary shaped substrates, and a myriad of nanoscale devices such as molecular tweezers, computational circuits, biosensors and molecular assembly lines. In this dissertation we study multiple problems in the theory, simulations and experiments of DNA self-assembly. We extend the Turing-universal mathematical framework of self-assembly known as the Tile Assembly Model by incorporating randomization during the assembly process. This allows us to reduce the tile complexity of linear assemblies. We develop multiple techniques to build linear assemblies of expected length N using far fewer tile types than previously possible. We abstract the fundamental properties of DNA and develop a biochemical system, which we call meta-DNA, based entirely on strands of DNA as the only component molecule. We further develop various enzyme-free protocols to manipulate meta-DNA systems and provide strand level details along with abstract notations for these mechanisms. We simulate DNA circuits by

  7. Controlled self-assembly of quantum dot-block copolymer colloids in multiphase microfluidic reactors.

    Science.gov (United States)

    Wang, Chih-Wei; Oskooei, Ali; Sinton, David; Moffitt, Matthew G

    2010-01-19

    The controlled self-assembly of large compound quantum dot micelles (QDCMs), consisting of constituents of polymer-stabilized quantum dots (QDs) and amphiphilic polystyrene-b-poly(acrylic acid) stabilizing chains, in gas-liquid segmented microfluidic reactors is demonstrated. Self-assembly is initiated by fast mixing of water with the polymer constituents via chaotic advection, as liquid plugs containing reactants move through a sinusoidal mixing channel. The resulting QDCMs are then processed within a postformation channel, where circulating flow patterns develop within the liquid plugs, followed by off-chip quenching and analysis by transmission electron microscopy (TEM). Particle processing via circulating flow is found to involve a combination of particle growth via collision-induced coalescence and shear-induced particle breakup. The final mean QDCM sizes represent kinetic states arising from the competition between these two mechanisms, depending on tunable chemical and flow parameters. A systematic investigation of the experimental variables that influence particle size and polydispersity, including water concentration, flow rate, and the gas-to-liquid flow ratio, is conducted, demonstrating tunability of QDCM sizes in the range of approximately 40-140 nm. The importance of shear-induced particle breakup in the limit of high shear is illustrated by a common minimum particle size, 41 +/- 1 nm, which is achieved for all water contents by increasing the total flow rate to sufficiently high values.

  8. Relationship between Side-Chain Polarity and the Self-Assembly Characteristics of Perylene Diimide Derivatives in Aqueous Solution.

    Science.gov (United States)

    Schill, Jurgen; Milroy, Lech-Gustav; Lugger, Jody A M; Schenning, Albertus P H J; Brunsveld, Luc

    2017-04-01

    Perylene-3,4,9,10-tetracarboxylic acid diimides (PDIs) have recently gained considerable interest for water-based biosensing applications. PDIs have been studied intensively in the bulk state, but their physical properties in aqueous solution in interplay with side-chain polarity are, however, poorly understood. Therefore, three perylene diimide based derivatives were synthesized to study the relationship between side-chain polarity and their self-assembly characteristics in water. The polarity of the side chains was found to dictate the size and morphology of the formed aggregates. Side-chain polarity rendered the self-assembly and photophysical properties of the PDIs-both important for imminent water-based applications-and these were revealed to be especially responsive to changes in solvent composition.

  9. The role of water-soluble meconium subfraction and lipid-soluble meconium subfraction on the superior mesenteric artery vasoconstriction in chick embryos.

    Science.gov (United States)

    Şiyve, Serdar; Ulusoy, Oktay; Karakuş, Osman Z; Murat, Nergis; Uslu, Mehmet E; Ateş, Oğuz; Hakgüder, Gülce; Olguner, Mustafa; Akgür, Feza M

    2017-03-01

    Intraamniotic meconium has been responsible for intestinal damage in gastroschisis and meconium-dependent intestinal ischemia has been proposed to induce additional intestinal damage in gastroschisis. This study is aimed to determine the effects of lipid and water-soluble meconium subfractions on the contractility of the superior mesenteric artery (SMA). The study was conducted on 18-day fertilized chick embryos (Gallus Domesticus). Meconium is fractioned into water and lipid-soluble components. Only one SMA tissue was prepared from each embryo and suspended in the organ bath. Isometric contraction responses (ICR) were created in SMA tissues by one hour of incubation in Krebs-Henseleit solution for each group. Groups consisted of control, meconium, water-soluble meconium subfraction and lipid-soluble meconium subfraction. ICR of the SMA specimens were evaluated with a transducer-amplifier system on a computer. The data were expressed (mean±1SD) as milliNewton (mN). The ICR of the meconium, water-soluble meconium subfraction and lipid-soluble meconium subfraction groups were significantly high when compared to the control group (psoluble meconium subfraction created more contraction response than the lipid-soluble meconium subfraction (psoluble meconium subfraction group (p>0.05). Water-soluble meconium subfraction has a profound vasoconstrictor effect on the SMA compared to the lipid-soluble meconium subfraction. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Solubility of phenolic compounds in water, organic and supercritical solvents

    OpenAIRE

    Queimada, António; Mota, Fátima; Direito, Filipe; Pinho, Simão; Macedo, Eugénia A.

    2009-01-01

    Phenolic compounds represent a class of important chemicals with both biological and industrial importance. Their production, either by chemical synthesis or extraction from different biological media requires the adequate knowledge of phase equilibria. Particularly, the solubility in aqueous systems organic and supercritical solvents are fundamental for a better design of separation and purification processes.

  11. Effects of soil drenching of water-soluble potassium silicate on ...

    African Journals Online (AJOL)

    Effects of soil drenching of water-soluble potassium silicate on commercial avocado ( Persea americana Mill.) orchard trees infected with Phytophthora cinnamomi Rands on root density, canopy health, induction and concentration of phenolic com.

  12. Abalone water-soluble matrix for self-healing biomineralization of tooth defects

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Zhenliang [Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou 350002 (China); Chen, Jingdi, E-mail: ibptcjd@fzu.edu.cn [Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou 350002 (China); Wang, Hailiang [The Affiliated Stomatological Hospital, Fujian Medical University, Fuzhou 350002 (China); Zhong, Shengnan; Hu, Yimin; Wang, Zhili [Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou 350002 (China); Zhang, Qiqing, E-mail: zhangqiq@126.com [Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou 350002 (China); Institute of Biomedical Engineering, Chinese Academy of Medical Science & Peking Union Medical College, Tianjin 300192 (China)

    2016-10-01

    Enamel cannot heal by itself if damaged. Hydroxyapatite (HAP) is main component of human enamel. Formation of enamel-like materials for healing enamel defects remains a challenge. In this paper, we successfully isolated the abalone water-soluble matrix (AWSM) with 1.53 wt% the abalone water-soluble protein (AWSPro) and 2.04 wt% the abalone water-soluble polysaccharide (AWSPs) from abandoned abalone shell, and self-healing biomineralization of tooth defects was successfully achieved in vitro. Based on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), hot field emission scanning electron microscopy (HFESEM) and energy dispersive spectrometer (EDS) analysis, the results showed that the AWSM can efficiently induce remineralization of HAP. The enamel-like HAP was successfully achieved onto etched enamel's surface due to the presence of the AWSM. Moreover, the remineralized effect of eroded enamel was growing with the increase of the AWSM. This study provides a solution to the resource waste and environmental pollution caused by abandoned abalone shell, and we provides a new method for self-healing remineralization of enamel defects by AWSM and develops a novel dental material for potential clinical dentistry application. - Graphical abstract: In this paper, we successfully isolated the abalone water-soluble matrix (AWSM) with 1.53 wt% abalone water-soluble protein (AWSPro) and 2.04 wt% abalone water-soluble polysaccharide (AWSPs) from abandoned abalone shell, and self-healing biomineralization of tooth defects was successfully achieved in vitro by self-organized. Display Omitted - Highlights: • Provides a solution to the resource waste and environmental pollution caused by abandoned abalone shell. • The abalone shell water-soluble matrix contains protein and polysaccharide. • The abalone water-soluble matrix can efficiently induce remineralization of HAP by self-organized. • Achieved self-healing biomineralization of tooth defects in

  13. Amino acids as co-amorphous stabilizers for poorly water-soluble drugs - Part 2

    DEFF Research Database (Denmark)

    Löbmann, K.; Laitinen, R.; Strachan, C.

    2013-01-01

    The formation of co-amorphous drug-drug mixtures has proved to be a powerful approach to stabilize the amorphous form and at the same time increase the dissolution of poorly water-soluble drugs. Molecular interactions in these co-amorphous formulations can play a crucial role in stabilization...... as small molecular weight excipients in co-amorphous formulations to stabilize the amorphous form of a poorly water-soluble drug through strong and specific molecular interactions with the drug....

  14. Changes in the content of water-soluble vitamins in Actinidia chinensis during cold storage

    OpenAIRE

    Zhu Xian-Bo; Pan Liang; Wu, Wei; Pen Jia-Qing; Qi Yin-Wei; Ren Xiao-Lin

    2016-01-01

    We assessed the effects of cold storage on nine water-soluble vitamins in 7 cultivars of Actinidia chinensis (kiwifruit) using high-performance liquid chromatography. Samples were collected at three time points during cold storage: one day, 30 days, and when edible. We found that vitamin C in most cultivars was raised with cold storage, but there was no consistent increased or decreased trend for other water-soluble vitamins across cultivars in storage. Aft...

  15. Photoluminescence of water-soluble NdF nanoparticles by codoping Li or Ba ions

    Science.gov (United States)

    Fan, Ting; Lü, Jiantao; Li, Na; Han, Dingan

    2013-02-01

    Water-soluble NdF3, NdF3:Li+, and NdF3:Ba nanoparticles coated with polyvinylpyrrolidone were synthesized by a simple hydrothermal method. The products were characterized by x-ray diffraction, field-emission scanning electron microscopy, and photoluminescence spectra at room temperature. Codoping with Li+ ions does not change the emission intensity of water-soluble NdF3 nanoparticles, whereas codoping with Ba ions improves the near-infrared emissions.

  16. Inhibition of copper corrosion by the formation of Schiff base self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing [Department of Chemical and Biological Engineering, Guilin University of Technology, Guilin 541004 (China); Liu, Zheng, E-mail: lisa4.6@163.com [Department of Chemical and Biological Engineering, Guilin University of Technology, Guilin 541004 (China); Han, Guo-Cheng, E-mail: hangc1981@163.com [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin 541004 (China); Chen, Shi-Liang [Department of Chemical and Biological Engineering, Guilin University of Technology, Guilin 541004 (China); Chen, Zhencheng [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin 541004 (China)

    2016-12-15

    Highlights: • The highest inhibition efficiency was 93.9% for CO{sub 2}-saturated simulative oilfield water. • HD2-SAMs on copper surface exhibited excellent inhibition effect at 30 °C. • The adsorption behavior of HD2-SAM followed the Langmuir adsorption isotherm. • The adsorption behavior of HD2-SAM is a typically chemical adsorption. - Abstract: Self-assembled monolayers (SAMs) of 4-((2-thiophenecarboxylic acid hydrazide) methylene) benzoic acid (HD2) (denoted as HD2-SAMs) were formed on copper surface. The SAMs were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. Polarization curve and weight loss methods indicated that the highest inhibition efficiency was 93.9% for CO{sub 2}-saturated simulative oilfield water at a self-assembled time of 3 h. Potential-time curve, electrochemical impedance tests showed that HD2-SAMs on copper surface exhibited excellent inhibition effect at 30 °C. The adsorption behavior of HD2-SAMs on the copper surface followed the Langmuir adsorption isotherm, which was indicative of typically chemical adsorption. Quantum chemistry calculation showed that O and N atoms can interact with Cu atoms by coordination bonds which were the mainly active area of the adsorption of HD2 molecules.

  17. Understanding the structure and performance of self-assembled triblock terpolymer membranes

    KAUST Repository

    Pendergast, MaryTheresa M.

    2013-10-01

    Nanoporous membranes represent a possible route towards more precise particle and macromolecular separations, which are of interest across many industries. Here, we explored membranes with vertically-aligned nanopores formed from a poly(isoprene-. b-styrene-. b-4 vinyl pyridine) (ISV) triblock terpolymer via a hybrid self-assembly/nonsolvent induced phase separation process (S-NIPS). ISV concentration, solvent composition, and evaporation time in the S-NIPS process were varied to tailor ordering of the selective layer and produce enhanced water permeability. Here, water permeability was doubled over previous versions of ISV membranes. This was achieved by increasing volatile solvent concentration, thereby decreasing the evaporation period required for self-assembly. Fine-tuning was required, however, since overly-rapid evaporation did not yield the desired pore structure. Transport models, used to relate the in-. situ structure to the performance of these materials, revealed narrowing of pores and blocking by the dense region below. It was shown that these vertically aligned nanoporous membranes compare favorably with commercial ultrafiltration membranes formed by NIPS and track-etching processes, which suggests that there is practical value in further developing and optimizing these materials for specific industrial separations. © 2013 Elsevier B.V.

  18. Surfactantless synthesis and textural properties of self-assembled mesoporous SnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Velasquez, Celso [Departamento de QuImica, Universidad Autonoma Metropolitana-Iztapalapa, PO Box 55-534, Mexico, DF 09340 (Mexico); Ojeda, MarIa Luisa [Instituto de QuImica, UNAM, Circuito Exterior, Ciudad Universitaria, CP 04510, Mexico, DF (Mexico); Campero, Antonio [Departamento de QuImica, Universidad Autonoma Metropolitana-Iztapalapa, PO Box 55-534, Mexico, DF 09340 (Mexico); Esparza, Juan Marcos [Departamento de QuImica, Universidad Autonoma Metropolitana-Iztapalapa, PO Box 55-534, Mexico, DF 09340 (Mexico); Rojas, Fernando [Departamento de QuImica, Universidad Autonoma Metropolitana-Iztapalapa, PO Box 55-534, Mexico, DF 09340 (Mexico)

    2006-07-28

    Ordered surfactantless self-assembled, mesoporous SnO{sub 2} adsorbents, consisting of tubular voids of nanometric sizes, are prepared by the sol-gel processing of tin (IV) tetra-tert-amyloxide, Sn(OAm{sup t}){sub 4}, whose molecules have been previously chelated with acetylacetone in the absence of water, to modulate their reactivity and to promote an incipient self-assembling of -O-Sn-O oligomeric species; ultimately, the necessary amount of water to induce the hydrolysis-condensation reactions is added to this aged sol, then producing tubular pore templates within the SnO{sub 2} xerogel network. A collection of mesoporous SnO{sub 2} xerogels of assorted structural properties has been obtained after calcination in air of precursory gels proceeding from an aged mixture of Sn(OAm{sup t}){sub 4} and acetylacetone at temperatures in the range 200-1000 deg. C. N{sub 2} sorption isotherms measured on these SnO{sub 2} solids evidence mesoporous structures of diverse textural characteristics (i.e. pore widths of 3-50 nm and surface areas of 10-140 m{sup 2} g{sup -1}) in which voids virtually behave as if they are independent cylindrical pores during capillary condensation and evaporation.

  19. Self-Assembly of Discrete Metal Complexes in Aqueous Solution via Block Copolypeptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Timothy J. Deming

    2013-01-01

    Full Text Available The integration of discrete metal complexes has been attracting significant interest due to the potential of these materials for soft metal-metal interactions and supramolecular assembly. Additionally, block copolypeptide amphiphiles have been investigated concerning their capacity for self-assembly into structures such as nanoparticles, nanosheets and nanofibers. In this study, we combined these two concepts by investigating the self-assembly of discrete metal complexes in aqueous solution using block copolypeptides. Normally, discrete metal complexes such as [Au(CN2]−, when molecularly dispersed in water, cannot interact with one another. Our results demonstrated, however, that the addition of block copolypeptide amphiphiles such as K183L19 to [Au(CN2]− solutions induced one-dimensional integration of the discrete metal complex, resulting in photoluminescence originating from multinuclear complexes with metal-metal interactions. Transmission electron microscopy (TEM showed a fibrous nanostructure with lengths and widths of approximately 100 and 20 nm, respectively, which grew to form advanced nanoarchitectures, including those resembling the weave patterns of Waraji (traditional Japanese straw sandals. This concept of combining block copolypeptide amphiphiles with discrete coordination compounds allows the design of flexible and functional supramolecular coordination systems in water.

  20. Flower-like superstructures of AIE-active tetraphenylethylene through solvophobic controlled self-assembly

    Science.gov (United States)

    Salimimarand, Mina; La, Duong Duc; Kobaisi, Mohammad Al; Bhosale, Sheshanath V.

    2017-02-01

    The development of well-organized structures with high luminescent properties in the solid and aggregated states is of both scientific and technological interest due to their applications in nanotechnology. In this paper we described the synthesis of amphiphilic and dumbbell shaped AIE-active tetraphenylethylene (TPE) derivatives and studied their self-assembly with solvophobic control. Interestingly, both TPE derivatives form a 3D flower-shape supramolecular structure from THF/water solutions at varying water fractions. SEM microscopy was used to visualise step-wise growth of flower-shape assembly. TPE derivatives also show good mechanochromic properties which can be observed in the process of grinding, fuming and heating. These TPE derivative self-assemblies are formed due to two main important properties: (i) the TPE-core along with alkyl chains, optimizing the dispersive interactions within a construct, and (ii) amide-linkage through molecular recognition. We believe such arrangements prevent crystallization and favour the directional growth of flower-shape nanostructures in a 3D fashion.

  1. Solubility of Stevioside and Rebaudioside A in water, ethanol and their binary mixtures

    Directory of Open Access Journals (Sweden)

    Liliana S. Celaya

    2016-10-01

    Full Text Available In order to investigate the solubility of Stevioside and Rebaudioside A in different solvents (ethanol, water, ethanol:water 30:70 and ethanol:water 70:30, supersaturated solutions of pre-crystalized steviol glycosides were maintained at different temperatures (from 5 °C to 50 °C to reach equilibrium. Under these conditions significant differences were found in the extent of solubility. Rebaudioside A was poorly soluble in ethanol and water, and Stevioside was poorly soluble in water. Solvent mixtures more effectively promoted solubilisation, and a significant effect of temperature on solubility was observed. The two steviol glycosides showed higher solubilities and this behavior was promoted by the presence of the other sweetener. The polarity indices of the solvents were determined, and helped to explain the observed behavior. Several solute-solvent and solute-solute interactions can occur, along with the incidence of a strong affinity between solvents. The obtained results are in accordance with technological applications of ethanol, water and their binary mixtures for Stevioside and Rebaudioside A separations.

  2. Analysis of the nucleation and crystal growth kinetics of lysozyme by a theory of self-assembly

    OpenAIRE

    Ataka, M.; Asai, M.

    1990-01-01

    Concentration changes in supersaturated solutions during the nucleation and growth of the orthorhombic form of hen egg-white lysozyme crystals have been observed for 121 d at 35 degrees C and pH 4.6, and with 3% NaCl. The effect of a variation in the initial protein concentration on the rate of approach to solubility in equilibrium is analyzed, by applying a model, originally developed for the understanding of protein self-assembly. It is shown that the observed kinetics can be explained fair...

  3. PS-b-PEO/Silica Films with Regular and Reverse Mesostructures of Large Characteristic Length Scales Prepared by Solvent Evaporation-Induced Self-Assembly

    Energy Technology Data Exchange (ETDEWEB)

    YU,KUI; BRINKER,C. JEFFREY; HURD,ALAN J.; EISENBERG,ADI

    2000-11-22

    Since the discovery of surfactant-templated silica by Mobil scientists in 1992, mesostructured silica has been synthesized in various forms including thin films, powders, particles, and fibers. In general, mesostructured silica has potential applications, such as in separation, catalysis, sensors, and fluidic microsystems. In respect to these potential applications, mesostructured silica in the form of thin films is perhaps one of the most promising candidates. The preparation of mesostructured silica films through preferential solvent evaporation-induced self-assembly (EISA) has recently received much attention in the laboratories. However, no amphiphile/silica films with reverse mesophases have ever been made through this EISA procedure. Furthermore, templates employed to date have been either surfactants or poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers, such as pluronic P-123, both of which are water-soluble and alcohol-soluble. Due to their relatively low molecular weight, the templated silica films with mesoscopic order have been limited to relatively small characteristic length scales. In the present communication, the authors report a novel synthetic method to prepare mesostructured amphiphilic/silica films with regular and reverse mesophases of large characteristic length scales. This method involves evaporation-induced self-assembly (EISA) of amphiphilic polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymers. In the present study, the PS-b-PEO diblocks are denoted as, for example, PS(215)-b-PEO(100), showing that this particular sample contains 215 S repeat units and 100 EO repeat units. This PS(215)-b-PEO(100) diblock possesses high molecular weight and does not directly mix with water or alcohol. To the authors knowledge, no studies have reported the use of water-insoluble and alcohol-insoluble amphiphilic diblocks as structure-directing agents in the synthesis of mesostructured silica films through

  4. WATER ACTIVITY DATA ASSESSMENT TO BE USED IN HANFORD WASTE SOLUBILITY CALCULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    DISSELKAMP RS

    2011-01-06

    The purpose of this report is to present and assess water activity versus ionic strength for six solutes:sodium nitrate, sodium nitrite, sodium chloride, sodium carbonate, sodium sulfate, and potassium nitrate. Water activity is given versus molality (e.g., ionic strength) and temperature. Water activity is used to estimate Hanford crystal hydrate solubility present in the waste.

  5. Photocatalytic hydrogen production from a simple water-soluble [FeFe]-hydrogenase model system.

    Science.gov (United States)

    Cao, Wei-Ning; Wang, Feng; Wang, Hong-Yan; Chen, Bin; Feng, Ke; Tung, Chen-Ho; Wu, Li-Zhu

    2012-08-21

    Combined with a simple water soluble [FeFe]-hydrogenase mimic 1, Ru(bpy)(3)(2+) and ascorbic acid enable hydrogen production photocatalytically. More than 88 equivalents of H(2) were achieved in water, which is much better than that obtained in an organic solvent or a mixture of organic solvent and water.

  6. Simultaneous enhancements of solubility and dissolution rate of poorly water-soluble febuxostat via salts

    Science.gov (United States)

    Zhang, Xian-Rui; Zhang, Lei

    2017-06-01

    Novel crystalline forms of febuxostat (HFEB) salts were synthesized by liquid-assisted cogrinding with 2-methylimidazole (2MI) and di-2-pyridylamine (DPA) and characterized by Hirshfeld surface analysis, IR, 1H NMR, single crystal and powder X-ray diffractions, TGA and DSC. Two new HFEB salts featured different stoichiometries: 2:1 molecular ratio in HFEB-2MI and 1:1 molecular ratio in HFEB-DPA. For HFEB-2MI salt, two HFEB molecules lost one proton forming a singly charged hydrogen carboxylate anion H(FEB)2-, which interacted with the disordered 2MI cation via the N3sbnd H3A⋯O1i (i: -x, -y, -z+1) and N4sbnd H4B⋯O1ii (ii: x, y+1, z-1) hydrogen bonds to form one-dimensional structure. For HFEB-DPA salt, one proton transferred from one HFEB to DPA, which were further connected by N4sbnd H1⋯O1 and N3sbnd H2⋯O2 hydrogen bonds to form an R22(8) ring motif. HFEB-2MI and HFEB-DPA salts exhibited increased equilibrium solubilities and intrinsic dissolution rates compared to those of HFEB in aqueous medium.

  7. Nootkatone encapsulation by cyclodextrins: Effect on water solubility and photostability.

    Science.gov (United States)

    Kfoury, Miriana; Landy, David; Ruellan, Steven; Auezova, Lizette; Greige-Gerges, Hélène; Fourmentin, Sophie

    2017-12-01

    Nootkatone (NO) is a sesquiterpenoid volatile flavor, used in foods, cosmetics and pharmaceuticals, possessing also insect repellent activity. Its application is limited because of its low aqueous solubility and stability; this could be resolved by encapsulation in cyclodextrins (CDs). This study evaluated the encapsulation of NO by CDs using phase solubility studies, Isothermal Titration Calorimetry, Nuclear Magnetic Resonance spectroscopy and molecular modeling. Solid CD/NO inclusion complex was prepared and characterized for encapsulation efficiency and loading capacity using UV-Visible. Thermal properties were investigated by thermogravimetric-differential thermal analysis and release studies were performed using multiple headspace extraction. Formation constants (K f ) proved the formation of stable inclusion complexes. NO aqueous solubility, photo- and thermal stability were enhanced and the release could be insured from solid complex in aqueous solution. This suggests that CDs are promising carrier to improve NO properties and, consequently, to enlarge its use in foods, cosmetics, pharmaceuticals and agrochemicals preparations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Prediction of solubilities for ginger bioactive compounds in hot water by the COSMO-RS method

    Science.gov (United States)

    Zaimah Syed Jaapar, Syaripah; Azian Morad, Noor; Iwai, Yoshio

    2013-04-01

    The solubilities in water of four main ginger bioactives, 6-gingerol, 6-shogaol, 8-gingerol and 10-gingerol, were predicted using a conductor-like screening model for real solvent (COSMO-RS) calculations. This study was conducted since no experimental data are available for ginger bioactive solubilities in hot water. The σ-profiles of these selected molecules were calculated using Gaussian software and the solubilities were calculated using the COSMO-RS method. The solubilities of these ginger bioactives were calculated at 50 to 200 °C. In order to validate the accuracy of the COSMO-RS method, the solubilities of five hydrocarbon molecules were calculated using the COSMO-RS method and compared with the experimental data in the literature. The selected hydrocarbon molecules were 3-pentanone, 1-hexanol, benzene, 3-methylphenol and 2-hydroxy-5-methylbenzaldehyde. The calculated results of the hydrocarbon molecules are in good agreement with the data in the literature. These results confirm that the solubilities of ginger bioactives can be predicted using the COSMO-RS method. The solubilities of the ginger bioactives are lower than 0.0001 at temperatures lower than 130 °C. At 130 to 200 °C, the solubilities increase dramatically with the highest being 6-shogaol, which is 0.00037 mole fraction, and the lowest is 10-gingerol, which is 0.000039 mole fraction at 200 °C.

  9. Experimental study on desorption of soluble matter as influenced by cations in static water

    Directory of Open Access Journals (Sweden)

    Wen-sheng XU

    2015-10-01

    Full Text Available With variation of drainage basin environments, desorption of soluble matter has become one of the significant erosion processes in rivers. It has a considerable impact on flow and sediment transport, as well as processes of river bed deformation and landform evolution throughout a watershed. In this study, considering influences on sediment movement, especially on cohesive sediment transport, Ca2+ and H+ were chosen as characteristic ions of soluble matter, and the total desorption quantity of Ca2+ and pH value when the desorption equilibrium is reached were employed as two indexes representing the desorption of soluble matter. By means of an indoor experiment, desorption of soluble matter as influenced by cations in static water was investigated. The results show that the total desorption quantity of soluble matter increases with the initial cation concentration until a maximum desorption quantity value is obtained and maintained. The total desorption quantity of soluble matter depends on properties of the specific cations in static water, and the stronger the affinity is between the cation and sediment surface, the higher the total desorption quantity will be. Finally, a strong approximate linear relationship between desorption quantities for different kinds of soluble matters was obtained, which means that variation of pH values can accurately reflect the desorption results of soluble matter.

  10. Development of self-assembling nanowires containing electronically active oligothiophenes

    Science.gov (United States)

    Tsai, Wei-Wen

    This dissertation discusses the development of conductive one-dimensional nanowires from self-assembling oligothiophene molecules. Self-assembly has been demonstrated to be a promising alternative approach towards high performance, solution processable, and low-cost organic electronics. One of the many challenges in this field is the control of supramolecular morphologies of ordered structures containing pi-conjugated moieties. This research demonstrated several successful strategies to achieve self assembly of conductive nanowires using synergistic interactions combining pi stacking and hydrogen bonding. The first approach used was to develop a hairpin-shaped sexithiophene molecule, which features two arms of the conjugated structure. The diamidocyclohexyl headgroup of this molecule successfully directs the self-assembly from hydrogen bonding among the amides, forming high-aspect-ratio one-dimensional nanowires with well-defined diameters of 3.0 +/- 0.3 nm. The molecular orientation in the nanostructures promotes formation of sexithiophene H and J aggregates that facilitate efficient charge transport. Organic field-effect transistors were fabricated to reveal improved intrinsic hole mobility from films of the nanostructures, 3.46 x 10-6 cm2V-1s-1, which is one order of magnitude higher than films cast from unassembled molecules. Bulk heterojunction solar cells were developed from this molecule and fullerenes utilizing solution-phase fabrication methods. Intimate mix of the molecule and phenyl-C61-butyric acid methyl ester creates structured interfaces for efficient exciton splitting. The charge carrier mobilities of each material are improved by self-assembly in solution and thermal-energy assisted phase separation.The photovoltaic devices achieved the highest open-circuit voltage of 0.62 V, short-circuit current of 1.79 mA/cm2, fill factor of 35%, and power conversion efficiency of 0.48%. Another strategy to one-dimensional nanowires studied here involved the

  11. Preface: Special Topic on Supramolecular Self-Assembly at Surfaces

    Science.gov (United States)

    Bartels, Ludwig; Ernst, Karl-Heinz; Gao, Hong-Jun; Thiel, Patricia A.

    2015-03-01

    Supramolecular self-assembly at surfaces is one of the most exciting and active fields in Surface Science today. Applications can take advantage of two key properties: (i) versatile pattern formation over a broad length scale and (ii) tunability of electronic structure and transport properties, as well as frontier orbital alignment. It provides a new frontier for Chemical Physics as it uniquely combines the versatility of Organic Synthesis and the Physics of Interfaces. The Journal of Chemical Physics is pleased to publish this Special Topic Issue, showcasing recent advances and new directions.

  12. Directed Formation of DNA Nanoarrays through Orthogonal Self-Assembly

    Directory of Open Access Journals (Sweden)

    Eugen Stulz

    2011-06-01

    Full Text Available We describe the synthesis of terpyridine modified DNA strands which selectively form DNA nanotubes through orthogonal hydrogen bonding and metal complexation interactions. The short DNA strands are designed to self-assemble into long duplexes through a sticky-end approach. Addition of weakly binding metals such as Zn(II and Ni(II induces the formation of tubular arrays consisting of DNA bundles which are 50-200 nm wide and 2-50 nm high. TEM shows additional long distance ordering of the terpy-DNA complexes into fibers.

  13. Nanoscale Nitrogen Doping in Silicon by Self-Assembled Monolayers

    OpenAIRE

    Bin Guan; Hamidreza Siampour; Zhao Fan; Shun Wang; Xiang Yang Kong; Abdelmadjid Mesli; Jian Zhang; Yaping Dan

    2015-01-01

    International audience; This Report presents a nitrogen-doping method by chemically forming self-assembled monolayers on silicon. Van der Pauw technique, secondary-ion mass spectroscopy and low temperature Hall effect measurements are employed to characterize the nitrogen dopants. The experimental data show that the diffusion coefficient of nitrogen dopants is 3.66 × 10−15 cm2 s−1, 2 orders magnitude lower than that of phosphorus dopants in silicon. It is found that less than 1% of nitrogen d...

  14. Exploring the properties and possibilities of self-assembling

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Castillo, Jaime

    2013-01-01

    The study (and potential application) of diphenylalanine peptide nanotubes is a popular topic that in recent years has experienced a boost in activity. This activity has been propelled forward by new articles continuously being published presenting even more spectacular properties of the nanotube...... and exciting possibilities. The major driving forces supporting the interest in the peptide nanotubes is the fast and simple assembly process combined with their remarkable stability towards alcohols, organic solvents, and biological analytes that was presented shortly after the self-assembling properties...

  15. Directed self-assembly graphoepitaxy template generation with immersion lithography

    Science.gov (United States)

    Ma, Yuansheng; Lei, Junjiang; Andres Torres, J.; Hong, Le; Word, James; Fenger, Germain; Tritchkov, Alexander; Lippincott, George; Gupta, Rachit; Lafferty, Neal; He, Yuan; Bekaert, Joost; Vanderberghe, Geert

    2015-07-01

    We present an optimization methodology for the template designs of subresolution contacts using directed self-assembly (DSA) with graphoepitaxy and immersion lithography. We demonstrate the flow using a 60-nm-pitch contact design in doublet with Monte Carlo simulations for DSA. We introduce the notion of template error enhancement factor (TEEF) to gauge the sensitivity of DSA printing infidelity to template printing infidelity and evaluate optimized template designs with TEEF metrics. Our data show that source mask optimization and inverse lithography technology are critical to achieve sub-80 nm non-L0 pitches for DSA patterns using 193i.

  16. Photobleaching-activated micropatterning on self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Scrimgeour, Jan; Kodali, Vamsi K; Kovari, Daniel T; Curtis, Jennifer E, E-mail: jennifer.curtis@physics.gatech.ed [School of Physics and Petit Institute for Bioengineering and Biosciences (IBB), Georgia Institute of Technology, 837 State St, Atlanta, GA 30332 (United States)

    2010-05-19

    Functional chemical micropatterns were fabricated by exploiting the photobleaching of dye-coupled species near methacrylate self-assembled monolayers. Using this approach we have demonstrated that multiple chemistries can be coupled to the monolayer using a standard fluorescence microscope. The surface bound functional groups remain active and patterns with feature sizes down to 3 {mu}m can be readily achieved with excellent signal-to-noise ratio. Control over the ligand binding density was demonstrated to illustrate the convenient route provided by this platform for fabricating complex spatial gradients in ligand density.

  17. Exploiting non-equilibrium phase separation for self-assembly.

    Science.gov (United States)

    Grünwald, Michael; Tricard, Simon; Whitesides, George M; Geissler, Phillip L

    2016-02-07

    Demixing can occur in systems of two or more particle species that experience different driving forces, e.g., mixtures of self-propelled active particles or of oppositely charged colloids subject to an electric field. Here we show with macroscopic experiments and computer simulations that the forces underlying such non-equilibrium segregation can be used to control the self-assembly of particles that lack attractive interactions. We demonstrate that, depending on the direction, amplitude and frequency of a periodic external force acting on one particle species, the structures formed by a second, undriven species can range from compact clusters to elongated, string-like patterns.

  18. Self-assembled manganese oxide structures through direct oxidation

    KAUST Repository

    Zhao, Chao

    2012-12-01

    The morphology and phase of self-assembled manganese oxides during different stages of thermal oxidation were studied. Very interesting morphological patterns of Mn oxide films were observed. At the initial oxidation stage, the surface was characterized by the formation of ring-shaped patterns. As the oxidation proceeded to the intermediate stage, concentric plates formed to relax the compressive stress. Our experimental results gave a clear picture of the evolution of the structures. We also examined the properties of the structures. © 2012 Elsevier B.V.

  19. Buckling Instability of Self-Assembled Colloidal Columns

    Science.gov (United States)

    Swan, James W.; Vasquez, Paula A.; Furst, Eric M.

    2014-09-01

    Suspended, slender self-assembled domains of magnetically responsive colloids are observed to buckle in microgravity. Upon cessation of the magnetic field that drives their assembly, these columns expand axially and buckle laterally. This phenomenon resembles the buckling of long beams due to thermal expansion; however, linear stability analysis predicts that the colloidal columns are inherently susceptible to buckling because they are freely suspended in a Newtonian fluid. The dominant buckling wavelength increases linearly with column thickness and is quantitatively described using an elastohydrodynamic model and the suspension thermodynamic equation of state.

  20. Preface: Special Topic on Supramolecular Self-Assembly at Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, Ludwig [Department of Chemistry and the Materials Science and Engineering Program, University of California - Riverside, Riverside, California 92521 (United States); Ernst, Karl-Heinz [EMPA, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dubendorf (Switzerland); Gao, Hong-Jun [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,Chinese Academy of Sciences, Beijing 100190 (China); Thiel, Patricia A. [Department of Chemistry, Department of Materials Science and Engineering, Ames Laboratory,Iowa State University, Ames, Iowa 50011 (United States)

    2015-03-14

    Supramolecular self-assembly at surfaces is one of the most exciting and active fields in Surface Science today. Applications can take advantage of two key properties: (i) versatile pattern formation over a broad length scale and (ii) tunability of electronic structure and transport properties, as well as frontier orbital alignment. It provides a new frontier for Chemical Physics as it uniquely combines the versatility of Organic Synthesis and the Physics of Interfaces. The Journal of Chemical Physics is pleased to publish this Special Topic Issue, showcasing recent advances and new directions.