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Sample records for self-assembled vesicle-capped nanotubes

  1. Loading of Vesicles into Soft Amphiphilic Nanotubes using Osmosis

    NARCIS (Netherlands)

    Erne, Petra M.; van Bezouwen, Laura S.; Stacko, Peter; van Dtjken, Derk Jan; Chen, Jiawen; Stuart, Marc C. A.; Boekema, Eghert J.; Feringa, Ben L.

    2015-01-01

    The facile assembly of higher-order nanoarchitectures from simple building blocks is demonstrated by the loading of vesicles into soft amphiphilic nanotubes using osmosis. The nanotubes are constructed from rigid interdigitated bilayers which are capped with vesicles comprising phospholipid-based

  2. Continuous fabrication of polymeric vesicles and nanotubes with fluidic channe

    NARCIS (Netherlands)

    Peng, F.; Deng, N.-N.; Tu, Y.; van Hest, J.C.M.; Wilson, D.A.

    2017-01-01

    Fluidic channels were employed to induce the self-assembly of poly(ethylene glycol)-b-polystyrene into polymeric vesicles and nanotubes. The laminar flow in the device enables controlled diffusion of two miscible liquids at the phase boundary, leading to the formation of homogeneous polymeric

  3. Spontaneous Vesicle Self-Assembly: A Mesoscopic View of Membrane Dynamics

    DEFF Research Database (Denmark)

    Shillcock, J. C.

    2012-01-01

    Amphiphilic vesicles are ubiquitous in living cells and industrially interesting as drug delivery vehicles. Vesicle self-assembly proceeds rapidly from nanometer to micrometer length scales and is too fast to image experimentally but too slow for molecular dynamics simulations. Here, we use...... parallel dissipative particle dynamics (DPD) to follow spontaneous vesicle self-assembly for up to 445 mu s with near-molecular resolution. The mean mass and radius of gyration of growing amphiphilic clusters obey power laws with exponents of 0.85 +/- 0.03 and 0.41 +/- 0.02, respectively. We show that DPD...... provides a computational window onto fluid dynamics on scales unreachable by other explicit-solvent simulations....

  4. 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...

  5. 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.

  6. Secretory Vesicle Priming by CAPS Is Independent of Its SNARE-Binding MUN Domain

    Directory of Open Access Journals (Sweden)

    Cuc Quynh Nguyen Truong

    2014-11-01

    Full Text Available Priming of secretory vesicles is a prerequisite for their Ca2+-dependent fusion with the plasma membrane. The key vesicle priming proteins, Munc13s and CAPSs, are thought to mediate vesicle priming by regulating the conformation of the t-SNARE syntaxin, thereby facilitating SNARE complex assembly. Munc13s execute their priming function through their MUN domain. Given that the MUN domain of Ca2+-dependent activator protein for secretion (CAPS also binds syntaxin, it was assumed that CAPSs prime vesicles through the same mechanism as Munc13s. We studied naturally occurring splice variants of CAPS2 in CAPS1/CAPS2-deficient cells and found that CAPS2 primes vesicles independently of its MUN domain. Instead, the pleckstrin homology domain of CAPS2 seemingly is essential for its priming function. Our findings indicate a priming mode for secretory vesicles. This process apparently requires membrane phospholipids, does not involve the binding or direct conformational regulation of syntaxin by MUN domains of CAPSs, and is therefore not redundant with Munc13 action.

  7. Defect- and dopant-controlled carbon nanotubes fabricated by self-assembly of graphene nanoribbons

    Institute of Scientific and Technical Information of China (English)

    Cun Zhang and Shaohua Chen

    2015-01-01

    Molecular dynamics simulations showed that a basal carbon nanotube can activate and guide the fabrication of single-walled carbon nanotubes (CNTs) on its internal surface by self-assembly of edge-unpassivated graphene nanoribbons with defects. Furthermore, the distribution of defects on self-assembled CNTs is controllable. The system temperature and defect fraction are two main factors that influence the success of self-assembly. Due to possible joint flaws formed at the boundaries under a relatively high constant temperature, a technique based on increasing the temperature is adopted. Self-assembly is always successful for graphene nanoribbons with relatively small defect fractions, while it will fail in cases with relatively large ones. Similar to the self-assembly of graphene nanoribbons with defects, graphene nanoribbons with different types of dopants can also be self-assembled into carbon nanotubes. The finding provides a possible fabrication technique not only for carbon nanotubes with metallic or semi-con- ductive properties but also for carbon nanotubes with electromagnetic induction characteristics.

  8. Structure formation in binary mixtures of lipids and detergents: self-assembly and vesicle division.

    Science.gov (United States)

    Noguchi, Hiroshi

    2013-01-14

    Self-assembly dynamics in binary surfactant mixtures and structure changes of lipid vesicles induced by detergent solution are studied using coarse-grained molecular simulations. Disk-shaped micelles, the bicelles, are stabilized by detergents surrounding the rim of a bilayer disk of lipids. The self-assembled bicelles are considerably smaller than bicelles formed from vesicle rupture, and their size is determined by the concentrations of lipids and detergents and the interactions between the two species. The detergent-adsorption induces spontaneous curvature of the vesicle bilayer and results in vesicle division into two vesicles or vesicle rupture into worm-like micelles. The division occurs mainly via the inverse pathway of the modified stalk model. For large spontaneous curvature of the monolayers of the detergents, a pore is often opened, thereby leading to vesicle division or worm-like micelle formation.

  9. The precise self-assembly of individual carbon nanotubes using magnetic capturing and fluidic alignment

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Joon S; Rust, Michael J; Do, Jaephil; Ahn, Chong H [Department of Electrical and Computer Engineering, Microsystems and BioMEMS Laboratory, University of Cincinnati, Cincinnati, OH 45221 (United States); Yun, Yeo-Heung; Schulz, Mark J [Department of Mechanical Engineering, University of Cincinnati, 45221 (United States); Shanov, Vesselin, E-mail: chong.ahn@uc.ed [Department of Chemical and Materials Engineering, University of Cincinnati, 45221 (United States)

    2009-08-12

    A new method for the self-assembly of a carbon nanotube (CNT) using magnetic capturing and fluidic alignment has been developed and characterized in this work. In this new method, the residual iron (Fe) catalyst positioned at one end of the CNT was utilized as a self-assembly driver to attract and position the CNT, while the assembled CNT was aligned by the shear force induced from the fluid flow through the assembly channel. The self-assembly procedures were successfully developed and the electrical properties of the assembled multi-walled carbon nanotube (MWNT) and single-walled carbon nanotube (SWNT) were fully characterized. The new assembly method developed in this work shows its feasibility for the precise self-assembly of parallel CNTs for electronic devices and nanobiosensors.

  10. Cationic membranes complexed with oppositely charged microtubules: hierarchical self-assembly leading to bio-nanotubes

    International Nuclear Information System (INIS)

    Raviv, Uri; Needleman, Daniel J; Safinya, Cyrus R

    2006-01-01

    The self-assembly of microtubules and charged membranes has been studied, using x-ray diffraction and electron microscopy. Polyelectrolyte lipid complexes usually form structures templated by the lipid phase, when the polyelectrolyte curvature is much larger than the membrane spontaneous curvature. When the polyelectrolyte curvature approaches the membrane spontaneous curvature, as in microtubules, two types of new structures emerge. Depending on the conditions, vesicles either adsorb onto the microtubule, forming a 'beads on a rod' structure, or coat the microtubule, which now forms the template. Tubulin oligomers then coat the external lipid layer, forming a lipid protein nanotube. The tubulin oligomer coverage at the external layer is determined by the membrane charge density. The energy barrier between the beads on a rod and the lipid-protein nanotube states depends on the membrane bending rigidity and membrane charge density. By controlling the lipid/tubulin stoichiometry we can switch between lipid-protein nanotubes with open ends to lipid-protein nanotubes with closed end with lipid cups. This forms the basis for controlled drug encapsulation and release

  11. Structure formation of lipid membranes: Membrane self-assembly and vesicle opening-up to octopus-like micelles

    Science.gov (United States)

    Noguchi, Hiroshi

    2013-02-01

    We briefly review our recent studies on self-assembly and vesicle rupture of lipid membranes using coarse-grained molecular simulations. For single component membranes, lipid molecules self-assemble from random gas states to vesicles via disk-shaped clusters. Clusters aggregate into larger clusters, and subsequently the large disks close into vesicles. The size of vesicles are determined by kinetics than by thermodynamics. When a vesicle composed of lipid and detergent types of molecules is ruptured, a disk-shaped micelle called bicelle can be formed. When both surfactants have negligibly low critical micelle concentration, it is found that bicelles connected with worm-like micelles are also formed depending on the surfactant ratio and spontaneous curvature of the membrane monolayer.

  12. Self-assembly of diphenylalanine backbone homologues and their combination with functionalized carbon nanotubes.

    Science.gov (United States)

    Dinesh, Bhimareddy; Squillaci, Marco A; Ménard-Moyon, Cécilia; Samorì, Paolo; Bianco, Alberto

    2015-10-14

    The integration of carbon nanotubes (CNTs) into organized nanostructures is of great interest for applications in materials science and biomedicine. In this work we studied the self-assembly of β and γ homologues of diphenylalanine peptides under different solvent and pH conditions. We aimed to investigate the role of peptide backbone in tuning the formation of different types of nanostructures alone or in combination with carbon nanotubes. In spite of having the same side chain, β and γ peptides formed distinctively different nanofibers, a clear indication of the role played by the backbone homologation on the self-assembly. The variation of the pH allowed to transform the nanofibers into spherical structures. Moreover, the co-assembly of β and γ peptides with carbon nanotubes covalently functionalized with the same peptide generated unique dendritic assemblies. This comparative study on self-assembly using diphenylalanine backbone homologues and of the co-assembly with CNT covalent conjugates is the first example exploring the capacity of β and γ peptides to adopt precise nanostructures, particularly in combination with carbon nanotubes. The dendritic organization obtained by mixing carbon nanotubes and peptides might find interesting applications in tissue engineering and neuronal interfacing.

  13. Self-assembly of star micelle into vesicle in solvents of variable quality: the star micelle retains its core-shell nanostructure in the vesicle.

    Science.gov (United States)

    Liu, Nijuan; He, Qun; Bu, Weifeng

    2015-03-03

    Intra- and intermolecular interactions of star polymers in dilute solutions are of fundamental importance for both theoretical interest and hierarchical self-assembly into functional nanostructures. Here, star micelles with a polystyrene corona and a small ionic core bearing platinum(II) complexes have been regarded as a model of star polymers to mimic their intra- and interstar interactions and self-assembled behaviors in solvents of weakening quality. In the chloroform/methanol mixture solvents, the star micelles can self-assemble to form vesicles, in which the star micelles shrink significantly and are homogeneously distributed on the vesicle surface. Unlike the morphological evolution of conventional amphiphiles from micellar to vesicular, during which the amphiphilic molecules are commonly reorganized, the star micelles still retain their core-shell nanostructures in the vesicles and the coronal chains of the star micelle between the ionic cores are fully interpenetrated.

  14. Self-assembly of colloids with magnetic caps

    Energy Technology Data Exchange (ETDEWEB)

    Novak, E.V., E-mail: ekaterina.novak@urfu.ru [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); Kantorovich, S.S. [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); University of Vienna, Sensengasse 8, Vienna (Austria)

    2017-06-01

    In our earlier work (Steinbach et al., 2016 ) we investigated a homogeneous system of magnetically capped colloidal particles that self-assembled via two structural patterns of different symmetry. The particles could form a compact, equilateral triangle with a three-fold rotational symmetry and zero dipole moment and a staggered chain with mirror symmetry with a net magnetisation perpendicular to the chain. The system exhibited a bistability already in clusters of three particles. Based on observations of a real magnetic particles system, analytical calculations and molecular dynamics simulations, it has been shown that the bistability is a result of an anisotropic magnetisation distribution with rotational symmetry inside the particles. The present study is a logical extension of the above research and forms a preparatory stage for the study of a self-assembly of such magnetic particles under the influence of an external magnetic field. Since the magnetic field is only an additive contribution to the total ground state energy, we can study the interparticle interaction energies of candidate ground state structures based on the field-free terms. - Highlights: • Analytical calculations of the energies of ground state candidates for colloids with magnetic caps. • Computer simulations confirmed the theoretical model. • The structural transition between ground states was found.

  15. Self-assembly of protein-based biomaterials initiated by titania nanotubes.

    Science.gov (United States)

    Forstater, Jacob H; Kleinhammes, Alfred; Wu, Yue

    2013-12-03

    Protein-based biomaterials are a promising strategy for creating robust highly selective biocatalysts. The assembled biomaterials must sufficiently retain the near-native structure of proteins and provide molecular access to catalytically active sites. These requirements often exclude the use of conventional assembly techniques, which rely on covalent cross-linking of proteins or entrapment within a scaffold. Here we demonstrate that titania nanotubes can initiate and template the self-assembly of enzymes, such as ribonuclease A, while maintaining their catalytic activity. Initially, the enzymes form multilayer thick ellipsoidal aggregates centered on the nanotube surface; subsequently, these nanosized entities assemble into a micrometer-sized enzyme material that has enhanced enzymatic activity and contains as little as 0.1 wt % TiO2 nanotubes. This phenomenon is uniquely associated with the active anatase (001)-like surface of titania nanotubes and does not occur on other anatase nanomaterials, which contain significantly fewer undercoordinated Ti surface sites. These findings present a nanotechnology-enabled mechanism of biomaterial growth and open a new route for creating stable protein-based biomaterials and biocatalysts without the need for chemical modification.

  16. Physically unclonable cryptographic primitives using self-assembled carbon nanotubes

    Science.gov (United States)

    Hu, Zhaoying; Comeras, Jose Miguel M. Lobez; Park, Hongsik; Tang, Jianshi; Afzali, Ali; Tulevski, George S.; Hannon, James B.; Liehr, Michael; Han, Shu-Jen

    2016-06-01

    Information security underpins many aspects of modern society. However, silicon chips are vulnerable to hazards such as counterfeiting, tampering and information leakage through side-channel attacks (for example, by measuring power consumption, timing or electromagnetic radiation). Single-walled carbon nanotubes are a potential replacement for silicon as the channel material of transistors due to their superb electrical properties and intrinsic ultrathin body, but problems such as limited semiconducting purity and non-ideal assembly still need to be addressed before they can deliver high-performance electronics. Here, we show that by using these inherent imperfections, an unclonable electronic random structure can be constructed at low cost from carbon nanotubes. The nanotubes are self-assembled into patterned HfO2 trenches using ion-exchange chemistry, and the width of the trench is optimized to maximize the randomness of the nanotube placement. With this approach, two-dimensional (2D) random bit arrays are created that can offer ternary-bit architecture by determining the connection yield and switching type of the nanotube devices. As a result, our cryptographic keys provide a significantly higher level of security than conventional binary-bit architecture with the same key size.

  17. Self-Assembled Cu-Sn-S Nanotubes with High (De)Lithiation Performance.

    Science.gov (United States)

    Lin, Jie; Lim, Jin-Myoung; Youn, Duck Hyun; Kawashima, Kenta; Kim, Jun-Hyuk; Liu, Yang; Guo, Hang; Henkelman, Graeme; Heller, Adam; Mullins, Charles Buddie

    2017-10-24

    Through a gelation-solvothermal method without heteroadditives, Cu-Sn-S composites self-assemble to form nanotubes, sub-nanotubes, and nanoparticles. The nanotubes with a Cu 3-4 SnS 4 core and Cu 2 SnS 3 shell can tolerate long cycles of expansion/contraction upon lithiation/delithiation, retaining a charge capacity of 774 mAh g -1 after 200 cycles with a high initial Coulombic efficiency of 82.5%. The importance of the Cu component for mitigation of the volume expansion and structural evolution upon lithiation is informed by density functional theory calculations. The self-generated template and calculated results can inspire the design of analogous Cu-M-S (M = metal) nanotubes for lithium batteries or other energy storage systems.

  18. Programmable self-assembly of carbon nanotubes assisted by reversible denaturation of a protein

    International Nuclear Information System (INIS)

    Nithiyasri, P; Parthasarathy, M; Balaji, K; Brindha, P

    2012-01-01

    Self-assembly of pristine multi-walled carbon nanotubes (CNTs) in aqueous dispersion using a protein, bovine serum albumin (BSA), has been demonstrated. Step-wise conformational changes in BSA as a function of temperature have been deployed to direct the assembly of nanotubes. More specifically, CNTs distributed randomly in native BSA at 35 °C as well as completely denatured BSA solution at 80 °C self-assemble in the intermediate temperature range of 45–65 °C, as evident from scanning and transmission electron microscopy. Fourier transform infrared (FTIR) and fluorescence studies indicate significant changes in the α-helical content of the protein with respect to the amide I and II bands and tryptophan emission intensity, respectively. The stability of CNT dispersion in BSA solution has been attributed to the hydrophobic interaction between nanotubes and the protein molecule by adding sodium cholate to the dispersion. Moreover, a mechanism based on electrostatic repulsion between BSA-bound CNTs has been proposed for the thermally reversible assembly of CNTs in BSA solution based on evidence from zeta potential measurements and FTIR spectroscopy. Thus the present report demonstrates bio-mimetic self-assembly of as-synthesized CNTs using changes in surface charge and conformation of an unfolding protein for biomedical applications and nanobiotechnology. (paper)

  19. Manipulation of self-assembly amyloid peptide nanotubes by dielectrophoresis (DEP)

    DEFF Research Database (Denmark)

    Castillo, Jaime; Tanzi, Simone; Dimaki, Maria

    2008-01-01

    Self-assembled amyloid peptide nanotubes (SAPNT) were manipulated and immobilized using dielectrophoresis. Micro-patterned electrodes of Au were fabricated by photolithography and lifted off on a silicon dioxide layer. SAPNT were manipulated by adjusting the amplitude and frequency of the applied...

  20. New route for self-assembly of α-lactalbumin nanotubes and their use as templates to grow silver nanotubes.

    Directory of Open Access Journals (Sweden)

    Wei-Chun Fu

    Full Text Available Nanotubes are formed by self-assembly of α-lactalbumin milk protein following a different route than established for the hydrolysis which involves V8 enzyme, phosphate buffer and appropriate amounts of calcium at neutral pH. The resulting nanotubes are used as templates for the growth of conductive silver nanotubes. TEM, SEM-EDS, AFM and FTIR are used for characterization.

  1. CAPS Activity in Priming Vesicle Exocytosis Requires CK2 Phosphorylation*

    OpenAIRE

    Nojiri, Mari; Loyet, Kelly M.; Klenchin, Vadim A.; Kabachinski, Gregory; Martin, Thomas F. J.

    2009-01-01

    CAPS (Ca2+-dependent activator protein for secretion) functions in priming Ca2+-dependent vesicle exocytosis, but the regulation of CAPS activity has not been characterized. Here we show that phosphorylation by protein kinase CK2 is required for CAPS activity. Dephosphorylation eliminated CAPS activity in reconstituting Ca2+-dependent vesicle exocytosis in permeable and intact PC12 cells. Ser-5, -6, and -7 and Ser-1281 were identified by mass spectrometry as the major phosphorylation sites in...

  2. Terminating DNA Tile Assembly with Nanostructured Caps.

    Science.gov (United States)

    Agrawal, Deepak K; Jiang, Ruoyu; Reinhart, Seth; Mohammed, Abdul M; Jorgenson, Tyler D; Schulman, Rebecca

    2017-10-24

    Precise control over the nucleation, growth, and termination of self-assembly processes is a fundamental tool for controlling product yield and assembly dynamics. Mechanisms for altering these processes programmatically could allow the use of simple components to self-assemble complex final products or to design processes allowing for dynamic assembly or reconfiguration. Here we use DNA tile self-assembly to develop general design principles for building complexes that can bind to a growing biomolecular assembly and terminate its growth by systematically characterizing how different DNA origami nanostructures interact with the growing ends of DNA tile nanotubes. We find that nanostructures that present binding interfaces for all of the binding sites on a growing facet can bind selectively to growing ends and stop growth when these interfaces are presented on either a rigid or floppy scaffold. In contrast, nucleation of nanotubes requires the presentation of binding sites in an arrangement that matches the shape of the structure's facet. As a result, it is possible to build nanostructures that can terminate the growth of existing nanotubes but cannot nucleate a new structure. The resulting design principles for constructing structures that direct nucleation and termination of the growth of one-dimensional nanostructures can also serve as a starting point for programmatically directing two- and three-dimensional crystallization processes using nanostructure design.

  3. Reversible Self-Assembly of Supramolecular Vesicles and Nanofibers Driven by Chalcogen-Bonding Interactions.

    Science.gov (United States)

    Chen, Liang; Xiang, Jun; Zhao, Yue; Yan, Qiang

    2018-05-29

    Chalcogen-bonding interactions have been viewed as new noncovalent forces in supramolecular chemistry. However, harnessing chalcogen bonds to drive molecular self-assembly processes is still unexplored. Here we report for the first time a novel class of supra-amphiphiles formed by Te···O or Se···O chalcogen-bonding interactions, and their self-assembly into supramolecular vesicles and nanofibers. A quasi-calix[4]chalcogenadiazole (C4Ch) as macrocyclic donor and a tailed pyridine N-oxide surfactant as molecular acceptor are designed to construct the donor-acceptor complex via chalcogen-chalcogen connection between the chalcogenadiazole moieties and oxide anion. The affinity of such chalcogen-bonding can dictate the geometry of supra-amphiphiles, driving diverse self-assembled morphologies. Furthermore, the reversible disassembly of these nanostructures can be promoted by introducing competing anions, such as halide ions, or by decreasing the systemic pH value.

  4. Self-assembled ordered carbon-nanotube arrays and membranes.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Siegal, Michael P.; Yelton, William Graham

    2004-11-01

    Imagine free-standing flexible membranes with highly-aligned arrays of carbon nanotubes (CNTs) running through their thickness. Perhaps with both ends of the CNTs open for highly controlled nanofiltration? Or CNTs at heights uniformly above a polymer membrane for a flexible array of nanoelectrodes or field-emitters? How about CNT films with incredible amounts of accessible surface area for analyte adsorption? These self-assembled crystalline nanotubes consist of multiple layers of graphene sheets rolled into concentric cylinders. Tube diameters (3-300 nm), inner-bore diameters (2-15 nm), and lengths (nanometers - microns) are controlled to tailor physical, mechanical, and chemical properties. We proposed to explore growth and characterize nanotube arrays to help determine their exciting functionality for Sandia applications. Thermal chemical vapor deposition growth in a furnace nucleates from a metal catalyst. Ordered arrays grow using templates from self-assembled hexagonal arrays of nanopores in anodized-aluminum oxide. Polymeric-binders can mechanically hold the CNTs in place for polishing, lift-off, and membrane formation. The stiffness, electrical and thermal conductivities of CNTs make them ideally suited for a wide-variety of possible applications. Large-area, highly-accessible gas-adsorbing carbon surfaces, superb cold-cathode field-emission, and unique nanoscale geometries can lead to advanced microsensors using analyte adsorption, arrays of functionalized nanoelectrodes for enhanced electrochemical detection of biological/explosive compounds, or mass-ionizers for gas-phase detection. Materials studies involving membrane formation may lead to exciting breakthroughs in nanofiltration/nanochromatography for the separation of chemical and biological agents. With controlled nanofilter sizes, ultrafiltration will be viable to separate and preconcentrate viruses and many strains of bacteria for 'down-stream' analysis.

  5. Height control of self-assembled quantum dots by strain engineering during capping

    NARCIS (Netherlands)

    Grossi, D.; Smereka, P.; Keizer, J.G.; Ulloa, J.M.; Koenraad, P.M.

    2014-01-01

    Strain engineering during the capping of III-V quantum dots has been explored as a means to control the height of strained self-assembled quantum dots. Results of Kinetic Monte Carlo simulations are confronted with cross-sectional Scanning Tunnel Microscopy (STM) measurements performed on InAs

  6. Click functionalization of phenyl-capped bithiophene on azide-terminated self-assembled monolayers

    International Nuclear Information System (INIS)

    Zheng, Yijun; Cui, Jiaxi; Ikeda, Taichi

    2015-01-01

    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 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 3 -SAMs and Ph2TPh units in Ph2TPh-functionalized SAMs were estimated to be 7.3 ± 0.3 × 10 −10 mol cm −2 and 4.6 ± 0.3 × 10 −10 mol cm −2 , respectively, by quartz crystal microbalance (QCM). Most of Ph2TPh-alkynes are considered to be anchored on N 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).

  7. 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).

  8. 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.

  9. High-speed logic integrated circuits with solution-processed self-assembled carbon nanotubes.

    Science.gov (United States)

    Han, Shu-Jen; Tang, Jianshi; Kumar, Bharat; Falk, Abram; Farmer, Damon; Tulevski, George; Jenkins, Keith; Afzali, Ali; Oida, Satoshi; Ott, John; Hannon, James; Haensch, Wilfried

    2017-09-01

    As conventional monolithic silicon technology struggles to meet the requirements for the 7-nm technology node, there has been tremendous progress in demonstrating the scalability of carbon nanotube field-effect transistors down to the size that satisfies the 3-nm node and beyond. However, to date, circuits built with carbon nanotubes have overlooked key aspects of a practical logic technology and have stalled at simple functionality demonstrations. Here, we report high-performance complementary carbon nanotube ring oscillators using fully manufacturable processes, with a stage switching frequency of 2.82 GHz. The circuit was built on solution-processed, self-assembled carbon nanotube arrays with over 99.9% semiconducting purity, and the complementary feature was achieved by employing two different work function electrodes.

  10. High-speed logic integrated circuits with solution-processed self-assembled carbon nanotubes

    Science.gov (United States)

    Han, Shu-Jen; Tang, Jianshi; Kumar, Bharat; Falk, Abram; Farmer, Damon; Tulevski, George; Jenkins, Keith; Afzali, Ali; Oida, Satoshi; Ott, John; Hannon, James; Haensch, Wilfried

    2017-09-01

    As conventional monolithic silicon technology struggles to meet the requirements for the 7-nm technology node, there has been tremendous progress in demonstrating the scalability of carbon nanotube field-effect transistors down to the size that satisfies the 3-nm node and beyond. However, to date, circuits built with carbon nanotubes have overlooked key aspects of a practical logic technology and have stalled at simple functionality demonstrations. Here, we report high-performance complementary carbon nanotube ring oscillators using fully manufacturable processes, with a stage switching frequency of 2.82 GHz. The circuit was built on solution-processed, self-assembled carbon nanotube arrays with over 99.9% semiconducting purity, and the complementary feature was achieved by employing two different work function electrodes.

  11. Self-assembled rosette nanotubes encapsulate and slowly release dexamethasone

    Directory of Open Access Journals (Sweden)

    Chen Y

    2011-05-01

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

  12. Self-Assembly of Telechelic Tyrosine End-Capped PEO Star Polymers in Aqueous Solution.

    Science.gov (United States)

    Edwards-Gayle, Charlotte J C; Greco, Francesca; Hamley, Ian W; Rambo, Robert P; Reza, Mehedi; Ruokolainen, Janne; Skoulas, Dimitrios; Iatrou, Hermis

    2018-01-08

    We investigate the self-assembly of two telechelic star polymer-peptide conjugates based on poly(ethylene oxide) (PEO) four-arm star polymers capped with oligotyrosine. The conjugates were prepared via N-carboxy anhydride-mediated ring-opening polymerization from PEO star polymer macroinitiators. Self-assembly occurs above a critical aggregation concentration determined via fluorescence probe assays. Peptide conformation was examined using circular dichroism spectroscopy. The structure of self-assembled aggregates was probed using small-angle X-ray scattering and cryogenic transmission electron microscopy. In contrast to previous studies on linear telechelic PEO-oligotyrosine conjugates that show self-assembly into β-sheet fibrils, the star architecture suppresses fibril formation and micelles are generally observed instead, a small population of fibrils only being observed upon pH adjustment. Hydrogelation is also suppressed by the polymer star architecture. These peptide-functionalized star polymer solutions are cytocompatible at sufficiently low concentration. These systems present tyrosine at high density and may be useful in the development of future enzyme or pH-responsive biomaterials.

  13. In-capillary self-assembly and proteolytic cleavage of polyhistidine peptide capped quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jianhao; Li, Jingyan; Li, Jinchen; Liu, Feifei [School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu, 213164 (China); Zhou, Xiang; Yao, Yi [Changzhou Qianhong Bio-pharma Co. Ltd, Changzhou 213164, Jiangsu (China); Wang, Cheli [School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu, 213164 (China); Qiu, Lin, E-mail: linqiupjj@gmail.com [School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu, 213164 (China); Jiang, Pengju, E-mail: pengju.jiang@gmail.com [School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu, 213164 (China); State Key Laboratory of Pharmaceutical Biotechnology, Nanjing, Jiangsu (China)

    2015-10-01

    A new method using fluorescence coupled capillary electrophoresis (CE-FL) for monitoring self-assembly and proteolytic cleavage of hexahistidine peptide capped quantum dots (QDs) inside a capillary has been developed in this report. QDs and the ATTO 590-labeled hexahistidine peptide (H6-ATTO) were injected into a capillary, sequentially. Their self-assembly inside the capillary was driven by a metal-affinity force which yielded a new fluorescence signal due to Förster resonance energy transfer (FRET). The highly efficient separation of fluorescent complexes and the FRET process were analyzed using CE-FL. The self-assembly of QDs and biomolecules was found to effectively take place inside the capillary. The kinetics of the assembly was monitored by CE-FL, and the approach was extended to the study of proteolytic cleavage of surface conjugated peptides. Being the first in-depth analysis of in-capillary nanoparticle–biomolecule assembly, the novel approach reported here provides inspiration to the development of QD-based FRET probes for biomedical applications. - Highlights: • We examined the self-assembly QDs with H6-ATTO inside a capillary. • We prove CE-FL to be a powerful method to resolve QDs-H6-ATTO complex. • We achieve chromatographic separation of QDs-H6-ATTO complex. • We discovered a novel strategy for the online detection of thrombin. • This technique integrated “injection, mixing, reaction, separation and detection”.

  14. Fabrication and characterization of PEDOT nanowires based on self-assembled peptide nanotube lithography

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Christiansen, Nikolaj Ormstrup; Castillo, Jaime

    2013-01-01

    In this article we demonstrate the use of self-assembled peptide nanotube structures as masking material in a rapid, mild and low cost fabrication of polymerized p-toluenesulfonate doped poly(3,4-ethylenedioxythiophene) (PEDOT:TsO) nanowire device. In this new fabrication approach the PEDOT:TsO n...

  15. Modulating the forces between self-assembling molecules to control the shape of vesicles and the mechanics and alignment of nanofiber networks

    Science.gov (United States)

    Greenfield, Megan Ann

    One of the great challenges in supramolecular chemistry is the design of molecules that can self-assemble into functional aggregates with well-defined three-dimensional structures and bulk material properties. Since the self-assembly of nanostructures is greatly influenced by both the nature of the self-assembling components and the environmental conditions in which the components assemble, this work explores how changes in the molecular design and the environment affect the properties of self-assembled structures. We first explore how to control the mechanical properties of self-assembled fibrillar networks by changing environmental conditions. We report here on how changing pH, screening ions, and solution temperature affect the gelation, stiffness, and response to deformation of peptide amphiphile gels. Although the morphology of PA gels formed by charge neutralization and salt-mediated charge screening are similar by electron microscopy, rheological measurements indicate that the calcium-mediated ionic bridges in CaCl2-PA gels form stronger intra- and inter-fiber crosslinks than the hydrogen bonds formed by the protonated carboxylic acid residues in HCl-PA gels. In contrast, the structure of PA gels changes drastically when the PA solution is annealed prior to gel formation. Annealed PA solutions are birefringent and can form viscoelastic strings of aligned nanofibers when manually dragged across a thin film of CaCl2. These aligned arrays of PA nanofibers hold great promise in controlling the orientation of cells in three-dimensions. Separately, we applied the principles of molecular design to create buckled membrane nanostructures that mimic the shape of viruses. When oppositely charged amphiphilic molecules are mixed they can form vesicles with a periodic two-dimensional ionic lattice that opposes the membrane's natural curvature and can result in vesicle buckling. Our results demonstrate that a large +3 to -1 charge imbalance between the cationic and anionic

  16. Self-assembled peptide nanotubes as an etching material for the rapid fabrication of silicon wires

    DEFF Research Database (Denmark)

    Larsen, Martin Benjamin Barbour Spanget; Andersen, Karsten Brandt; Svendsen, Winnie Edith

    2011-01-01

    This study has evaluated self-assembled peptide nanotubes (PNTS) and nanowires (PNWS) as etching mask materials for the rapid and low-cost fabrication of silicon wires using reactive ion etching (RIE). The self-assembled peptide structures were fabricated under mild conditions and positioned on c...... characterization by SEM and I-V measurements. Additionally, the fabricated silicon structures were functionalized with fluorescent molecules via a biotin-streptavidin interaction in order to probe their potential in the development of biosensing devices....

  17. Hydrogen Bonded Supramolecular Polymers in Both Apolar and Aqueous Media: Self-Assembly and Reversible Conversion of Vesicles and Gels%Hydrogen Bonded Supramolecular Polymers in Both Apolar and Aqueous Media: Self-Assembly and Reversible Conversion of Vesicles and Gels

    Institute of Scientific and Technical Information of China (English)

    杜平; 孔军; 王贵涛; 赵新; 李光玉; 蒋锡夔; 黎占亭

    2011-01-01

    In a preliminary letter (Tetrahedron Lett. 2010, 51, 188), we reported two new hydrazide-based quadruple hydrogen-bonding motifs, this is, two monopodal (la and lb) and five dipodal (2a, 2b and 3a--3c) aromatic hydrazide derivatives, and the formation of supramolecular polymers and vesicles from the dipodal motifs in hydrocarbons. In this paper, we present a full picture on the properties of these hydrogen-bonding motifs with an emphasis on their self-assembling behaviors in aqueous media. SEM, AFM, TEM and fluorescent micrographs indicate that all the dipodal compounds also form vesicles in polar methanol and water-methanol (up to 50% of water) mixtures. Control experiments show that lb does not form vesicles in same media. Addition of lb to the solution of the dipodal compounds inhibits the latter's capacity of forming vesicles. At high concentrations, 3b and 3c also gelate discrete solvents, including hydrocarbons, esters, methanol, and methanol-water mixture. Concentration-dependent SEM investigations reveal that the vesicles of 3b and 3c fuse to form gels and the gel of 3c can de-aggregate to form the vesicles reversibly.

  18. Matrix vesicles in the fibrous cap of atherosclerotic plaque: possible contribution to plaque rupture.

    Science.gov (United States)

    Bobryshev, Y V; Killingsworth, M C; Lord, R S A; Grabs, A J

    2008-10-01

    Plaque rupture is the most common type of plaque complication and leads to acute ischaemic events such as myocardial infarction and stroke. Calcification has been suggested as a possible indicator of plaque instability. Although the role of matrix vesicles in the initial stages of arterial calcification has been recognized, no studies have yet been carried out to examine a possible role of matrix vesicles in plaque destabilization. Tissue specimens selected for the present study represented carotid specimens obtained from patients undergoing carotid endarterectomy. Serial frozen cross-sections of the tissue specimens were cut and mounted on glass slides. The thickness of the fibrous cap (FCT) in each advanced atherosclerotic lesion, containing a well developed lipid/necrotic core, was measured at its narrowest sites in sets of serial sections. According to established criteria, atherosclerotic plaque specimens were histologically subdivided into two groups: vulnerable plaques with thin fibrous caps (FCT <100 microm) and presumably stable plaques, in which fibrous caps were thicker than 100 microm. Twenty-four carotid plaques (12 vulnerable and 12 presumably stable plaques) were collected for the present analysis of matrix vesicles in fibrous caps. In order to provide a sufficient number of representative areas from each plaque, laser capture microdissection (LCM) was carried out. The quantification of matrix vesicles in ultrathin sections of vulnerable and stable plaques revealed that the numbers of matrix vesicles were significantly higher in fibrous caps of vulnerable plaques than those in stable plaques (8.908+0.544 versus 6.208+0.467 matrix vesicles per 1.92 microm2 standard area; P= 0.0002). Electron microscopy combined with X-ray elemental microanalysis showed that some matrix vesicles in atherosclerotic plaques were undergoing calcification and were characterized by a high content of calcium and phosphorus. The percentage of calcified matrix vesicles

  19. On-Chip Chemical Self-Assembly of Semiconducting Single-Walled Carbon Nanotubes (SWNTs) : Toward Robust and Scale Invariant SWNTs Transistors

    NARCIS (Netherlands)

    Derenskyi, Vladimir; Gomulya, Widianta; Talsma, Wytse; Salazar-Rios, Jorge Mario; Fritsch, Martin; Nirmalraj, Peter; Riel, Heike; Allard, Sybille; Scherf, Ullrich; Loi, Maria A.

    2017-01-01

    In this paper, the fabrication of carbon nanotubes field effect transistors by chemical self-assembly of semiconducting single walled carbon nanotubes (s-SWNTs) on prepatterned substrates is demonstrated. Polyfluorenes derivatives have been demonstrated to be effective in selecting s-SWNTs from raw

  20. Counterions control whether self-assembly leads to formation of stable and well-defined unilamellar nanotubes or nanoribbons and nanorods

    DEFF Research Database (Denmark)

    Shi, Dong; Schwall, Christian; Sfintes, George

    2014-01-01

    Self-assembly of the amphiphilic π-conjugated carbenium ion ATOTA-1(+) in aqueous solution selectively leads to discrete and highly stable nanotubes or nanoribbons and nanorods, depending on the nature of the counterion (Cl(-) vs. PF6(-), respectively). The nanotubes formed by the Cl(-) salt...

  1. Fabrication of Carbon Nanotube Thin Films by Evaporation-Induced Self-Assembly

    OpenAIRE

    Li, Han

    2015-01-01

    In summary, we have prepared single-wall carbon nanotube (SWNT) thin films by the method of evaporation-induced self-assembly (EISA). Using the scalable two-plate or lens setups, sorts of different film types or patterns of SWNTs has been successfully fabricated directly from the evaporation of solvents and could be precisely controlled by the concentrations of SWNT in ambient conditions. The special geometry of meniscus as the capillary bridge has not only given rise to a much higher efficie...

  2. Self-assembling Synthesis of Vanadium Oxide Nanotubes and Simple Determination of the Content of Ⅴ(Ⅳ)

    Institute of Scientific and Technical Information of China (English)

    MAI Li-qiang; CHEN Wen; XU Qing; ZHU Quan-yao; HAN Chun-hua; PENG Jun-feng

    2003-01-01

    High-yielding low-cost vanadium oxide nanotubes were prepared by the hydrothermal self-assembling process from vanadium pentoxide and organic molecules as structure-directing templates. Moreover, a new method was discovered for determining the content of V (Ⅳ) in vanadium oxide nanotubes by thermogravimetric analysis ( TGA ). This method is simple, precise and feasible and can be extended to determine the content of low oxidation state in the other transition metal oxide nanomaterials.

  3. Self-assembled peptide nanotubes as electronic materials: An evaluation from first-principles calculations

    International Nuclear Information System (INIS)

    Akdim, Brahim; Pachter, Ruth; Naik, Rajesh R.

    2015-01-01

    In this letter, we report on the evaluation of diphenylalanine (FF), dityrosine (YY), and phenylalanine-tryptophan (FW) self-assembled peptide nanotube structures for electronics and photonics applications. Realistic bulk peptide nanotube material models were used in density functional theory calculations to mimic the well-ordered tubular nanostructures. Importantly, validated functionals were applied, specifically by using a London dispersion correction to model intertube interactions and a range-separated hybrid functional for accurate bandgap calculations. Bandgaps were found consistent with available experimental data for FF, and also corroborate the higher conductance reported for FW in comparison to FF peptide nanotubes. Interestingly, the predicted bandgap for the YY tubular nanostructure was found to be slightly higher than that of FW, suggesting higher conductance as well. In addition, the band structure calculations along the high symmetry line of nanotube axis revealed a direct bandgap for FF. The results enhance our understanding of the electronic properties of these material systems and will pave the way into their application in devices

  4. Supramolecular Self-Assembly of Histidine-Capped-Dialkoxy-Anthracene: A Visible Light Triggered Platform for facile siRNA Delivery

    KAUST Repository

    Patil, Sachin; Moosa, Basem; Alsaiari, Shahad; Alamoudi, Kholod; Alshamsan, Aws; Almailk, Abdulaziz; Adil, Karim; Eddaoudi, Mohamed; Khashab, Niveen M.

    2016-01-01

    Supramolecular self-assembly of histidine-capped-dialkoxy-anthracene (HDA) results in the formation of light responsive nanostructures.Single-crystal X-ray diffraction analysis of HDA shows two types of hydrogen bonding. The first hydrogen bond

  5. Gold nanoparticles covalently assembled onto vesicle structures as possible biosensing platform

    Directory of Open Access Journals (Sweden)

    M. Fátima Barroso

    2016-05-01

    Full Text Available In this contribution a strategy is shown to covalently immobilize gold nanoparticles (AuNPs onto vesicle bilayers with the aim of using this nanomaterial as platform for the future design of immunosensors. A novel methodology for the self-assembly of AuNPs onto large unilamellar vesicle structures is described. The vesicles were formed with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC and 1-undecanethiol (SH. After, the AuNPs photochemically synthesized in pure glycerol were mixed and anchored onto SH–DOPC vesicles. The data provided by voltammetry, spectrometry and microscopy techniques indicated that the AuNPs were successfully covalently anchored onto the vesicle bilayer and decorated vesicles exhibit a spherical shape with a size of 190 ± 10 nm. The developed procedure is easy, rapid and reproducible to start designing a possible immunosensor by using environmentally friendly procedures.

  6. DNA biosensor by self-assembly of carbon nanotubes and DNA to detect riboflavin

    Energy Technology Data Exchange (ETDEWEB)

    Li Jing [College of Chemistry and Chemical Engineering. Chongqing University, ChongQing, 400044 (China); Zhang Yunhuai, E-mail: xp2031@163.com [College of Chemistry and Chemical Engineering. Chongqing University, ChongQing, 400044 (China); Yang Tongyi [School of Life Science. NanJing University, Nanjing, 210093 (China); Zhang Huai [Liming Research Institute of Chemical Industry, LuoYang, 471001 (China); Yang Yixuan [State Key Laboratory of Chemical Resource Engineering. Beijing University of Chemical Technology, Beijing 100029 (China); Xiao Peng [College of Mathematics and Physics, Chongqing University, Chongqing 400044 (China)

    2009-10-15

    The fabrication of biosensors via self-assembly of single-walled carbon nanotubes (SWNTs) and DNA on a platinum electrode was presented in this paper. The carboxylic SWNTs were assembled on an amine-modified platinum electrode surface and followed by the assembly of NH{sub 2}-DNA with the carboxyl-amine coupling. The decorated surface was characterized by Field Emission Electron Microscopy (FEG-SEM) and electrochemical experiments, which showed that the reaction of DNA-SWNTs biosensor was quasi-reversible. The mechanism of DNA and riboflavin (VB{sub 2}) was studied by cyclic voltammetry and UV-Vis spectroscopy. The fabricated SWNTs-reinforced biosensor exhibits high sensitivity and low detection limit for the tested VB{sub 2} compared to the reported methods.

  7. Synthesis of high quality single-walled carbon nanotubes via a catalytic layer reinforced by self-assembled monolayers

    International Nuclear Information System (INIS)

    Adhikari, Prashanta Dhoj; Song, Wooseok; Cha, Myoung-Jun; Park, Chong-Yun

    2013-01-01

    This work reports the synthesis of high quality single-walled carbon nanotubes (SWCNT) using a catalytic layer reinforced by self-assembled monolayers (SAM). Amine-SAM was introduced on a SiO 2 /Si substrate and then an iron nanoparticles solution was dropped on the substrate by spin-coating. This catalytic template was used to grow carbon nanotubes by chemical vapor deposition and the synthesized SWCNT were observed to be prominent, based on the size distribution. Highly dense SWCNT with a diameter of about 1.1-1.2 nm were produced at 800-850 °C. Moreover, the diameter distribution of the SWCNT was more selective at a growth temperature of 900 °C. These findings provide important insights for a SAM support layer that can play the role as a restriction for the agglomeration of iron catalyst and is promising for the synthesis of high quality SWCNT. - Highlights: • Fe nanoparticles on self-assembled monolayers (SAM) containing template is underlined. • Its catalytic behavior to synthesis single-walled carbon nanotubes is studied. • The role of SAM on catalytic template is explored

  8. Fringing-field dielectrophoretic assembly of ultrahigh-density semiconducting nanotube arrays with a self-limited pitch

    Science.gov (United States)

    Cao, Qing; Han, Shu-Jen; Tulevski, George S.

    2014-09-01

    One key challenge of realizing practical high-performance electronic devices based on single-walled carbon nanotubes is to produce electronically pure nanotube arrays with both a minuscule and uniform inter-tube pitch for sufficient device-packing density and homogeneity. Here we develop a method in which the alternating voltage-fringing electric field formed between surface microelectrodes and the substrate is utilized to assemble semiconducting nanotubes into well-aligned, ultrahigh-density and submonolayered arrays, with a consistent pitch as small as 21±6 nm determined by a self-limiting mechanism, based on the unique field focusing and screening effects of the fringing field. Field-effect transistors based on such nanotube arrays exhibit record high device transconductance (>50 μS μm-1) and decent on current per nanotube (~1 μA per tube) together with high on/off ratios at a drain bias of -1 V.

  9. DNA-mediated self-assembly of carbon nanotubes on gold

    International Nuclear Information System (INIS)

    Sanchez-Pomales, Germarie; Rivera-Velez, Nelson E; Cabrera, Carlos R

    2007-01-01

    This report presents the use of disulfide-modified single-stranded DNA (ssDNA) to form DNA self-assembled monolayers (SAMs) and mixed DNA-carbon nanotube (CNT) hybrids SAMs on gold substrates. Mixed DNA-CNT SAMs are composed of DNA, mercaptohexanol (MCH) and DNA-CNT aggregates. Both, DNA-CNT and DNA areas of the mixed SAMs were analyzed and compared to traditional DNA SAMs. The results suggest the formation of a more compact and densely packed monolayer of DNA-CNT in comparison with DNA. The use of DNA-CNT hybrids to form SAMs on gold substrates might represent a new approach to improve the immobilization of DNA strands on gold, and might therefore help with the development of enhanced DNA sensors

  10. Densifying carbon nanotubes on assembly surface by the self-contraction of silk fibroin

    Science.gov (United States)

    Jiang, Chunyang; Yang, Xueqin; Zhao, Jingna; Li, Qingsong; Zhang, Ke-Qin; Zhang, Xiaohua; Li, Qingwen

    2018-04-01

    High densification of carbon nanotubes (CNTs) is important for high utilization efficiency of their superior properties in macroscopic assemblies. However, the conventional "top-down" compressing strategies have met problems to modify CNT assemblies at and below the micrometer scale. Here we report a molecular way to strap CNTs together via the self-contraction of silk fibroin (SF) during its drying process, resulting in a localized densification below the micrometer scale. Importantly, after the thermal removal of SF molecules, the densified assembly was well maintained. The SF-induced densification increased the average strength from 355 MPa to 960 MPa for CNT fibers, and from 1.45 GPa to 1.82 GPa for CNT ribbons, which contain much more CNTs on the surface.

  11. Assembly of cells and vesicles for organ engineering

    International Nuclear Information System (INIS)

    Taguchi, Tetsushi

    2011-01-01

    The development of materials and technologies for the assembly of cells and/or vesicles is a key for the next generation of tissue engineering. Since the introduction of the tissue engineering concept in 1993, various types of scaffolds have been developed for the regeneration of connective tissues in vitro and in vivo. Cartilage, bone and skin have been successfully regenerated in vitro, and these regenerated tissues have been applied clinically. However, organs such as the liver and pancreas constitute numerous cell types, contain small amounts of extracellular matrix, and are highly vascularized. Therefore, organ engineering will require the assembly of cells and/or vesicles. In particular, adhesion between cells/vesicles will be required for regeneration of organs in vitro. This review introduces and discusses the key technologies and materials for the assembly of cells/vesicles for organ regeneration. (topical review)

  12. Capping Ligand Vortices as "Atomic Orbitals" in Nanocrystal Self-Assembly.

    Science.gov (United States)

    Waltmann, Curt; Horst, Nathan; Travesset, Alex

    2017-11-28

    We present a detailed analysis of the interaction between two nanocrystals capped with ligands consisting of hydrocarbon chains by united atom molecular dynamics simulations. We show that the bonding of two nanocrystals is characterized by ligand textures in the form of vortices. These results are generalized to nanocrystals of different types (differing core and ligand sizes) where the structure of the vortices depends on the softness asymmetry. We provide rigorous calculations for the binding free energy, show that these energies are independent of the chemical composition of the cores, and derive analytical formulas for the equilibrium separation. We discuss the implications of our results for the self-assembly of single-component and binary nanoparticle superlattices. Overall, our results show that the structure of the ligands completely determines the bonding of nanocrystals, fully supporting the predictions of the recently proposed Orbifold topological model.

  13. Electrostatically Driven Assembly of Charged Amphiphiles Forming Crystallized Membranes, Vesicles and Nanofiber Arrays

    Science.gov (United States)

    Leung, Cheuk Yui Curtis

    Charged amphiphilic molecules can self-assemble into a large variety of objects including membranes, vesicles and fibers. These micro to nano-scale structures have been drawing increasing attention due to their broad applications, especially in biotechnology and biomedicine. In this dissertation, three self-assembled systems were investigated: +3/-1 self-assembled catanionic membranes, +2/-1 self-assembled catanionic membranes and +1 self-assembled nanofibers. Transmission electron microscopy (TEM) combined with synchrotron small and wide angle x-ray scattering (SAXS and WAXS) were used to characterize the coassembled structures from the mesoscopic to nanometer scale. We designed a system of +3 and -1 ionic amphiphiles that coassemble into crystalline ionic bilayer vesicles with large variety of geometries that resemble polyhedral cellular crystalline shells and archaea wall envelopes. The degree of ionization of the amphiphiles and their intermolecular electrostatic interactions can be controlled by varying pH. The molecular packing of these membranes showed a hexagonal to rectangular-C to hexagonal phase transition with increasing pH, resulting in significant changes to the membrane morphology. A similar mixture of +2 and -1 ionic amphiphiles was also investigated. In addition to varying pH, which controls the headgroup attractions, we also adjust the tail length of the amphiphiles to control the van der Waals interactions between the tails. A 2D phase diagram was developed to show how pH and tail length can be used to control the intermolecular packing within the membranes. Another system of self-assembled nanofiber network formed by positively charged amphiphiles was also studied. These highly charged fibers repel each other and are packed in hexagonal lattice with lattice constant at least eight times of the fiber diameter. The d-spacing and the crystal structure can be controlled by varying the solution concentration and temperature.

  14. Binary breath figures for straightforward and controllable self-assembly of microspherical caps.

    Science.gov (United States)

    Gong, Jianliang; Xu, Bingang; Tao, Xiaoming; Li, Lei

    2016-05-11

    The intense interest surrounding asymmetrical microparticles originates from their unique anisotropic properties and promising applications. In this work, direct self-assembly of polymeric microspherical caps without the assistance of any additives has been achieved by using low-surface-tension methanol (MeOH) and high-surface-tension water as binary breath figures (BFs). With the evaporation of polystyrene (PS) solution containing low-boiling-point solvent in the binary vapors, the formed MeOH BFs could quickly diffuse into solution, while water BFs tended to remain at the solution surface. This led to the formation of a gradient nonsolvent layer at the vapor/solution interface, which induced the formation of nuclei and guided further asymmetrical growth of polymer particles. After the spontaneous removal of MeOH, water and residual solvent by evaporation, polymeric microspherical caps were left on the substrate. Through controlling the proportion of water introduced by adjusting the ratios of MeOH and water, polymeric microspherical caps with a range of controllable shapes (divided at different positions of a sphere) were successfully obtained. The formation mechanism was explained based on the difference of vapor pressure, surface tension and miscibility between the employed solvents and nonsolvents. A solvent possessing a high vapor pressure, low surface tension and good miscibility with MeOH contributed to the formation of microspherical caps. This flexible, green and straightforward technique is a nondestructive strategy, and avoids complicated work on design, preparation and removal of hard templates and additives.

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

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  16. Self-Assembly of Hierarchical DNA Nanotube Architectures with Well-Defined Geometries.

    Science.gov (United States)

    Jorgenson, Tyler D; Mohammed, Abdul M; Agrawal, Deepak K; Schulman, Rebecca

    2017-02-28

    An essential motif for the assembly of biological materials such as actin at the scale of hundreds of nanometers and beyond is a network of one-dimensional fibers with well-defined geometry. Here, we demonstrate the programmed organization of DNA filaments into micron-scale architectures where component filaments are oriented at preprogrammed angles. We assemble L-, T-, and Y-shaped DNA origami junctions that nucleate two or three micron length DNA nanotubes at high yields. The angles between the nanotubes mirror the angles between the templates on the junctions, demonstrating that nanoscale structures can control precisely how micron-scale architectures form. The ability to precisely program filament orientation could allow the assembly of complex filament architectures in two and three dimensions, including circuit structures, bundles, and extended materials.

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

    Science.gov (United States)

    Waltmann, Curt; Horst, Nathan; Travesset, Alex

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

  18. Transformation of self-assembled InAs/InP quantum dots into quantum rings without capping.

    Science.gov (United States)

    Sormunen, Jaakko; Riikonen, Juha; Mattila, Marco; Tiilikainen, Jouni; Sopanen, Markku; Lipsanen, Harri

    2005-08-01

    Transformation of self-assembled InAs quantum dots (QDs) on InP(100) into quantum rings (QRs) is studied. In contrast to the typical approach to III--V semiconductor QR growth, the QDs are not capped to form rings. Atomic force micrographs reveal a drastic change from InAs QDs into rings after a growth interruption in tertiarybutylphosphine ambient. Strain energy relief in the InAs QD is discussed and a mechanism for dot-to-ring transformation by As/P exchange reactions is proposed.

  19. Direct Synthesis of Polymer Nanotubes by Aqueous Dispersion Polymerization of a Cyclodextrin/Styrene Complex.

    Science.gov (United States)

    Chen, Xi; Liu, Lei; Huo, Meng; Zeng, Min; Peng, Liao; Feng, Anchao; Wang, Xiaosong; Yuan, Jinying

    2017-12-22

    A one-step synthesis of nanotubes by RAFT dispersion polymerization of cyclodextrin/styrene (CD/St) complexes directly in water is presented. The resulted amphiphilic PEG-b-PS diblock copolymers self-assemble in situ into nanoparticles with various morphologies. Spheres, worms, lamellae, and nanotubes were controllably obtained. Because of the complexation, the swelling degree of polystyrene (PS) blocks by free St is limited, resulting in limited mobility of PS chains. Consequently, kinetically trapped lamellae and nanotubes were obtained instead of spherical vesicles. During the formation of nanotubes, small vesicles first formed at the ends of the tape-like lamellae, then grew and fused into nanotubes with a limited chain rearrangement. The introduction of a host-guest interaction based on CDs enables the aqueous dispersion polymerization of water-immiscible monomers, and produces kinetically trapped nanostructures, which could be a powerful technique for nanomaterials synthesis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

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

    2016-09-14

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

  1. Assembly and melting of DNA nanotubes from single-sequence tiles

    International Nuclear Information System (INIS)

    Sobey, T L; Renner, S; Simmel, F C

    2009-01-01

    DNA melting and renaturation studies are an extremely valuable tool to study the kinetics and thermodynamics of duplex dissociation and reassociation reactions. These are important not only in a biological or biotechnological context, but also for DNA nanotechnology which aims at the construction of molecular materials by DNA self-assembly. We here study experimentally the formation and melting of a DNA nanotube structure, which is composed of many copies of an oligonucleotide containing several palindromic sequences. This is done using temperature-controlled UV absorption measurements correlated with atomic force microscopy, fluorescence microscopy and transmission electron microscopy techniques. In the melting studies, important factors such as DNA strand concentration, hierarchy of assembly and annealing protocol are investigated. Assembly and melting of the nanotubes are shown to proceed via different pathways. Whereas assembly occurs in several hierarchical steps related to the formation of tiles, lattices and tubes, melting of DNA nanotubes appears to occur in a single step. This is proposed to relate to fundamental differences between closed, three-dimensional tube-like structures and open, two-dimensional lattices. DNA melting studies can lead to a better understanding of the many factors that affect the assembly process which will be essential for the assembly of increasingly complex DNA nanostructures.

  2. Self-assembled nanogaps for molecular electronics

    DEFF Research Database (Denmark)

    Tang, Qingxin; Tong, Yanhong; Jain, Titoo

    2009-01-01

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

  3. Insight of Transmembrane Processes of Self-Assembling Nanotubes Based on a Cyclic Peptide Using Coarse Grained Molecular Dynamics Simulation.

    Science.gov (United States)

    Fu, Yankai; Yan, Tingxuan; Xu, Xia

    2017-09-28

    Transmembrane self-assembling cyclic peptide (SCP) nanotubes are promising candidates for delivering specific molecules through cell membranes. The detailed mechanisms behind the transmembrane processes, as well as stabilization factors of transmembrane structures, are difficult to elucidate through experiments. In this study, the effects of peptide sequence and oligomeric state on the transmembrane capabilities of SCP nanotubes and the perturbation of embedded SCP nanotubes acting on the membrane were investigated based on coarse grained molecular dynamics simulation. The simulation results reveal that hydrophilic SCP oligomers result in the elevation of the energy barrier while the oligomerization of hydrophobic SCPs causes the reduction of the energy barrier, further leading to membrane insertion. Once SCP nanotubes are embedded, membrane properties such as density, thickness, ordering state and lateral mobility are adjusted along the radial direction. This study provides insight into the transmembrane strategy of SCP nanotubes and sheds light on designing novel transport systems.

  4. Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles

    Directory of Open Access Journals (Sweden)

    Bo Liedberg

    2013-09-01

    Full Text Available Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadiene-b-poly(ethylene oxide (PB-PEO/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation.

  5. On-Chip Chemical Self-Assembly of Semiconducting Single-Walled Carbon Nanotubes (SWNTs): Toward Robust and Scale Invariant SWNTs Transistors.

    Science.gov (United States)

    Derenskyi, Vladimir; Gomulya, Widianta; Talsma, Wytse; Salazar-Rios, Jorge Mario; Fritsch, Martin; Nirmalraj, Peter; Riel, Heike; Allard, Sybille; Scherf, Ullrich; Loi, Maria A

    2017-06-01

    In this paper, the fabrication of carbon nanotubes field effect transistors by chemical self-assembly of semiconducting single walled carbon nanotubes (s-SWNTs) on prepatterned substrates is demonstrated. Polyfluorenes derivatives have been demonstrated to be effective in selecting s-SWNTs from raw mixtures. In this work the authors functionalized the polymer with side chains containing thiols, to obtain chemical self-assembly of the selected s-SWNTs on substrates with prepatterned gold electrodes. The authors show that the full side functionalization of the conjugated polymer with thiol groups partially disrupts the s-SWNTs selection, with the presence of metallic tubes in the dispersion. However, the authors determine that the selectivity can be recovered either by tuning the number of thiol groups in the polymer, or by modulating the polymer/SWNTs proportions. As demonstrated by optical and electrical measurements, the polymer containing 2.5% of thiol groups gives the best s-SWNT purity. Field-effect transistors with various channel lengths, using networks of SWNTs and individual tubes, are fabricated by direct chemical self-assembly of the SWNTs/thiolated-polyfluorenes on substrates with lithographically defined electrodes. The network devices show superior performance (mobility up to 24 cm 2 V -1 s -1 ), while SWNTs devices based on individual tubes show an unprecedented (100%) yield for working devices. Importantly, the SWNTs assembled by mean of the thiol groups are stably anchored to the substrate and are resistant to external perturbation as sonication in organic solvents. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. A Carbon Dioxide Bubble-Induced Vortex Triggers Co-Assembly of Nanotubes with Controlled Chirality.

    Science.gov (United States)

    Zhang, Ling; Zhou, Laicheng; Xu, Na; Ouyang, Zhenjie

    2017-07-03

    It is challenging to prepare co-organized nanotube systems with controlled nanoscale chirality in an aqueous liquid flow field. Such systems are responsive to a bubbled external gas. A liquid vortex induced by bubbling carbon dioxide (CO 2 ) gas was used to stimulate the formation of nanotubes with controlled chirality; two kinds of achiral cationic building blocks were co-assembled in aqueous solution. CO 2 -triggered nanotube formation occurs by formation of metastable intermediate structures (short helical ribbons and short tubules) and by transition from short tubules to long tubules in response to chirality matching self-assembly. Interestingly, the chirality sign of these assemblies can be selected for by the circulation direction of the CO 2 bubble-induced vortex during the co-assembly process. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Dielectrophoretic assembly of carbon nanotube devices

    DEFF Research Database (Denmark)

    Dimaki, Maria

    The purpose of this project has been to assemble single-walled carbon nanotubes on electrodes at the tip of a biocompatible cantilever and use these for chemical species sensing in air and liquid, for example in order to measure the local activity from ion channels in the cell membrane....... The electrical resistance of carbon nanotubes has been shown to be extremely sensitive to gas molecules. Dielectrophoresis is a method capable of quickly attracting nanotubes on microelectrodes by using an electric field, thus enabling nanotube integration in microsystems. Dielectrophoresis offers also....... A model for the dielectrophoretic assembly of carbon nanotubes on microelectrodes was developed and several simulations were conducted using values from the available literature for the various key parameters. The model can give qualitative results regarding the parameters dominating the dielectrophoretic...

  8. Defined DNA-mediated assemblies of gene-expressing giant unilamellar vesicles

    DEFF Research Database (Denmark)

    Hadorn, M.; Boenzli, E.; Sørensen, Kristian T.

    2013-01-01

    The technological aspects of artificial vesicles as prominent cell mimics are evolving toward higher-order assemblies of functional vesicles with tissuelike architectures. Here, we demonstrate the spatially controlled DNA-directed bottom-up synthesis of complex microassemblies and macroassemblies...

  9. Spectroscopic imaging studies of nanoscale polarity and mass transport phenomena in self-assembled organic nanotubes.

    Science.gov (United States)

    Xu, Hao; Nagasaka, Shinobu; Kameta, Naohiro; Masuda, Mitsutoshi; Ito, Takashi; Higgins, Daniel A

    2017-08-02

    Synthetic organic nanotubes self-assembled from bolaamphiphile surfactants are now being explored for use as drug delivery vehicles. In this work, several factors important to their implementation in drug delivery are explored. All experiments are performed with the nanotubes immersed in ethanol. First, Nile Red (NR) and a hydroxylated Nile Red derivative (NR-OH) are loaded into the nanotubes and spectroscopic fluorescence imaging methods are used to determine the apparent dielectric constant of their local environment. Both are found in relatively nonpolar environments, with the NR-OH molecules preferring regions of relatively higher dielectric constant compared to NR. Unique two-color imaging fluorescence correlation spectroscopy (imaging FCS) measurements are then used along with the spectroscopic imaging results to deduce the dielectric properties of the environments sensed by mobile and immobile populations of probe molecules. The results reveal that mobile NR molecules pass through less polar regions, likely within the nanotube walls, while immobile NR molecules are found in more polar regions, possibly near the nanotube surfaces. In contrast, mobile and immobile NR-OH molecules are found to locate in environments of similar polarity. The imaging FCS results also provide quantitative data on the apparent diffusion coefficient for each dye. The mean diffusion coefficient for the NR dye was approximately two-fold larger than that of NR-OH. Slower diffusion by the latter could result from its additional hydrogen bonding interactions with polar triglycine, amine, and glucose moieties near the nanotube surfaces. The knowledge gained in these studies will allow for the development of nanotubes that are better engineered for applications in the controlled transport and release of uncharged, dipolar drug molecules.

  10. Ultrasound-responsive ultrathin multiblock copolyamide vesicles

    Science.gov (United States)

    Huang, Lei; Yu, Chunyang; Huang, Tong; Xu, Shuting; Bai, Yongping; Zhou, Yongfeng

    2016-02-01

    This study reports the self-assembly of novel polymer vesicles from an amphiphilic multiblock copolyamide, and the vesicles show a special structure with an ultrathin wall thickness of about 4.5 nm and a combined bilayer and monolayer packing model. Most interestingly, the vesicles are ultrasound-responsive and can release the encapsulated model drugs in response to ultrasonic irradiation.This study reports the self-assembly of novel polymer vesicles from an amphiphilic multiblock copolyamide, and the vesicles show a special structure with an ultrathin wall thickness of about 4.5 nm and a combined bilayer and monolayer packing model. Most interestingly, the vesicles are ultrasound-responsive and can release the encapsulated model drugs in response to ultrasonic irradiation. Electronic supplementary information (ESI) available: Details of experiments and characterization, and FT-IR, TEM, DPD, FL and micro-DSC results. See DOI: 10.1039/c5nr08596a

  11. Exploring the properties and possibilities of self-assembling

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Castillo, Jaime

    2013-01-01

    structures ranging from piezo electricity over semi conductance to fluorescence. If such peptide nanotubes could be controlled and incorporated in sensors such as a biological field effect transistor it would greatly reduce the fabrication costs while at the same time providing researchers with new...... 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...... and illustrated their potential use as sensitive temperature sensor....

  12. 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 The redox activities of water-soluble iron(II) tetrasulfophthalocyanine (FeTSPc) and single-walled carbon nanotube-poly(m-aminobenzene sulfonic acid) (SWCNT-PABS) adsorbed on a gold surface precoated with a self-assembled monolayer (SAM) of 2...

  13. Polymer Vesicles as Robust Scaffolds for the Directed Assembly of Highly Crystalline Nanocrystals †

    KAUST Repository

    Wang, Mingfeng

    2009-12-15

    We report the incorporation of various inorganic nanoparticles (NPs) (PbS, LaOF, LaF3, and TiO2, each capped by oleic acid, and CdSe/ZnS core/shell QDs capped by trioctylphosphine oxide) into vesicles (d = 70-150 nm) formed by a sample of poly(styrene-b-acrylic acid) (PS4o4-b-PAA 62, where the subscripts refer to the degree of polymerization) in mixtures of tetrahydrofuran (THF), dioxane, and water. The block copolymer formed mixtures of crew-cut micelles and vesicles with some enhancement of the vesicle population when the NPs were present. The vesicle fraction could be isolated by selective sedimentation via centrifugation, followed by redispersion in water. The NPs appeared to be incorporated into the PAA layers on the internal and external walls of the vesicles (strongly favoring the former). NPs on the exterior surface of the vesicles could be removed completely by treating the samples with a solution of ethylenediaminetetraacetate (EDTA) in water. The triangular nanoplatelets of LaF3 behaved differently. Stacks of these platelets were incorporated into solid colloidal entities, similar in size to the empty vesicles that accompanied them, during the coassembly as water was added to the polymer/LaF3/THF/ dioxane mixture. © 2009 American Chemical Society.

  14. Self-assembled DNA Structures for Nanoconstruction

    Science.gov (United States)

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

    2004-09-01

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

  15. The structure of the COPII transport-vesicle coat assembled on membranes.

    Science.gov (United States)

    Zanetti, Giulia; Prinz, Simone; Daum, Sebastian; Meister, Annette; Schekman, Randy; Bacia, Kirsten; Briggs, John A G

    2013-09-17

    Coat protein complex II (COPII) mediates formation of the membrane vesicles that export newly synthesised proteins from the endoplasmic reticulum. The inner COPII proteins bind to cargo and membrane, linking them to the outer COPII components that form a cage around the vesicle. Regulated flexibility in coat architecture is essential for transport of a variety of differently sized cargoes, but structural data on the assembled coat has not been available. We have used cryo-electron tomography and subtomogram averaging to determine the structure of the complete, membrane-assembled COPII coat. We describe a novel arrangement of the outer coat and find that the inner coat can assemble into regular lattices. The data reveal how coat subunits interact with one another and with the membrane, suggesting how coordinated assembly of inner and outer coats can mediate and regulate packaging of vesicles ranging from small spheres to large tubular carriers. DOI:http://dx.doi.org/10.7554/eLife.00951.001.

  16. General Syntheses of Nanotubes Induced by Block Copolymer Self-Assembly

    DEFF Research Database (Denmark)

    Zhao, Jianming; Huang, Wei; Si, Pengchao

    2018-01-01

    Amphiphilic block copolymer templating strategies are extensively used for syntheses of mesoporous materials. However, monodisperse tubular nanostructures are limited. Here, a general method is developed to synthesize monodisperse nanotubes with narrow diameter distribution induced by self...

  17. Quantum-Chemical Insights into the Self-Assembly of Carbon-Based Supramolecular Complexes

    Directory of Open Access Journals (Sweden)

    Joaquín Calbo

    2018-01-01

    Full Text Available Understanding how molecular systems self-assemble to form well-organized superstructures governed by noncovalent interactions is essential in the field of supramolecular chemistry. In the nanoscience context, the self-assembly of different carbon-based nanoforms (fullerenes, carbon nanotubes and graphene with, in general, electron-donor molecular systems, has received increasing attention as a means of generating potential candidates for technological applications. In these carbon-based systems, a deep characterization of the supramolecular organization is crucial to establish an intimate relation between supramolecular structure and functionality. Detailed structural information on the self-assembly of these carbon-based nanoforms is however not always accessible from experimental techniques. In this regard, quantum chemistry has demonstrated to be key to gain a deep insight into the supramolecular organization of molecular systems of high interest. In this review, we intend to highlight the fundamental role that quantum-chemical calculations can play to understand the supramolecular self-assembly of carbon-based nanoforms through a limited selection of supramolecular assemblies involving fullerene, fullerene fragments, nanotubes and graphene with several electron-rich π-conjugated systems.

  18. Self-assembled nanogaps for molecular electronics.

    Science.gov (United States)

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

    2009-06-17

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

  19. Self-assembled nanogaps for molecular electronics

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  20. Interactions between citrate-capped gold nanoparticles and polymersomes

    Science.gov (United States)

    Zhang, Xiaohan; Lopez, Anand; Liu, Yibo; Wang, Feng; Liu, Juewen

    2018-06-01

    Polymersomes are vesicles formed by self-assembled amphiphilic block copolymers. Polymersomes generally have better stability than liposomes and they have been widely used in making drug delivery vehicles. In this work, the interaction between two types of polymersomes and citrate-capped gold nanoparticles (AuNPs) was studied. The following two polymers: poly(2-methyloxazoline-b-dimethylsiloxane-b-2-methyloxazoline) (called P1) and poly(butadiene-b-ethylene oxide) (called P2) were respectively used to form polymersomes. While P1 only formed spherical vesicle structures, worm-like structures were also observed with P2 as indicated by cryo-TEM. Both polymersomes adsorbed AuNPs leading to their subsequent aggregation. A lower polymersome concentration produced more obvious aggregation of AuNPs as judged from the color change. Capping AuNPs with glutathione inhibited adsorption of AuNPs. Considering the surface property of the polymers, the interaction with AuNPs was likely due to van der Waals forces. P1 polymersomes encapsulated calcein stably and AuNPs did not induce leakage. The P1/AuNP complex was more efficiently internalized by HeLa cells compared to free P1 polymersomes, further indicating a stable adsorption under cell culture conditions. In summary, this work indicates citrate-capped AuNPs form stable adsorption complexes with these polymersomes and their interactions have been explored.

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

    Science.gov (United States)

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

    2010-01-13

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

  2. Rectifying Properties of a Nitrogen/Boron-Doped Capped-Carbon-Nanotube-Based Molecular Junction

    International Nuclear Information System (INIS)

    Zhao Peng; Zhang Ying; Wang Pei-Ji; Zhang Zhong; Liu De-Sheng

    2011-01-01

    Based on the non-equilibrium Green's function method and first-principles density functional theory calculations, we investigate the electronic transport properties of a nitrogen/boron-doped capped-single-walled carbon-nanotube-based molecular junction. Obvious rectifying behavior is observed and it is strongly dependent on the doping site. The best rectifying performance can be carried out when the nitrogen/boron atom dopes at a carbon site in the second layer. Moreover, the rectifying performance can be further improved by adjusting the distance between the C 60 nanotube caps. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  3. Polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes

    DEFF Research Database (Denmark)

    Johansson, Alicia; Calleja, M.; Dimaki, Maria

    2004-01-01

    A polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes has been designed and realized. Multi-walled carbon nanotubes from aqueous solution have been assembled between two metal electrodes that are separated by 2 mu m and embedded in the polymer cantilever. The entire chip......, except for the metallic electrodes and wiring, was fabricated in the photoresist SU-8. SU-8 allows for an inexpensive, flexible and fast fabrication method, and the cantilever platform provides a hydrophobic surface that should be well suited for nanotube assembly. The device can be integrated in a micro...

  4. 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.

  5. High-Performance Lithium-Sulfur Batteries with a Self-Assembled Multiwall Carbon Nanotube Interlayer and a Robust Electrode-Electrolyte Interface.

    Science.gov (United States)

    Kim, Hee Min; Hwang, Jang-Yeon; Manthiram, Arumugam; Sun, Yang-Kook

    2016-01-13

    Elemental sulfur electrode has a huge advantage in terms of charge-storage capacity. However, the lack of electrical conductivity results in poor electrochemical utilization of sulfur and performance. This problem has been overcome to some extent previously by using a bare multiwall carbon nanotube (MWCNT) paper interlayer between the sulfur cathode and the polymeric separator, resulting in good electron transport and adsorption of dissolved polysulfides. To advance the interlayer concept further, we present here a self-assembled MWCNT interlayer fabricated by a facile, low-cost process. The Li-S cells fabricated with the self-assembled MWCNT interlayer and a high loading of 3 mg cm(-2) sulfur exhibit a first discharge specific capacity of 1112 mAh g(-1) at 0.1 C rate and retain 95.8% of the capacity at 0.5 C rate after 100 cycles as the self-assembled MWCNT interlayer facilitates good interfacial contact between the interlayer and the sulfur cathode and fast electron and lithium-ion transport while trapping and reutilizing the migrating polysulfides. The approach presented here has the potential to advance the commercialization feasibility of the Li-S batteries.

  6. 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. Keywords: Self-assembly, Gold electrode, Carbon nanotubes, Electrochemical detection, Mercury

  7. Supramolecular Self-Assembly of Histidine-Capped-Dialkoxy-Anthracene: A Visible Light Triggered Platform for facile siRNA Delivery

    KAUST Repository

    Patil, Sachin

    2016-06-29

    Supramolecular self-assembly of histidine-capped-dialkoxy-anthracene (HDA) results in the formation of light responsive nanostructures.Single-crystal X-ray diffraction analysis of HDA shows two types of hydrogen bonding. The first hydrogen bond is established between the imidazole moieties while the second involves the oxygen atom of one amide group and the hydrogen atom of a second amide group. When protonated in acidic aqueous media, HDA successfully complexes siRNA yielding spherical nanostructures. This biocompatible platform controllably delivers siRNA with high efficacy upon visible light irradiation leading up to 90% of gene silencing in live cells.

  8. Heterojunction nanowires having high activity and stability for the reduction of oxygen: Formation by self-assembly of iron phthalocyanine with single walled carbon nanotubes (FePc/SWNTs)

    KAUST Repository

    Zhu, Jia; Jia, Nana; Yang, Lijun; Su, Dong; Park, Jinseong; Choi, YongMan; Gong, Kuanping

    2014-01-01

    A self-assembly approach to preparing iron phthalocyanine/single-walled carbon nanotube (FePc/SWNT) heterojunction nanowires as a new oxygen reduction reaction (ORR) electrocatalyst has been developed by virtue of water-adjusted dispersing in 1

  9. Integrating DNA strand-displacement circuitry with DNA tile self-assembly

    Science.gov (United States)

    Zhang, David Yu; Hariadi, Rizal F.; Choi, Harry M.T.; Winfree, Erik

    2013-01-01

    DNA nanotechnology has emerged as a reliable and programmable way of controlling matter at the nanoscale through the specificity of Watson–Crick base pairing, allowing both complex self-assembled structures with nanometer precision and complex reaction networks implementing digital and analog behaviors. Here we show how two well-developed frameworks, DNA tile self-assembly and DNA strand-displacement circuits, can be systematically integrated to provide programmable kinetic control of self-assembly. We demonstrate the triggered and catalytic isothermal self-assembly of DNA nanotubes over 10 μm long from precursor DNA double-crossover tiles activated by an upstream DNA catalyst network. Integrating more sophisticated control circuits and tile systems could enable precise spatial and temporal organization of dynamic molecular structures. PMID:23756381

  10. Selective Metal-Ion-Mediated Vesicle Adhesion Based on Dynamic Self-Organization of a Pyrene-Appended Glutamic Acid.

    Science.gov (United States)

    Xing, Pengyao; Wang, Yajie; Yang, Minmin; Zhang, Yimeng; Wang, Bo; Hao, Aiyou

    2016-07-13

    Vesicles with dynamic membranes provide an ideal model system for investigating biological membrane activities, whereby vesicle aggregation behaviors including adhesion, fusion, fission, and membrane contraction/extension have attracted much attention. In this work we utilize an aromatic amino acid (pyrene-appended glutamic acid, PGlu) to prepare nanovesicles that aggregate to form vesicle clusters selectively induced by Fe(3+) or Cu(2+), and the vesicles transform into irregular nano-objects when interacting with Al(3+). Vesicle clusters have better stability than pristine vesicles, which hinders the spontaneous morphological transformation from vesicles into lamellar nanosheets with long incubation period. The difference between complexation of Fe(3+) and Al(3+) with vesicles was studied by various techniques. On the basis of metal ion-vesicle interactions, this self-assembled nanovesicle system also behaves as an effective fluorescent sensor for Fe(3+) and Al(3+), which cause fluorescence quenching and enhanced excimer emission, respectively.

  11. Layer-by-Layer Self-Assembling Gold Nanorods and Glucose Oxidase onto Carbon Nanotubes Functionalized Sol-Gel Matrix for an Amperometric Glucose Biosensor

    Directory of Open Access Journals (Sweden)

    Baoyan Wu

    2015-09-01

    Full Text Available A novel amperometric glucose biosensor was fabricated by layer-by-layer self-assembly of gold nanorods (AuNRs and glucose oxidase (GOD onto single-walled carbon nanotubes (SWCNTs-functionalized three-dimensional sol-gel matrix. A thiolated aqueous silica sol containing SWCNTs was first assembled on the surface of a cleaned Au electrode, and then the alternate self-assembly of AuNRs and GOD were repeated to assemble multilayer films of AuNRs-GOD onto SWCNTs-functionalized silica gel for optimizing the biosensor. Among the resulting glucose biosensors, the four layers of AuNRs-GOD-modified electrode showed the best performance. The sol-SWCNTs-(AuNRs- GOD4/Au biosensor exhibited a good linear range of 0.01–8 mM glucose, high sensitivity of 1.08 μA/mM, and fast amperometric response within 4 s. The good performance of the proposed glucose biosensor could be mainly attributed to the advantages of the three-dimensional sol-gel matrix and stereo self-assembly films, and the natural features of one-dimensional nanostructure SWCNTs and AuNRs. This study may provide a new facile way to fabricate the enzyme-based biosensor with high performance.

  12. Layer-by-Layer Self-Assembling Gold Nanorods and Glucose Oxidase onto Carbon Nanotubes Functionalized Sol-Gel Matrix for an Amperometric Glucose Biosensor.

    Science.gov (United States)

    Wu, Baoyan; Hou, Shihua; Miao, Zhiying; Zhang, Cong; Ji, Yanhong

    2015-09-18

    A novel amperometric glucose biosensor was fabricated by layer-by-layer self-assembly of gold nanorods (AuNRs) and glucose oxidase (GOD) onto single-walled carbon nanotubes (SWCNTs)-functionalized three-dimensional sol-gel matrix. A thiolated aqueous silica sol containing SWCNTs was first assembled on the surface of a cleaned Au electrode, and then the alternate self-assembly of AuNRs and GOD were repeated to assemble multilayer films of AuNRs-GOD onto SWCNTs-functionalized silica gel for optimizing the biosensor. Among the resulting glucose biosensors, the four layers of AuNRs-GOD-modified electrode showed the best performance. The sol-SWCNTs-(AuNRs- GOD)₄/Au biosensor exhibited a good linear range of 0.01-8 mM glucose, high sensitivity of 1.08 μA/mM, and fast amperometric response within 4 s. The good performance of the proposed glucose biosensor could be mainly attributed to the advantages of the three-dimensional sol-gel matrix and stereo self-assembly films, and the natural features of one-dimensional nanostructure SWCNTs and AuNRs. This study may provide a new facile way to fabricate the enzyme-based biosensor with high performance.

  13. New archetypes in self-assembled Phe-Phe motif induced nanostructures from nucleoside conjugated-diphenylalanines.

    Science.gov (United States)

    Datta, Dhrubajyoti; Tiwari, Omshanker; Ganesh, Krishna N

    2018-02-15

    During the last two decades, the molecular self-assembly of the short peptide diphenylalanine (Phe-Phe) motif has attracted increasing focus due to its unique morphological structure and utility for potential applications in biomaterial chemistry, sensors and bioelectronics. Due to the ease of their synthetic modifications and a plethora of available experimental tools, the self-assembly of free and protected diphenylalanine scaffolds (H-Phe-Phe-OH, Boc-Phe-Phe-OH and Boc-Phe-Phe-OMe) has unfurled interesting tubular, vesicular or fibrillar morphologies. Developing on this theme, here we attempt to examine the effect of structure and properties (hydrophobic and H-bonding) modifying the functional C-terminus conjugated substituents on Boc-Phe-Phe on its self-assembly process. The consequent self-sorting due to H-bonding, van der Waals force and π-π interactions, generates monodisperse nano-vesicles from these peptides characterized via their SEM, HRTEM, AFM pictures and DLS experiments. The stability of these vesicles to different external stimuli such as pH and temperature, encapsulation of fluorescent probes inside the vesicles and their release by external trigger are reported. The results point to a new direction in the study and applications of the Phe-Phe motif to rationally engineer new functional nano-architectures.

  14. Functionalization of Block Copolymer Vesicle Surfaces

    Directory of Open Access Journals (Sweden)

    Wolfgang Meier

    2011-01-01

    Full Text Available In dilute aqueous solutions certain amphiphilic block copolymers self-assemble into vesicles that enclose a small pool of water with a membrane. Such polymersomes have promising applications ranging from targeted drug-delivery devices, to biosensors, and nanoreactors. Interactions between block copolymer membranes and their surroundings are important factors that determine their potential biomedical applications. Such interactions are influenced predominantly by the membrane surface. We review methods to functionalize block copolymer vesicle surfaces by chemical means with ligands such as antibodies, adhesion moieties, enzymes, carbohydrates and fluorophores. Furthermore, surface-functionalization can be achieved by self-assembly of polymers that carry ligands at their chain ends or in their hydrophilic blocks. While this review focuses on the strategies to functionalize vesicle surfaces, the applications realized by, and envisioned for, such functional polymersomes are also highlighted.

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

    KAUST Repository

    Liu, Yijing

    2015-11-11

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

  16. Assembling the CMS yoke end-caps

    CERN Multimedia

    Laurent Guiraud

    2001-01-01

    A crane is used to piece together one of the end-caps that will provide the path for magnetic flux return on the CMS experiment. A total of six end-cap discs will be assembled before being positioned on the barrel yoke to complete the huge 12 500 tonne cylinder yoke. The magnetic field produced will be greater than any other solenoid created to date at 4 T, 100 000 times greater than the Earth's natural magnetic field, and will store enough energy to melt 18 tonnes of gold.

  17. Surface morphology and dewettability of self-organized thermosets involving epoxy and POSS-capped poly(ethylene oxide) telechelics

    International Nuclear Information System (INIS)

    Wang, Lei; Zheng, Sixun

    2012-01-01

    A heptaphenyl polyhedral oligomeric silsesquioxane-capped poly(ethylene oxide) (POSS-capped PEO) telechelics was synthesized via the Huisgen 1,3-dipolar cycloaddition between 3-azidopropylheptaphenyl POSS and α,ω-dialkynyl-terminated poly(ethylene oxide). The organic–inorganic amphiphile was incorporated into epoxy to obtain the organic–inorganic nanocomposites. The morphology of the nanocomposites was investigated by means of atomic force microscopy (AFM) and dynamic mechanical thermal analysis (DMTA). It was found that the epoxy thermosets containing POSS-capped PEO telechelics were microphase-separated. The formation of the nanophases in the thermosets followed a self-assembly mechanism. The static contact angle measurements show that the nanocomposites displayed a significant enhancement in surface hydrophobicity as well as reduction in surface free energy. The improvement in surface dewettability was ascribed to the enrichment of POSS cages at the surface of the nanocomposites and the formation of the specific surface morphology as evidenced by X-ray photoelectron spectroscopy (XPS) and surface atomic force microscopy (AFM). -- Highlights: ► POSS-capped PEO telechelics was synthesized via click chemistry approach. ► The organic–inorganic amphiphile can be self-assembled into the nanophases in epoxy. ► The hybrid nanocomposites were successfully prepared via a self-assembly approach. ► The nanocomposites displayed a significant enhancement in surface hydrophobicity.

  18. Self-assembly of palladium nanoparticles on functional TiO{sub 2} nanotubes for a nonenzymatic glucose sensor

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xianlan [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Li, Gang; Zhang, Guowei [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); Hou, Keyu [College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Pan, Haibo, E-mail: hbpan@fzu.edu.cn [College of Chemistry, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Du, Min [Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China)

    2016-05-01

    Polydiallyldimethylammonium chloride, PDDA, was used as a stabilizer and linker for functionalized TiO{sub 2} nanotubes (TiO{sub 2} NTs). Self-assembled process with palladium nanoparticles (NPs) was successfully synthesized and used for the oxidation of glucose on glassy carbon electrodes. Based on the voltammetric and amperometric results, Pd NPs efficiently catalyzed the oxidation of glucose at − 0.05 V in the presence of 0.1 M NaCl and showed excellent resistance toward interference poisoning from such interfering species as ascorbic acid, uric acid and urea. To further increase sensitivity, the Pd NPs-PDDA-TiO{sub 2} NTs/GCE was electrochemically treated with H{sub 2}SO{sub 4} and NaOH, the glucose oxidation current was magnified 2.5 times than that before pretreatments due to greatly enhancing the electron transport property of the sensor based on the increased defect sites and surface oxide species. In view of the physiological level of glucose, the wide linear concentration range of glucose (4 × 10{sup −7}–8 × 10{sup −4} M) with a detection limit of 8 × 10{sup −8} M (S/N = 3) was obviously good enough for clinical application. - Highlights: • PDDA was used as a stabilizer and linker for functionalized TiO{sub 2} nanotubes. • Self-assembled process with palladium nanoparticles was synthesized. • After treated both H{sub 2}SO{sub 4} and NaOH, the glucose response was magnified to 2.5 times. • The wide linear concentration range of glucose was obtained with a limit of 8 × 10{sup −8} M.

  19. Self-assembly of graphitic carbon nitride nanosheets–carbon nanotube composite for electrochemical simultaneous determination of catechol and hydroquinone

    International Nuclear Information System (INIS)

    Zhang, Hanqiang; Huang, Yihong; Hu, Shirong; Huang, Qitong; Wei, Chan; Zhang, Wuxiang; Yang, Weize; Dong, Peihui; Hao, Aiyou

    2015-01-01

    Graphical abstract: Schematic diagram of hydrothermal synthesis graphitic carbon nitride nanosheets-carbon nanotube composite and theirs application for electrochemical sensing catechol and hydroquinone. - Highlights: • Self-assembly of graphitic carbon nitride nanosheets-carbon nanotube composite. • CNNS-CNT show more stronger conductivity than CNNS and CNT. • CNNS-CNT has been performed for detection of catechol and hydroquinone. • The probe was applied to detect practical samples with satisfactory results. - Abstract: In this paper, three-dimensional (3D) graphitic carbon nitride nanosheets-carbon nanotube (CNNS-CNT) composite was synthesized via hydrothermal reaction of 2D CNNS and 1D CNT-COOH by π-π stacking and electrostatic interactions. This CNNS-CNT composite was characterized by transmission electron microscope, scanning electron microscope, x-ray diffraction and fourier-transform infrared. In addition, the CNNS-CNT composite displayed excellent conductivity comparing with CNNS and CNT-COOH monomer. This composite was applied for electrochemical simultaneous determination of catechol (CC) and hydroquinone (HQ) with good sensitivity, wide linear range and low detection limit. In addition, this CNNS-CNT composite modified electrode was also applied to detect practical samples with satisfactory results

  20. In silico assembly and nanomechanical characterization of carbon nanotube buckypaper

    International Nuclear Information System (INIS)

    Cranford, Steven W; Buehler, Markus J

    2010-01-01

    Carbon nanotube sheets or films, also known as 'buckypaper', have been proposed for use in actuating, structural and filtration systems, based in part on their unique and robust mechanical properties. Computational modeling of such a fibrous nanostructure is hindered by both the random arrangement of the constituent elements as well as the time- and length-scales accessible to atomistic level molecular dynamics modeling. Here we present a novel in silico assembly procedure based on a coarse-grain model of carbon nanotubes, used to attain a representative mesoscopic buckypaper model that circumvents the need for probabilistic approaches. By variation in assembly parameters, including the initial nanotube density and ratio of nanotube type (single- and double-walled), the porosity of the resulting buckypaper can be varied threefold, from approximately 0.3 to 0.9. Further, through simulation of nanoindentation, the Young's modulus is shown to be tunable through manipulation of nanotube type and density over a range of approximately 0.2-3.1 GPa, in good agreement with experimental findings of the modulus of assembled carbon nanotube films. In addition to carbon nanotubes, the coarse-grain model and assembly process can be adapted for other fibrous nanostructures such as electrospun polymeric composites, high performance nonwoven ballistic materials, or fibrous protein aggregates, facilitating the development and characterization of novel nanomaterials and composites as well as the analysis of biological materials such as protein fiber films and bulk structures.

  1. Long-range energy transfer in self-assembled quantum dot-DNA cascades

    Science.gov (United States)

    Goodman, Samuel M.; Siu, Albert; Singh, Vivek; Nagpal, Prashant

    2015-11-01

    The size-dependent energy bandgaps of semiconductor nanocrystals or quantum dots (QDs) can be utilized in converting broadband incident radiation efficiently into electric current by cascade energy transfer (ET) between layers of different sized quantum dots, followed by charge dissociation and transport in the bottom layer. Self-assembling such cascade structures with angstrom-scale spatial precision is important for building realistic devices, and DNA-based QD self-assembly can provide an important alternative. Here we show long-range Dexter energy transfer in QD-DNA self-assembled single constructs and ensemble devices. Using photoluminescence, scanning tunneling spectroscopy, current-sensing AFM measurements in single QD-DNA cascade constructs, and temperature-dependent ensemble devices using TiO2 nanotubes, we show that Dexter energy transfer, likely mediated by the exciton-shelves formed in these QD-DNA self-assembled structures, can be used for efficient transport of energy across QD-DNA thin films.The size-dependent energy bandgaps of semiconductor nanocrystals or quantum dots (QDs) can be utilized in converting broadband incident radiation efficiently into electric current by cascade energy transfer (ET) between layers of different sized quantum dots, followed by charge dissociation and transport in the bottom layer. Self-assembling such cascade structures with angstrom-scale spatial precision is important for building realistic devices, and DNA-based QD self-assembly can provide an important alternative. Here we show long-range Dexter energy transfer in QD-DNA self-assembled single constructs and ensemble devices. Using photoluminescence, scanning tunneling spectroscopy, current-sensing AFM measurements in single QD-DNA cascade constructs, and temperature-dependent ensemble devices using TiO2 nanotubes, we show that Dexter energy transfer, likely mediated by the exciton-shelves formed in these QD-DNA self-assembled structures, can be used for efficient

  2. Sugar-Decorated Sugar Vesicles : Lectin-Carbohydrate Recognition at the Surface of Cyclodextrin Vesicles

    NARCIS (Netherlands)

    Voskuhl, Jens; Stuart, Marc C. A.; Ravoo, Bart Jan

    2010-01-01

    An artificial glycocalix self-assembles when unilamellar bilayer vesicles of amphiphilic beta-cyclodextrins are decorated with maltose and lactose by host-guest interactions. To this end, maltose and lactose were conjugated with adamantane through a tetra(ethyleneglycol) spacer. Both

  3. Method of fabricating self-powered nuclear radiation detector assemblies

    International Nuclear Information System (INIS)

    Playfoot, K.; Bauer, R.F.; Sekella, Y.M.

    1982-01-01

    In a method of fabricating a self-powered nuclear radiation detector assembly an emitter electrode wire and signal cable center wire are connected and disposed within the collector electrode tubular sheath with compressible insulating means disposed between the wires and the tubular sheath. The above assembly is reduced in diameter while elongating the tubular sheath and the emitter wire and signal cable wire. The emitter wire is reduced to a predetermined desired diameter, and is trimmed to a predetermined length. An end cap is hermetically sealed to the tubular sheath at the extending end of the emitter with insulating means between the emitter end and the end cap. (author)

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

    Science.gov (United States)

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

    2012-02-01

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

  5. Bovine binder-of-sperm protein BSP1 promotes protrusion and nanotube formation from liposomes

    International Nuclear Information System (INIS)

    Lafleur, Michel; Courtemanche, Lesley; Karlsson, Goeran; Edwards, Katarina; Schwartz, Jean-Louis; Manjunath, Puttaswamy

    2010-01-01

    Research highlights: → Binder-of-sperm protein 1 (BSP1) modifies the morphology of lipidic vesicles inducing bead necklace-like and thread-like structures. → In the presence of multilamellar liposomes, BSP1 leads to the formation of long nanotubes. → The insertion of BSP1 in the external lipid leaflet of membranes induces local changes in bilayer curvature. -- Abstract: Binder-of-sperm (BSP) proteins interact with sperm membranes and are proposed to extract selectively phosphatidylcholine and cholesterol from these. This change in lipid composition is a key step in sperm capacitation. The present work demonstrates that the interactions between the protein BSP1 and model membranes composed with phosphatidylcholine lead to drastic changes in the morphology of the lipidic self-assemblies. Using cryo-electron microscopy and fluorescence microscopy, we show that, in the presence of the protein, the lipid vesicles elongate, and form bead necklace-like structures that evolve toward small vesicles or thread-like structures. In the presence of multilamellar vesicles, where a large reservoir of lipid is available, the presence of BSP proteins lead to the formation of long nanotubes. Long spiral-like threads, associated with lipid/protein complexes, are also observed. The local curvature of lipid membranes induced by the BSP proteins may be involved in lipid domain formation and the extraction of some lipids during the sperm maturation process.

  6. Flow-driven alignment of carbon nanotubes during floating evaporative self assembly

    Science.gov (United States)

    Berson, Arganthael; Jinkins, Katherine; Chan, Jason; Brady, Gerald; Gronski, Kjerstin; Gopalan, Padma; Evensen, Harold; Arnold, Michael

    2017-11-01

    Individual semi-conducting single-wall carbon nanotubes (s-SWCNTs) exhibit exceptional electronic properties, which makes them promising candidates for the next generation of semi-conductor electronics. In practice, field-effect transistors (FETs) are fabricated from arrays of s-SWCNTs deposited onto a substrate. In order to achieve high electronic performance, the s-SWCNTs in these arrays must be densely packed and well aligned. Floating Evaporative Self Assembly (FESA) is a new deposition technique developed at the UW-Madison that can achieve such high-quality s-SWCNT alignment. For example, it was used to fabricate the first s-SWCNT-based FETs to outperform gallium arsenide and silicon FETs. In FESA, a droplet of ink containing the s-SWCNTs is deposited onto a pool of water. The ink spreads on the water surface towards a substrate that is vertically pulled out of the water. A band of aligned s-SWCNTs is deposited with each drop of ink. High-speed imaging is combined with cross-polarized microscopy to elucidate the mechanisms behind the exceptional alignment of s-SWCNTs. Two key mechanisms are 1) the collection of s-SWCNTs at the ink-water interface and 2) the depinning of the air-ink-substrate contact line. Avenues for scaling up FESA will be presented.

  7. Nanotubes from Partially Hydrolysed α-Lactalbumin

    DEFF Research Database (Denmark)

    Geng, Xiaolu

    on the hydrolysis pattern. Increasing calcium level enhanced the effect of pH on self-assembly process, whereas the low level of a-La concentration (10 gL-1) was shown to limit the self-assembly. By tuning the rate of hydrolysis or self-assembly, via altering these three factors, one can control the formation of a......-La nanotubes and gels. In addition, by using small and wide angle X-ray scattering techniques, the structure of the a- La derived nanotubes was characterized. The results showed that the nanotubes formed under most of the conditions have a similar size with an outer diameter of 19 nm, inner diameter of 6.6 nm...

  8. Thermodynamics versus Kinetics Dichotomy in the Linear Self-Assembly of Mixed Nanoblocks.

    Science.gov (United States)

    Ruiz, L; Keten, S

    2014-06-05

    We report classical and replica exchange molecular dynamics simulations that establish the mechanisms underpinning the growth kinetics of a binary mix of nanorings that form striped nanotubes via self-assembly. A step-growth coalescence model captures the growth process of the nanotubes, which suggests that high aspect ratio nanostructures can grow by obeying the universal laws of self-similar coarsening, contrary to systems that grow through nucleation and elongation. Notably, striped patterns do not depend on specific growth mechanisms, but are governed by tempering conditions that control the likelihood of depropagation and fragmentation.

  9. Layer-by-layer self-assembling copper tetrasulfonated phthalocyanine on carbon nanotube modified glassy carbon electrode for electro-oxidation of 2-mercaptoethanol

    International Nuclear Information System (INIS)

    Shaik, Mahabul; Rao, V.K.; Gupta, Manish; Pandey, P.

    2012-01-01

    This paper describes the electrocatalytic activity of layer-by-layer self-assembled copper tetrasulfonated phthalocyanine (CuPcTS) on carbon nanotube (CNT)-modified glassy carbon (GC) electrode. CuPcTS is immobilized on the negatively charged CNT surface by alternatively assembling a cationic poly(diallyldimethylammonium chloride) (PDDA) layer and a CuPcTS layer. UV–vis absorption spectra and electrochemical measurements suggested the successive linear depositions of the bilayers of CuPcTs and PDDA on CNT. The surface morphology was observed using scanning electron microscopy. The viability of this CuPcTS/PDDA/CNT modified GC electrode as a redox mediator for the anodic oxidation and sensitive amperometric determination of 2-mercaptoethanol (2-ME) in alkaline conditions is described. The effect of number of bilayers of CuPcTS/PDDA and pH on electrochemical oxidation of 2-ME was studied. The proposed electrochemical sensor displayed excellent characteristics towards the determination of 2-ME in 0.1 M NaOH; such as low overpotentials (− 0.15 V vs Ag/AgCl), linear concentration range of 3 × 10 −5 M to 6 × 10 −3 M, and with a detection limit of 2.5 × 10 −5 M using simple amperometry. - Highlights: ► Carbon nanotubes (CNT) were drop-dried on glassy carbon electrode (GCE). ► Copper tetrasulfonated phthalocyanine (CuPcTS) was deposited on CNT/GCE. ► Layer-by-layer self-assembling method is used for depositing CuPcTS. ► Electrocatalytic oxidation of 2-mercaptoethanol (ME) was studied at this electrode ► The detection limit of ME at modified electrode was 25 μM by amperometry.

  10. Investigation of parameters controlling the dielectrophoretic assembly of carbon nanotubes on microelectrodes

    DEFF Research Database (Denmark)

    Dimaki, Maria; Bøggild, Peter

    2008-01-01

    Networks of single-walled carbon nanotubes were assembled onto microelectrodes by dielectrophoresis. The dependence of the obtained networks on several assembly parameters such as bias voltage, field application time, frequency, electrode geometry and the nanotube solvent were investigated both s...

  11. A Water-Soluble Cyclotriveratrylene-Based Supra-amphiphile: Synthesis, pH-Responsive Self-Assembly in Water, and Its Application in Controlled Drug Release.

    Science.gov (United States)

    Xia, Danyu; Li, Yang; Jie, Kecheng; Shi, Bingbing; Yao, Yong

    2016-06-17

    A new water-soluble cyclotriveratrylene (WCTV) was designed and synthesized, and benzyldimethyldodecylammonium chloride (G) was chosen as the guest molecule to construct a supra-amphiphile by the host-guest interaction between WCTV and G in water, which is pH responsive. The supra-amphiphiles self-assembled into vesicles in water. When the pH of the solution was below 7.0, the supra-amphiphile disassociated, and the vesicles collapsed. Then, the pH-responsive self-assembly system was utilized for controlled drug release.

  12. Fabrication of Propeller-Shaped Supra-amphiphile for Construction of Enzyme-Responsive Fluorescent Vesicles.

    Science.gov (United States)

    Li, Jie; Liu, Kaerdun; Han, Yuchun; Tang, Ben Zhong; Huang, Jianbin; Yan, Yun

    2016-10-04

    Propeller-shaped molecules have been recognized to display fantastic AIE (aggregation induced emission), but they can hardly self-assemble into nanostructures. Herein, we for the first time report that ionic complexation between a water-soluble tetrapheneyl derivative and an enzyme substrate in aqueous media produces a propeller-shaped supra-amphiphile that self-assembles into enzyme responsive fluorescent vesicles. The supra-amphiphile was fabricated upon complexation between a water-soluble propeller-shaped AIE luminogen TPE-BPA and myristoylcholine chloride (MChCl) in aqueous media. MChCl filled in the intramolecular voids of propeller-shaped TPE-BPA upon supra-amphiphile formation, which endows the supra-amphiphile superior self-assembling ability to the component molecules thus leading to the formation of fluorescent vesicles. Because MChCl is the substrate of cholinesterases, the vesicles dissemble in the presence of cholinesterases, and the fluorescent intensity can be correlated to the level of enzymes. The resulting fluorescent vesicles may be used to recognize the site of Alzheimer's disease, to encapsulate the enzyme inhibitor, and to release the inhibitor at the disease site.

  13. Self-Assembled CNT-Polymer Hybrids in Single-Walled Carbon Nanotubes Dispersed Aqueous Triblock Copolymer Solutions

    Science.gov (United States)

    Vijayaraghavan, D.; Manjunatha, A. S.; Poojitha, C. G.

    2018-04-01

    We have carried out scanning electron microscopy (SEM), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), electrical conductivity, and 1H NMR studies as a function of temperature on single-walled carbon nanotubes (SWCNTs) dispersed aqueous triblock copolymer (P123) solutions. The single-walled carbon nanotubes in this system aggregate to form bundles, and the bundles aggregate to form net-like structures. Depending on the temperature and phases of the polymer, this system exhibits three different self-assembled CNT-polymer hybrids. We find CNT-unimer hybrid at low temperatures, CNT-micelle hybrid at intermediate temperatures wherein the polymer micelles are adsorbed in the pores of the CNT nets, and another type of CNT-micelle hybrid at high temperatures wherein the polymer micelles are adsorbed on the surface of the CNT bundles. Our DSC thermogram showed two peaks related to these structural changes in the CNT-polymer hybrids. Temperature dependence of the 1H NMR chemical shifts of the molecular groups of the polymer and the AC electrical conductivity of the composite also showed discontinuous changes at the temperatures at which the CNT-polymer hybrid's structural changes are seen. Interestingly, for a higher CNT concentration (0.5 wt.%) in the system, the aggregated polymer micelles adsorbed on the CNTs exhibit cone-like and cube-like morphologies at the intermediate and at high temperatures respectively.

  14. Membrane Protrusion Coarsening and Nanotubulation within Giant Unilamellar Vesicles

    KAUST Repository

    Węgrzyn, Ilona

    2011-11-16

    Hydrophobic side groups on a stimuli-responsive polymer, encapsulated within a single giant unilamellar vesicle, enable membrane attachment during compartment formation at elevated temperatures. We thermally modulated the vesicle through implementation of an IR laser via an optical fiber, enabling localized directed heating. Polymer-membrane interactions were monitored using confocal imaging techniques as subsequent membrane protrusions occurred and lipid nanotubes formed in response to the polymer hydrogel contraction. These nanotubes, bridging the vesicle membrane to the contracting hydrogel, were retained on the surface of the polymer compartment, where they were transformed into smaller vesicles in a process reminiscent of cellular endocytosis. This development of a synthetic vesicle system containing a stimuli-responsive polymer could lead to a new platform for studying inter/intramembrane transport through lipid nanotubes. © 2011 American Chemical Society.

  15. 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.

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

    KAUST Repository

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

    2017-01-01

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

  17. Ordered patterns and structures via interfacial self-assembly: superlattices, honeycomb structures and coffee rings.

    Science.gov (United States)

    Ma, Hongmin; Hao, Jingcheng

    2011-11-01

    Self-assembly is now being intensively studied in chemistry, physics, biology, and materials engineering and has become an important "bottom-up" approach to create intriguing structures for different applications. Self-assembly is not only a practical approach for creating a variety of nanostructures, but also shows great superiority in building hierarchical structures with orders on different length scales. The early work in self-assembly focused on molecular self-assembly in bulk solution, including the resultant dye aggregates, liposomes, vesicles, liquid crystals, gels and so on. Interfacial self-assembly has been a great concern over the last two decades, largely because of the unique and ingenious roles of this method for constructing materials at interfaces, such as self-assembled monolayers, Langmuir-Blodgett films, and capsules. Nanocrystal superlattices, honeycomb films and coffee rings are intriguing structural materials with more complex features and can be prepared by interfacial self-assembly on different length scales. In this critical review, we outline the recent development in the preparation and application of colloidal nanocrystal superlattices, honeycomb-patterned macroporous structures by the breath figure method, and coffee-ring-like patterns (247 references). This journal is © The Royal Society of Chemistry 2011

  18. Self-assembled NiFe{sub 2}O{sub 4}/carbon nanotubes sponge for enhanced glucose biosensing application

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yingchun; Zhao, Minggang, E-mail: zhaomg@ouc.edu.cn; Chen, Jing; Fan, Sisi; Liang, Jingjing; Ding, Longjiang; Chen, Shougang, E-mail: sgchen@ouc.edu.cn

    2016-01-30

    Graphical abstract: - Highlights: • Self-assembled NiFe{sub 2}O{sub 4}/CNTs sponge was prepared by ice-templating method. • The mechanism of NiFe{sub 2}O{sub 4} modified CNTs relied on π-π interactions and static cling. • The porous structure made for GO{sub x} load, electrons transport and reactants diffusion. • Double catalysis and enhanced glucose sensing were achieved with elements Ni and Fe. - Abstract: In this work, self-assembled NiFe{sub 2}O{sub 4}/carbon nanotubes (CNTs) sponge was prepared by ice-templating method. The device synergized the advantageous features of both the 3D porous nanostructure and the catalytic properties of CNTs with GOx and NiFe{sub 2}O{sub 4} nanoparticles. The porous network construction of the NiFe{sub 2}O{sub 4}/CNTs sheets offered enlarged specific surface for GOx immobilization and opened channels for facilitating the electrons transport and reactants diffusion. With the help of the abnormal-valence elements Ni and Fe, double catalysis has happened and the enhanced glucose biosensing performance has been achieved. The fabricated glucose biosensor exhibited two large linear ranges (0–3.0 and 3.2–12.4 mM) and distinct sensitivities (84.1 and 24.6 μA mM{sup −1} cm{sup −2}).

  19. Self-assembled electrical materials from contorted aromatics

    Science.gov (United States)

    Xiao, Shengxiong

    This thesis describes the design, synthesis, self-assembly and electrical properties of new types of contorted polycyclic aromatic hydrocarbons. These topologically interesting contorted aromatics show promising transistor characteristics as new building blocks for organic field-effect transistors (OFETs) at different length scales. In chapter 2, a class of pentacenes that are substituted along their long edges with aromatic rings were synthesized. Their solid-state assemblies were studied by X-ray crystallography. Their performance as thin film transistors (TFTs) and single crystal field effect transistors (SCFETs) were systematically evaluated. A structure-property relationship between these highly phenylated pentacenes was found. Chapter 3 explores the new concept of whether a non-planar aromatic core could yield efficacious electronic materials, as the ultimate success in the organic electronics will require a holistic approach to creating new building blocks. Synthesis, functionalization and assembly of a new type of contorted hexabenzocoronene (HBC) whose aromatic core is heavily distorted away from planarity due to the steric congestion around its proximal carbons were discussed. Structural studies by X-ray crystallography showed that these HBC molecules stack into columnar structures in the solid state, which are ideal for conduction. Chapter 4 describes that microscale liquid crystalline thin film OFETs of tetradodecyloxy HBC showed the best transistor properties of all discotic columnar materials. Chapter 5 details the fabrication and characterization of nanoscale single crystalline fiber OFETs of octadodecyloxyl HBC. In Chapter 6 we show that a molecular scale monolayer of HBC acid chlorides could be self-assembled on SiO2 insulating layer and could be organized laterally between the ends of 2 nm carbon nanotube gaps to form high quality FETs that act as environmental and chemical sensors. Chapter 7 details the enforced one-dimensional photoconductivity

  20. Self-assembled three-dimensional hierarchical graphene/polypyrrole nanotube hybrid aerogel and its application for supercapacitors.

    Science.gov (United States)

    Ye, Shibing; Feng, Jiachun

    2014-06-25

    A three-dimensional hierarchical graphene/polypyrrole aerogel (GPA) has been fabricated using graphene oxide (GO) and already synthesized one-dimensional hollow polypyrrole nanotubes (PNTs) as the feedstock. The amphiphilic GO is helpful in effectively promoting the dispersion of well-defined PNTs to result in a stable, homogeneous GO/PNT complex solution, while the PNTs not only provide a large accessible surface area for fast transport of hydrate ions but also act as spacers to prevent the restacking of graphene sheets. By a simple one-step reduction self-assembly process, hierarchically structured, low-density, highly compressible GPAs are easily obtained, which favorably combine the advantages of graphene and PNTs. The supercapacitor electrodes based on such materials exhibit excellent electrochemical performance, including a high specific capacitance up to 253 F g(-1), good rate performance, and outstanding cycle stability. Moreover, this method may be feasible to prepare other graphene-based hybrid aerogels with structure-controllable nanostructures in large scale, thereby holding enormous potential in many application fields.

  1. Self-Assembly Carbon Nanotubes on Cantilever Biosensor for Sensitivity Enhancement

    Energy Technology Data Exchange (ETDEWEB)

    He, Johnny H [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); Sun Shaoqing [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); Ye Jianshan [Department of Biological Science, National University of Singapore, 14 Science Drive 4, Singapore 117543 (Singapore); Lim, T M [Department of Biological Science, National University of Singapore, 14 Science Drive 4, Singapore 117543 (Singapore)

    2006-04-01

    In recent years, highly sensitive and selective as well as cost-effective sensing and detection of biomolecules (e.g. virus, bacterial, DNA and protein) by MEMS/NEMS (Micro- /Nano Electro- Mechanical-System) structures have attracted extensive attention for its importance in clinical diagnostics, treatment, and various genome projects. Meanwhile, Substantial research efforts have been spent on the improvement of sensitivity of bioMEMS structures. Among a variety of methods that have been investigated, surface modification by nanoparticles (NPs) turns out to be an attractive way, which provides a platform for the enhancement of the sensitivity for biosensor devices. However, conventional applications for surface modification were mostly implemented on microelectrodes. Thus, in this paper, we demonstrate a new approach for surface enhancement on Au-coated silicon microcantilevers in micro-/nano-system. By self-assembly surface binding of multi-walled carbon nanotubes (MWCNTs) on the Au monolayer on top of the Si microcantilever surfaces, much larger surface area could be created for bio-molecular binding (such as antibodies or single DNA strands, which act as probes to capture target molecules). Therefore, this could enable specific interactions and selective binding to target biomolecules with a very low sample size, which greatly increases the sensitivity of detection. It should be noted that functionalization of MWCNTs with terminal carboxylic functionalities (in DCC solution) onto the Au surfaces of Si microchips have been introduced in our study. Further applications of MWCNTs functionalization are worth exploring in biomolecular detection for their exceptional mechanical and unique electronic properties. The successful binding of MWCNTs was testified as shown obviously on AFM image.

  2. Self-assembly of versatile tubular-like In2O3 nanostructures

    International Nuclear Information System (INIS)

    Zhong Miao; Zheng Maojun; Ma Li; Li Yanbo

    2007-01-01

    Versatile indium oxide tubular nanostructures (well-aligned nanotube arrays, flower-like tubular structures, and square nanotubes) were fabricated by a facile and reliable chemical vapor deposition (CVD) technique, taking advantage of the self-assembly property and substrate-induced epitaxial growth mechanism. The technique has a few advantages, such as low growth temperature, nonexistence of catalyst, template-free synthesis, direct bonding to the semiconductor substrates, etc. This strategy might extend the approach of synthesizing desirable nanostructures of other important low-melting metal oxides for potential applications

  3. Dynamic assembly of MinD on phospholipid vesicles regulated by ATP and MinE

    OpenAIRE

    Hu, Zonglin; Gogol, Edward P.; Lutkenhaus, Joe

    2002-01-01

    Selection of the division site in Escherichia coli is regulated by the min system and requires the rapid oscillation of MinD between the two halves of the cell under the control of MinE. In this study we have further investigated the molecular basis for this oscillation by examining the interaction of MinD with phospholipid vesicles. We found that MinD bound to phospholipid vesicles in the presence of ATP and, upon binding, assembled into a well-ordered helical array that deformed the vesicle...

  4. Programmable DNA tile self-assembly using a hierarchical sub-tile strategy.

    Science.gov (United States)

    Shi, Xiaolong; Lu, Wei; Wang, Zhiyu; Pan, Linqiang; Cui, Guangzhao; Xu, Jin; LaBean, Thomas H

    2014-02-21

    DNA tile based self-assembly provides a bottom-up approach to construct desired nanostructures. DNA tiles have been directly constructed from ssDNA and readily self-assembled into 2D lattices and 3D superstructures. However, for more complex lattice designs including algorithmic assemblies requiring larger tile sets, a more modular approach could prove useful. This paper reports a new DNA 'sub-tile' strategy to easily create whole families of programmable tiles. Here, we demonstrate the stability and flexibility of our sub-tile structures by constructing 3-, 4- and 6-arm DNA tiles that are subsequently assembled into 2D lattices and 3D nanotubes according to a hierarchical design. Assembly of sub-tiles, tiles, and superstructures was analyzed using polyacrylamide gel electrophoresis and atomic force microscopy. DNA tile self-assembly methods provide a bottom-up approach to create desired nanostructures; the sub-tile strategy adds a useful new layer to this technique. Complex units can be made from simple parts. The sub-tile approach enables the rapid redesign and prototyping of complex DNA tile sets and tiles with asymmetric designs.

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

    Science.gov (United States)

    Xing, Pengyao; Zhao, Yanli

    2016-09-01

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

  6. NMR derived model of GTPase effector domain (GED self association: relevance to dynamin assembly.

    Directory of Open Access Journals (Sweden)

    Swagata Chakraborty

    Full Text Available Self-association of dynamin to form spiral structures around lipidic vesicles during endocytosis is largely mediated by its 'coiled coil' GTPase Effector Domain (GED, which, in vitro, self-associates into huge helical assemblies. Residue-level structural characterizations of these assemblies and understanding the process of association have remained a challenge. It is also impossible to get folded monomers in the solution phase. In this context, we have developed here a strategy to probe the self-association of GED by first dissociating the assembly using Dimethyl Sulfoxide (DMSO and then systematically monitoring the refolding into helix and concomitant re-association using NMR spectroscopy, as DMSO concentration is progressively reduced. The short segment, Arg109 - Met116, acts as the nucleation site for helix formation and self-association. Hydrophobic and complementary charge interactions on the surfaces drive self-association, as the helices elongate in both the directions resulting in an antiparallel stack. A small N-terminal segment remains floppy in the assembly. Following these and other published results on inter-domain interactions, we have proposed a plausible mode of dynamin self assembly.

  7. Nano Cu interaction with single amino acid tyrosine derived self-assemblies; study through XRD, AFM, confocal Raman microscopy, SERS and DFT methods

    Science.gov (United States)

    Govindhan, Raman; Karthikeyan, Balakrishnan

    2017-12-01

    3,5-Bis(trifluoromethyl)benzylamine derivatives of single amino acid tyrosine produced self-assembled nanotubes (BTTNTs) as simple Phe-Phe. It has been observed that tyrosine derivative gives exclusively micro and nano tubes irrespective of the concentration of the precursor monomer. However, the introduced xenobiotic trifluoromethyl group (TFM) present in key backbone positionsof the self assembly gives the specific therapeutic function has been highlighted. Herein this work study of such self assembled nanotubes were studied through experimental and theoretical methods. The interaction of nanocopper cluster with the nanotubes (Cu@BTTNTs) were extensively studied by various methods like XRD, AFM, confocal Raman microscopy, SERS and theoretical methods like Mulliken's atomic charge analysis. SERS reveals that the interactions of Cu cluster with NH2, OH, NH and phenyl ring π-electrons system of BTTNTs. DFT studies gave the total dipole moment values of Cu@BTTNTs and explained the nature of interaction.

  8. 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

  9. The Self-Assembly of Nanogold for Optical Metamaterials

    Science.gov (United States)

    Nidetz, Robert A.

    2011-12-01

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

  10. Facile fabrication of polyaniline nanotubes using the self-assembly behavior based on the hydrogen bonding: a mechanistic study and application in high-performance electrochemical supercapacitor electrode

    International Nuclear Information System (INIS)

    Wu, Wenling; Pan, Duo; Li, Yanfeng; Zhao, Guanghui; Jing, Lingyun; Chen, Suli

    2015-01-01

    At present, the in situ synthesis of polyaniline (PANI) nanotubes via self-assembly of organic dopant acid is a particularly charming task in supercapacitors. Herein, we report the formation of uniform PANI nanotubes doped with malic acid (MA) and other organic acids, such as propionic acid (PA), succinic acid (SA), tartaric acid (TA) and citric acid (CA), which simultaneously acts as a dopant acid as well as a structure-directing agent. The morphology, structure and thermal stability of PANI nanotubes were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectra, Ultraviolet-visible spectra (UV–vis), X-ray diffraction (XRD), thermogravimetric analysis (TGA). Meanwhile, the electrochemical performance of the fabricated electrodes was evaluated by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). Furthermore, the PANI-MA and PANI-CA nanotubes, with [aniline]/[acid] molar ratio of 4:1, possessed highest specific capacitance of 658 F/g and 617 F/g at the current density of 0.1 A/g in 1.0 M H 2 SO 4 electrolyte due to their unique nanotubular structures. It makes PANI nanotubes a promising electrode material for high performance supercapacitors

  11. Facile Synthesis of Polyaniline Nanotubes Using Self-Assembly Method Based on the Hydrogen Bonding: Mechanism and Application in Gas Sensing

    Directory of Open Access Journals (Sweden)

    Changqing Yin

    2017-10-01

    Full Text Available Based on hydrogen bonding, the highly uniform polyaniline (PANI nanotubes were synthesized by self-assembly method using citric acid (CA as the dopant and the structure-directing agent by optimizing the molar ratio of CA to aniline monomer (Ani. Synthesis conditions like reaction temperature and mechanical stirring were considered to explore the effects of hydrogen bonding on the morphologies. The effects of CA on the final morphology of the products were also investigated. The as-synthesized CA doped polyaniline (PANI nanomaterials were further deposited on the plate electrodes for the test of gas sensing performance to ammonia (NH3. The sensitivity to various concentrations of NH3, the repeatability, and the stability of the sensors were also tested and analyzed. As a result, it was found that the PANI nanomaterial synthesized at the CA/Ani molar ratio of 0.5 has highly uniform tubular morphology and shows the best sensing performance to NH3. It makes the PANI nanotubes a promising material for high performance gas sensing to NH3.

  12. S-layer architectures : extending the morphogenetic potential of S-layer protein self-assembly

    International Nuclear Information System (INIS)

    Schuster, D.

    2013-01-01

    supporting substances for the fabrication of pure S-layer cages is very difficult. Providing a sufficient volume within lipid vesicles, giant unilamellar vesicles (GUVs) specifically coated with S-layer protein on the inside and/or on the outside could be fabricated. The use of carbon nanotubes as templates for S-layer recrystallization paved the way for the design of novel S-layer decorated tubular morphologies. The results of this project constitute a key enabling technology for the fabrication of nanoporous protein cages and fibers by exerting self-assembly strategies common in nature. Such nano containers can be used for the construction of artificial viruses, for controlled drug targeting and delivery, affinity matrices, and for the synthesis of spatially constrained nanoparticles (author) [de

  13. Tunneling nanotube (TNT)-mediated neuron-to neuron transfer of pathological Tau protein assemblies.

    Science.gov (United States)

    Tardivel, Meryem; Bégard, Séverine; Bousset, Luc; Dujardin, Simon; Coens, Audrey; Melki, Ronald; Buée, Luc; Colin, Morvane

    2016-11-04

    A given cell makes exchanges with its neighbors through a variety of means ranging from diffusible factors to vesicles. Cells use also tunneling nanotubes (TNTs), filamentous-actin-containing membranous structures that bridge and connect cells. First described in immune cells, TNTs facilitate HIV-1 transfer and are found in various cell types, including neurons. We show that the microtubule-associated protein Tau, a key player in Alzheimer's disease, is a bona fide constituent of TNTs. This is important because Tau appears beside filamentous actin and myosin 10 as a specific marker of these fine protrusions of membranes and cytosol that are difficult to visualize. Furthermore, we observed that exogenous Tau species increase the number of TNTs established between primary neurons, thereby facilitating the intercellular transfer of Tau fibrils. In conclusion, Tau may contribute to the formation and function of the highly dynamic TNTs that may be involved in the prion-like propagation of Tau assemblies.

  14. Conducting polymers, buckminsterfullerenes, and carbon nanotubes: optoelectronic materials based on architectural diversity of the π-conjugated structure

    International Nuclear Information System (INIS)

    Dai, L.

    2001-01-01

    Recent discovery of superconductivity in self assembled poly(3-hexylthiophene) two-dimensional conjugated sheets indicates the possible applications of plastics even in superconducting optoelectronic devices. Just as the discovery of C 60 has created an entirely new branch of carbon chemistry, the subsequent discovery of carbon nanotubes by lijima in 1991 opened up a new era in material science and nanotechnology. These elongated nanotubes consist of carbon hexagons arranged in a concentric manner with both ends normally capped by fullerene-like structures containing pentagons. Having a conjugated all-carbon structure with unusual molecular symmetries, fullerenes and carbon nanotubes also show interesting electronic, photonic, magnetic and mechanical properties, attractive for various applications, including optical limiters, photovoltaic cells and field emitting displays. For most of the above applications, it is highly desirable to prepare ordered/micropatterned conducting polymers, fullerenes, and carbon nanotubes. Although the microfabrication of conducting polymers has been an active research area for some years, it is a very recent development for fullerenes and carbon nanotubes. Recently, we doped polyaniline (PANI) with a hydrogensulfated fullerenol derivative containing multiple -OSO 3 H groups (i.e. C 60 (OH) 6 (OSO 3 H) 6 ) to produce three-dimensional PANI conductors with a room-temperature conductivity of up to 100 S cm -1 . This value of conductivity is about six orders of magnitude higher than the typical value for C 60 doped conducting polymers. Later, in collaboration with Wan's group at the Chinese Academy of Sciences, we have also synthesized PANI nanotubes via a self assembled C 60 (OH) 6 (OSO 3 H) 6 supramolecular template using (NH 4 ) 2 S 2 O 8 as an oxidant. These results, together with the more recent discovery of a hollow sphere, self assembled by the potassium salt of pentaphenyl fullerene (Ph 5 C 60 K) in water, clearly indicate that

  15. Programmable DNA tile self-assembly using a hierarchical sub-tile strategy

    International Nuclear Information System (INIS)

    Shi, Xiaolong; Lu, Wei; Wang, Zhiyu; Pan, Linqiang; Cui, Guangzhao; Xu, Jin; LaBean, Thomas H

    2014-01-01

    DNA tile based self-assembly provides a bottom-up approach to construct desired nanostructures. DNA tiles have been directly constructed from ssDNA and readily self-assembled into 2D lattices and 3D superstructures. However, for more complex lattice designs including algorithmic assemblies requiring larger tile sets, a more modular approach could prove useful. This paper reports a new DNA ‘sub-tile’ strategy to easily create whole families of programmable tiles. Here, we demonstrate the stability and flexibility of our sub-tile structures by constructing 3-, 4- and 6-arm DNA tiles that are subsequently assembled into 2D lattices and 3D nanotubes according to a hierarchical design. Assembly of sub-tiles, tiles, and superstructures was analyzed using polyacrylamide gel electrophoresis and atomic force microscopy. DNA tile self-assembly methods provide a bottom-up approach to create desired nanostructures; the sub-tile strategy adds a useful new layer to this technique. Complex units can be made from simple parts. The sub-tile approach enables the rapid redesign and prototyping of complex DNA tile sets and tiles with asymmetric designs. (paper)

  16. Self-assembled cellulose materials for biomedicine: A review.

    Science.gov (United States)

    Yang, Jisheng; Li, Jinfeng

    2018-02-01

    Cellulose-based materials have reached a growing interest for the improvement of biomedicine, due to their good biocompatibility, biodegradability, and low toxicity. Self-assembly is a spontaneous process by which organized structures with particular functions and properties could be obtained without additional complicated processing steps. This article describes the modifications, properties and applications of cellulose and its derivatives, which including a detailed review of representative types of solvents such as NMMO, DMAc/LiCl, some molten salt hydrates, some aqueous solutions of metal complexes, ionic liquids and NaOH-water system etc. The modifications were frequently performed by esterification, etherification, ATRP, RAFT, ROP and other novel methods. Stimuli-responsive cellulose-based materials, such as temperature-, pH-, light- and redox-responsive, were synthesized for their superior performance. Additionally, the applications of cellulose-based materials which can self-assemble into micelles, vesicles and other aggregates, for drug/gene delivery, bioimaging, biosensor, are also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Towards self-assembled devices, a carbon nanotube approach

    OpenAIRE

    Del Rio Castillo, Antonio Esau

    2012-01-01

    2010/2011 In the last decade the nanostructured carbon materials, especially single walled carbon nanotubes (SWNTs), had emerged as probable substitutes for Silicon in the next generation of electronic devices. This is due to their unique physic and chemical properties. Likewise, scientists all around the world have made a huge effort to introduce carbon materials into the market. Despite this effort, commercial application for carbon nanotubes in electronic devices has not yet been achiev...

  18. Y2O3:Yb/Er nanotubes: Layer-by-layer assembly on carbon-nanotube templates and their upconversion luminescence properties

    International Nuclear Information System (INIS)

    Huang, Weishi; Shen, Jianfeng; Wan, Lei; Chang, Yu; Ye, Mingxin

    2012-01-01

    Graphical abstract: Well-shaped Y 2 O 3 :Yb/Er nanotubes have been successfully synthesized on a large scale via layer-by-layer assembly on carbon nanotubes templates followed by a subsequent heat treatment process. The as-prepared Y 2 O 3 :Yb/Er nanotubes show a strong red emission corresponding to the 4 F 9/2 – 4 I 15/2 transition of the Er 3+ ions under excitation at 980 nm. Display Omitted Highlights: ► Well-shaped Y 2 O 3 :Yb/Er nanotubes have been successfully synthesized. ► CNTs were used as templates for Y 2 O 3 :Yb/Er nanotubes. ► LBL assembly and calcination were used for preparation of Y 2 O 3 :Yb/Er nanotubes. ► The as-prepared Y 2 O 3 :Yb/Er nanotubes show a strong red emission. -- Abstract: Well-shaped Y 2 O 3 :Yb/Er nanotubes have been successfully synthesized on a large scale via layer-by-layer (LBL) assembly on carbon nanotubes (CNTs) templates followed by a subsequent heat treatment process. The crystal structure, element analysis, morphology and upconversion luminescence properties were characterized. XRD results demonstrate that the diffraction peaks of the samples calcinated at 800 °C or above can be indexed to the pure cubic phase of Y 2 O 3 . SEM images indicate that a large quantity of uniform and rough nanotubes with diameters of about 30–60 nm can be observed. The as-prepared Y 2 O 3 :Yb/Er nanotubes show a strong red emission corresponding to the 4 F 9/2 – 4 I 15/2 transition of the Er 3+ ions under excitation at 980 nm, which have potential applications in such fields as nanoscale devices, molecular catalysts, nanobiotechnology, photonics and optoelectronics.

  19. Heterogeneous electron transfer kinetics and electrocatalytic behaviour of mixed self-assembled ferrocenes and SWCNT layers

    CSIR Research Space (South Africa)

    Nkosi, D

    2010-01-01

    Full Text Available The electron transfer dynamics and electrocatalytic behaviour of ferrocene-terminated self-assembled monolayers (SAMs), co-adsorbed with single-walled carbon nanotubes (SWCNTs) on a gold electrode, have been interrogated for the first time...

  20. Core microstructure, morphology and chain arrangement of block copolymer self-assemblies as investigated by thermal field-flow fractionation.

    Science.gov (United States)

    Muza, U L; Greyling, G; Pasch, H

    2018-05-28

    The self-assembly of block copolymers (BCPs), as a result of solvent selectivity for one block, has recently received significant attention due to novel applications of BCPs in pharmaceuticals, biomedicine, cosmetics, electronics and nanotechnology. The correlation of BCP microstructure and the structure of the resulting self-assemblies requires advanced analytical methods. However, traditional bulk characterization techniques are limited in the quest of providing detailed information regarding molar mass (M w ), hydrodynamic size (D h ), chemical composition, and morphology for these self-assemblies. In the present study, thermal field-flow fractionation (ThFFF) is utilised to investigate the impact of core microstructure on the resultant solution properties of vesicles prepared from polystyrene-polybutadiene block copolymers (PS-b-PBd) with 1.2- and 1.4-polybutadiene blocks, respectively. As compared to investigations on the impact of the corona microstructure, the impact of core microstructure on micellar properties has largely been neglected in previous work. In N,N-dimethylacetamide (DMAc) these BCPs form vesicles having PS shells and PBd cores. D h , M w , aggregation number, and critical micelle concentration of these micelles are shown to be sensitive to the core microstructure, therefore, demonstrating the potential of microstructural differences to be used for providing tuneable pathways to specific self-assemblies. It is shown that micelles prepared from BCPs of similar PS and PBd block sizes are successfully separated by ThFFF. It is further demonstrated in this study that PS-b-PBd vesicles and PS homopolymers of identical surface chemistry (PS) and comparable D h in DMAc, can be separated by ThFFF. Copyright © 2018. Published by Elsevier B.V.

  1. Electrostatic assembly of CTAB-capped silver nanoparticles along predefined λ-DNA template

    International Nuclear Information System (INIS)

    Wei Gang; Wang Li; Zhou Hualan; Liu Zhiguo; Song Yonghai; Li Zhuang

    2005-01-01

    Cetyltrimethylammonium bromide (CTAB)-capped positively-charged silver nanoparticles synthesized in water-ethanol system was electrostatic assembled on predefined aligned λ-DNA template. Silver nanowire can be obtained by changing the reaction time and the particles concentration. In our work, the length of the silver nanowire obtained is about 10 μm, and the dimension of the wires is about 20 nm. AFM data reveal that the assembly of CTAB-capped silver nanoparticles on DNA is ordered, but there is space between two particles absorbed on the DNA template. X-ray photoelectron spectroscopy (XPS) was applied to characterize the linear silver clusters, which provides an additional proof that the silver particles were assembled onto DNA template with fine order

  2. Facially amphiphilic thiol capped gold and silver nanoparticles

    Indian Academy of Sciences (India)

    Abstract. A series of bile acid-derived facially amphiphilic thiols have been used to cap sliver and gold nanoparticles. The self-assembling properties of these steroid-capped nanoparticles have been investigated and reported in this article.

  3. Controllable self-assembly of sodium caseinate with a zwitterionic vitamin-derived bolaamphiphile.

    Science.gov (United States)

    Sun, Li-Hui; Sun, Yu-Long; Yang, Li-Jun; Zhang, Jian; Chen, Zhong-Xiu

    2013-11-06

    The control of self-assembly of sodium caseinate (SC) including the formation of mixed layers, microspheres, or nanoparticles is highly relevant to the microstructure of food and the design of promising drug delivery systems. In this paper, we designed a structure-switchable zwitterionic bolaamphiphile, 1,12-diaminododecanediorotate (DDO), from orotic acid, which has special binding sites and can guide the self-assembly of SC. Complexation between SC and DDO was investigated using dynamic light scattering, transmission electron microscopy, differential scanning calorimetry, and fluorescence spectra measurements. Monomeric DDO was bound to the negatively charged sites on the SC micelle and made the structure of SC more compact with decreased electrostatic repulsion between the head groups. Vesicular DDO led to reassociation of vesicles with enlarged size via preferable hydrophobic interactions. Moreover, the aggregation between SC and DDO was found to be temperature-dependent and reversible. This research provides an effective way to control the reversible self-assembly of SC by the zwitterionic vitamin-derived bolaamphiphile.

  4. Glucosamine-Based Supramolecular Nanotubes for Human Mesenchymal Cell Therapy.

    Science.gov (United States)

    Talloj, Satish Kumar; Cheng, Bill; Weng, Jen-Po; Lin, Hsin-Chieh

    2018-04-23

    Herein, we demonstrate an example of glucosamine-based supramolecular hydrogels that can be used for human mesenchymal cell therapy. We designed and synthesized a series of amino acid derivatives based on a strategy of capping d-glucosamine moiety at the C-terminus and fluorinated benzyl group at the N-terminus. From a systematic study on chemical structures, we discovered that the glucosamine-based supramolecular hydrogel [pentafluorobenzyl (PFB)-F-Glu] self-assembled with one-dimensional nanotubular structures at physiological pH. The self-assembly of a newly discovered PFB-F-Glu motif is attributed to the synergistic effect of π-π stacking and extensive intermolecular hydrogen bonding network in aqueous medium. Notably, PFB-F-Glu nanotubes are proven to be nontoxic to human mesenchymal stem cells (hMSCs) and have been shown to enhance hMSC proliferation while maintaining their pluripotency. Retaining of pluripotency capabilities provides potentially unlimited source of undifferentiated cells for the treatment of future cell therapies. Furthermore, hMSCs cultured on PFB-F-Glu are able to secrete paracrine factors that downregulate profibrotic gene expression in lipopolysaccharide-treated human skin fibroblasts, which demonstrates that PFB-F-Glu nanotubes have the potential to be used for wound healing applications. Overall, this article addresses the importance of chemical design to generate supramolecular biomaterials for stem cell therapy.

  5. Self-assembly of virus-like particles of porcine circovirus type 2 capsid protein expressed from Escherichia coli

    Directory of Open Access Journals (Sweden)

    Cai Xuepeng

    2010-07-01

    Full Text Available Abstract Background Porcine circovirus 2 (PCV2 is a serious problem to the swine industry and can lead to significant negative impacts on profitability of pork production. Syndrome associated with PCV2 is known as porcine circovirus closely associated with post-weaning multisystemic wasting syndrome (PMWS. The capsid (Cap protein of PCV2 is a major candidate antigen for development of recombinant vaccine and serological diagnostic method. The recombinant Cap protein has the ability to self-assemble into virus-like particles (VLPs in vitro, it is particularly opportunity to develop the PV2 VLPs vaccine in Escherichia coli,(E.coli , because where the cost of the vaccine must be weighed against the value of the vaccinated pig, when it was to extend use the VLPs vaccine of PCV2. Results In this report, a highly soluble Cap-tag protein expressed in E.coli was constructed with a p-SMK expression vector with a fusion tag of small ubiquitin-like modifiers (SUMO. The recombinant Cap was purified using Ni2+ affinity resins, whereas the tag was used to remove the SUMO protease. Simultaneously, the whole native Cap protein was able to self-assemble into VLPs in vitro when viewed under an electron microscope. The Cap-like particles had a size and shape that resembled the authentic Cap. The result could also be applied in the large-scale production of VLPs of PCV2 and could be used as a diagnostic antigen or a potential VLP vaccine against PCV2 infection in pigs. Conclusion we have, for the first time, utilized the SUMO fusion motif to successfully express the entire authentic Cap protein of PCV2 in E. coli. After the cleavage of the fusion motif, the nCap protein has the ability to self-assemble into VLPs, which can be used as as a potential vaccine to protect pigs from PCV2-infection.

  6. Self-assembly of virus-like particles of porcine circovirus type 2 capsid protein expressed from Escherichia coli

    Science.gov (United States)

    2010-01-01

    Background Porcine circovirus 2 (PCV2) is a serious problem to the swine industry and can lead to significant negative impacts on profitability of pork production. Syndrome associated with PCV2 is known as porcine circovirus closely associated with post-weaning multisystemic wasting syndrome (PMWS). The capsid (Cap) protein of PCV2 is a major candidate antigen for development of recombinant vaccine and serological diagnostic method. The recombinant Cap protein has the ability to self-assemble into virus-like particles (VLPs) in vitro, it is particularly opportunity to develop the PV2 VLPs vaccine in Escherichia coli,(E.coli ), because where the cost of the vaccine must be weighed against the value of the vaccinated pig, when it was to extend use the VLPs vaccine of PCV2. Results In this report, a highly soluble Cap-tag protein expressed in E.coli was constructed with a p-SMK expression vector with a fusion tag of small ubiquitin-like modifiers (SUMO). The recombinant Cap was purified using Ni2+ affinity resins, whereas the tag was used to remove the SUMO protease. Simultaneously, the whole native Cap protein was able to self-assemble into VLPs in vitro when viewed under an electron microscope. The Cap-like particles had a size and shape that resembled the authentic Cap. The result could also be applied in the large-scale production of VLPs of PCV2 and could be used as a diagnostic antigen or a potential VLP vaccine against PCV2 infection in pigs. Conclusion we have, for the first time, utilized the SUMO fusion motif to successfully express the entire authentic Cap protein of PCV2 in E. coli. After the cleavage of the fusion motif, the nCap protein has the ability to self-assemble into VLPs, which can be used as as a potential vaccine to protect pigs from PCV2-infection. PMID:20646322

  7. Self-assembled three-dimensional and compressible interdigitated thin-film supercapacitors and batteries

    Science.gov (United States)

    Nyström, Gustav; Marais, Andrew; Karabulut, Erdem; Wågberg, Lars; Cui, Yi; Hamedi, Mahiar M.

    2015-01-01

    Traditional thin-film energy-storage devices consist of stacked layers of active films on two-dimensional substrates and do not exploit the third dimension. Fully three-dimensional thin-film devices would allow energy storage in bulk materials with arbitrary form factors and with mechanical properties unique to bulk materials such as compressibility. Here we show three-dimensional energy-storage devices based on layer-by-layer self-assembly of interdigitated thin films on the surface of an open-cell aerogel substrate. We demonstrate a reversibly compressible three-dimensional supercapacitor with carbon nanotube electrodes and a three-dimensional hybrid battery with a copper hexacyanoferrate ion intercalating cathode and a carbon nanotube anode. The three-dimensional supercapacitor shows stable operation over 400 cycles with a capacitance of 25 F g−1 and is fully functional even at compressions up to 75%. Our results demonstrate that layer-by-layer self-assembly inside aerogels is a rapid, precise and scalable route for building high-surface-area 3D thin-film devices. PMID:26021485

  8. Robust forests of vertically aligned carbon nanotubes chemically assembled on carbon substrates.

    Science.gov (United States)

    Garrett, David J; Flavel, Benjamin S; Shapter, Joseph G; Baronian, Keith H R; Downard, Alison J

    2010-02-02

    Forests of vertically aligned carbon nanotubes (VACNTs) have been chemically assembled on carbon surfaces. The structures show excellent stability over a wide potential range and are resistant to degradation from sonication in acid, base, and organic solvent. Acid-treated single-walled carbon nanotubes (SWCNTs) were assembled on amine-terminated tether layers covalently attached to pyrolyzed photoresist films. Tether layers were electrografted to the carbon substrate by reduction of the p-aminobenzenediazonium cation and oxidation of ethylenediamine. The amine-modified surfaces were incubated with cut SWCNTs in the presence of N,N'-dicyclohexylcarbodiimide (DCC), giving forests of vertically aligned carbon nanotubes (VACNTs). The SWCNT assemblies were characterized by scanning electron microscopy, atomic force microscopy, and electrochemistry. Under conditions where the tether layers slow electron transfer between solution-based redox probes and the underlying electrode, the assembly of VACNTs on the tether layer dramatically increases the electron-transfer rate at the surface. The grafting procedure, and hence the preparation of VACNTs, is applicable to a wide range of materials including metals and semiconductors.

  9. Carbon nanotube-templated assembly of regioregular poly(3-alkylthiophene) in solution

    Science.gov (United States)

    Zhu, Jiahua; Stevens, Eric; He, Youjun; Hong, Kunlun; Ivanov, Ilia

    2016-09-01

    Control of structural heterogeneity by rationally encoding of the molecular assemblies is a key enabling design of hierarchical, multifunctional materials of the future. Here we report the strategies to gain such control using solution- based assembly to construct a hybrid nano-assembly and a network hybrid structure of regioregular poly(3- alkylthiophene) - carbon nanotube (P3AT-CNT). The opto-electronic performance of conjugated polymer (P3AT) is defined by the structure of the aggregate in solution and in the solid film. Control of P3AT aggregation would allow formation of broad range of morphologies with very distinct electro-optical. We utilize interactive templating to confine the assembly behavior of conjugated polymers, replacing poorly controlled solution processing approach. Perfect crystalline surface of the single-walled and multi-walled carbon nanotube (SWCNT/MWCNT) acts as a template, seeding P3AT aggregation of the surface of the nanotube. The seed continues directional growth through pi-pi stacking leading to the formation of to well-defined P3AT-CNT morphologies, including comb-like nano-assemblies, super- structures and gel networks. Interconnected, highly-branched network structure of P3AT-CNT hybrids is of particular interest to enable efficient, long-range, balanced charge carrier transport. The structure and opto-electionic function of the intermediate assemblies and networks of P3AT/CNT hybrids are characterized by transmission election microscopy and UV-vis absorption.

  10. A facile self-assembly approach to prepare palladium/carbon nanotubes catalyst for the electro-oxidation of ethanol

    Science.gov (United States)

    Wen, Cuilian; Zhang, Xinyuan; Wei, Ying; Zhang, Teng; Chen, Changxin

    2018-02-01

    A facile self-assembly approach is reported to prepare palladium/carbon nanotubes (Pd/CNTs) catalyst for the electro-oxidation of ethanol. In this method, the Pd-oleate/CNTs was decomposed into the Pd/CNTs at an optimal temperature of 195 °C in air, in which no inert gas is needed for the thermal decomposition process due to the low temperature used and the decomposed products are also environmental friendly. The prepared Pd/CNTs catalyst has a high metallic Pd0 content and the Pd particles in the catalyst are disperse, uniform-sized with an average size of ˜2.1 nm, and evenly distributed on the CNTs. By employing our strategy, the problems including the exfoliation of the metal particles from the CNTs and the aggregation of the metal particles can be solved. Comparing with the commercial Pd/C one, the prepared Pd/CNTs catalyst exhibits a much higher electrochemical activity and stability for the electro-oxidation of ethanol in the direct ethanol fuel cells.

  11. Mussel-Inspired Dopamine and Carbon Nanotube Leading to a Biocompatible Self-Rolling Conductive Hydrogel Film.

    Science.gov (United States)

    Jiang, Junzi; Huang, Yong; Wang, Yitian; Xu, Hui; Xing, Malcolm; Zhong, Wen

    2017-08-18

    We report a novel self-rolling, conductive, and biocompatible multiwall carbon nanotube (MWCNT)-dopamine-polyethylene glycol (PEG) hydrogel film. The gel can self-fold into a thin tube when it is transferred from a glass slide to an aqueous environment, regardless of the concentrations of the MWCNT. The film presents a highly organized pattern, which results from the self-assembly of hydrophilic dopamine and hydrophobic carbon nanotubes. By exploring the biomedical potential, we found that MWCNT-included rolled film is nontoxic and can promote cell growth. For further functional verification by qPCR (quantitative polymerase chain reaction), bone marrow derived mesenchymal cells present higher levels of osteogenic differentiations in response to a higher concentration of CNTs. The results suggest that the self-rolling, conductive CNT-dopamine-PEG hydrogel could have multiple potentials, including biomedical usage and as a conductive biosensor.

  12. 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 ...

  13. Janus cyclic peptide-polymer nanotubes

    Science.gov (United States)

    Danial, Maarten; My-Nhi Tran, Carmen; Young, Philip G.; Perrier, Sébastien; Jolliffe, Katrina A.

    2013-11-01

    Self-assembled nanotubular structures have numerous potential applications but these are limited by a lack of control over size and functionality. Controlling these features at the molecular level may allow realization of the potential of such structures. Here we report a new generation of self-assembled cyclic peptide-polymer nanotubes with dual functionality in the form of either a Janus or mixed polymeric corona. A ‘relay’ synthetic strategy is used to prepare nanotubes with a demixing or mixing polymeric corona. Nanotube structure is assessed in solution using 1H-1H nuclear Overhauser effect spectroscopy NMR, and in bulk using differential scanning calorimetry. The Janus nanotubes form artificial pores in model phospholipid bilayers. These molecules provide a viable pathway for the development of intriguing nanotubular structures with dual functionality via a demixing or a mixing polymeric corona and may provide new avenues for the creation of synthetic transmembrane protein channel mimics.

  14. Activated Carbon Fibers "Thickly Overgrown" by Ag Nanohair Through Self-Assembly and Rapid Thermal Annealing

    Science.gov (United States)

    Yan, Xuefeng; Xu, Sijun; Wang, Qiang; Fan, Xuerong

    2017-11-01

    Anisotropic nanomaterial-modified carbon fibers attract increasing attention because of their superior properties over traditional ones. In this study, activated carbon fibers (ACFs) "thickly overgrown" by Ag nanohair were prepared through self-assembly and rapid thermal annealing. Viscose fibers with well-dispersed silver nanoparticles (AgNPs) on surfaces were first prepared through self-assembly of hyperbranched poly(amino-amine) (HBPAA)-capped AgNPs on viscose surfaces. HBPAA endowed the AgNP surfaces with negative charges and abundant amino groups, allowing AgNPs to monodispersively self-assemble to fiber surfaces. Ag nanohair-grown ACFs were prepared by sequential pre-oxidation and carbonization. Because the carbonization furnace was open-ended, ACFs are immediately transferrable to the outside of the furnace. Therefore, the Ag liquid adsorbed by ACF pores squeezed out to form Ag nanowires through thermal contraction. FESEM characterization indicated that Ag nanohairs stood on ACF surface and grew from ACF caps. XPS and XRD characterization showed that Ag successfully assembled to fiber surfaces and retained its metallic state even after high-temperature carbonization. TG analysis suggested that Ag nanohair-grown ACFs maintained their excellent thermal stabilities. Finally, the fabricated ACFs showed excellent and durable antibacterial activities, and the developed method may provide a potential strategy for preparing metal nanowire-grown ACFs.

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

    Science.gov (United States)

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

    2018-04-18

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

  16. Sandwich morphology and superior dye-removal performances for nanofiltration membranes self-assemblied via graphene oxide and carbon nanotubes

    Science.gov (United States)

    Kang, Hui; Shi, Jie; Liu, Liyan; Shan, Mingjing; Xu, Zhiwei; Li, Nan; Li, Jing; Lv, Hanming; Qian, Xiaoming; Zhao, Lihuan

    2018-01-01

    To tune interlayer spacing, regulate water channel and improve stability of composite membrane, graphene oxide (GO) and oxidized carbon nanotubes (OCNTs) were assembled alternately to form sandwich morphology on a polyacrylonitrile substrate by layer-by-layer self-assembly technique. Polyelectrolyte played a part in cross-linking between GO and OCNTs. The effects about concentration ratio of GO and OCNTs on nanofiltration performance were investigated in detail. The composite membrane was used for dye rejection. When composite membrane with concentration ratio of GO and OCNTs was 10:1, water flux and rejection rate for methyl blue reached 21.71 L/(m2 h) and 99.3%, respectively. Meanwhile, this composite membrane had higher flux compared with reported literatures in which rejection also reached up to 99%. When concentration ratio of composite membranes about GO and OCNTs were 10:1 and 15:1, dye rejection for methyl blue remained 99.3% and 99.6% respectively after operating time of 50 h. Irreversible fouling ratio of composite membrane in a concentration ratio of 10:1 was only 4.4%, indicating that composite membrane had excellent antifouling performance for Bovine Serum Albumin. It was speculated that proper distribution of OCNTs in the sandwich morphology formed proper support points and water channels which benefited for a more stable performance.

  17. Theoretical properties of carbon nanotubes

    International Nuclear Information System (INIS)

    Palser, A.H.

    2000-01-01

    Carbon nanotubes are invariably terminated with hemi-fullerene caps. In order to investigate the effect of these caps on the electronic structure, a method is developed to enumerate every hemi-fullerene cap which is commensurate with a given nanotube body. This algorithm is then applied to nanotubes for which I + m ≤ 25. The results of this algorithm are then used to study the effects of caps with different symmetries on the electronic structure of metallic and semi-conducting nanotubes within the Hueckel model. It is found that caps can cause localised and resonance states, although the likelihood of localised states occurring in capped metallic nanotubes is shown to be small. In addition, caps induce a non-uniform charge distribution, in which negative charge tends to accumulate on pentagon vertices. The thesis ends by describing two new density matrix methods for performing linear-scaling electronic-structure calculations within the independent electron approximation. Example calculations demonstrate that these methods provide efficient and robust ways of performing linear-scaling calculations, either grand canonically (at a fixed chemical potential) or canonically (at a fixed electron count). (author)

  18. Selective growth of carbon nanotube on silicon substrates

    Institute of Scientific and Technical Information of China (English)

    ZOU Xiao-ping; H. ABE; T. SHIMIZU; A. ANDO; H. TOKUMOT; ZHU Shen-ming; ZHOU Hao-shen

    2006-01-01

    The carbon nanotube (CNT) growth of iron oxide-deposited trench-patterns and the locally-ordered CNT arrays on silicon substrate were achieved by simple thermal chemical vapor deposition(STCVD) of ethanol vapor. The CNTs were uniformly synthesized with good selectivity on trench-patterned silicon substrates. This fabrication process is compatible with currently used semiconductor-processing technologies,and the carbon-nanotube fabrication process can be widely applied for the development of electronic devices using carbon-nanotube field emitters as cold cathodes and can revolutionize the area of field-emitting electronic devices. The site-selective growth of CNT from an iron oxide nanoparticle catalyst patterned were also achieved by drying-mediated self-assembly technique. The present method offers a simple and cost-effective method to grow carbon nanotubes with self-assembled patterns.

  19. Self-inductance of chiral conducting nanotubes

    International Nuclear Information System (INIS)

    Miyamoto, Yoshiyuki; Rubio, Angel; Louie, Steven G.; Cohen, Marvin L.

    1998-01-01

    Chiral conductivity in nanotubes has recently been predicted theoretically. The realization and application of chiral conducting nanotubes can be of great interest from both fundamental and technological viewpoints. These chiral currents, if they are realized, can be detected by measuring the self-inductance. We have treated Maxwell's equations for chiral conducting nanotubes (nanocoils) and find that the self-inductance and the resistivity of nanocoils should depend on the frequency of the alternating current even when the capacitance of the nanocoils is not taken into account. This is in contrast to elementary treatment of ordinary coils. This fact is useful to distinguish nanocoils by electrical measurements

  20. Self-Assembly of Large-Scale Shape-Controlled DNA Nano-Structures

    Science.gov (United States)

    2014-12-16

    for single-molecule imaging. Nano Lett. 11, 657-660 (2011). 46. Dang, X. N. et at. Virus -templated self-assembled single-walled carbon nanotubes for...email: alik(a)rics.bwh.harvard edu). NATURE C0,M.MUN! CAT !0N5 14:2275 I DOI: 10.1038/ncomm53275 | wwwnature.com/naturecommunications 1 @ 2013 Macmillan...prevent non-specific binding between hydrogel and microtube, the inside surface of microtube was treated with a corona treater (BD-20AC from Electro

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-03-15

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

  2. Self-assembly behaviours of peptide-drug conjugates: influence of multiple factors on aggregate morphology and potential self-assembly mechanism

    Science.gov (United States)

    Fan, Qin; Ji, Yujie; Wang, Jingjing; Wu, Li; Li, Weidong; Chen, Rui; Chen, Zhipeng

    2018-04-01

    Peptide-drug conjugates (PDCs) as self-assembly prodrugs have the unique and specific features to build one-component nanomedicines. Supramolecular structure based on PDCs could form various morphologies ranging from nanotube, nanofibre, nanobelt to hydrogel. However, the assembly process of PDCs is too complex to predict or control. Herein, we investigated the effects of extrinsic factors on assembly morphology and the possible formation of nanostructures based on PDCs. To this end, we designed a PDC consisting of hydrophobic drug (S)-ketoprofen (Ket) and valine-glutamic acid dimeric repeats peptide (L-VEVE) to study their assembly behaviour. Our results showed that the critical assembly concentration of Ket-L-VEVE was 0.32 mM in water to form various nanostructures which experienced from micelle, nanorod, nanofibre to nanoribbon. The morphology was influenced by multiple factors including molecular design, assembly time, pH and hydrogen bond inhibitor. On the basis of experimental results, we speculated the possible assembly mechanism of Ket-L-VEVE. The π-π stacking interaction between Ket molecules could serve as an anchor, and hydrogen bonded-induced β-sheets and hydrophilic/hydrophobic balance between L-VEVE peptide play structure-directing role in forming filament-like or nanoribbon morphology. This work provides a new sight to rationally design and precisely control the nanostructure of PDCs based on aromatic fragment.

  3. Self Assembled Carbon Nanotube Enhanced Ultracapacitors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this NASA STTR program is to develop single wall carbon nanotube (SWCNT) based ultracapacitors for energy storage devices (ESD) application, using...

  4. Y{sub 2}O{sub 3}:Yb/Er nanotubes: Layer-by-layer assembly on carbon-nanotube templates and their upconversion luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Weishi; Shen, Jianfeng; Wan, Lei; Chang, Yu [Department of Materials Science, Fudan University, Shanghai 200433 (China); Ye, Mingxin, E-mail: mxye@fudan.edu.cn [Department of Materials Science, Fudan University, Shanghai 200433 (China); Center of Special Materials and Technology, Fudan University, Shanghai 200433 (China)

    2012-11-15

    Graphical abstract: Well-shaped Y{sub 2}O{sub 3}:Yb/Er nanotubes have been successfully synthesized on a large scale via layer-by-layer assembly on carbon nanotubes templates followed by a subsequent heat treatment process. The as-prepared Y{sub 2}O{sub 3}:Yb/Er nanotubes show a strong red emission corresponding to the {sup 4}F{sub 9/2}–{sup 4}I{sub 15/2} transition of the Er{sup 3+} ions under excitation at 980 nm. Display Omitted Highlights: ► Well-shaped Y{sub 2}O{sub 3}:Yb/Er nanotubes have been successfully synthesized. ► CNTs were used as templates for Y{sub 2}O{sub 3}:Yb/Er nanotubes. ► LBL assembly and calcination were used for preparation of Y{sub 2}O{sub 3}:Yb/Er nanotubes. ► The as-prepared Y{sub 2}O{sub 3}:Yb/Er nanotubes show a strong red emission. -- Abstract: Well-shaped Y{sub 2}O{sub 3}:Yb/Er nanotubes have been successfully synthesized on a large scale via layer-by-layer (LBL) assembly on carbon nanotubes (CNTs) templates followed by a subsequent heat treatment process. The crystal structure, element analysis, morphology and upconversion luminescence properties were characterized. XRD results demonstrate that the diffraction peaks of the samples calcinated at 800 °C or above can be indexed to the pure cubic phase of Y{sub 2}O{sub 3}. SEM images indicate that a large quantity of uniform and rough nanotubes with diameters of about 30–60 nm can be observed. The as-prepared Y{sub 2}O{sub 3}:Yb/Er nanotubes show a strong red emission corresponding to the {sup 4}F{sub 9/2}–{sup 4}I{sub 15/2} transition of the Er{sup 3+} ions under excitation at 980 nm, which have potential applications in such fields as nanoscale devices, molecular catalysts, nanobiotechnology, photonics and optoelectronics.

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

    Science.gov (United States)

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

    2018-02-01

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

  6. 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.

  7. Block copolymer self-assembly and co-assembly : shape function and application

    NARCIS (Netherlands)

    Li, F.

    2009-01-01

    Amphiphilic block copolymers can, in selective solvents such as water, assemble into various shapes and architectures. Among those, polymer vesicles, polymer micelles and polymer fibers are very popular structures in current nanotechnology. These objects each have their own particular properties and

  8. Stereochemistry in subcomponent self-assembly.

    Science.gov (United States)

    Castilla, Ana M; Ramsay, William J; Nitschke, Jonathan R

    2014-07-15

    incorporated in self-assembly reactions to control the stereochemistry of increasingly complex architectures. This strategy has also allowed exploration of the degree to which stereochemical information is propagated through tetrahedral frameworks cooperatively, leading to the observation of stereochemical coupling across more than 2 nm between metal stereocenters and the enantioselective synthesis of a face-capped tetrahedron containing no carbon stereocenters via a stereochemical memory effect. Several studies on the communication of stereochemistry between the configurationally flexible metal centers in tetrahedral metal-organic cages have shed light on the factors governing this process, allowing the synthesis of an asymmetric cage, obtained in racemic form, in which all symmetry elements have been broken. Finally, we discuss how stereochemical diversity leads to structural complexity in the structures prepared through subcomponent self-assembly. Initial use of octahedral metal templates with facial stereochemistry in subcomponent self-assembly, which predictably gave rise to structures of tetrahedral symmetry, was extended to meridional metal centers. These lower-symmetry linkages have allowed the assembly of a series of increasingly intricate 3D architectures of varying functionality. The knowledge gained from investigating different aspects of the stereochemistry of metal-templated assemblies thus not only leads to new means of structural control but also opens pathways toward functions such as stereoselective guest binding and transformation.

  9. Atomic-scale structure and formation of self-assembled In(Ga)As quantum rings

    NARCIS (Netherlands)

    Offermans, P.; Koenraad, P.M.; Wolter, J.H.; Granados, D.; Garcia, J.M.; Fomin, V.; Gladilin, V.N.; Devreese, J.T.

    2006-01-01

    The authors present an at.-scale anal. of the In distribution of self-assembled (In,Ga)As quantum rings (QRs), which are formed from InAs quantum dots by capping with a thin layer of GaAs and subsequent annealing. The size and shape of QRs as obsd. by cross-sectional scanning tunneling microscopy

  10. Functionalization and large scale assembly of carbon nanotubes

    OpenAIRE

    Majumder, Anindya

    2016-01-01

    Assembly of nanoparticles provides effective building blocks for physical, chemical and biological systems which have surprisingly collective intrinsic physical properties. One-dimensional nanomaterials are one of the most spectacular and promising candidates for technological application in the field of nanotechnology. Single-walled carbon nanotubes represent an anisotropic and perfectly one-dimensional group of nanomaterials with extraordinary electronic, mechanical, chemical and thermal pr...

  11. Layer-by-Layer Assembled Nanotubes as Biomimetic Nanoreactors for Calcium Carbonate Deposition.

    Science.gov (United States)

    He, Qiang; Möhwald, Helmuth; Li, Junbai

    2009-09-17

    Enzyme-loaded magnetic polyelectrolyte multilayer nanotubes prepared by layer-by-layer assembly combined with the porous template could be used as biomimetic nanoreactors. It is demonstrated that calcium carbonate can be biomimetically synthesized inside the cavities of the polyelectrolyte nanotubes by the catalysis of urease, and the size of the calcium carbonate precipitates was controlled by the cavity dimensions. The metastable structure of the calcium carbonate precipitates inside the nanotubes was protected by the outer shell of the polyelectrolyte multilayers. These features may allow polyelectrolyte nanotubes to be applied in the fields of nanomaterials synthesis, controlled release, and drug delivery. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. 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.

  13. Atomic-scale structure of self-assembled In(Ga)As quantum rings in GaAs

    NARCIS (Netherlands)

    Offermans, P.; Koenraad, P.M.; Wolter, J.H.; Granados, D.; Garcia, J.M.; Fomin, V.; Gladilin, V.N.; Devreese, J.T.

    2005-01-01

    We present an atomic-scale analysis of the indium distribution of self-assembled In(Ga)As quantum rings (QRs) which are formed from InAs quantum dots by capping with a thin layer of GaAs and subsequent annealing. We find that the size and shape of QRs as observed by cross-sectional scanning

  14. Layer-by-layer self-assembly in the development of electrochemical energy conversion and storage devices from fuel cells to supercapacitors.

    Science.gov (United States)

    Xiang, Yan; Lu, Shanfu; Jiang, San Ping

    2012-11-07

    As one of the most effective synthesis tools, layer-by-layer (LbL) self-assembly technology can provide a strong non-covalent integration and accurate assembly between homo- or hetero-phase compounds or oppositely charged polyelectrolytes, resulting in highly-ordered nanoscale structures or patterns with excellent functionalities and activities. It has been widely used in the developments of novel materials and nanostructures or patterns from nanotechnologies to medical fields. However, the application of LbL self-assembly in the development of highly efficient electrocatalysts, specific functionalized membranes for proton exchange membrane fuel cells (PEMFCs) and electrode materials for supercapacitors is a relatively new phenomenon. In this review, the application of LbL self-assembly in the development and synthesis of key materials of PEMFCs including polyelectrolyte multilayered proton-exchange membranes, methanol-blocking Nafion membranes, highly uniform and efficient Pt-based electrocatalysts, self-assembled polyelectrolyte functionalized carbon nanotubes (CNTs) and graphenes will be reviewed. The application of LbL self-assembly for the development of multilayer nanostructured materials for use in electrochemical supercapacitors will also be reviewed and discussed (250 references).

  15. Tunneling nanotube (TNT)-mediated neuron-to neuron transfer of pathological Tau protein assemblies

    OpenAIRE

    TARDIVEL , Meryem; Bégard , Séverine; Bousset , Luc; Dujardin , Simon; Coens , Audrey; Melki , Ronald; Buée , Luc; Colin , Morvane

    2016-01-01

    A given cell makes exchanges with its neighbors through a variety of means ranging from diffusible factors to vesicles. Cells use also tunneling nanotubes (TNTs), filamentous-actin-containing membranous structures that bridge and connect cells. First described in immune cells, TNTs facilitate HIV-1 transfer and are found in various cell types, including neurons. We show that the microtubule-associated protein Tau, a key player in Alzheimer?s disease, is a bona fide constituent of TNTs. This i...

  16. Synthesis, transfer printing, electrical and optical properties, and applications of materials composed of self-assembled, aligned single-walled carbon nanotubes

    Science.gov (United States)

    Pint, Cary L.

    Super growth of single-walled carbon nanotubes (SWNTs) has emerged as a unique method for synthesizing self-assembled, pristine, aligned SWNT materials composed of ultra-long (millimeter-long) nanotubes. This thesis focuses on novel routes of synthesizing such self-assembled SWNTs and the challenges that arise in integrating this material into next-generation applications. First of all, this work provides unique insight into growth termination of aligned SWNTs, emphasizing the mechanism that inhibits the growth of infinitely long nanotubes. Exhaustive real-time growth studies, combined with ex-situ and in-situ TEM characterization emphasizes that Ostwald ripening and subsurface diffusion of catalyst particles play a key role in growth termination. As a result, rational steps to solving this problem can enhance growth, and may ultimately lead to the meter or kilometer-long SWNTs that are necessary for a number of applications. In addition, other novel synthesis routes are discussed, such as the ability to form macroscopic fibrils of SWNTs, called "flying carpets" from 40 nm thick substrates, and the ability to achieve supergrowth of SWNTs that are controllably doped with nitrogen. In the latter case, molecular heterojunctions of doped and undoped sections in a single strand of ultralong SWNTs are demonstrated Secondly, as supergrowth is conducted on alumina coated SiO2 substrates, any applications will require that one can transfer the SWNTs to host surfaces with minimal processing. This work demonstrates a unique contact transfer route by which both patterned arrays of SWNTs, or homogenous SWNT carpets, can be transferred to any host surface. In the first case, the SWNTs are grown vertically aligned, and transferred in patterns of horizontally aligned SWNT. This transfer process relies on simple water-vapor etching of amorphous carbons at the catalyst following growth, and strong van der Waals adhesion of the high surface-area SWNT to host surfaces (gecko effect

  17. Lipids, lipid bilayers and vesicles as seen by neutrons

    International Nuclear Information System (INIS)

    Seto, Hideki

    2011-01-01

    Lipid molecules self-assemble into bilayers in water with their hydrocarbon chains facing inward due to their amphiphilic nature. The structural and dynamical properties of lipids and lipid bilayers have been studied by neutron scattering intensively. In this article, 3 topics are shown as typical examples. 1) a time-resolved small-angle neutron scattering on uni-lamellar vesicles composed of deuterated and protonated lipids to determine lipid kinetics, 2) small-angle neutron scattering to investigate spontaneous formation of nanopores on uni-lamellar vesicles, and 3) neutron spin echo study to determine bending modulus of lipid bilayers. (author)

  18. A redox-assisted supramolecular assembly of manganese oxide nanotube

    International Nuclear Information System (INIS)

    Tao Li; Sun Chenggao; Fan Meilian; Huang Caijuan; Wu Hailong; Chao Zisheng; Zhai Hesheng

    2006-01-01

    In this paper, we report the hydrothermal synthesis of manganese oxide nanotube from an aqueous medium of pH 7, using KMnO 4 and MnCl 2 as inorganic precursors, polyoxyethylene (10) nonyl phenyl ether (TX-10) a surfactant and acetaldehyde an additive. The characterization of X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and N 2 adsorption at 77 K (BET) reveals that the synthesized manganese oxide nanotube has a mesopore size of ca. 3.65 nm and a wall thickness of ca. 12 nm, with the wall being composed of microporous crystals of monoclinic manganite. The X-ray photoelectron spectroscopy (XPS) result demonstrates a decrease of the binding energy of the Mn 3+ in the manganese oxide nanotube, which may be related to both the nanotubular morphology and the crystalline pore wall. A mechanism of a redox-assisted supramolecular assembly, regulated by acetaldehyde, is postulated

  19. Quantitative Collection and Enzymatic Activity of Glucose Oxidase Nanotubes Fabricated by Templated Layer-by-Layer Assembly.

    Science.gov (United States)

    Zhang, Shouwei; Demoustier-Champagne, Sophie; Jonas, Alain M

    2015-08-10

    We report on the fabrication of enzyme nanotubes in nanoporous polycarbonate membranes via the layer-by-layer (LbL) alternate assembly of polyethylenimine (PEI) and glucose oxidase (GOX), followed by dissolution of the sacrificial template in CH2Cl2, collection, and final dispersion in water. An adjuvant-assisted filtration methodology is exploited to extract quantitatively the nanotubes without loss of activity and morphology. Different water-soluble CH2Cl2-insoluble adjuvants are tested for maximal enzyme activity and nanotube stability; whereas NaCl disrupts the tubes by screening electrostatic interactions, the high osmotic pressure created by fructose also contributes to loosening the nanotubular structures. These issues are solved when using neutral, high molar mass dextran. The enzymatic activity of intact free nanotubes in water is then quantitatively compared to membrane-embedded nanotubes, showing that the liberated nanotubes have a higher catalytic activity in proportion to their larger exposed surface. Our study thus discloses a robust and general methodology for the fabrication and quantitative collection of enzymatic nanotubes and shows that LbL assembly provides access to efficient enzyme carriers for use as catalytic swarming agents.

  20. Studies on the secretion of maize root-cap slime. Pt. 3

    International Nuclear Information System (INIS)

    Paull, R.E.; Jones, R.L.

    1975-01-01

    Autoradiography was used to localize the sites of incorporation of L-[ 3 H]fucose into root tips of maize (Zea mays L. cv. S.X. 17). By light microscopy, accumulation of label from [ 3 H]fucose could be seen in the peripheral cells of the root cap. Extraction of sections prepared by freeze-substitution showed that most of the label in the cytoplasm of peripheral root-cap cells is water-soluble whereas label associated with the wall is sodium-hydroxide-soluble. In the electron microscope, glutaraldehyde-fixed peripheral cells of maize root caps are characterized by the presence of numerous dictyosomes and vesicles. The distended dictyosome cisternae and vesicles have large deposits of silver after staining with periodic acid-silver methanamine. An accumulation of material similar to that found in dictyosomes and vesicles is observed between the cell membrane and wall in glutaraldehyde-formaldehyde-fixed tissue. At the electron-microscope level label in peripheral root cap cells incubated in [ 3 H]fucose for periods from 10 to 120 min was found primarily over dictyosomes and vesicles. In pulse-chase experiments label was chased from the diclyosomes and vesicles to the exterior of the cell in 20-30 min. Less than 19% of the label in pulse-chase experiments was associated with organelles other than dictyosomes vesicles. (orig.) [de

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  2. Preparation of FeS2 nanotube arrays based on layer-by-layer assembly and their photoelectrochemical properties

    International Nuclear Information System (INIS)

    Wang, Mudan; Xue, Dongpeng; Qin, Haiying; Zhang, Lei; Ling, Guoping; Liu, Jiabin; Fang, Youtong; Meng, Liang

    2016-01-01

    Graphical abstract: - Highlights: • Amorphous Fe 2 O 3 nanotube arrays are prepared via layer-by-layer assembly. • Pyrite FeS 2 nanotube arrays are obtained by sulfurizing Fe 2 O 3 nanotube arrays. • Various electrochemical properties are characterized. • A comparison between FeS 2 nanotube and nanoparticle films is conducted. • Nanotube arrays show enhanced corrosion resistance and photoresponse. - Abstract: Well-aligned one-dimensional iron pyrite FeS 2 nanotube arrays have been fabricated via layer-by-layer assembly technique on ZnO nanorod arrays in combination with subsequent sulfurization. The as-prepared products were confirmed to be pure phase pyrite FeS 2 with Fe/S ratio approaching 1/2. Typical nanotube structure was observed for the FeS 2 with average outer diameter of 150 ± 20 nm and wall thickness of 50 ± 5 nm. Comparisons of photoelectrochemical properties between FeS 2 nanotubes and FeS 2 nanoparticles were conducted. Tafel polarization curves and electrochemical impedance spectroscopy indicate that FeS 2 nanotubes possess high corrosion resistance and electrochemical stability. The J–V curves show that the photocurrent at 1.0 V for FeS 2 nanotubes is more than five times larger than that of FeS 2 nanoparticles, indicating enhanced photoresponse and rapid charge transfer performances of 1-D nanotube structure. The enhanced photoelectrochemical properties mainly benefit from the unique architecture features of nanotube array structure.

  3. Using Ag-embedded TiO{sub 2} nanotubes array as recyclable SERS substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Yunhan, E-mail: yhling@mail.tsinghua.edu.cn [Lab of Advanced Materials, School of Materials Science & Engineering, Tsinghua University, Beijing 100084 (China); Zhuo, Yuqing; Huang, Liang [Lab of Advanced Materials, School of Materials Science & Engineering, Tsinghua University, Beijing 100084 (China); Mao, Duolu [School of Physical and Electronic Information Engineering, Qinghai Nationalities University, Xining, Qinghai 810007 (China)

    2016-12-01

    Highlights: • Ag embedded nanoparticles inside nanotube have better SERS enhancement than surface cap. • Ag NPs reconstruction via self-migration with UV and humidity control. • Self-cleaning effects both on organic molecule photo-oxidation as well as Ag ions photo-reduction. - Abstract: A simple strategy for synthesizing Ag-loaded TiO{sub 2} nanotube film for use as multifunctional photocatalyst and recyclable surface-enhanced Raman scattering (SERS) substrate is introduced. Highly aligned TiO{sub 2} nanotube arrays (TNTA) prepared via electrochemical anodization were used as a 3D rough host for silver nanoparticles. Ag deposits were sputtered in a vacuum, and it was found that their morphologies were mainly influenced by the diameters of nanotubes and the UV irradiation induced aging process, especially the self-migration of silver along the tubular wall. SERS and the self-cleaning effect were observed using Rhodamine 6G (R6G) as the probe molecule. The results showed that narrow nanotube and silver nanoparticles embedment contributed significantly to both the phenomenal SERS and recyclability.

  4. Tuning the optical properties of carbon nanotube solutions using amphiphilic self-assembly

    Science.gov (United States)

    Arnold, Michael S.; Stupp, Samuel I.; Hersam, Mark C.

    2003-07-01

    Recently it has been shown that aqueous solutions of sodium dodecyl sulfate (SDS) encapsulated and polymer wrapped single-walled carbon nanotubes (SWNTs) fluoresce in the near infrared (NIR) in the regime of the E11 van Hove transitions for semiconducting SWNTs. For bundled SWNTs, fluorescence is observed to be quenched along with a shift and broadening of the absorbance spectrum. Here, we study two other commercially available surfactants, BRIJ-97 and Triton-X-100, by analysis of carbon nanotube fluorescence and absorptivity in the NIR. It is found that changing the surfactant alters the corresponding optical properties of the solubilized carbon nanotubes. The NIR absorbance spectra of BRIJ-97 and Triton-X-100 carbon nanotube solutions are also compared with the absorbance spectrum of NaCl destabilized SDS-SWNT solutions. By controlling the amount of NaCl added to an aqueous solution of SDS-SWNTs, the optical absorbance spectrum can be made to match that of BRIJ-97 and Triton-X-100 solutions. Lastly, a correlation is drawn between the amount of shift in the absorbance spectrum and the fluorescence intensity, independent of surfactant used. This shift and decrease in fluorescence intensity may be due to carbon nanotube bundling.

  5. Extracellular Vesicles, Tunneling Nanotubes, and Cellular Interplay: Synergies and Missing Links

    Science.gov (United States)

    Nawaz, Muhammad; Fatima, Farah

    2017-01-01

    The process of intercellular communication seems to have been a highly conserved evolutionary process. Higher eukaryotes use several means of intercellular communication to address both the changing physiological demands of the body and to fight against diseases. In recent years, there has been an increasing interest in understanding how cell-derived nanovesicles, known as extracellular vesicles (EVs), can function as normal paracrine mediators of intercellular communication, but can also elicit disease progression and may be used for innovative therapies. Over the last decade, a large body of evidence has accumulated to show that cells use cytoplasmic extensions comprising open-ended channels called tunneling nanotubes (TNTs) to connect cells at a long distance and facilitate the exchange of cytoplasmic material. TNTs are a different means of communication to classical gap junctions or cell fusions; since they are characterized by long distance bridging that transfers cytoplasmic organelles and intracellular vesicles between cells and represent the process of heteroplasmy. The role of EVs in cell communication is relatively well-understood, but how TNTs fit into this process is just emerging. The aim of this review is to describe the relationship between TNTs and EVs, and to discuss the synergies between these two crucial processes in the context of normal cellular cross-talk, physiological roles, modulation of immune responses, development of diseases, and their combinatory effects in tissue repair. At the present time this review appears to be the first summary of the implications of the overlapping roles of TNTs and EVs. We believe that a better appreciation of these parallel processes will improve our understanding on how these nanoscale conduits can be utilized as novel tools for targeted therapies. PMID:28770210

  6. From self-organization to self-assembly: a new materialism?

    Science.gov (United States)

    Vincent, Bernadette Bensaude

    2016-09-01

    While self-organization has been an integral part of academic discussions about the distinctive features of living organisms, at least since Immanuel Kant's Critique of Judgement, the term 'self-assembly' has only been used for a few decades as it became a hot research topic with the emergence of nanotechnology. Could it be considered as an attempt at reducing vital organization to a sort of assembly line of molecules? Considering the context of research on self-assembly I argue that the shift of attention from self-organization to self-assembly does not really challenge the boundary between chemistry and biology. Self-assembly was first and foremost investigated in an engineering context as a strategy for manufacturing without human intervention and did not raise new perspectives on the emergence of vital organization itself. However self-assembly implies metaphysical assumptions that this paper tries to disentangle. It first describes the emergence of self-assembly as a research field in the context of materials science and nanotechnology. The second section outlines the metaphysical implications and will emphasize a sharp contrast between the ontology underlying two practices of self-assembly developed under the umbrella of synthetic biology. And unexpectedly, we shall see that chemists are less on the reductionist side than most synthetic biologists. Finally, the third section ventures some reflections on the kind of design involved in self-assembly practices.

  7. Vesicles to concentrate iron in low-Iron media: An attempt to mimic marine siderophores

    Czech Academy of Sciences Publication Activity Database

    Bednárová, Lucie; Brandel, J.; d'Hardemare, A. d. M.; Bednár, J.; Serratrice, G.; Pierre, J. L.

    2008-01-01

    Roč. 14, č. 12 (2008), s. 3680-3686 ISSN 0947-6539 Institutional research plan: CEZ:AV0Z40550506 Keywords : iron * marine siderophore mimics * micelles * self-assembly * vesicles Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.454, year: 2008

  8. Polyaniline nanotubes and their dendrites doped with different naphthalene sulfonic acids

    International Nuclear Information System (INIS)

    Zhang Zhiming; Wei Zhixiang; Zhang Lijuan; Wan Meixiang

    2005-01-01

    Polyaniline (PANI) nanotubes (130-250 nm in average diameter) doped with α-naphthalene sulfonic acid (α-NSA), β-naphthalene sulfonic acid (β-NSA) and 1,5-naphthalene disulfonic acid were synthesized via a self-assembly process. It was found that the formation yield, morphology (hollow or solid), size, crystalline and electrical properties of the nanostructures are affected by the position and number of -SO 3 H groups attached to the naphthalene ring of NSA as well as the synthesis conditions. Moreover, these nanotubes aggregate to form a dendritic morphology when the polymerization is performed at a static state. The micelles composed of dopant or dopant/anilinium cations might act in a template-like fashion in forming self-assembled PANI nanotubes, which was further confirmed by X-ray diffraction measurements, while the aggregated morphology of the nanotubes might result from polymer chain interactions including π-π interactions, hydrogen and ionic bonds

  9. Direct visualization of efficient energy transfer in single oligo(p-phenylene vinylene) vesicles

    NARCIS (Netherlands)

    Hoeben, F.J.M.; Shklyarevskiy, I.O.; Pouderoijen, M.J.; Engelkamp, H.; Schenning, A.P.H.J.; Christianen, P.C.M.; Maan, J.C.; Meijer, E.W.

    2006-01-01

    Monitoring self-assembled objects: Optical studies and scanning confocal microscopy have been used to monitor intermolecular energy transfer (ENT) in mixed vesicles of donor/acceptor oligo(p-phenylene vinylene)s (OPVs) in water (see picture) over time. This probing of the ongoing exchange process

  10. Pathology Residents Comprise Inspection Team for a CAP Self-Inspection

    Directory of Open Access Journals (Sweden)

    Stacy G. Beal MD

    2017-03-01

    Full Text Available We report our experience at the University of Florida in which residents and fellows served as the inspection team for a College of American Pathologists (CAP self-inspection. We aimed to determine whether the CAP self-inspection could serve as a learning opportunity for pathology residents and fellows. To prepare for the inspection, we provided a series of 4 lunchtime seminars covering numerous laboratory management topics relating to inspections and laboratory quality. Preparation for the inspection began approximately 4 months prior to the date of the inspection. The intent was to simulate a CAP peer inspection, with the exception that the date was announced. The associate residency program director served as the team leader. All residents and fellows completed inspector training provided by CAP, and the team leader completed the team leader training. A 20 question pre- and posttest was administered; additionally, an anonymous survey was given after the inspection. The residents’ and fellows’ posttest scores were an average of 15% higher than on the pretest ( P < .01. The surveys as well as subjective comments were overwhelmingly positive. In conclusion, the resident’s and fellow’s experience as an inspector during a CAP self-inspection was a useful tool to learn accreditation and laboratory management.

  11. Surface-Engineered Nanocontainers Based on Molecular Self-Assembly and Their Release of Methenamine

    Directory of Open Access Journals (Sweden)

    Minghui Zhang

    2018-02-01

    Full Text Available The mixing of polymers and nanoparticles is opening pathways for engineering flexible composites that exhibit advantageous functional properties. To fabricate controllable assembling nanocomposites for efficiently encapsulating methenamine and releasing them on demand, we functionalized the surface of natural halloysite nanotubes (HNTs selectively with polymerizable gemini surfactant which has peculiar aggregation behavior, aiming at endowing the nanomaterials with self-assembly and stimulative responsiveness characteristics. The micromorphology, grafted components and functional groups were identified using transmission electron microscopy (TEM, thermogravimetric analysis (TGA, Fourier transform infrared (FTIR spectroscopy, and X-ray photoelectron spectroscopy (XPS. The created nanocomposites presented various characteristics of methenamine release with differences in the surface composition. It is particularly worth mentioning that the controlled release was more efficient with the increase of geminized monomer proportion, which is reasonably attributed to the fact that the amphiphilic geminized moieties with positive charge and obvious hydrophobic interactions interact with the outer and inner surface in different ways through fabricating polymeric shell as release stoppers at nanotube ends and forming polymer brush into the nanotube lumen for guest immobilization. Meanwhile, the nanocomposites present temperature and salinity responsive characteristics for the release of methenamine. The combination of HNTs with conjugated functional polymers will open pathways for engineering flexible composites which are promising for application in controlled release fields.

  12. Chemical reactions directed Peptide self-assembly.

    Science.gov (United States)

    Rasale, Dnyaneshwar B; Das, Apurba K

    2015-05-13

    Fabrication of self-assembled nanostructures is one of the important aspects in nanoscience and nanotechnology. The study of self-assembled soft materials remains an area of interest due to their potential applications in biomedicine. The versatile properties of soft materials can be tuned using a bottom up approach of small molecules. Peptide based self-assembly has significant impact in biology because of its unique features such as biocompatibility, straight peptide chain and the presence of different side chain functionality. These unique features explore peptides in various self-assembly process. In this review, we briefly introduce chemical reaction-mediated peptide self-assembly. Herein, we have emphasised enzymes, native chemical ligation and photochemical reactions in the exploration of peptide self-assembly.

  13. Large-area fluidic assembly of single-walled carbon nanotubes through dip-coating and directional evaporation

    Science.gov (United States)

    Kim, Pilnam; Kang, Tae June

    2017-12-01

    We present a simple and scalable fluidic-assembly approach, in which bundles of single-walled carbon nanotubes (SWCNTs) are selectively aligned and deposited by directionally controlled dip-coating and solvent evaporation processes. The patterned surface with alternating regions of hydrophobic polydimethyl siloxane (PDMS) (height 100 nm) strips and hydrophilic SiO2 substrate was withdrawn vertically at a constant speed ( 3 mm/min) from a solution bath containing SWCNTs ( 0.1 mg/ml), allowing for directional evaporation and subsequent selective deposition of nanotube bundles along the edges of horizontally aligned PDMS strips. In addition, the fluidic assembly was applied to fabricate a field effect transistor (FET) with highly oriented SWCNTs, which demonstrate significantly higher current density as well as high turn-off ratio (T/O ratio 100) as compared to that with randomly distributed carbon nanotube bundles (T/O ratio <10).

  14. Fabrication and characterization of CaP-coated nanotube arrays

    International Nuclear Information System (INIS)

    Kung, Kuan-Chen; Chen, Jia-Ling; Liu, Yen-Ting; Lee, Tzer-Min

    2015-01-01

    Modified anodization techniques have been shown to improve the biocompatibility of titanium. This study demonstrated the anodic formation of self-organized nanotube arrays on titanium from an electrolyte solution containing 1 M H 3 PO 4 and 1 wt% hydrofluoric acid (HF). Our aim was to investigate the effects of sputter-deposited CaP on nanotube arrays. SEM images revealed a surface with uniform morphology and an average pore diameter of 29 nm. XRD results indicated that the phase of the nanotube arrays was amorphous. Electron spectroscopy for chemical analysis (ESCA) confirmed that the nanotube arrays were coated with calcium and phosphorus. Cell culture experiments using human osteosarcoma (HOS) cells demonstrated that the CaP/nanotube arrays had a pronounced effect on initial cell attachment as well as on the number of cells at 1, 7, and 14 days. Compared to as-polished titanium, the CaP/nanotube arrays accelerated cell proliferation, attachment, and spreading. Our results demonstrate the pronounced effects of CaP/nanotube arrays on the biological responses of HOS cells. - Highlights: • Self-organized nanotube arrays were anodically formed on titanium. • Surfaces of nanotube arrays exhibited uniform morphology and pore size. • According to ESCA results, Ca and P were successfully coated on nanotube arrays. • CaP/nanotube arrays accelerated the attachment and spreading of cells. • CaP/nanotube arrays were shown to affect biological responses of cells

  15. Fabrication and characterization of CaP-coated nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Kuan-Chen; Chen, Jia-Ling [Institute of Oral Medicine, National Cheng Kung University, Tainan 701, Taiwan (China); Liu, Yen-Ting [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Lee, Tzer-Min, E-mail: tmlee@mail.ncku.edu.tw [Institute of Oral Medicine, National Cheng Kung University, Tainan 701, Taiwan (China); Medical Device Innovation Center, National Cheng Kung University, Tainan 701, Taiwan (China); School of Dentistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China)

    2015-03-01

    Modified anodization techniques have been shown to improve the biocompatibility of titanium. This study demonstrated the anodic formation of self-organized nanotube arrays on titanium from an electrolyte solution containing 1 M H{sub 3}PO{sub 4} and 1 wt% hydrofluoric acid (HF). Our aim was to investigate the effects of sputter-deposited CaP on nanotube arrays. SEM images revealed a surface with uniform morphology and an average pore diameter of 29 nm. XRD results indicated that the phase of the nanotube arrays was amorphous. Electron spectroscopy for chemical analysis (ESCA) confirmed that the nanotube arrays were coated with calcium and phosphorus. Cell culture experiments using human osteosarcoma (HOS) cells demonstrated that the CaP/nanotube arrays had a pronounced effect on initial cell attachment as well as on the number of cells at 1, 7, and 14 days. Compared to as-polished titanium, the CaP/nanotube arrays accelerated cell proliferation, attachment, and spreading. Our results demonstrate the pronounced effects of CaP/nanotube arrays on the biological responses of HOS cells. - Highlights: • Self-organized nanotube arrays were anodically formed on titanium. • Surfaces of nanotube arrays exhibited uniform morphology and pore size. • According to ESCA results, Ca and P were successfully coated on nanotube arrays. • CaP/nanotube arrays accelerated the attachment and spreading of cells. • CaP/nanotube arrays were shown to affect biological responses of cells.

  16. Self-Assembly of Mesoporous Nanotubes Assembled from Interwoven Ultrathin Birnessite-type MnO2 Nanosheets for Asymmetric Supercapacitors

    Science.gov (United States)

    Huang, Ming; Zhang, Yuxin; Li, Fei; Zhang, Lili; Ruoff, Rodney S.; Wen, Zhiyu; Liu, Qing

    2014-01-01

    Porous nanotubes comprised of MnO2 nanosheets were fabricated with a one-pot hydrothermal method using polycarbonate membrane as the template. The diameter and thickness of nanotubes can be controlled by choice of the membrane pore size and the chemistry. The porous MnO2 nanotubes were used as a supercapacitor electrode. The specific capacitance in a three-electrode system was 365 F g−1 at a current density of 0.25 A g−1 with capacitance retention of 90.4% after 3000 cycles. An asymmetric supercapacitor with porous MnO2 nanotubes as the positive electrode and activated graphene as the negative electrode yielded an energy density of 22.5 Wh kg−1 and a maximum power density of 146.2 kW kg−1; these values exceeded those reported for other MnO2 nanostructures. The supercapacitor performance was correlated with the hierarchical structure of the porous MnO2 nanotubes. PMID:24464344

  17. 4-N-pyridin-2-yl-benzamide nanotubes compatible with mouse stem cell and oral delivery in Drosophila

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Jhillu S; Das, Pragna P; Bag, Indira; Krishnan, Anita; Jagannadh, Bulusu; Mohapatra, Debendra K; Bhadra, Manika Pal [Division of Organic Chemistry-I, Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500007 (India); Lavanya, Madugula P; Bhadra, Utpal [Functional Genomics and Gene Silencing Group, Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007 (India)

    2010-04-16

    p-aminobenzoic acid (PABA), a structural moiety of many commercial drugs, is self-assembled with linker alkyl side chains to form tubular nanostructures. The tubes exhibited fluorescence either intrinsic or from fluorescent molecules embedded in the wall during self-assembly. Uptake and inter-cellular delivery of the conjugated nanotubes in human cancer cells and in mouse embryonic stem cells were demonstrated by fluorescence imaging and flow cytometry. Biocompatibility, cytotoxicity and clearance were monitored both ex vivo in mouse multipotent embryonic stem cells and in vivo in adult Drosophila. Accumulation of nanotubes had no adverse effects and abnormalities on stem cell morphology and proliferation rate. A distinct distribution of two separate nanotubes in various internal organs of Drosophila interprets that accumulation of nanomaterials might be interdependent on the side chain modifications and physiological settings of cell or tissue types. Unlike carbon nanomaterials, exposure of PABA nanotubes does not produce any hazards including locomotion defects and mortality of adult flies. Despite differential uptake and clearance from multiple live tissues, the use of self-assembled nanotubes can add new dimensions and scope to the development of dual-purpose oral carriers for the fulfilment of many biological promises.

  18. 4-N-pyridin-2-yl-benzamide nanotubes compatible with mouse stem cell and oral delivery in Drosophila

    International Nuclear Information System (INIS)

    Yadav, Jhillu S; Das, Pragna P; Bag, Indira; Krishnan, Anita; Jagannadh, Bulusu; Mohapatra, Debendra K; Bhadra, Manika Pal; Lavanya, Madugula P; Bhadra, Utpal

    2010-01-01

    p-aminobenzoic acid (PABA), a structural moiety of many commercial drugs, is self-assembled with linker alkyl side chains to form tubular nanostructures. The tubes exhibited fluorescence either intrinsic or from fluorescent molecules embedded in the wall during self-assembly. Uptake and inter-cellular delivery of the conjugated nanotubes in human cancer cells and in mouse embryonic stem cells were demonstrated by fluorescence imaging and flow cytometry. Biocompatibility, cytotoxicity and clearance were monitored both ex vivo in mouse multipotent embryonic stem cells and in vivo in adult Drosophila. Accumulation of nanotubes had no adverse effects and abnormalities on stem cell morphology and proliferation rate. A distinct distribution of two separate nanotubes in various internal organs of Drosophila interprets that accumulation of nanomaterials might be interdependent on the side chain modifications and physiological settings of cell or tissue types. Unlike carbon nanomaterials, exposure of PABA nanotubes does not produce any hazards including locomotion defects and mortality of adult flies. Despite differential uptake and clearance from multiple live tissues, the use of self-assembled nanotubes can add new dimensions and scope to the development of dual-purpose oral carriers for the fulfilment of many biological promises.

  19. Self-assembly behavior of pH- and thermosensitive amphiphilic triblock copolymers in solution: experimental studies and self-consistent field theory simulations.

    Science.gov (United States)

    Cai, Chunhua; Zhang, Liangshun; Lin, Jiaping; Wang, Liquan

    2008-10-09

    We investigated, both experimentally and theoretically, the self-assembly behaviors of pH- and thermosensitive poly(L-glutamic acid)- b-poly(propylene oxide)-b-poly(L-glutamic acid) (PLGA-b-PPO-b-PLGA) triblock copolymers in aqueous solution by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), circular dichroism (CD), and self-consistent field theory (SCFT) simulations. Vesicles were observed when the hydrophilic PLGA block length is shorter or the pH value of solution is lower. The vesicles were found to transform to spherical micelles when the PLGA block length increases or its conformation changes from helix to coil with increasing the pH value. In addition, increasing temperature gives rise to a decrease in the size of aggregates, which is related to the dehydration of the PPO segments at higher temperatures. The SCFT simulation results show that the vesicles transform to the spherical micelles with increasing the fraction or statistical length of A block in model ABA triblock copolymer, which corresponds to the increase in the PLGA length or its conformation change from helix to coil in experiments, respectively. The SCFT calculations also provide chain distribution information in the aggregates. On the basis of both experimental and SCFT results, the mechanism of the structure change of the PLGA- b-PPO- b-PLGA aggregates was proposed.

  20. A Capping Step During Automated Glycan Assembly Enables Access to Complex Glycans in High Yield.

    Science.gov (United States)

    Yu, Yang; Kononov, Andrew; Delbianco, Martina; Seeberger, Peter H

    2018-04-20

    The products of multi-step automated solid phase syntheses are purified after release from the resin. Capping of unreacted nucleophiles is commonplace in automated oligonucleotide synthesis to minimize accumulation of deletion sequences. To date, capping was not used routinely during automated glycan assembly (AGA) since previous capping protocols suffered from long reaction times and conditions incompatible with some protective groups. Here, a method using methanesulfonic acid and acetic anhydride for the fast and quantitative capping of hydroxyl groups that failed to be glycosylated is reported. Commonly used protective groups in AGA are stable under these capping conditions. The introduction of a capping step into the coupling cycle drastically improved overall yields by decreasing side-products and simplifying purification, while reducing building block consumption. To illustrate the method, the biologically important tetrasaccharide Lc4, as well as a 50-mer polymannoside were prepared. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Self-Assembly of Nanoclusters into Mono-, Few-, and Multilayered Sheets via Dipole-Induced Asymmetric van der Waals Attraction.

    Science.gov (United States)

    Wu, Zhennan; Liu, Jiale; Li, Yanchun; Cheng, Ziyi; Li, Tingting; Zhang, Hao; Lu, Zhongyuan; Yang, Bai

    2015-06-23

    Two-dimensional (2D) nanomaterials possessing regular layered structures and versatile chemical composition are highly expected in many applications. Despite the importance of van der Waals (vdW) attraction in constructing and maintaining layered structures, the origin of 2D anisotropy is not fully understood, yet. Here, we report the 2D self-assembly of ligand-capped Au15 nanoclusters into mono-, few-, and multilayered sheets in colloidal solution. Both the experimental results and computer simulation reveal that the 2D self-assembly is initiated by 1D dipolar attraction common in nanometer-sized objects. The dense 1D attachment of Au15 leads to a redistribution of the surface ligands, thus generating asymmetric vdW attraction. The deliberate control of the coordination of dipolar and vdW attraction further allows to manipulate the thickness and morphologies of 2D self-assembly architectures.

  2. Endocytic vesicle rupture is a conserved mechanism of cellular invasion by amyloid proteins.

    Science.gov (United States)

    Flavin, William P; Bousset, Luc; Green, Zachary C; Chu, Yaping; Skarpathiotis, Stratos; Chaney, Michael J; Kordower, Jeffrey H; Melki, Ronald; Campbell, Edward M

    2017-10-01

    Numerous pathological amyloid proteins spread from cell to cell during neurodegenerative disease, facilitating the propagation of cellular pathology and disease progression. Understanding the mechanism by which disease-associated amyloid protein assemblies enter target cells and induce cellular dysfunction is, therefore, key to understanding the progressive nature of such neurodegenerative diseases. In this study, we utilized an imaging-based assay to monitor the ability of disease-associated amyloid assemblies to rupture intracellular vesicles following endocytosis. We observe that the ability to induce vesicle rupture is a common feature of α-synuclein (α-syn) assemblies, as assemblies derived from WT or familial disease-associated mutant α-syn all exhibited the ability to induce vesicle rupture. Similarly, different conformational strains of WT α-syn assemblies, but not monomeric or oligomeric forms, efficiently induced vesicle rupture following endocytosis. The ability to induce vesicle rupture was not specific to α-syn, as amyloid assemblies of tau and huntingtin Exon1 with pathologic polyglutamine repeats also exhibited the ability to induce vesicle rupture. We also observe that vesicles ruptured by α-syn are positive for the autophagic marker LC3 and can accumulate and fuse into large, intracellular structures resembling Lewy bodies in vitro. Finally, we show that the same markers of vesicle rupture surround Lewy bodies in brain sections from PD patients. These data underscore the importance of this conserved endocytic vesicle rupture event as a damaging mechanism of cellular invasion by amyloid assemblies of multiple neurodegenerative disease-associated proteins, and suggest that proteinaceous inclusions such as Lewy bodies form as a consequence of continued fusion of autophagic vesicles in cells unable to degrade ruptured vesicles and their amyloid contents.

  3. Directed assembly of carbon nanotubes on soft substrates for use as a flexible biosensor array

    International Nuclear Information System (INIS)

    Koh, Juntae; Yang Lee, Byung; Kim, Tae Hyun; Lee, Joohyung; Hong, Seunghun; Yi, Mihye; Jhon, Young Min

    2008-01-01

    We have developed a method to selectively assemble and align carbon nanotubes (CNTs) on soft substrates for use as flexible biosensors. In this strategy, a thin oxide layer was deposited on soft substrates via low temperature plasma enhanced chemical vapor deposition, and a linker-free assembly process was applied on the oxide surface where the assembly of carbon nanotubes was guided by methyl-terminated molecular patterns on the oxide surface. The electrical characterization of the fabricated CNT devices exhibited a typical p-type gating effect and 1/f noise behavior. The bare oxide regions near CNTs were functionalized with glutamate oxidase to fabricate selective biosensors to detect two forms of glutamate substances existing in different situations: L-glutamic acid, a neurotransmitting material, and monosodium glutamate, a food additive.

  4. Self-Assembly of Infinite Structures

    Directory of Open Access Journals (Sweden)

    Scott M. Summers

    2009-06-01

    Full Text Available We review some recent results related to the self-assembly of infinite structures in the Tile Assembly Model. These results include impossibility results, as well as novel tile assembly systems in which shapes and patterns that represent various notions of computation self-assemble. Several open questions are also presented and motivated.

  5. 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

  6. 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 ...

  7. Self-assembly in monoelaidin aqueous dispersions: direct vesicles to cubosomes transition.

    Directory of Open Access Journals (Sweden)

    Anan Yaghmur

    Full Text Available In the present study, synchrotron small-angle X-ray scattering (SAXS and Cryo-TEM were used to characterize the temperature-induced structural transitions of monoelaidin (ME aqueous dispersion in the presence of the polymeric stabilizer F127. We prove that the direct transition from vesicles to cubosomes by heating this dispersion is possible. The obtained results were compared with the fully hydrated bulk ME phase.Our results indicate the formation of ME dispersion, which is less stable than that based on the congener monoolein (MO. In addition, the temperature-dependence behavior significantly differs from the fully hydrated bulk phase. SAXS findings indicate a direct L(alpha-V(2 internal transition in the dispersion. While the transition temperature is conserved in the dispersion, the formed cubosomes with internal Im3m symmetry clearly contain more water and this ordered interior is retained over a wider temperature range as compared to its fully hydrated bulk system. At 25 degrees C, Cryo-TEM observations reveal the formation of most likely closely packed onion-like vesicles. Above the lamellar to non-lamellar phase transition at 65 degrees C, flattened cubosomes with an internal nanostructure are observed. However, they have only arbitrary shapes and thus, their morphology is significantly different from that of the well-shaped analogous MO cubosome and hexosome particles.Our study reveals a direct liposomes-cubosomes transition in ME dispersion. The obtained results suggest that the polymeric stabilizer F127 especially plays a significant role in the membrane fusion processes. F127 incorporates in considerable amount into the internal nanostructure and leads to the formation of a highly swollen Im3m phase.

  8. Magnetism, structures and stabilities of cluster assembled TM@Si nanotubes (TM = Cr, Mn and Fe): a density functional study.

    Science.gov (United States)

    Dhaka, Kapil; Bandyopadhyay, Debashis

    2016-08-02

    The present study reports transition metal (TM = Cr, Mn and Fe) doped silicon nanotubes with tunable band structures and magnetic properties by careful selection of cluster assemblies as building blocks using the first-principles density functional theory. We found that the transition metal doping and in addition, the hydrogen termination process can stabilize the pure silicon nanoclusters or cluster assemblies and then it could be extended as magnetic nanotubes with finite magnetic moments. Study of the band structures and density of states (DOS) of different empty and TM doped nanotubes (Type 1 to Type 4) show that these nanotubes are useful as metals, semiconductors, semi-metals and half-metals. These designer magnetic materials could be useful in spintronics and magnetic devices of nanoscale order.

  9. Self-assembled nanomaterials for photoacoustic imaging

    Science.gov (United States)

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

    2016-01-01

    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.

  10. 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.

  11. 3D Programmable Micro Self Assembly

    National Research Council Canada - National Science Library

    Bohringer, Karl F; Parviz, Babak A; Klavins, Eric

    2005-01-01

    .... We have developed a "self assembly tool box" consisting of a range of methods for micro-scale self-assembly in 2D and 3D We have shown physical demonstrations of simple 3D self-assemblies which lead...

  12. 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

  13. Influence of solution pH on the electron transport of the self-assembled nanoarrays of single-walled carbon nanotube-cobalt tetra-aminophthalocyanine on gold electrodes: Electrocatalytic detection of epinephrine

    Energy Technology Data Exchange (ETDEWEB)

    Ozoemena, Kenneth I. [Chemistry Department, University of Pretoria, Pretoria 0002 (South Africa)], E-mail: kenneth.ozoemena@up.ac.za; Nkosi, Dudu; Pillay, Jeseelan [Chemistry Department, University of Pretoria, Pretoria 0002 (South Africa)

    2008-02-15

    This paper provides first evidence of the impact of solution pH on the heterogeneous electron transfer rate constants of self-assembled films of single-walled carbon nanotubes (SWCNT) and SWCNT integrated to cobalt(II)tetra-aminophthalocyanine (SWCNT-CoTAPc) by sequential self-assembly. Using cyclic voltammetry and electrochemical impedance spectroscopy, we proved that both SAMs exhibit notable differences in their response to different buffered solution pH, with and without the presence of redox probe, [Fe(CN){sub 6}]{sup 4-}/[Fe(CN){sub 6}]{sup 3-}. Surface pK{sub a} value for the Au-Cys-SWCNT-CoTAPc was estimated as ca. 7.8, compared to that of the Au-Cys-SWCNT of about 5.5. Interestingly, both redox-active SAMs gave similar analytical response for epinephrine, giving well-resolved square wave voltammograms, with linear concentration range up to 130 {mu}M, sensitivity of ca. 9.4 x 10{sup -3} AM{sup -1}, and limit of detection ca. 6 {mu}M. This analytical result implies that there is no detectable advantage of one of the SAMs over the other in the electrocatalytic detection of this neurotransmitter.

  14. Low-cost silver capped polystyrene nanotube arrays as super-hydrophobic substrates for SERS applications.

    Science.gov (United States)

    Lovera, Pierre; Creedon, Niamh; Alatawi, Hanan; Mitchell, Micki; Burke, Micheal; Quinn, Aidan J; O'Riordan, Alan

    2014-05-02

    In this paper, we describe the fabrication, simulation and characterization of dense arrays of freestanding silver capped polystyrene nanotubes, and demonstrate their suitability for surface enhanced Raman scattering (SERS) applications. Substrates are fabricated in a rapid, low-cost and scalable way by melt wetting of polystyrene (PS) in an anodized alumina (AAO) template, followed by silver evaporation. Scanning electron microscopy reveals that substrates are composed of a dense array of freestanding polystyrene nanotubes topped by silver nanocaps. SERS characterization of the substrates, employing a monolayer of 4-aminothiophenol (4-ABT) as a model molecule, exhibits an enhancement factor of ∼1.6 × 10(6), in agreement with 3D finite difference time domain simulations. Contact angle measurements of the substrates revealed super-hydrophobic properties, allowing pre-concentration of target analyte into a small volume. These super-hydrophobic properties of the samples are taken advantage of for sensitive detection of the organic pollutant crystal violet, with detection down to ∼400 ppt in a 2 μl aliquot demonstrated.

  15. Low-cost silver capped polystyrene nanotube arrays as super-hydrophobic substrates for SERS applications

    International Nuclear Information System (INIS)

    Lovera, Pierre; Creedon, Niamh; Alatawi, Hanan; Mitchell, Micki; Burke, Micheal; Quinn, Aidan J; O’Riordan, Alan

    2014-01-01

    In this paper, we describe the fabrication, simulation and characterization of dense arrays of freestanding silver capped polystyrene nanotubes, and demonstrate their suitability for surface enhanced Raman scattering (SERS) applications. Substrates are fabricated in a rapid, low-cost and scalable way by melt wetting of polystyrene (PS) in an anodized alumina (AAO) template, followed by silver evaporation. Scanning electron microscopy reveals that substrates are composed of a dense array of freestanding polystyrene nanotubes topped by silver nanocaps. SERS characterization of the substrates, employing a monolayer of 4-aminothiophenol (4-ABT) as a model molecule, exhibits an enhancement factor of ∼1.6 × 10 6 , in agreement with 3D finite difference time domain simulations. Contact angle measurements of the substrates revealed super-hydrophobic properties, allowing pre-concentration of target analyte into a small volume. These super-hydrophobic properties of the samples are taken advantage of for sensitive detection of the organic pollutant crystal violet, with detection down to ∼400 ppt in a 2 μl aliquot demonstrated. (paper)

  16. Structure-directing star-shaped block copolymers: supramolecular vesicles for the delivery of anticancer drugs.

    Science.gov (United States)

    Yang, Chuan; Liu, Shao Qiong; Venkataraman, Shrinivas; Gao, Shu Jun; Ke, Xiyu; Chia, Xin Tian; Hedrick, James L; Yang, Yi Yan

    2015-06-28

    Amphiphilic polycarbonate/PEG copolymer with a star-like architecture was designed to facilitate a unique supramolecular transformation of micelles to vesicles in aqueous solution for the efficient delivery of anticancer drugs. The star-shaped amphipilic block copolymer was synthesized by initiating the ring-opening polymerization of trimethylene carbonate (TMC) from methyl cholate through a combination of metal-free organo-catalytic living ring-opening polymerization and post-polymerization chain-end derivatization strategies. Subsequently, the self-assembly of the star-like polymer in aqueous solution into nanosized vesicles for anti-cancer drug delivery was studied. DOX was physically encapsulated into vesicles by dialysis and drug loading level was significant (22.5% in weight) for DOX. Importantly, DOX-loaded nanoparticles self-assembled from the star-like copolymer exhibited greater kinetic stability and higher DOX loading capacity than micelles prepared from cholesterol-initiated diblock analogue. The advantageous disparity is believed to be due to the transformation of micelles (diblock copolymer) to vesicles (star-like block copolymer) that possess greater core space for drug loading as well as the ability of such supramolecular structures to encapsulate DOX. DOX-loaded vesicles effectively inhibited the proliferation of 4T1, MDA-MB-231 and BT-474 cells, with IC50 values of 10, 1.5 and 1.0mg/L, respectively. DOX-loaded vesicles injected into 4T1 tumor-bearing mice exhibited enhanced accumulation in tumor tissue due to the enhanced permeation and retention (EPR) effect. Importantly, DOX-loaded vesicles demonstrated greater tumor growth inhibition than free DOX without causing significant body weight loss or cardiotoxicity. The unique ability of the star-like copolymer emanating from the methyl cholate core provided the requisite modification in the block copolymer interfacial curvature to generate vesicles of high loading capacity for DOX with significant

  17. Photoelectrochemical Properties of FeO Supported on TiO2-Based Thin Films Converted from Self-Assembled Hydrogen Titanate Nanotube Powders

    Directory of Open Access Journals (Sweden)

    Kyung-Jong Noh

    2012-01-01

    Full Text Available A photoanode was fabricated using hematite (α-Fe2O3 nanoparticles which had been held in a thin film of hydrogen titanate nanotubes (H-TiNT, synthesized by repetitive self-assembling method on FTO (fluorine-doped tin oxide glass, which were incorporated via dipping process in aqueous Fe(NO33 solution. Current voltage (I-V electrochemical properties of the photoanode heat-treated at 500°C for 10 min in air were evaluated under ultraviolet-visible light irradiation. Microstructure and crystallinity changes were also investigated. The prepared Fe2O3/H-TiNT/FTO composite thin film exhibited about threefold as much photocurrent as the Fe2O3/FTO film. The improvement in photocurrent was considered to be caused by reduced recombination of electrons and holes, with an appropriate amount of Fe2O3 spherical nanoparticles supported on the H-TiNT/FTO film. Nanosized spherical Fe2O3 particles with about 65 wt% on the H-TiNT/FTO film showed best performance in our study.

  18. Carbon nanotube based gecko inspired self-cleaning adhesives

    Science.gov (United States)

    Sethi, Sunny; Ge, Liehui; Ajayan, Pulickel; Ali, Dhinojwala

    2008-03-01

    Wall climbing organisms like geckos have unique ability to attach to different surfaces without use of any viscoelastic material. The hairy structure found in gecko feet allows them to obtain intimate contact over a large area thus allowing then to adhere using van der Waals interactions. Not only high adhesion, the geometry of the hairs makes gecko feet self cleaning, thus allowing them to walk continuously without worrying about loosing adhesive strength. Such properties if mimicked synthetically could form basis of a new class of materials, which, unlike conventional adhesives would show two contradictory properties, self cleaning and high adhesion. Such materials would form essential component of applications like wall climbing robot. We tried to synthesize such material using micropatterened vertically aligned carbon nanotubes. When dealing with large areas, probability of defects in the structure increase, forming patterns instead of using uniform film of carbon nanotubes helps to inhibit crack propagation, thus gives much higher adhesive strength than a uniform film. When carbon nanotube patterns with optimized aspect ratio are used, both high adhesion and self cleaning properties are observed.

  19. Preparation and characterization of highly water-soluble magnetic Fe{sub 3}O{sub 4} nanoparticles via surface double-layered self-assembly method of sodium alpha-olefin sulfonate

    Energy Technology Data Exchange (ETDEWEB)

    Li, Honghong; Qin, Li [School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Feng, Ying [Department of Bridge Engineering, Shanxi Railway Institute, Weinan 714000 (China); Hu, Lihua [School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Zhou, Chunhua, E-mail: chm_zhouch@ujn.edu.cn [School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

    2015-06-15

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

  20. Thermal expansion producing easier formation of a black phosphorus nanotube from nanoribbon on carbon nanotube

    Science.gov (United States)

    Cao, Jing; Cai, Kun

    2018-02-01

    As a novel one-dimensional material having excellent electrical properties, a black phosphorus (BP) nanotube has wide potential applications in nanodevices. A BP nanotube has not yet, however, been discovered in experiments or fabricated via chemical synthesis. In this study, the feasibility of forming a nanotube from a parallelogram nanoribbon upon a carbon nanotube (CNT) at different temperatures is discussed through the use of molecular dynamics simulations. Results obtained demonstrate that an ideal BP nanotube from the same nanoribbon can be obtained via self-assembly on a CNT at 50 K or lower temperature. At temperatures between 50-100 K, the BP nanotube formed from a single ribbon has defects at both ends. When the temperature is higher than 100 K, it is difficult to obtain a BP nanotube of high quality. It is discovered that when the ribbon can only wind upon the same CNT at low temperature, it may form into an ideal nanotube by increasing the temperature of the system. The reason is that the BP ribbon has a higher thermal expansion than the CNT under the same temperature difference.

  1. Self-Assembled PbSe Nanowire:Perovskite Hybrids

    KAUST Repository

    Yang, Zhenyu

    2015-12-02

    © 2015 American Chemical Society. Inorganic semiconductor nanowires are of interest in nano- and microscale photonic and electronic applications. Here we report the formation of PbSe nanowires based on directional quantum dot alignment and fusion regulated by hybrid organic-inorganic perovskite surface ligands. All material synthesis is carried out at mild temperatures. Passivation of PbSe quantum dots was achieved via a new perovskite ligand exchange. Subsequent in situ ammonium/amine substitution by butylamine enables quantum dots to be capped by butylammonium lead iodide, and this further drives the formation of a PbSe nanowire superlattice in a two-dimensional (2D) perovskite matrix. The average spacing between two adjacent nanowires agrees well with the thickness of single atomic layer of 2D perovskite, consistent with the formation of a new self-assembled semiconductor nanowire:perovskite heterocrystal hybrid.

  2. Self-Assembled PbSe Nanowire:Perovskite Hybrids

    KAUST Repository

    Yang, Zhenyu; Yassitepe, Emre; Voznyy, Oleksandr; Janmohamed, Alyf; Lan, Xinzheng; Levina, Larissa; Comin, Riccardo; Sargent, Edward H.

    2015-01-01

    © 2015 American Chemical Society. Inorganic semiconductor nanowires are of interest in nano- and microscale photonic and electronic applications. Here we report the formation of PbSe nanowires based on directional quantum dot alignment and fusion regulated by hybrid organic-inorganic perovskite surface ligands. All material synthesis is carried out at mild temperatures. Passivation of PbSe quantum dots was achieved via a new perovskite ligand exchange. Subsequent in situ ammonium/amine substitution by butylamine enables quantum dots to be capped by butylammonium lead iodide, and this further drives the formation of a PbSe nanowire superlattice in a two-dimensional (2D) perovskite matrix. The average spacing between two adjacent nanowires agrees well with the thickness of single atomic layer of 2D perovskite, consistent with the formation of a new self-assembled semiconductor nanowire:perovskite heterocrystal hybrid.

  3. Inverse Problem in Self-assembly

    Science.gov (United States)

    Tkachenko, Alexei

    2012-02-01

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

  4. Bola-amphiphile self-assembly

    DEFF Research Database (Denmark)

    Svaneborg, Carsten

    2012-01-01

    Bola-amphiphiles are rod-like molecules where both ends of the molecule likes contact with water, while the central part of the molecule dislikes contact with water. What do such molecules do when they are dissolved in water? They self-assemble into micelles. This is a Dissipartive particle...... dynamics simulation of this self-assembly behaviour....

  5. Synthesis and Characterization of Self-assembled polyaniline nanotubes/silica nanocomposites

    Czech Academy of Sciences Publication Activity Database

    Ciric-Marjanovic, G.; Dragičevic, L.; Milojevic, M.; Mojovic, M.; Mentus, S.; Dojčinovic, B.; Marjanovic, B.; Stejskal, Jaroslav

    2009-01-01

    Roč. 113, č. 20 (2009), s. 7116-7127 ISSN 1520-6106 R&D Projects: GA AV ČR IAA400500905 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyaniline * conducting polymer * nanotubes Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.471, year: 2009

  6. Lubrication synergy: Mixture of hyaluronan and dipalmitoylphosphatidylcholine (DPPC) vesicles

    DEFF Research Database (Denmark)

    Raj, Akanksha; Wang, Min; Zander, Thomas

    2017-01-01

    consisting of non-homogeneous phospholipid bilayer with hyaluronan/DPPC aggregates on top. The presence of these aggregates generates a long-range repulsive surface force as two such surfaces are brought together. However, the aggregates are easily deformed, partly rearranged into multilayer structures......Phospholipids and hyaluronan have been implied to fulfil important roles in synovial joint lubrication. Since both components are present in synovial fluid, self-assembly structures formed by them should also be present. We demonstrate by small angle X-ray scattering that hyaluronan associates...... with the outer shell of dipalmitoylphophatidylcholine (DPPC) vesicles in bulk solution. Further, we follow adsorption to silica from mixed hyaluronan/DPPC vesicle solution by Quartz Crystal Microbalance with Dissipation measurements. Atomic Force Microscope imaging visualises the adsorbed layer structure...

  7. Conducting carbonized polyaniline nanotubes

    International Nuclear Information System (INIS)

    Mentus, Slavko; Ciric-Marjanovic, Gordana; Trchova, Miroslava; Stejskal, Jaroslav

    2009-01-01

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min -1 up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 μm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 μm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm -1 , increased to 0.7 S cm -1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  8. Conducting carbonized polyaniline nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mentus, Slavko; Ciric-Marjanovic, Gordana [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade (Serbia); Trchova, Miroslava; Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Square 2, 162 06 Prague 6 (Czech Republic)], E-mail: gordana@ffh.bg.ac.rs

    2009-06-17

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min{sup -1} up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 {mu}m, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 {mu}m, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm{sup -1}, increased to 0.7 S cm{sup -1} upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  9. In-situ observations of catalyst dynamics during surface-bound carbon nanotube nucleation

    DEFF Research Database (Denmark)

    Hofmann, S; Sharma, R; Du, G

    2007-01-01

    nanoparticles on SiOx support show crystalline lattice fringe contrast and high deformability before and during nanotube formation. A single-walled carbon nanotube nucleates by lift-off of a carbon cap. Cap stabilization and nanotube growth involve the dynamic reshaping of the catalyst nanocrystal itself...

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

    Science.gov (United States)

    Fu, Xiuli; Chen, Lingxin; Li, Jinhua

    2012-08-21

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

  11. 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.

  12. Multivalent protein assembly using monovalent self-assembling building blocks

    NARCIS (Netherlands)

    Petkau - Milroy, K.; Sonntag, M.H.; Colditz, A.; Brunsveld, L.

    2013-01-01

    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

  13. Control of peptide nanotube diameter by chemical modifications of an aromatic residue involved in a single close contact

    Science.gov (United States)

    Tarabout, Christophe; Roux, Stéphane; Gobeaux, Frédéric; Fay, Nicolas; Pouget, Emilie; Meriadec, Cristelle; Ligeti, Melinda; Thomas, Daniel; IJsselstijn, Maarten; Besselievre, François; Buisson, David-Alexandre; Verbavatz, Jean-Marc; Petitjean, Michel; Valéry, Céline; Perrin, Lionel; Rousseau, Bernard; Artzner, Franck; Paternostre, Maité; Cintrat, Jean-Christophe

    2011-01-01

    Supramolecular self-assembly is an attractive pathway for bottom-up synthesis of novel nanomaterials. In particular, this approach allows the spontaneous formation of structures of well-defined shapes and monodisperse characteristic sizes. Because nanotechnology mainly relies on size-dependent physical phenomena, the control of monodispersity is required, but the possibility of tuning the size is also essential. For self-assembling systems, shape, size, and monodispersity are mainly settled by the chemical structure of the building block. Attempts to change the size notably by chemical modification usually end up with the loss of self-assembly. Here, we generated a library of 17 peptides forming nanotubes of monodisperse diameter ranging from 10 to 36 nm. A structural model taking into account close contacts explains how a modification of a few Å of a single aromatic residue induces a fourfold increase in nanotube diameter. The application of such a strategy is demonstrated by the formation of silica nanotubes of various diameters. PMID:21518895

  14. Simulation of dielectrophoretic assembly of carbon nanotubes using 3D finite element analysis

    International Nuclear Information System (INIS)

    Berger, S D; McGruer, N E; Adams, G G

    2015-01-01

    One of the most important methods for selective and repeatable assembly of carbon nanotubes (CNTs) is alternating current dielectrophoresis (DEP). This method has been demonstrated experimentally as a viable technique for nano-scale manufacturing of novel CNT based devices. Previous numerical analyses have studied the motion of nanotubes, the volume from which they are assembled, and the rate of assembly, but have been restricted by various simplifying assumptions. In this paper we present a method for simulating the motion and behavior of CNTs subjected to dielectrophoresis using a three-dimensional electrostatic finite element analysis. By including the CNT in the finite element model, we can accurately predict the effect of the CNT on the electric field and the resulting force distribution across the CNT can be determined. We have used this information to calculate the motion of CNTs assembling onto the electrodes, and show how they tend to move towards the center of an electrode and come into contact at highly skewed angles. Our analysis suggests that the CNTs move to the electrode gap only after initially contacting the electrodes. We have also developed a model of the elastic deformation of CNTs as they approach the electrodes demonstrating how the induced forces can significantly alter the CNT shape during assembly. These results show that the CNT does not behave as a rigid body when in close proximity to the electrodes. In the future this method can be applied to a variety of real electrode geometries on a case-by-case basis and will provide more detailed insight into the specific motion and assembly parameters necessary for effective DEP assembly. (paper)

  15. Heterojunction nanowires having high activity and stability for the reduction of oxygen: Formation by self-assembly of iron phthalocyanine with single walled carbon nanotubes (FePc/SWNTs)

    KAUST Repository

    Zhu, Jia

    2014-04-01

    A self-assembly approach to preparing iron phthalocyanine/single-walled carbon nanotube (FePc/SWNT) heterojunction nanowires as a new oxygen reduction reaction (ORR) electrocatalyst has been developed by virtue of water-adjusted dispersing in 1-cyclohexyl-pyrrolidone (CHP) of the two components. The FePc/SWNT nanowires have a higher Fermi level compared to pure FePc (d-band center, DFT. =. -0.69. eV versus -0.87. eV, respectively). Consequently, an efficient channel for transferring electron to the FePc surface is readily created, facilitating the interaction between FePc and oxygen, so enhancing the ORR kinetics. This heterojunction-determined activity in ORR illustrates a new stratagem to preparing non-noble ORR electrocatalysts of significant importance in constructing real-world fuel cells. © 2013 Elsevier Inc.

  16. Self-assembling peptide semiconductors

    Science.gov (United States)

    Tao, Kai; Makam, Pandeeswar; Aizen, Ruth; Gazit, Ehud

    2017-01-01

    Semiconductors are central to the modern electronics and optics industries. Conventional semiconductive materials bear inherent limitations, especially in emerging fields such as interfacing with biological systems and bottom-up fabrication. A promising candidate for bioinspired and durable nanoscale semiconductors is the family of self-assembled nanostructures comprising short peptides. The highly ordered and directional intermolecular π-π interactions and hydrogen-bonding network allow the formation of quantum confined structures within the peptide self-assemblies, thus decreasing the band gaps of the superstructures into semiconductor regions. As a result of the diverse architectures and ease of modification of peptide self-assemblies, their semiconductivity can be readily tuned, doped, and functionalized. Therefore, this family of electroactive supramolecular materials may bridge the gap between the inorganic semiconductor world and biological systems. PMID:29146781

  17. 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.

  18. Strategies for specifically directing metal functionalization of protein nanotubes: constructing protein coated silver nanowires

    International Nuclear Information System (INIS)

    Carreño-Fuentes, Liliana; Palomares, Laura A; Ramírez, Octavio T; Ascencio, Jorge A; Medina, Ariosto; Aguila, Sergio

    2013-01-01

    Biological molecules that self-assemble in the nanoscale range are useful multifunctional materials. Rotavirus VP6 protein self-assembles into tubular structures in the absence of other rotavirus proteins. Here, we present strategies for selectively directing metal functionalization to the lumen of VP6 nanotubes. The specific in situ metal reduction in the inner surface of nanotube walls was achieved by the simple modification of a method previously reported to functionalize the nanotube outer surface. Silver nanorods and nanowires as long as 1.5 μm were formed inside the nanotubes by coalescence of nanoparticles. Such one-dimensional structures were longer than others previously obtained using bioscaffolds. The interactions between silver ions and the nanotube were simulated to understand the conditions that allowed nanowire formation. Molecular docking showed that a naturally occurring arrangement of aspartate residues enabled the stabilization of silver ions on the internal surface of the VP6 nanotubes. This is the first time that such a spatial arrangement has been proposed for the nucleation of silver nanoparticles, opening the possibility of using such an array to direct functionalization of other biomolecules. These results demonstrate the natural capabilities of VP6 nanotubes to function as a versatile biotemplate for nanomaterials. (paper)

  19. Polarization switching and patterning in self-assembled peptide tubular structures

    Science.gov (United States)

    Bdikin, Igor; Bystrov, Vladimir; Delgadillo, Ivonne; Gracio, José; Kopyl, Svitlana; Wojtas, Maciej; Mishina, Elena; Sigov, Alexander; Kholkin, Andrei L.

    2012-04-01

    Self-assembled peptide nanotubes are unique nanoscale objects that have great potential for a multitude of applications, including biosensors, nanotemplates, tissue engineering, biosurfactants, etc. The discovery of strong piezoactivity and polar properties in aromatic dipeptides [A. Kholkin, N. Amdursky, I. Bdikin, E. Gazit, and G. Rosenman, ACS Nano 4, 610 (2010)] opened up a new perspective for their use as biocompatible nanoactuators, nanomotors, and molecular machines. Another, as yet unexplored functional property is the ability to switch polarization and create artificial polarization patterns useful in various electronic and optical applications. In this work, we demonstrate that diphenylalanine peptide nanotubes are indeed electrically switchable if annealed at a temperature of about 150 °C. The new orthorhombic antipolar structure that appears after annealing allows for the existence of a radial polarization component, which is directly probed by piezoresponse force microscopy (PFM) measurements. Observation of the relatively stable polarization patterns and hysteresis loops via PFM testifies to the local reorientation of molecular dipoles in the radial direction. The experimental results are complemented with rigorous molecular calculations and create a solid background of electric-field induced deformation of aromatic rings and corresponding polarization switching in this emergent material.

  20. Mechanism of membranous tunnelling nanotube formation in viral genome delivery.

    Directory of Open Access Journals (Sweden)

    Bibiana Peralta

    2013-09-01

    Full Text Available In internal membrane-containing viruses, a lipid vesicle enclosed by the icosahedral capsid protects the genome. It has been postulated that this internal membrane is the genome delivery device of the virus. Viruses built with this architectural principle infect hosts in all three domains of cellular life. Here, using a combination of electron microscopy techniques, we investigate bacteriophage PRD1, the best understood model for such viruses, to unveil the mechanism behind the genome translocation across the cell envelope. To deliver its double-stranded DNA, the icosahedral protein-rich virus membrane transforms into a tubular structure protruding from one of the 12 vertices of the capsid. We suggest that this viral nanotube exits from the same vertex used for DNA packaging, which is biochemically distinct from the other 11. The tube crosses the capsid through an aperture corresponding to the loss of the peripentonal P3 major capsid protein trimers, penton protein P31 and membrane protein P16. The remodeling of the internal viral membrane is nucleated by changes in osmolarity and loss of capsid-membrane interactions as consequence of the de-capping of the vertices. This engages the polymerization of the tail tube, which is structured by membrane-associated proteins. We have observed that the proteo-lipidic tube in vivo can pierce the gram-negative bacterial cell envelope allowing the viral genome to be shuttled to the host cell. The internal diameter of the tube allows one double-stranded DNA chain to be translocated. We conclude that the assembly principles of the viral tunneling nanotube take advantage of proteo-lipid interactions that confer to the tail tube elastic, mechanical and functional properties employed also in other protein-membrane systems.

  1. Method for synthesizing carbon nanotubes

    Science.gov (United States)

    Fan, Hongyou

    2012-09-04

    A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

  2. Equilibrium polymerization models of re-entrant self-assembly

    Science.gov (United States)

    Dudowicz, Jacek; Douglas, Jack F.; Freed, Karl F.

    2009-04-01

    As is well known, liquid-liquid phase separation can occur either upon heating or cooling, corresponding to lower and upper critical solution phase boundaries, respectively. Likewise, self-assembly transitions from a monomeric state to an organized polymeric state can proceed either upon increasing or decreasing temperature, and the concentration dependent ordering temperature is correspondingly called the "floor" or "ceiling" temperature. Motivated by the fact that some phase separating systems exhibit closed loop phase boundaries with two critical points, the present paper analyzes self-assembly analogs of re-entrant phase separation, i.e., re-entrant self-assembly. In particular, re-entrant self-assembly transitions are demonstrated to arise in thermally activated equilibrium self-assembling systems, when thermal activation is more favorable than chain propagation, and in equilibrium self-assembly near an adsorbing boundary where strong competition exists between adsorption and self-assembly. Apparently, the competition between interactions or equilibria generally underlies re-entrant behavior in both liquid-liquid phase separation and self-assembly transitions.

  3. Lithium storage performance of carbon nanotubes prepared from polyaniline for lithium-ion batteries

    International Nuclear Information System (INIS)

    Xiang Xiaoxia; Huang Zhengzheng; Liu Enhui; Shen Haijie; Tian Yingying; Xie Hui; Wu Yuhu; Wu Zhilian

    2011-01-01

    Highlights: → Polyaniline nanotube is synthesized by the self-assembly method in aqueous media. → Carbon nanotubes were prepared from polyaniline nanotube by physical activation. → Activation leads to large surface area, and surface nitrogen and oxygen functional groups. → Such physical and chemical properties lead to the good electrochemical properties. → After 20 cycles, a reversible capacity of 728 mAh g -1 was obtained. - Abstract: Carbon nanotubes with large surface area and surface nitrogen and oxygen functional groups are prepared by carbonizing and activating of polyaniline nanotubes, which is synthesized by polymerization of aniline with the self-assembly method in aqueous media. The physicochemical properties of the carbon nanotubes are characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller, elemental analyses and X-ray photoelectron spectroscopy measurements. The surface area and pore diameter are 618.9 m 2 g -1 and 3.10 nm. The electrochemical properties of the carbon nanotubes as anode materials in lithium ion batteries are evaluated. At a current density of 100 mA g -1 , the activated carbon nanotube shows an enormously first discharge capacity of about 1370 mAh g -1 and a charge capacity of 907 mAh g -1 . After 20 cycling tests, the activated carbon nanotube retains a reversible capacity of 728 mAh g -1 . These indicate it may be a promising candidate for an anode material for lithium secondary batteries.

  4. Biophotofuel cell anode containing self-organized titanium dioxide nanotube array

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Yong X., E-mail: yong.gan@utoledo.edu [Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, 2801 W Bancroft Street, Toledo, OH 43606 (United States); Gan, Bo J. [Ottawa Hills High School, 2532 Evergreen Road, Toledo, OH 43606 (United States); Su Lusheng [Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, 2801 W Bancroft Street, Toledo, OH 43606 (United States)

    2011-09-15

    Graphical abstract: Highlights: {center_dot} A photoactive anode containing highly ordered TiO{sub 2} nanotube array was made and the formation mechanism of self-organized TiO{sub 2} nanotube array on Ti was revealed. {center_dot} Effect of electrolyte concentration and voltage on the size distribution of the nanotubes was investigated. {center_dot} Self-organized TiO{sub 2} nanotube array anode possesses good photo-catalytic behavior of biomass decomposition under ultraviolet (UV) radiation. {center_dot} The fuel cell generates electricity and hydrogen via photoelectrochemical decomposition of ethanol, apple vinegar, sugar and tissue paper. - Abstract: We made a biophotofuel cell consisting of a titanium dioxide nanotube array photosensitive anode for biomass decomposition, and a low-hydrogen overpotential metal, Pt, as the cathode for hydrogen production. The titanium dioxide nanotubes (TiO{sub 2} NTs) were prepared via electrochemical oxidation of pure Ti in NaF solutions. Scanning electron microscopy was used to analyze the morphology of the nanotubes. The average diameter, wall thickness and length of the as-prepared TiO{sub 2} NTs were 88 {+-} 16 nm, 10 {+-} 2 nm and 491 {+-} 56 nm, respectively. Such dimensions are affected by the NaF concentration and the applied voltage during processing. Higher NaF concentrations result in the formation of longer and thicker nanotubes. The higher the voltage is, the thicker the nanotubes. The photosensitive anode made from the highly ordered TiO{sub 2} NTs has good photo-catalytic property, as can be seen from the test results of ethanol, apple vinegar, sugar and tissue paper decomposition under ultraviolet (UV) radiation. It is concluded that the biophotofuel cell with the TiO{sub 2} nanotube photoanode and a Pt cathode can generate electricity, hydrogen and clean water depending on the pH value and the oxygen presence in the solutions.

  5. A self-sensing carbon nanotube/cement composite for traffic monitoring

    International Nuclear Information System (INIS)

    Han Baoguo; Yu Xun; Kwon, Eil

    2009-01-01

    In this paper, a self-sensing carbon nanotube (CNT)/cement composite is investigated for traffic monitoring. The cement composite is filled with multi-walled carbon nanotubes whose piezoresistive properties enable the detection of mechanical stresses induced by traffic flow. The sensing capability of the self-sensing CNT/cement composite is explored in laboratory tests and road tests. Experimental results show that the fabricated self-sensing CNT/cement composite presents sensitive and stable responses to repeated compressive loadings and impulsive loadings, and has remarkable responses to vehicular loadings. These findings indicate that the self-sensing CNT/cement composite has great potential for traffic monitoring use, such as in traffic flow detection, weigh-in-motion measurement and vehicle speed detection.

  6. Theory of Disk-to-Vesicle Transformation

    Science.gov (United States)

    Li, Jianfeng; Shi, An-Chang

    2009-03-01

    Self-assembled membranes from amphiphilic molecules, such as lipids and block copolymers, can assume a variety of morphologies dictated by energy minimization of system. The membrane energy is characterized by a bending modulus (κ), a Gaussian modulus (κG), and the line tension (γ) of the edge. Two basic morphologies of membranes are flat disks that minimize the bending energy at the cost of the edge energy, and enclosed vesicles that minimize the edge energy at the cost of bending energy. In our work, the transition from disk to vesicle is studied theoretically using the string method, which is designed to find the minimum energy path (MEP) or the most probable transition path between two local minima of an energy landscape. Previous studies of disk-to-vesicle transition usually approximate the transitional states by a series of spherical cups, and found that the spherical cups do not correspond to stable or meta-stable states of the system. Our calculation demonstrates that the intermediate shapes along the MEP are very different from spherical cups. Furthermore, some of these transitional states can be meta-stable. The disk-to-vesicle transition pathways are governed by two scaled parameters, κG/κ and γR0/4κ, where R0 is the radius of the disk. In particular, a meta-stable intermediate state is predicted, which may correspond to the open morphologies observed in experiments and simulations.

  7. Formation of supported lipid bilayers of charged E. coli lipids on modified gold by vesicle fusion

    Directory of Open Access Journals (Sweden)

    Ileana F. Márquez

    2017-01-01

    Full Text Available We describe a simple way of fusing E. coli lipid vesicles onto a gold surface. Supported lipid bilayers on metal surfaces are interesting for several reasons: transducing a biological signal to an electric readout, using surface analytical tools such as Surface Plasmon Resonance (SPR, Infrared Reflection Absorption Spectroscopy, Neutron Reflectivity or Electrochemistry. The most widely used method to prepare supported lipid membranes is fusion of preexisting liposomes. It is quite efficient on hydrophilic surfaces such as glass, mica or SiO2, but vesicle fusion on metals and metal oxide surfaces (as gold, titanium oxide or indium tin oxide, remains a challenge, particularly for vesicles containing charged lipids, as is the case of bacterial lipids. We describe a simple method based on modifying the gold surface with a charged mercaptopropionic acid self-assembled monolayer and liposomes partially solubilized with detergent. The formed bilayers were characterized using a Quartz Crystal Microbalance with dissipation (QCM-D and Atomic Force Microscopy (AFM. Some advantages of this protocol are that the stability of the self-assembled monolayer allows for repeated use of the substrate after detergent removal of the bilayer and that the amount of detergent required for optimal fusion can be determined previously using the lipid-detergent solubility curve.

  8. Site-specific forest-assembly of single-wall carbon nanotubes on electron-beam patterned SiOx/Si substrates

    International Nuclear Information System (INIS)

    Wei Haoyan; Kim, Sang Nyon; Kim, Sejong; Huey, Bryan D.; Papadimitrakopoulos, Fotios; Marcus, Harris L.

    2008-01-01

    Based on electron-beam direct writing on the SiO x /Si substrates, favorable absorption sites for ferric cations (Fe 3+ ions) were created on the surface oxide layer. This allowed Fe 3+ -assisted self-assembled arrays of single-wall carbon nanotube (SWNT) probes to be produced. Auger investigation indicated that the incident energetic electrons depleted oxygen, creating more dangling bonds around Si atoms at the surface of the SiO x layer. This resulted in a distinct difference in the friction forces from unexposed regions as measured by lateral force microscopy (LFM). Atomic force microscopy (AFM) affirmed that the irradiated domains absorbed considerably more Fe 3+ ions upon immersion into pH 2.2 aqueous FeCl 3 solution. This rendered a greater yield of FeO(OH)/FeOCl precipitates, primarily FeO(OH), upon subsequent washing with lightly basic dimethylformamide (DMF) solution. Such selective metal-functionalization established the basis for the subsequent patterned forest-assembly of SWNTs as demonstrated by resonance Raman spectroscopy

  9. Onset of self-assembly

    International Nuclear Information System (INIS)

    Chitanvis, S.M.

    1998-01-01

    We have formulated a theory of self-assembly based on the notion of local gauge invariance at the mesoscale. Local gauge invariance at the mesoscale generates the required long-range entropic forces responsible for self-assembly in binary systems. Our theory was applied to study the onset of mesostructure formation above a critical temperature in estane, a diblock copolymer. We used diagrammatic methods to transcend the Gaussian approximation and obtain a correlation length ξ∼(c-c * ) -γ , where c * is the minimum concentration below which self-assembly is impossible, c is the current concentration, and γ was found numerically to be fairly close to 2/3. The renormalized diffusion constant vanishes as the critical concentration is approached, indicating the occurrence of critical slowing down, while the correlation function remains finite at the transition point. copyright 1998 The American Physical Society

  10. Live visualizations of single isolated tubulin protein self-assembly via tunneling current: effect of electromagnetic pumping during spontaneous growth of microtubule.

    Science.gov (United States)

    Sahu, Satyajit; Ghosh, Subrata; Fujita, Daisuke; Bandyopadhyay, Anirban

    2014-12-03

    As we bring tubulin protein molecules one by one into the vicinity, they self-assemble and entire event we capture live via quantum tunneling. We observe how these molecules form a linear chain and then chains self-assemble into 2D sheet, an essential for microtubule, --fundamental nano-tube in a cellular life form. Even without using GTP, or any chemical reaction, but applying particular ac signal using specially designed antenna around atomic sharp tip we could carry out the self-assembly, however, if there is no electromagnetic pumping, no self-assembly is observed. In order to verify this atomic scale observation, we have built an artificial cell-like environment with nano-scale engineering and repeated spontaneous growth of tubulin protein to its complex with and without electromagnetic signal. We used 64 combinations of plant, animal and fungi tubulins and several doping molecules used as drug, and repeatedly observed that the long reported common frequency region where protein folds mechanically and its structures vibrate electromagnetically. Under pumping, the growth process exhibits a unique organized behavior unprecedented otherwise. Thus, "common frequency point" is proposed as a tool to regulate protein complex related diseases in the future.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-02

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

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

    International Nuclear Information System (INIS)

    Nayak, Nimai C; Shin, Kwanwoo

    2008-01-01

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

  13. Photoinitiated Polymerization-Induced Self-Assembly of Glycidyl Methacrylate for the Synthesis of Epoxy-Functionalized Block Copolymer Nano-Objects.

    Science.gov (United States)

    Tan, Jianbo; Liu, Dongdong; Huang, Chundong; Li, Xueliang; He, Jun; Xu, Qin; Zhang, Li

    2017-08-01

    Herein, a novel photoinitiated polymerization-induced self-assembly formulation via photoinitiated reversible addition-fragmentation chain transfer dispersion polymerization of glycidyl methacrylate (PGMA) in ethanol-water at room temperature is reported. It is demonstrated that conducting polymerization-induced self-assembly (PISA) at low temperatures is crucial for obtaining colloidal stable PGMA-based diblock copolymer nano-objects. Good control is maintained during the photo-PISA process with a high rate of polymerization. The polymerization can be switched between "ON" and "OFF" in response to visible light. A phase diagram is constructed by varying monomer concentration and degree of polymerization. The PGMA-based diblock copolymer nano-objects can be further cross-linked by using a bifunctional primary amine reagent. Finally, silver nanoparticles are loaded within cross-linked vesicles via in situ reduction, exhibiting good catalytic properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Self assembly of rectangular shapes on concentration programming and probabilistic tile assembly models.

    Science.gov (United States)

    Kundeti, Vamsi; Rajasekaran, Sanguthevar

    2012-06-01

    Efficient tile sets for self assembling rectilinear shapes is of critical importance in algorithmic self assembly. A lower bound on the tile complexity of any deterministic self assembly system for an n × n square is [Formula: see text] (inferred from the Kolmogrov complexity). Deterministic self assembly systems with an optimal tile complexity have been designed for squares and related shapes in the past. However designing [Formula: see text] unique tiles specific to a shape is still an intensive task in the laboratory. On the other hand copies of a tile can be made rapidly using PCR (polymerase chain reaction) experiments. This led to the study of self assembly on tile concentration programming models. We present two major results in this paper on the concentration programming model. First we show how to self assemble rectangles with a fixed aspect ratio ( α:β ), with high probability, using Θ( α + β ) tiles. This result is much stronger than the existing results by Kao et al. (Randomized self-assembly for approximate shapes, LNCS, vol 5125. Springer, Heidelberg, 2008) and Doty (Randomized self-assembly for exact shapes. In: proceedings of the 50th annual IEEE symposium on foundations of computer science (FOCS), IEEE, Atlanta. pp 85-94, 2009)-which can only self assembly squares and rely on tiles which perform binary arithmetic. On the other hand, our result is based on a technique called staircase sampling . This technique eliminates the need for sub-tiles which perform binary arithmetic, reduces the constant in the asymptotic bound, and eliminates the need for approximate frames (Kao et al. Randomized self-assembly for approximate shapes, LNCS, vol 5125. Springer, Heidelberg, 2008). Our second result applies staircase sampling on the equimolar concentration programming model (The tile complexity of linear assemblies. In: proceedings of the 36th international colloquium automata, languages and programming: Part I on ICALP '09, Springer-Verlag, pp 235

  15. 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).

  16. Large branched self-assembled DNA complexes

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  17. Two-Dimensional Fluidization of Nanomaterials via Biomimetic Membranes towards Assisted Self Assembly

    Science.gov (United States)

    Kelly, Kathleen

    Materials that take advantage of the exceptional properties of nano-meter sized aggregates of atoms are poised to play an important role in future technologies. Prime examples for such nano-materials that have an extremely large surface to volume ratio and thus are physically determined by surface related effects are quantum dots (qdots) and carbon nanotubes (CNTs). The production of such manmade nano-objects has by now become routine and even commercialized. However, the controlled assembly of individual nano-sized building blocks into larger structures of higher geometric and functional complexity has proven to be much more challenging. Yet, this is exactly what is required for many applications that have transformative potential for new technologies. If the tedious procedure to sequentially position individual nano-objects is to be forgone, the assembly of such objects into larger structures needs to be implicitly encoded and many ways to bestow such self-assembly abilities onto nano objects are being developed. Yet, as overall size and complexity of such self-assembled structures increases, kinetic and geometric frustration begin to prevent the system to achieve the desired configuration. In nature, this problem is solved by relying on guided or forced variants of the self-assembly approach. To translate such concepts into the realm of man-made nano-technology, ways to dynamically manipulate nano-materials need to be devised. Thus, in the first part of this work, I provide a proof of concept that supported lipid bilayers (SLBs) that exhibit free lateral diffusion of their constituents can be utilized as a two-dimensional platform for active nano-material manipulation. We used streptavidin coated quantum dots (Q-dots) as a model nano-building-block. Q-dots are 0-dimensional nanomaterials engineered to be fluorescent based solely on their diameter making visualization convenient. Biotinylated lipids were used to tether Q-dots to a SLB and we observed that the 2

  18. Block copolymer vesicles-using concepts from polymer chemistry to mimic biomembranes

    OpenAIRE

    Kita-Tokarczyk, Katarzyna; Grumelard, Julie; Haefele, Thomas; Meier, Wolfgang

    2005-01-01

    A review. Owing to the increasing interest in self-assembled structures from block copolymer materials, we present here a review of recent literature concerning amphiphilic block copolymer vesicles. A vesicular morphol. is applicable not only in such fields like delivery-release and biomineralization, but also has been utilized for prepn. of nanoreactors and incorporation of biol. macromols. The organization of this paper is the following: we first provide the readers with the overview of the...

  19. Thermodynamics and Structural Evolution during a Reversible Vesicle-Micelle Transition of a Vitamin-Derived Bolaamphiphile Induced by Sodium Cholate.

    Science.gov (United States)

    Tian, Jun-Nan; Ge, Bing-Qiang; Shen, Yun-Feng; He, Yu-Xuan; Chen, Zhong-Xiu

    2016-03-09

    Interaction of endogenous sodium cholate (SC) with dietary amphiphiles would induce structural evolution of the self-assembled aggregates, which inevitably affects the hydrolysis of fat in the gut. Current work mainly focused on the interaction of bile salts with classical double-layered phospholipid vesicles. In this paper, the thermodynamics and structural evolution during the interaction of SC with novel unilamellar vesicles formed from vitamin-derived zwitterionic bolaamphiphile (DDO) were characterized. It was revealed that an increased temperature and the presence of NaCl resulted in narrowed micelle-vesicle coexistence and enlarged the vesicle region. The coexistence of micelles and vesicles mainly came from the interaction of monomeric SC with DDO vesicles, whereas micellar SC contributed to the total solubilization of DDO vesicles. This research may enrich the thermodynamic mechanism behind the structure transition of the microaggregates formed by amphiphiles in the gut. It will also contribute to the design of food formulation and drug delivery system.

  20. Self-Organization and the Self-Assembling Process in Tissue Engineering

    Science.gov (United States)

    Eswaramoorthy, Rajalakshmanan; Hadidi, Pasha; Hu, Jerry C.

    2015-01-01

    In recent years, the tissue engineering paradigm has shifted to include a new and growing subfield of scaffoldless techniques which generate self-organizing and self-assembling tissues. This review aims to provide a cogent description of this relatively new research area, with special emphasis on applications toward clinical use and research models. Particular emphasis is placed on providing clear definitions of self-organization and the self-assembling process, as delineated from other scaffoldless techniques in tissue engineering and regenerative medicine. Significantly, during formation, self-organizing and self-assembling tissues display biological processes similar to those that occur in vivo. These help lead to the recapitulation of native tissue morphological structure and organization. Notably, functional properties of these tissues also approach native tissue values; some of these engineered tissues are already in clinical trials. This review aims to provide a cohesive summary of work in this field, and to highlight the potential of self-organization and the self-assembling process to provide cogent solutions to current intractable problems in tissue engineering. PMID:23701238

  1. Size and shape tunability of self-assembled InAs/GaAs nanostructures through the capping rate

    Science.gov (United States)

    Utrilla, Antonio D.; Grossi, Davide F.; Reyes, Daniel F.; Gonzalo, Alicia; Braza, Verónica; Ben, Teresa; González, David; Guzman, Alvaro; Hierro, Adrian; Koenraad, Paul M.; Ulloa, Jose M.

    2018-06-01

    The practical realization of epitaxial quantum dot (QD) nanocrystals led before long to impressive experimental advances in optoelectronic devices, as well as to the emergence of new technological fields. However, the necessary capping process is well-known to hinder a precise control of the QD morphology and therefore of the possible electronic structure required for certain applications. A straightforward approach is shown to tune the structural and optical properties of InAs/GaAs QDs without the need for any capping material different from GaAs or annealing process. The mere adjust of the capping rate allows controlling kinetically the QD dissolution process induced by the surface In-Ga intermixing taking place during overgrowth, determining the final metastable structure. While low capping rates make QDs evolve into more thermodynamically favorable quantum ring structures, increasing capping rates help preserve the QD height and shape, simultaneously improving the luminescence properties. Indeed, a linear relationship between capping rate and QD height is found, resulting in a complete preservation of the original QD geometry for rates above ∼2.0 ML s-1. In addition, the inhibition of In diffusion from the QDs top to the areas in between them yields thinner WLs, what could improve the performance of several QD-based optoelectronic devices.

  2. Vertically aligned single-walled carbon nanotubes by chemical assembly--methodology, properties, and applications.

    Science.gov (United States)

    Diao, Peng; Liu, Zhongfan

    2010-04-06

    Single-walled carbon nanotubes (SWNTs), as one of the most promising one-dimension nanomaterials due to its unique structure, peculiar chemical, mechanical, thermal, and electronic properties, have long been considered as an important building block to construct ordered alignments. Vertically aligned SWNTs (v-SWNTs) have been successfully prepared by using direct growth and chemical assembly strategies. In this review, we focus explicitly on the v-SWNTs fabricated via chemical assembly strategy. We provide the readers with a full and systematic summary covering the advances in all aspects of this area, including various approaches for the preparation of v-SWNTs using chemical assembly techniques, characterization, assembly kinetics, and electrochemical properties of v-SWNTs. We also review the applications of v-SWNTs in electrochemical and bioelectrochemical sensors, photoelectric conversion, and scanning probe microscopy.

  3. Physical principles for DNA tile self-assembly.

    Science.gov (United States)

    Evans, Constantine G; Winfree, Erik

    2017-06-19

    DNA tiles provide a promising technique for assembling structures with nanoscale resolution through self-assembly by basic interactions rather than top-down assembly of individual structures. Tile systems can be programmed to grow based on logical rules, allowing for a small number of tile types to assemble large, complex assemblies that can retain nanoscale resolution. Such algorithmic systems can even assemble different structures using the same tiles, based on inputs that seed the growth. While programming and theoretical analysis of tile self-assembly often makes use of abstract logical models of growth, experimentally implemented systems are governed by nanoscale physical processes that can lead to very different behavior, more accurately modeled by taking into account the thermodynamics and kinetics of tile attachment and detachment in solution. This review discusses the relationships between more abstract and more physically realistic tile assembly models. A central concern is how consideration of model differences enables the design of tile systems that robustly exhibit the desired abstract behavior in realistic physical models and in experimental implementations. Conversely, we identify situations where self-assembly in abstract models can not be well-approximated by physically realistic models, putting constraints on physical relevance of the abstract models. To facilitate the discussion, we introduce a unified model of tile self-assembly that clarifies the relationships between several well-studied models in the literature. Throughout, we highlight open questions regarding the physical principles for DNA tile self-assembly.

  4. Application of Carbon Nanotube Assemblies for Sound Generation and Heat Dissipation

    Science.gov (United States)

    Kozlov, Mikhail; Haines, Carter; Oh, Jiyoung; Lima, Marcio; Fang, Shaoli

    2011-03-01

    Nanotech approaches were explored for the efficient transformation of an electrical signal into sound, heat, cooling action, and mechanical strain. The studies are based on the aligned arrays of multi-walled carbon nanotubes (MWNT forests) that can be grown on various substrates using a conventional CVD technique. They form a three-dimensional conductive network that possesses uncommon electrical, thermal, acoustic and mechanical properties. When heated with an alternating current or a near-IR laser modulated in 0.01--20 kHz range, the nanotube forests produce loud, audible sound. High generated sound pressure and broad frequency response (beyond 20 kHz) show that the forests act as efficient thermo-acoustic (TA) transducers. They can generate intense third and fourth TA harmonics that reveal peculiar interference-like patterns from ac-dc voltage scans. A strong dependence of the patterns on forest height can be used for characterization of carbon nanotube assemblies and for evaluation of properties of thermal interfaces. Because of good coupling with surrounding air, the forests provide excellent dissipation of heat produced by IC chips. Thermoacoustic converters based on forests can be used for thermo- and photo-acoustic sound generation, amplification and noise cancellation.

  5. Integration of the End Cap TEC+ of the CMS Silicon Strip Tracker

    CERN Document Server

    Adler, Volker; Ageron, Michel; Agram, Jean-Laurent; Atz, Bernd; Barvich, Tobias; Baulieu, Guillaume; Beaumont, Willem; Beissel, Franz; Bergauer, Thomas; Berst, Jean-Daniel; Blüm, Peter; Bock, E; Bogelsbacher, F; de Boer, Wim; Bonnet, Jean-Luc; Bonnevaux, Alain; Boudoul, Gaelle; Bouhali, Othmane; Braunschweig, Wolfgang; Bremer, R; Brom, Jean-Marie; Butz, Erik; Chabanat, Eric; Chabert, Eric Christian; Clerbaux, Barbara; Contardo, Didier; De Callatay, Bernard; Dehm, Philip; Delaere, Christophe; Della Negra, Rodolphe; Dewulf, Jean-Paul; D'Hondt, Jorgen; Didierjean, Francois; Dierlamm, Alexander; Dirkes, Guido; Dragicevic, Marko; Drouhin, Frédéric; Ernenwein, Jean-Pierre; Esser, Hans; Estre, Nicolas; Fahrer, Manuel; Feld, Lutz; Fernández, J; Florins, Benoit; Flossdorf, Alexander; Flucke, Gero; Flügge, Günter; Fontaine, Jean-Charles; Freudenreich, Klaus; Frey, Martin; Friedl, Markus; Furgeri, Alexander; Giraud, Noël; Goerlach, Ulrich; Goorens, Robert; Graehling, Philippe; Grégoire, Ghislain; Gregoriev, E; Gross, Laurent; Hansel, S; Haroutunian, Roger; Hartmann, Frank; Heier, Stefan; Hermanns, Thomas; Heydhausen, Dirk; Heyninck, Jan; Hosselet, J; Hrubec, Josef; Jahn, Dieter; Juillot, Pierre; Kaminski, Jochen; Karpinski, Waclaw; Kaussen, Gordon; Keutgen, Thomas; Klanner, Robert; Klein, Katja; König, Stefan; Kosbow, M; Krammer, Manfred; Ledermann, Bernhard; Lemaître, Vincent; De Lentdecker, Gilles; Linn, Alexander; Lounis, Abdenour; Lübelsmeyer, Klaus; Lumb, Nicholas; Maazouzi, Chaker; Mahmoud, Tariq; Michotte, Daniel; Militaru, Otilia; Mirabito, Laurent; Müller, Thomas; Neukermans, Lionel; Ollivetto, C; Olzem, Jan; Ostapchuk, Andrey; Pandoulas, Demetrios; Pein, Uwe; Pernicka, Manfred; Perriès, Stephane; Piaseki, C; Pierschel, Gerhard; Piotrzkowski, Krzysztof; Poettgens, Michael; Pooth, Oliver; Rouby, Xavier; Sabellek, Andreas; Schael, Stefan; Schirm, Norbert; Schleper, Peter; Schmitz, Stefan Antonius; Schultz von Dratzig, Arndt; Siedling, Rolf; Simonis, Hans-Jürgen; Stahl, Achim; Steck, Pia; Steinbruck, G; Stoye, Markus; Strub, Roger; Tavernier, Stefaan; Teyssier, Daniel; Theel, Andreas; Trocmé, Benjamin; Udo, Fred; Van der Donckt, M; Van der Velde, C; Van Hove, Pierre; Vanlaer, Pascal; Van Lancker, Luc; Van Staa, Rolf; Vanzetto, Sylvain; Weber, Markus; Weiler, Thomas; Weseler, Siegfried; Wickens, John; Wittmer, Bruno; Wlochal, Michael; De Wolf, Eddi A; Zhukov, Valery; Zoeller, Marc Henning

    2009-01-01

    The silicon strip tracker of the CMS experiment has been completed and inserted into the CMS detector in late 2007. The largest sub-system of the tracker is its end cap system, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted into the TEC support structures. Each end cap consists of 144 petals, and the insertion of these petals into the end cap structure is referred to as TEC integration. The two end caps were integrated independently in Aachen (TEC+) and at CERN (TEC--). This note deals with the integration of TEC+, describing procedures for end cap integration and for quality control during testing of integrated sections of the end cap and presenting results from the testing.

  6. Biomedical Applications of Self-Assembling Peptides

    NARCIS (Netherlands)

    Radmalekshahi, Mazda; Lempsink, Ludwijn; Amidi, Maryam; Hennink, Wim E.; Mastrobattista, Enrico

    2016-01-01

    Self-assembling peptides have gained increasing attention as versatile molecules to generate diverse supramolecular structures with tunable functionality. Because of the possibility to integrate a wide range of functional domains into self-assembling peptides including cell attachment sequences,

  7. Role of CAP350 in centriolar tubule stability and centriole assembly.

    Directory of Open Access Journals (Sweden)

    Mikael Le Clech

    Full Text Available BACKGROUND: Centrioles are microtubule-based cylindrical structures composed of nine triplet tubules and are required for the formation of the centrosome, flagella and cilia. Despite theirs importance, centriole biogenesis is poorly understood. Centrosome duplication is initiated at the G1/S transition by the sequential recruitment of a set of conserved proteins under the control of the kinase Plk4. Subsequently, the procentriole is assembled by the polymerization of centriolar tubules via an unknown mechanism involving several tubulin paralogs. METHODOLOGY/PRINCIPAL FINDINGS: Here, we developed a cellular assay to study centrosome duplication and procentriole stability based on its sensitivity to the microtubule-depolymerizing drug nocodazole. By using RNA interference experiments, we show that the stability of growing procentrioles is regulated by the microtubule-stabilizing protein CAP350, independently of hSAS-6 and CPAP which initiate procentriole growth. Furthermore, our analysis reveals the critical role of centriolar tubule stability for an efficient procentriole growth. CONCLUSIONS/SIGNIFICANCE: CAP350 belongs to a new class of proteins which associate and stabilize centriolar tubules to control centriole duplication.

  8. Synthetic Self-Assembled Materials in Biological Environments

    NARCIS (Netherlands)

    Versluis, F.; van Esch, J.H.; Eelkema, R.

    2016-01-01

    Synthetic self-assembly has long been recognized as an excellent approach for the formation of ordered structures on the nanoscale. Although the development of synthetic self-assembling materials has often been inspired by principles observed in nature (e.g., the assembly of lipids, DNA,

  9. Fuel assemblies

    International Nuclear Information System (INIS)

    Nakatsuka, Masafumi.

    1979-01-01

    Purpose: To prevent scattering of gaseous fission products released from fuel assemblies stored in an fbr type reactor. Constitution; A cap provided with means capable of storing gas is adapted to amount to the assembly handling head, for example, by way of threading in a storage rack of spent fuel assemblies consisting of a bottom plate, a top plate and an assembly support mechanism. By previously eliminating the gas inside of the assembly and the cap in the storage rack, gaseous fission products upon loading, if released from fuel rods during storage, are stored in the cap and do not scatter in the storage rack. (Horiuchi, T.)

  10. Self-assembly of cyclodextrins

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  11. Tuning peptide self-assembly by an in-tether chiral center

    Science.gov (United States)

    Hu, Kuan; Xiong, Wei; Li, Hu; Zhang, Pei-Yu; Yin, Feng; Zhang, Qianling; Jiang, Fan; Li, Zigang

    2018-01-01

    The self-assembly of peptides into ordered nanostructures is important for understanding both peptide molecular interactions and nanotechnological applications. However, because of the complexity and various self-assembling pathways of peptide molecules, design of self-assembling helical peptides with high controllability and tunability is challenging. We report a new self-assembling mode that uses in-tether chiral center-induced helical peptides as a platform for tunable peptide self-assembly with good controllability. It was found that self-assembling behavior was governed by in-tether substitutional groups, where chirality determined the formation of helical structures and aromaticity provided the driving force for self-assembly. Both factors were essential for peptide self-assembly to occur. Experiments and theoretical calculations indicate long-range crystal-like packing in the self-assembly, which was stabilized by a synergy of interpeptide π-π and π-sulfur interactions and hydrogen bond networks. In addition, the self-assembled peptide nanomaterials were demonstrated to be promising candidate materials for applications in biocompatible electrochemical supercapacitors.

  12. Reception Test of Petals for the End Cap TEC+ of the CMS Silicon Strip Tracker

    CERN Document Server

    Bremer, R; Klein, Katja; Schmitz, Stefan Antonius; Adler, Volker; Adolphi, Roman; Ageron, Michel; Agram, Jean-Laurent; Atz, Bernd; Barvich, Tobias; Baulieu, Guillaume; Beaumont, Willem; Beissel, Franz; Bergauer, Thomas; Berst, Jean-Daniel; Blüm, Peter; Bock, E; Bogelsbacher, F; de Boer, Wim; Bonnet, Jean-Luc; Bonnevaux, Alain; Boudoul, Gaelle; Bouhali, Othmane; Braunschweig, Wolfgang; Brom, Jean-Marie; Butz, Erik; Chabanat, Eric; Chabert, Eric Christian; Clerbaux, Barbara; Contardo, Didier; De Callatay, Bernard; Dehm, Philip; Delaere, Christophe; Della Negra, Rodolphe; Dewulf, Jean-Paul; D'Hondt, Jorgen; Didierjean, Francois; Dierlamm, Alexander; Dirkes, Guido; Dragicevic, Marko; Drouhin, Frédéric; Ernenwein, Jean-Pierre; Esser, Hans; Estre, Nicolas; Fahrer, Manuel; Fernández, J; Florins, Benoit; Flossdorf, Alexander; Flucke, Gero; Flügge, Günter; Fontaine, Jean-Charles; Freudenreich, Klaus; Frey, Martin; Friedl, Markus; Furgeri, Alexander; Giraud, Noël; Goerlach, Ulrich; Goorens, Robert; Graehling, Philippe; Grégoire, Ghislain; Gregoriev, E; Gross, Laurent; Hansel, S; Haroutunian, Roger; Hartmann, Frank; Heier, Stefan; Hermanns, Thomas; Heydhausen, Dirk; Heyninck, Jan; Hosselet, J; Hrubec, Josef; Jahn, Dieter; Juillot, Pierre; Kaminski, Jochen; Karpinski, Waclaw; Kaussen, Gordon; Keutgen, Thomas; Klanner, Robert; König, Stefan; Kosbow, M; Krammer, Manfred; Ledermann, Bernhard; Lemaître, Vincent; De Lentdecker, Gilles; Linn, Alexander; Lounis, Abdenour; Lübelsmeyer, Klaus; Lumb, Nicholas; Maazouzi, Chaker; Mahmoud, Tariq; Michotte, Daniel; Militaru, Otilia; Mirabito, Laurent; Müller, Thomas; Neukermans, Lionel; Ollivetto, C; Olzem, Jan; Ostapchuk, Andrey; Pandoulas, Demetrios; Pein, Uwe; Pernicka, Manfred; Perriès, Stephane; Piaseki, C; Pierschel, Gerhard; Piotrzkowski, Krzysztof; Poettgens, Michael; Pooth, Oliver; Rouby, Xavier; Sabellek, Andreas; Schael, Stefan; Schirm, Norbert; Schleper, Peter; Schultz von Dratzig, Arndt; Siedling, Rolf; Simonis, Hans-Jürgen; Stahl, Achim; Steck, Pia; Steinbruck, G; Stoye, Markus; Strub, Roger; Tavernier, Stefaan; Teyssier, Daniel; Theel, Andreas; Trocmé, Benjamin; Udo, Fred; Van der Donckt, M; Van der Velde, C; Van Hove, Pierre; Vanlaer, Pascal; Van Lancker, Luc; Van Staa, Rolf; Vanzetto, Sylvain; Weber, Markus; Weiler, Thomas; Weseler, Siegfried; Wickens, John; Wittmer, Bruno; Wlochal, Michael; De Wolf, Eddi A; Zhukov, Valery; Zoeller, Marc Henning

    2009-01-01

    The silicon strip tracker of the CMS experiment has been completed and was inserted into the CMS detector in late 2007. The largest sub system of the tracker are its end caps, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted onto the TEC support structures. Each end cap consists of 144 such petals, which were built and fully qualified by several institutes across Europe. From

  13. Emulsion Solvent Evaporation-Induced Self-Assembly of Block Copolymers Containing pH-Sensitive Block.

    Science.gov (United States)

    Wu, Yuqing; Wang, Ke; Tan, Haiying; Xu, Jiangping; Zhu, Jintao

    2017-09-26

    A simple yet efficient method is developed to manipulate the self-assembly of pH-sensitive block copolymers (BCPs) confined in emulsion droplets. Addition of acid induces significant variation in morphological transition (e.g., structure and surface composition changes) of the polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) assemblies, due to the hydrophobic-hydrophilic transition of the pH-sensitive P4VP block via protonation. In the case of pH > pKa (P4VP) (pKa (P4VP) = 4.8), the BCPs can self-assemble into pupa-like particles because of the nearly neutral wetting of PS and P4VP blocks at the oil/water interface. As expected, onion-like particles obtained when pH is slightly lower than pKa (P4VP) (e.g., pH = 3.00), due to the interfacial affinity to the weakly hydrophilic P4VP block. Interestingly, when pH was further decreased to ∼2.5, interfacial instability of the emulsion droplets was observed, and each emulsion droplet generated nanoscale assemblies including vesicles, worm-like and/or spherical micelles rather than a nanostructured microparticle. Furthermore, homopolymer with different molecular weights and addition ratio are employed to adjust the interactions among copolymer blocks. By this means, particles with hierarchical structures can be obtained. Moreover, owing to the kinetically controlled processing, we found that temperature and stirring speed, which can significantly affect the kinetics of the evaporation of organic solvent and the formation of particles, played a key role in the morphology of the assemblies. We believe that manipulation of the property for the aqueous phase is a promising strategy to rationally design and fabricate polymeric assemblies with desirable shapes and internal structures.

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

    Science.gov (United States)

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

    2013-11-26

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

  15. A bioscaffolding strategy for hierarchical zeolites with a nanotube-trimodal network.

    Science.gov (United States)

    Li, Guannan; Huang, Haibo; Yu, Bowen; Wang, Yun; Tao, Jiawei; Wei, Yingxu; Li, Shougui; Liu, Zhongmin; Xu, Yan; Xu, Ruren

    2016-02-01

    Hierarchical zeolite monoliths with multimodal porosity are of paramount importance as they open up new horizons for advanced applications. So far, hierarchical zeolites based on nanotube scaffolds have never been reported. Inspired by the organization of biominerals, we have developed a novel precursor scaffolding-solid phase crystallization strategy for hierarchical zeolites with a unique nanotube scaffolding architecture and nanotube-trimodal network, where biomolecular self-assembly (BSA) provides a scaffolding blueprint. By vapor-treating Sil-1 seeded precursor scaffolds, zeolite MFI nanotube scaffolds are self-generated, during which evolution phenomena such as segmented voids and solid bridges are observed, in agreement with the Kirkendall effect in a solid-phase crystallization system. The nanotube walls are made of intergrown single crystals rendering good mechanical stability. The inner diameter of the nanotube is tunable between 30 and 90 nm by varying the thickness of the precursor layers. Macropores enclosed by cross-linked nanotubes can be modulated by the choice of BSA. Narrow mesopores are formed by intergrown nanocrystals. Hierarchical ZSM-5 monoliths with nanotube (90 nm), micropore (0.55 nm), mesopore (2 nm) and macropore (700 nm) exhibit superior catalytic performance in the methanol-to-hydrocarbon (MTH) conversion compared to conventional ZSM-5. BSA remains intact after crystallization, allowing a higher level of organization and functionalization of the zeolite nanotube scaffolds. The current work may afford a versatile strategy for hierarchical zeolite monoliths with nanotube scaffolding architectures and a nanotube-multimodal network leading to self-supporting and active zeolite catalysts, and for applications beyond.

  16. Field penetration induced charge redistribution effects on the field emission properties of carbon nanotubes - a first-principle study

    International Nuclear Information System (INIS)

    Chen, C.-W.; Lee, M.-H.; Clark, S.J.

    2004-01-01

    The effect of field penetration induced charge redistribution on the field emission properties of carbon nanotubes (CNTs) have been studied by the first-principle calculations. It is found that the carbon nanotube becomes polarized under external electric field leading to a charge redistribution. The resulting band bending induced by field penetration into the nanotube tip surface can further reduce the effective workfunction of the carbon nanotubes. The magnitude of the redistributed charge ΔQ is found to be nearly linear to the applied external field strength. In addition, we found that the capped (9, 0) zigzag nanotube demonstrates better field emission properties than the capped (5, 5) armchair nanotube due to the fact that the charge redistribution of π electrons along the zigzag-like tube axis is easier than for the armchair-like tube. The density of states (DOS) of the capped region of the nanotube is found to be enhanced with a value 30% higher than that of the sidewall part for the capped (5, 5) nanotube and 40% for the capped (9, 0) nanotube under an electric field of 0.33 V/A. Such enhancements of the DOS at the carbon nanotube tip show that electrons near the Fermi level will emit more easily due to the change of the surface band structure resulting from the field penetration in a high field

  17. Self-Assembled TiO2 Nanotube Arrays with U-Shaped Profile by Controlling Anodization Temperature

    Directory of Open Access Journals (Sweden)

    Jingfei Chen

    2010-01-01

    Full Text Available TiO2 nanotube arrays with uniform diameter from top to bottom were fabricated. The synthesizing approach is based on the investigation of the influence of electrolyte temperature on the tube diameter. We found that the inner diameter of the tubes increased with the electrolyte temperature. Accordingly, we improved the tube profile from the general V shape to U shape by raising the electrolyte temperature gradually. This is a simple and fast approach to fabricate uniform TiO2 nanotubes in diameter. The improved TiO2 nanotube arrays may show better properties and have broad potential applications.

  18. Building polyhedra by self-assembly: theory and experiment.

    Science.gov (United States)

    Kaplan, Ryan; Klobušický, Joseph; Pandey, Shivendra; Gracias, David H; Menon, Govind

    2014-01-01

    We investigate the utility of a mathematical framework based on discrete geometry to model biological and synthetic self-assembly. Our primary biological example is the self-assembly of icosahedral viruses; our synthetic example is surface-tension-driven self-folding polyhedra. In both instances, the process of self-assembly is modeled by decomposing the polyhedron into a set of partially formed intermediate states. The set of all intermediates is called the configuration space, pathways of assembly are modeled as paths in the configuration space, and the kinetics and yield of assembly are modeled by rate equations, Markov chains, or cost functions on the configuration space. We review an interesting interplay between biological function and mathematical structure in viruses in light of this framework. We discuss in particular: (i) tiling theory as a coarse-grained description of all-atom models; (ii) the building game-a growth model for the formation of polyhedra; and (iii) the application of these models to the self-assembly of the bacteriophage MS2. We then use a similar framework to model self-folding polyhedra. We use a discrete folding algorithm to compute a configuration space that idealizes surface-tension-driven self-folding and analyze pathways of assembly and dominant intermediates. These computations are then compared with experimental observations of a self-folding dodecahedron with side 300 μm. In both models, despite a combinatorial explosion in the size of the configuration space, a few pathways and intermediates dominate self-assembly. For self-folding polyhedra, the dominant intermediates have fewer degrees of freedom than comparable intermediates, and are thus more rigid. The concentration of assembly pathways on a few intermediates with distinguished geometric properties is biologically and physically important, and suggests deeper mathematical structure.

  19. Atomic Layer Deposition on Carbon Nanotubes and their Assemblies

    Science.gov (United States)

    Stano, Kelly Lynn

    Global issues related to energy and the environment have motivated development of advanced material solutions outside of traditional metals ceramics, and polymers. Taking inspiration from composites, where the combination of two or more materials often yields superior properties, the field of organic-inorganic hybrids has recently emerged. Carbon nanotube (CNT)-inorganic hybrids have drawn widespread and increasing interest in recent years due to their multifunctionality and potential impact across several technologically important application areas. Before the impacts of CNT-inorganic hybrids can be realized however, processing techniques must be developed for their scalable production. Optimization in chemical vapor deposition (CVD) methods for synthesis of CNTs and vertically aligned CNT arrays has created production routes both high throughput and economically feasible. Additionally, control of CVD parameters has allowed for growth of CNT arrays that are able to be drawn into aligned sheets and further processed to form a variety of aligned 1, 2, and 3-dimensional bulk assemblies including ribbons, yarns, and foams. To date, there have only been a few studies on utilizing these bulk assemblies for the production of CNT-inorganic hybrids. Wet chemical methods traditionally used for fabricating CNT-inorganic hybrids are largely incompatible with CNT assemblies, since wetting and drying the delicate structures with solvents can destroy their structure. It is therefore necessary to investigate alternative processing strategies in order to advance the field of CNT-inorganic hybrids. In this dissertation, atomic layer deposition (ALD) is evaluated as a synthetic route for the production of large-scale CNT-metal oxide hybrids as well as pure metal oxide architectures utilizing CNT arrays, ribbons, and ultralow density foams as deposition templates. Nucleation and growth behavior of alumina was evaluated as a function of CNT surface chemistry. While highly graphitic

  20. Aqueous cholesteric liquid crystals using uncharged rodlike polypeptides. Polypeptide vesicles by conformation-specific assembly. Ordered chiral macroporous hybrid silica-polypeptide composites

    Science.gov (United States)

    Bellomo, Enrico Giuseppe

    2005-07-01

    Aqueous cholesteric liquid crystals using uncharged rodlike polypeptides . The aqueous, lyotropic liquid-crystalline phase behavior of an alpha helical polypeptide, has been studied using optical microscopy and X-ray scattering. Solutions of optically pure polypeptide were found to form cholesteric liquid crystals at volume fractions that decreased with increasing average chain length. At very high volume fractions, the formation of a hexagonal mesophase was observed. The pitch of the cholesteric phase could be varied by a mixture of enantiomeric samples, where the pitch increased as the mixture approached equimolar. The cholesteric phases could be untwisted, using either magnetic field or shear flow, into nematic phases, which relaxed into cholesterics upon removal of field or shear. We have found that the phase diagram of this polypeptide in aqueous solution parallels that of poly(gamma-benzyl glutamate) in organic solvents, thus providing a useful system for liquid-crystal applications requiring water as solvent. Polypeptide vesicles by conformation-specific assembly. We have found that block copolymers composed of polypeptide segments provide significant advantages in controlling both the function and supramolecular structure of bioinspired self-assemblies. Incorporation of the stable chain conformations found in proteins into block copolymers was found to provide an additional element of control, beyond amphiphilicity and composition that defines self-assembled architecture. The abundance of functionality present in amino acids, and the ease by which they can be incorporated into these materials, also provides a powerful mechanism to impart block copolypeptides with function. This combination of structure and function work synergistically to enable significant advantages in the preparation of therapeutic agents as well as provide insight into design of self-assemblies beginning to approach the complexity of natural structures such as virus capsids. Ordered

  1. Design strategies for self-assembly of discrete targets

    International Nuclear Information System (INIS)

    Madge, Jim; Miller, Mark A.

    2015-01-01

    Both biological and artificial self-assembly processes can take place by a range of different schemes, from the successive addition of identical building blocks to hierarchical sequences of intermediates, all the way to the fully addressable limit in which each component is unique. In this paper, we introduce an idealized model of cubic particles with patterned faces that allows self-assembly strategies to be compared and tested. We consider a simple octameric target, starting with the minimal requirements for successful self-assembly and comparing the benefits and limitations of more sophisticated hierarchical and addressable schemes. Simulations are performed using a hybrid dynamical Monte Carlo protocol that allows self-assembling clusters to rearrange internally while still providing Stokes-Einstein-like diffusion of aggregates of different sizes. Our simulations explicitly capture the thermodynamic, dynamic, and steric challenges typically faced by self-assembly processes, including competition between multiple partially completed structures. Self-assembly pathways are extracted from the simulation trajectories by a fully extendable scheme for identifying structural fragments, which are then assembled into history diagrams for successfully completed target structures. For the simple target, a one-component assembly scheme is most efficient and robust overall, but hierarchical and addressable strategies can have an advantage under some conditions if high yield is a priority

  2. Formation of self assembled PbTe quantum dots in CdTe on Si(111)

    Science.gov (United States)

    Felder, F.; Fognini, A.; Rahim, M.; Fill, M.; Müller, E.; Zogg, H.

    2010-01-01

    We describe the growth and formation of self assembled PbTe quantum dots in a CdTe host on a silicon (111) substrate. Annealing yields different photoluminescence spectra depending on initial PbTe layer thickness, thickness of the CdTe cap layer and annealing temperature. Generally two distinct emission peaks at ˜0.3 eV and ˜0.45 eV are visible. Model calculations explaining their temperature dependence are performed. The dot size corresponds well with the estimated sizes from electron microscopy images. The quantum dots may be used as absorber within a mid-infrared detector.

  3. Organic Nano vesicular Cargoes for Sustained Drug Delivery: Synthesis, Vesicle Formation, Controlling “Pearling” States, and Terfenadine Loading/Release Studies

    International Nuclear Information System (INIS)

    Botcha, A.K.; Chandrasekar, R.; Dulla, B.; Reddy, E.R.; Rajadurai, M.S.; Chennubhotla, K.S.; Kulkarni, P.; Kulkarni, P.

    2014-01-01

    “Sustained drug delivery systems” which are designed to accomplish long-lasting therapeutic effect are one of the challenging topics in the area of nano medicine. We developed an innovative strategy to prepare nontoxic and polymer stabilized organic nano vesicles (diameter: 200 nm) from a novel bolaamphiphile, where two hydrogen bonding acetyl cytosine molecules connected to 4,4′′-positions of the 2,6-bispyrazolylpyridine through two flexible octyne chains. The nano vesicles behave like biological membrane by spontaneously self-assembling into “pearl-like” chains and subsequently forming long nano tubes (diameter: 150 nm), which further develop into various types of network-junctions through self-organization. For drug loading and delivery applications, the nano vesicles were externally protected with biocompatible poly(ethyleneglycol)-2000 to prevent them from fusion and ensuing tube formation. Nontoxic nature of the nano vesicles was demonstrated by zebra fish teratogenicity assay. Biocompatible nano vesicles were loaded with “terfenadine” drug and successfully utilized to transport and release drug in sustained manner (up to 72 h) in zebra fish larvae, which is recognized as an emerging in vivo model system Synthetic nano

  4. Preparation and characterization of layer-by-layer self-assembled polyelectrolyte multilayer films doped with surface-capped SiO2 nanoparticles.

    Science.gov (United States)

    Yang, Guangbin; Ma, Hongxia; Yu, Laigui; Zhang, Pingyu

    2009-05-15

    SiO(2) nanoparticles capped with gamma-aminopropyltrimethoxysilane were doped into polyelectrolyte (poly(allylamine hydrochloride), PAH, and poly(acrylic acid), PAA) multilayer films via spin-assisted layer-by-layer self-assembly. The resulting as-prepared multilayer films were heated at a proper temperature to generate cross-linked composite films with increased adhesion to substrates. The tribological behavior of the multilayer films was evaluated on a microtribometer. It was found that SiO(2)-doped composite films had better wear resistance than pure polyelectrolyte multilayers, possibly because doped SiO(2) nanoparticles were capable of enhancing load-carrying capacity and had "miniature ball bearings" effect. Moreover, heat-treatment had significant effect on the morphology of the composite films. Namely, heat-treated (SiO(2)/PAA)(9) film had a larger roughness than the as-prepared one, due to heat-treatment-induced agglomeration of SiO(2) nanoparticles and initiation of defects. However, heat-treated (PAH/PAA)(3)/(SiO(2)/PAA)(3)(PAH/PAA)(3) film had greatly reduced roughness than the as-prepared one, and it showed considerably improved wear resistance as well. This could be closely related to the "sandwich-like" structure of the composite multilayer film. Namely, the outermost strata of composite multilayer film were able to eliminate defects associated with the middle strata, allowing nanoparticles therein to maintain strength and robustness while keeping soft and fluid-like exposed surface. And the inner strata were well anchored to substrate and acted as an initial "bed" for SiO(2) nanoparticles to be inhabited, resulting in good antiwear ability.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  6. Bioinspired peptide nanotubes: Deposition technology and physical properties

    International Nuclear Information System (INIS)

    Shklovsky, J.; Beker, P.; Amdursky, N.; Gazit, E.; Rosenman, G.

    2010-01-01

    Proteins and peptides have the intrinsic ability to self-assemble into elongated solid nanofibrils, which give rise to amyloid progressive neurodegenerative diseases (Alzheimer's, Parkinson, etc.). It has been found that of the core recognition motif of Aβ peptide is the diphenylalanine element. The diphenylalanine peptide can self-assemble into well-ordered peptide nanotubes (PNT). In this paper we report on our newly developed process-vapor deposition of PNT and 'bottom-up' nanotechnological techniques of PNT patterning. Study of several physical properties of PNT such as optical and electrochemical are presented. The results may lead to the development of a new generation of PNT-based bioinspired functional nanodevices.

  7. Polymorphism of lipid self-assembly systems

    International Nuclear Information System (INIS)

    Takahashi, Hiroshi

    2002-01-01

    When lipid molecules are dispersed into an aqueous medium, various self-organized structures are formed, depending on conditions (temperature, concentration, etc), in consequence of the amphipathic nature of the molecules. In addition, lipid self-assembly systems exhibit polymorphic phase transition behavior. Since lipids are one of main components of biomembranes, studies on the structure and thermodynamic properties of lipid self-assembly systems are fundamentally important for the consideration of the stability of biomembranes. (author)

  8. Toward a molecular programming language for algorithmic self-assembly

    Science.gov (United States)

    Patitz, Matthew John

    Self-assembly is the process whereby relatively simple components autonomously combine to form more complex objects. Nature exhibits self-assembly to form everything from microscopic crystals to living cells to galaxies. With a desire to both form increasingly sophisticated products and to understand the basic components of living systems, scientists have developed and studied artificial self-assembling systems. One such framework is the Tile Assembly Model introduced by Erik Winfree in 1998. In this model, simple two-dimensional square 'tiles' are designed so that they self-assemble into desired shapes. The work in this thesis consists of a series of results which build toward the future goal of designing an abstracted, high-level programming language for designing the molecular components of self-assembling systems which can perform powerful computations and form into intricate structures. The first two sets of results demonstrate self-assembling systems which perform infinite series of computations that characterize computably enumerable and decidable languages, and exhibit tools for algorithmically generating the necessary sets of tiles. In the next chapter, methods for generating tile sets which self-assemble into complicated shapes, namely a class of discrete self-similar fractal structures, are presented. Next, a software package for graphically designing tile sets, simulating their self-assembly, and debugging designed systems is discussed. Finally, a high-level programming language which abstracts much of the complexity and tedium of designing such systems, while preventing many of the common errors, is presented. The summation of this body of work presents a broad coverage of the spectrum of desired outputs from artificial self-assembling systems and a progression in the sophistication of tools used to design them. By creating a broader and deeper set of modular tools for designing self-assembling systems, we hope to increase the complexity which is

  9. Small unilamellar vesicles as reagents: a chemically defined, quantitative assay for lectins

    Energy Technology Data Exchange (ETDEWEB)

    Rando, R.R.

    1981-01-01

    Samll unilamellar vesicles containing synthetic glycolipids can be prepared. These vesicles are aggregated by the appropriate lectin (Orr et al., 1979; Rando and Bangerter, 1979; Slama and Rando, 1980). It is shown here that extent of aggregation of these vesicles as measured by light scattering at 360 nm, is, under certain conditions, linear with amount of lectin added. This forms the basis of a rapid and simple quantitative assay for lectins using the modified vesicles as a defined chemical substrate. The assay is sensitive to lectin concentrations in the low ..mu..g range. The assay is applied here to studies on concanavalin A, Ricinus communis agglutinin and the ..cap alpha..-fucosyl binding lectin from Ulex europaeus (Type I).

  10. Rosette nanotubes show low acute pulmonary toxicity in vivo

    Directory of Open Access Journals (Sweden)

    W Shane Journeay

    2008-10-01

    Full Text Available W Shane Journeay1, Sarabjeet S Suri1, Jesus G Moralez2, Hicham Fenniri2, Baljit Singh11Immunology Research Group, Toxicology Graduate Program and Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, S7N 5B4, Canada; 2National Institute of Nanotechnology, National Research Council (NINT-NRC and Department of Chemistry, University of Alberta, 11421 Saskatchewan Drive, Edmonton, AB, T6G 2M9, CanadaAbstract: Nanotubes are being developed for a large variety of applications ranging from electronics to drug delivery. Common carbon nanotubes such as single-walled and multi-walled carbon nanotubes have been studied in the greatest detail but require solubilization and removal of catalytic contaminants such as metals prior to being introduced to biological systems for medical application. The present in vivo study characterizes the degree and nature of inflammation caused by a novel class of self-assembling rosette nanotubes, which are biologically inspired, naturally water-soluble and free of metal content upon synthesis. Upon pulmonary administration of this material we examined responses at 24 h and 7d post-exposure. An acute inflammatory response is triggered at 50 and 25 μg doses by 24 h post-exposure but an inflammatory response is not triggered by a 5 μg dose. Lung inflammation observed at a 50 μg dose at 24 h was resolving by 7d. This work suggests that novel nanostructures with biological design may negate toxicity concerns for biomedical applications of nanotubes. This study also demonstrates that water-soluble rosette nanotube structures represent low pulmonary toxicity, likely due to their biologically inspired design, and their self-assembled architecture.Keywords: nanotoxicology, biocompatibility, nanomedicine, pulmonary drug delivery, lung inflammation

  11. Self-assembled Ti3C2Tx/SCNT composite electrode with improved electrochemical performance for supercapacitor.

    Science.gov (United States)

    Fu, Qishan; Wang, Xinyu; Zhang, Na; Wen, Jing; Li, Lu; Gao, Hong; Zhang, Xitian

    2018-02-01

    Two-dimensional titanium carbide has gained considerable attention in recent years as an electrode material for supercapacitors due to its high melting point, good electrical conductivity, hydrophilicity and large electrochemically active surfaces. However, the irreversible restacking during synthesis restricts its development and practical applications. Here, Ti 3 C 2 T x /SCNT self-assembled composite electrodes were rationally designed and successfully synthesized by introducing single-walled carbon nanotubes (SCNTs) as interlayer spacers to decrease the restacking of the Ti 3 C 2 T x sheets during the synthesis process. SCNTs can not only increase the specific surface area as well as the interlayer space of the Ti 3 C 2 T x electrode, but also increase the accessible capability of electrolyte ions, and thus it improved the electrochemical performance of the electrode. The as-prepared Ti 3 C 2 T x /SCNT self-assembled composite electrode achieved a high areal capacitance of 220mF/cm 2 (314F/cm 3 ) and a remarkable capacitance retention of 95% after 10,000cycles. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Self-grafting carbon nanotubes on polymers for stretchable electronics

    Science.gov (United States)

    Morales, Piero; Moyanova, Slavianka; Pavone, Luigi; Fazi, Laura; Mirabile Gattia, Daniele; Rapone, Bruno; Gaglione, Anderson; Senesi, Roberto

    2018-06-01

    Elementary bidimensional circuitry made of single-wall carbon-nanotube-based conductors, self-grafted on different polymer films, is accomplished in an attempt to develop a simple technology for flexible and stretchable electronic devices. Unlike in other studies of polymer-carbon nanotube composites, no chemical functionalization of single-wall carbon nanotubes is necessary for stable grafting onto several polymeric surfaces, suggesting viable and cheap fabrication technologies for stretchable microdevices. Electrical characterization of both unstretched and strongly stretched conductors is provided, while an insight on the mechanisms of strong adhesion to the polymer is obtained by scanning electron microscopy of the surface composite. As a first example of technological application, the electrical functionality of a carbon-nanotube-based 6-sensor (electrode) grid was demonstrated by recording of subdural electrocorticograms in freely moving rats over approximately three months. The results are very promising and may serve as a basis for future work targeting clinical applications.

  13. Theoretical Simulation on the Assembly of Carbon Nanotubes Between Electrodes by AC Dielectrophoresis

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2008-01-01

    Full Text Available Abstract The assembly of single-walled carbon nanotubes (SWCNTs using the AC dielectrophoresis technique is studied theoretically. It is found that the comb electrode bears better position control of SWCNTs compared to the parallel electrode. In the assembly, when some SWCNTs bridge the electrode first, they can greatly alter the local electrical field so as to “screen off” later coming SWCNTs, which contributes to the formation of dispersed SWCNT array. The screening distance scales with the gap width of electrodes and the length of SWCNTs, which provides a way to estimate the assembled density of SWCNTs. The influence of thermal noise on SWCNTs alignment is also analyzed in the simulation. It is shown that the status of the array distribution for SWCNTs is decided by the competition between the thermal noise and the AC electric-field strength. This influence of the thermal noise can be suppressed by using higher AC voltage to assemble the SWCNTs.

  14. Vesicles and vesicle gels - structure and dynamics of formation

    International Nuclear Information System (INIS)

    Gradzielski, M

    2003-01-01

    Vesicles constitute an interesting morphology formed by self-aggregating amphiphilic molecules. They exhibit a rich structural variety and are of interest both from a fundamental point of view (for studying closed bilayer systems) and from a practical point of view (whenever one is interested in the encapsulation of active molecules). In many circumstances vesicular structures have to be formed by external forces, but of great interest are amphiphilic systems, where they form spontaneously. Here the question arises of whether this means that they are also thermodynamically stable structures, which at least in some systems appears to be the case. If such vesicles are well defined in size, it is possible to pack them densely and thereby form vesicle gels that possess highly elastic properties even for relatively low volume fractions of amphiphile. Conditions for the formation and the microstructure of such vesicle gels have been studied in some detail for the case of unilamellar vesicles. Another important and topical issue is the dynamics of vesicle formation/breakdown, as the understanding of the transition process will open the way to a deeper understanding of their stability and also allow controlling of the structures formed, by means of their formation processes. Significant progress in the study of the transformation processes has been achieved, in particular by means of time-resolved scattering experiments. (topical review)

  15. Time-resolved small-angle neutron scattering of a micelle-to-vesicle transition

    Energy Technology Data Exchange (ETDEWEB)

    Egelhaaf, S U [Institut Max von Laue - Paul Langevin (ILL), 38 -Grenoble (France); Schurtenberger, P [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-04-01

    Amphiphilic molecules spontaneously self-assemble in solution to form a variety of aggregates. Only limited information is available on the kinetics of the structural transitions as well as on the existence of non-equilibrium or metastable states. Aqueous mixtures of lecithin and bile salt are very interesting biological model-systems which exhibit a spontaneous transition from polymer-like mixed micelles to vesicles upon dilution. The small-angle neutron scattering (SANS) instrument D22, with its very high neutron flux and the broad range of scattering vectors covered in a single instrumental setting, allowed us for the first time to perform time-resolved scattering experiments in order to study the micelle-to-vesicle transition. The temporal evolution of the aggregate structures were followed and detailed information was obtained even on molecular length-scales. (author). 5 refs.

  16. Equation of State for Phospholipid Self-Assembly

    DEFF Research Database (Denmark)

    Marsh, Derek

    2016-01-01

    Phospholipid self-assembly is the basis of biomembrane stability. The entropy of transfer from water to self-assembled micelles of lysophosphatidylcholines and diacyl phosphatidylcholines with different chain lengths converges to a common value at a temperature of 44°C. The corresponding enthalpies...... of transfer converge at ∼-18°C. An equation of state for the free energy of self-assembly formulated from this thermodynamic data depends on the heat capacity of transfer as the sole parameter needed to specify a particular lipid. For lipids lacking calorimetric data, measurement of the critical micelle...

  17. Simultaneous alignment and dispersion of carbon nanotubes with lyotropic liquid crystals

    NARCIS (Netherlands)

    Lagerwall, J.P.F.; Scalia, G.; Haluska, M.; Dettlaff-Weglikowska, U.; Giesselmann, F.; Roth, S.

    2006-01-01

    We demonstrate that single-wall carbon nanotubes (SWCNTs) can be macroscopically aligned by means of templating in a lyotropic nematic liquid crystal (LC), a self-assembling anisotropic fluid with orientational but no translational order. The CNTs spontaneously adopt the alignment of the host, as we

  18. Hierarchical self-assembly of a bow-shaped molecule bearing self-complementary hydrogen bonding sites into extended supramolecular assemblies.

    Science.gov (United States)

    Ikeda, Masato; Nobori, Tadahito; Schmutz, Marc; Lehn, Jean-Marie

    2005-01-07

    The bow-shaped molecule 1 bearing a self-complementary DAAD-ADDA (D=donor A=acceptor) hydrogen-bonding array generates, in hydrocarbon solvents, highly ordered supramolecular sheet aggregates that subsequently give rise to gels by formation of an entangled network. The process of hierarchical self-assembly of compound 1 was investigated by the concentration and temperature dependence of UV-visible and (1)H NMR spectra, fluorescence spectra, and electron microscopy data. The temperature dependence of the UV-visible spectra indicates a highly cooperative process for the self-assembly of compound 1 in decaline. The electron micrograph of the decaline solution of compound 1 (1.0 mM) revealed supramolecular sheet aggregates forming an entangled network. The selected area electronic diffraction patterns of the supramolecular sheet aggregates were typical for single crystals, indicative of a highly ordered assembly. The results exemplify the generation, by hierarchical self-assembly, of highly organized supramolecular materials presenting novel collective properties at each level of organization.

  19. 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.

  20. Colloidal Self-Assembly Driven by Deformability & Near-Critical Phenomena

    NARCIS (Netherlands)

    Evers, C.H.J.|info:eu-repo/dai/nl/338775188

    2016-01-01

    Self-assembly is the spontaneous formation of patterns or structures without human intervention. This thesis aims to increase our understanding of self-assembly. In self-assembly of proteins, the building blocks are very small and complex. Consequently, grasping the basic principles that drive the

  1. Electrical investigations of layer-by-layer films of carbon nanotubes

    International Nuclear Information System (INIS)

    Palumbo, M; Lee, K U; Ahn, B T; Suri, A; Coleman, K S; Zeze, D; Wood, D; Pearson, C; Petty, M C

    2006-01-01

    Single-wall carbon nanotubes (SWNTs) with anionic or cationic coatings have been prepared by exploiting the ability of certain surfactants to form a monolayer shell around the nanotube. The presence of electrically charged functional groups on the surface of the SWNT allows thin film deposition to proceed via the electrostatic layer-by-layer method. This self-assembly process was monitored using the quartz microbalance technique and Raman spectroscopy, while the morphology of the resulting thin layers was studied with atomic force microscopy. A variety of different architectures has been built up. In one arrangement, a single species of a modified SWNT (anionic or cationic) was alternated with a passive polymer to form a composite structure. A 'superlattice' architecture comprising alternating anionic and cationic modified nanotubes was also fabricated. The in-plane and out-of-plane dc conductivities of the films were measured at room temperature and contrasted with reference architectures (i.e. those containing no nanotubes). The results showed clearly that the incorporation of SWNTs into the multilayer assemblies provided electrically conductive thin films. It is suggested that the current versus voltage behaviour, particularly in the out-of-plane direction, is controlled by quantum mechanical tunnelling of carriers between the nanotubes

  2. Quantifying quality in DNA self-assembly

    Science.gov (United States)

    Wagenbauer, Klaus F.; Wachauf, Christian H.; Dietz, Hendrik

    2014-01-01

    Molecular self-assembly with DNA is an attractive route for building nanoscale devices. The development of sophisticated and precise objects with this technique requires detailed experimental feedback on the structure and composition of assembled objects. Here we report a sensitive assay for the quality of assembly. The method relies on measuring the content of unpaired DNA bases in self-assembled DNA objects using a fluorescent de-Bruijn probe for three-base ‘codons’, which enables a comparison with the designed content of unpaired DNA. We use the assay to measure the quality of assembly of several multilayer DNA origami objects and illustrate the use of the assay for the rational refinement of assembly protocols. Our data suggests that large and complex objects like multilayer DNA origami can be made with high strand integration quality up to 99%. Beyond DNA nanotechnology, we speculate that the ability to discriminate unpaired from paired nucleic acids in the same macromolecule may also be useful for analysing cellular nucleic acids. PMID:24751596

  3. Self assembly of organic nanostructures and dielectrophoretic assembly of inorganic nanowires.

    Science.gov (United States)

    Dholakia, Geetha; Kuo, Steven; Allen, E. L.

    2007-03-01

    Self assembly techniques enable the organization of organic molecules into nanostructures. Currently engineering strategies for efficient assembly and routine integration of inorganic nanoscale objects into functional devices is very limited. AC Dielectrophoresis is an efficient technique to manipulate inorganic nanomaterials into higher dimensional structures. We used an alumina template based sol-gel synthesis method for the growth of various metal oxide nanowires with typical diameters of 100-150 nm, ranging in length from 3-10 μm. Here we report the dielectrophoretic assembly of TiO2 nanowires, an important material for photocatalysis and photovoltaics, onto interdigitated devices. Self assembly in organic nanostructures and its dependence on structure and stereochemistry of the molecule and dielectrophoretic field dependence in the assembly of inorganic nanowires will be compared and contrasted. Tunneling spectroscopy and DOS of these nanoscale systems will also be discussed.

  4. Mannose-decorated cyclodextrin vesicles: The interplay of multivalency and surface density in lectin–carbohydrate recognition

    Directory of Open Access Journals (Sweden)

    Ulrike Kauscher

    2012-09-01

    Full Text Available Cyclodextrin vesicles are versatile models for biological cell membranes since they provide a bilayer membrane that can easily be modified by host–guest interactions with functional guest molecules. In this article, we investigate the multivalent interaction of the lectin concanavalin A (ConA with cyclodextrin vesicles decorated with mannose–adamantane conjugates with one, two or three adamantane units as well as one or two mannose units. The carbohydrate–lectin interaction in this artificial, self-assembled glycocalyx was monitored in an agglutination assay by the increase of optical density at 400 nm. It was found that there is a close relation between the carbohydrate density at the cyclodextrin vesicle surface and the multivalent interaction with ConA, and the most efficient interaction (i.e., fastest agglutination at lowest concentration was observed for mannose–adamantane conjugates, in which both the cyclodextrin–adamantane and the lectin–mannose interaction is inherently multivalent.

  5. Centrioles: Some Self-Assembly Required

    OpenAIRE

    Song, Mi Hye; Miliaras, Nicholas B.; Peel, Nina; O'Connell, Kevin F.

    2008-01-01

    Centrioles play an important role in organizing microtubules and are precisely duplicated once per cell cycle. New (daughter) centrioles typically arise in association with existing (mother) centrioles (canonical assembly), suggesting that mother centrioles direct the formation of daughter centrioles. However, under certain circumstances, centrioles can also self-assemble free of an existing centriole (de novo assembly). Recent work indicates that the canonical and de novo pathways utilize a ...

  6. Improvement of the bio-functional properties of TiO{sub 2} nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Roguska, A. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Pisarek, M., E-mail: mpisarek@ichf.edu.pl [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Belcarz, A. [Chair and Department of Biochemistry and Biotechnology, Medical University of Lublin, Chodźki 1, 20-093 Lublin (Poland); Marcon, L. [Interdisciplinary Research Institute, USR CNRS 3078 Parc de la Haute Borne, 50 av. de Halley 59658 Villeneuve d’Ascq (France); Holdynski, M. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Andrzejczuk, M. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Janik-Czachor, M. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland)

    2016-12-01

    Highlights: • The methods of biofunctional properties improvement of TiO{sub 2} nanotubes are proposed. • The increase of TiO{sub 2} nanotubes diameter promotes the U2OS cell proliferation. • Calcium phosphate coating deposited TiO{sub 2} nanotube layer promotes the cell growth. • Deposition of Ag nanoparticles inhibits the survivability of S. epidermidis cells. - Abstract: Titanium oxide nanotubes with diameters from ca. 40–120 nm fabricated by the anodic oxidation of Ti at a constant voltage (10–28 V) were investigated to identify factors improving their bio-functional properties. Prepared substrates were subsequently annealed at 450 °C and 650 °C to obtain nanotubes having a crystalline structure, and were then examined by SEM, XRD, XPS, BET and contact angle measurement techniques. The thermally stabilized surfaces were subjected to bidirectional functionalization: by deposition of a thin layer of Ca-P and by loading with silver nanoparticles. Three factors were found to promote the proliferation of osteoblast (U2OS) cells: a larger nanotube diameter, a higher annealing temperature, and the presence of a thin Ca-P layer. Differentiation of these cells (by ALP test) was stimulated by a higher (650 °C) nanotube annealing temperature, but not by a thin Ca-P layer. The TiO{sub 2} nanotubes-modified samples exhibited noticeable antibacterial properties. Moreover, the additional deposition of Ag nanoparticles almost completely inhibited the survivability of S. epidermidis cells beyond 3 h of contact. In conclusion, TiO{sub 2} nanotubes-modified surfaces exhibit distinct bone forming ability and significant antibacterial properties, and can be easily functionalized by a thin Ca-P layer or nano-Ag deposition for further improvement of the above functionalities.

  7. 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.

  8. The self-assembly of monodisperse nanospheres within microtubes

    International Nuclear Information System (INIS)

    Zheng Yuebing; Juluri, Bala Krishna; Huang, Tony Jun

    2007-01-01

    Self-assembled monodisperse nanospheres within microtubes have been fabricated and characterized. In comparison with colloidal crystals formed on planar substrates, colloidal nanocrystals self-assembled in microtubes demonstrate high spatial symmetry in their optical transmission and reflection properties. The dynamic self-assembly process inside microtubes is investigated by combining temporal- and spatial-spectrophotometric measurements. The understanding of this process is achieved through both experimentally recorded reflection spectra and finite difference time domain (FDTD)-based simulation results

  9. Quantitative computational models of molecular self-assembly in systems biology.

    Science.gov (United States)

    Thomas, Marcus; Schwartz, Russell

    2017-05-23

    Molecular self-assembly is the dominant form of chemical reaction in living systems, yet efforts at systems biology modeling are only beginning to appreciate the need for and challenges to accurate quantitative modeling of self-assembly. Self-assembly reactions are essential to nearly every important process in cell and molecular biology and handling them is thus a necessary step in building comprehensive models of complex cellular systems. They present exceptional challenges, however, to standard methods for simulating complex systems. While the general systems biology world is just beginning to deal with these challenges, there is an extensive literature dealing with them for more specialized self-assembly modeling. This review will examine the challenges of self-assembly modeling, nascent efforts to deal with these challenges in the systems modeling community, and some of the solutions offered in prior work on self-assembly specifically. The review concludes with some consideration of the likely role of self-assembly in the future of complex biological system models more generally.

  10. Coccolithophores put a CAP on calcification and carbon

    Science.gov (United States)

    Rickaby, R. E. M.; Lee, R. B. Y.; Mavridou, D. A. I.; Papadakos, G.; McClelland, H. L. O.; Anderson, C. J.

    2014-12-01

    Unlike the majority of biomineralization, mediated via proteins, the coccolithophores employ acidic polysaccharides (CAPs) as the template for the multitude of intricate calcium carbonate liths which are precipitated inside their cells and expelled to form an external spherical armour. Massive accumulations of these calcium carbonate coccoliths (we estimate a flux of ~ 6x1025 liths/year) form sediments on the deep seafloor, a dominant sink of carbon from the atmosphere over geological timescales, and a buffer for seawater chemistry. This acidic, coccolith-associated polysaccharide (CAP) plays a dual role, likely determined by the calcifying vesicle chemistry, promoting and limiting precipitation. We have developed and demonstrated novel techniques for the extraction and characterisation of these biomineral-mediating molecules, encapsulated and preserved within liths from sediments as old as the Mesozoic. Modern cultures of extant coccolithophores show that the composition of CAP is distinctive for different species, and even strains of e.g. Emiliania huxleyi, suggestive that interactions with galacturonic acid residues are key to dictating the architecture of the liths. Furthermore, it appears that the galacturonic acid content reflects an adaptive response of the CAP to the chemistry within the coccolith vesicle where calcification is induced; in particular the size of the internal carbon pool and inferred saturation state. Extraction of CAPs from the Coccolithale fraction of sediments suggests that the galacturonic acid content of these relatively large and inefficient carbon concentrators evolves in response to declining CO2 availability and thus may provide a novel means for reconstructing paleo pCO2.

  11. Self-assembly growth of alloyed NiPt nanocrystals with holothuria-like shape for oxygen evolution reaction with enhanced catalytic activity

    Directory of Open Access Journals (Sweden)

    Tao Ding

    2016-01-01

    Full Text Available Self-assembly growth of alloyed NiPt nanocrystals with holothuria-like wire shape has been achieved via a facile and moderate hydrothermal process at 120 °C for 1 h from the reaction of nickel nitrate and chloroplatinic acid in alkaline solution in the presence of ethanediamine and hydrazine hydrate. The holothuria-like alloyed NiPt wires are Ni-rich in composition (Ni23.6Pt and uniform in diameter with many tiny tips outstretched from the wires surface. The holothuria-like wires are assembled from granular subunits with the assistance of capping molecular of ethanediamine and the wires display an improved oxygen evolution reaction catalytic activity.

  12. Efficient Photocatalytic Degradation of Rhodamine B Dye by Aligned Arrays of Self-Assembled Hydrogen Titanate Nanotubes

    Directory of Open Access Journals (Sweden)

    Sriparna Chatterjee

    2014-01-01

    Full Text Available We show that an aligned array of hydrothermally grown, multiwalled hydrogen titanate (H2Ti3O7 nanotubes—anchored to both faces of a metallic Ti foil—acts as an efficient photocatalyst. We studied the degradation of rhodamine B dye in the presence of the nanostructured photocatalyst under UV irradiation, by monitoring the optical absorption of the dye. Rhodamine B was chosen as a representative—and particularly harmful—industrial pollutant dye. The inner and outer diameters of the H2Ti3O7 nanotubes were 5 nm and 10 nm, respectively. The nanotube array catalyst is recyclable and structurally stable. Most importantly, it shows comparable or higher photodecomposition rate constant than those of both H2Ti3O7 nanotube powder and P-25 (Degussa. The enhanced photocatalytic performance may be ascribed to the nanotube array having a superhydrophilic surface with a high accessible surface area.

  13. Centrioles: some self-assembly required.

    Science.gov (United States)

    Song, Mi Hye; Miliaras, Nicholas B; Peel, Nina; O'Connell, Kevin F

    2008-12-01

    Centrioles play an important role in organizing microtubules and are precisely duplicated once per cell cycle. New (daughter) centrioles typically arise in association with existing (mother) centrioles (canonical assembly), suggesting that mother centrioles direct the formation of daughter centrioles. However, under certain circumstances, centrioles can also selfassemble free of an existing centriole (de novo assembly). Recent work indicates that the canonical and de novo pathways utilize a common mechanism and that a mother centriole spatially constrains the self-assembly process to occur within its immediate vicinity. Other recently identified mechanisms further regulate canonical assembly so that during each cell cycle, one and only one daughter centriole is assembled per mother centriole.

  14. DNAzyme-Based Logic Gate-Mediated DNA Self-Assembly.

    Science.gov (United States)

    Zhang, Cheng; Yang, Jing; Jiang, Shuoxing; Liu, Yan; Yan, Hao

    2016-01-13

    Controlling DNA self-assembly processes using rationally designed logic gates is a major goal of DNA-based nanotechnology and programming. Such controls could facilitate the hierarchical engineering of complex nanopatterns responding to various molecular triggers or inputs. Here, we demonstrate the use of a series of DNAzyme-based logic gates to control DNA tile self-assembly onto a prescribed DNA origami frame. Logic systems such as "YES," "OR," "AND," and "logic switch" are implemented based on DNAzyme-mediated tile recognition with the DNA origami frame. DNAzyme is designed to play two roles: (1) as an intermediate messenger to motivate downstream reactions and (2) as a final trigger to report fluorescent signals, enabling information relay between the DNA origami-framed tile assembly and fluorescent signaling. The results of this study demonstrate the plausibility of DNAzyme-mediated hierarchical self-assembly and provide new tools for generating dynamic and responsive self-assembly systems.

  15. The Bretherton Problem for a Vesicle

    Science.gov (United States)

    Barakat, Joseph; Spann, Andrew; Shaqfeh, Eric

    2016-11-01

    The motion of a lipid bilayer vesicle through a circular tube is investigated by singular perturbation theory in the limit of vanishing clearance. The vesicle is treated as a sac of fluid enclosed by a thin, elastic sheet that admits a bending stiffness. It is assumed that the vesicle is axisymmetric and swollen to a near-critical volume such that the clearance "e" between the membrane and the tube wall is very small. In this limit, bending resistance is of negligible importance compared to the isotropic tension, allowing the vesicle to be treated as a "no-slip bubble." The effective membrane tension is found to scale inversely with "e" raised to the 3/2 power with a comparatively weak Marangoni gradient. The extra pressure drop is found to have a leading contribution due to the cylindrical midsection, which scales inversely with "e," as well as a correction due to the end caps, which scales inversely with the square root of "e." The apparent viscosity is predicted as a unique function of the geometry. The theory exhibits excellent agreement with a simplified, "quasi-parallel" theory and with direct numerical simulations using the boundary element method. The results of this work are compared to those for bubbles, rigid particles, and red blood cells in confined flows.

  16. A homogeneous and “off–on” fluorescence aptamer-based assay for chloramphenicol using vesicle quantum dot-gold colloid composite probes

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yang-Bao [State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211 (China); Ren, Hong-Xia [Key Laboratory of Asymmetric Synthesis and Chirotechnology of Sichuan Province, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); University of Chinese Academy of Sciences, Beijing 10049 (China); Gan, Ning, E-mail: ganning@nbu.edu.cn [State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211 (China); Zhou, You [State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211 (China); Cao, Yuting, E-mail: caoyuting@nbu.edu.cn [State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211 (China); Li, Tianhua [State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211 (China); Chen, Yinji [Faculty of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210000 (China)

    2016-07-27

    In this work, a novel homogeneous and signal “off–on” aptamer based fluorescence assay was successfully developed to detect chloramphenicol (CAP) residues in food based on the fluorescence resonance energy transfer (FRET). The vesicle nanotracer was prepared through labeling single stranded DNA binding protein (SSB) on limposome-CdSe/ZnS quantum dot (SSB/L-QD) complexes. It was worth mentioning that the signal tracer (SSB/L-QD) with vesicle shape, which was fabricated being encapsulated with a number of quantum dots and SSB. The nanotracer has excellent signal amplification effects. The vesicle composite probe was formed by combining aptamer labeled nano-gold (Au-Apt) and SSB/L-QD. Which based on SSB's specific affinity towards aptamer. This probe can't emit fluoresce which is in “off” state because the signal from SSB/L-QD as donor can be quenched by the Au-aptas acceptor. When CAP was added in the composite probe solution, the aptamer on the Au-Apt can be preferentially bounded with CAP then release from the composite probe, which can turn the “off” signal of SSB/L-QD tracer into “on” state. The assay indicates excellent linear response to CAP from 0.001 nM to 10 nM and detection limit down to 0.3 pM. The vesicle probes with size of 88 nm have strong signal amplification. Because a larger number of QDs can be labeled inside the double phosphorus lipid membrane. Besides, it was employed to detect CAP residues in the milk samples with results being agreed well with those from ELISA, verifying its accuracy and reliability. - Highlights: • Homogeneous and “off–on” fluorescence aptamer-based assay was developed to detect chloramphenicol (CAP) residues in food. • This probe was fabricated based on a vesicle QDs signal tracer (SSB/L-QD) combining with Au-Aptamer. • The detection mechanism was based on FRET with high specificity. • The results for CAP detection in the milk samples agreed well with those from ELISA, while

  17. Freezing-induced self-assembly of amphiphilic molecules

    Science.gov (United States)

    Albouy, P. A.; Deville, S.; Fulkar, A.; Hakouk, K.; Impéror-Clerc, M.; Klotz, M.; Liu, Q.; Marcellini, M.; Perez, J.

    The self-assembly of amphiphilic molecules usually takes place in a liquid phase, near room temperature. Here, using small angle X-ray scattering (SAXS) experiments performed in real time, we show that freezing of aqueous solutions of copolymer amphiphilic molecules can induce self-assembly below 0{\\deg}C.

  18. Progress in LAr EndCap Calorimetry: News from the Hadronic EndCap Group.

    CERN Multimedia

    Oram, C.J.

    With module production and testing completed for the Hadronic EndCap calorimeter, the attention of the HEC group is heavily directed towards wheel assembly in building 180. Three of the four HEC wheels are now assembled and rotated, and work is progressing on assembling the final wheel. This year has been a busy year for the installation of components in the EndCap C cryostat: the signal feedthrough installation was completed April 22nd, the pre-sampler shortly thereafter and the Electro-Magnetic EndCap August 13th. This allowed the HEC group to start transferring the HEC wheels from the T6A storage cradle into the cryostat. The operation started in mid-September and has progressed, on or ahead of schedule, since then with the major milestones being: Insertion of 67 ton front HEC wheel October 3rd Insertion of 90 ton rear HEC wheel October 22nd. The wheel alignment has proved to be excellent, with the position of the centre of the front(rear) wheel with respect to the nominal position being displaced b...

  19. Oxide nanostructures through self-assembly

    Science.gov (United States)

    Aggarwal, S.; Ogale, S. B.; Ganpule, C. S.; Shinde, S. R.; Novikov, V. A.; Monga, A. P.; Burr, M. R.; Ramesh, R.; Ballarotto, V.; Williams, E. D.

    2001-03-01

    A prominent theme in inorganic materials research is the creation of uniformly flat thin films and heterostructures over large wafers, which can subsequently be lithographically processed into functional devices. This letter proposes an approach that will lead to thin film topographies that are directly counter to the above-mentioned philosophy. Recent years have witnessed considerable research activity in the area of self-assembly of materials, stimulated by observations of self-organized behavior in biological systems. We have fabricated uniform arrays of nonplanar surface features by a spontaneous assembly process involving the oxidation of simple metals, especially under constrained conditions on a variety of substrates, including glass and Si. In this letter we demonstrate the pervasiveness of this process through examples involving the oxidation of Pd, Cu, Fe, and In. The feature sizes can be controlled through the grain size and thickness of the starting metal thin film. Finally, we demonstrate how such submicron scale arrays can serve as templates for the design and development of self-assembled, nanoelectronic devices.

  20. Dynamics of self-assembled cytosine nucleobases on graphene

    Science.gov (United States)

    Saikia, Nabanita; Johnson, Floyd; Waters, Kevin; Pandey, Ravindra

    2018-05-01

    Molecular self-assembly of cytosine (C n ) bases on graphene was investigated using molecular dynamics methods. For free-standing C n bases, simulation conditions (gas versus aqueous) determine the nature of self-assembly; the bases prefer to aggregate in the gas phase and are stabilized by intermolecular H-bonds, while in the aqueous phase, the water molecules disrupt base-base interactions, which facilitate the formation of π-stacked domains. The substrate-induced effects, on the other hand, find the polarity and donor-acceptor sites of the bases to govern the assembly process. For example, in the gas phase, the assembly of C n bases on graphene displays short-range ordered linear arrays stabilized by the intermolecular H-bonds. In the aqueous phase, however, there are two distinct configurations for the C n bases assembly on graphene. For the first case corresponding to low surface coverage, the bases are dispersed on graphene and are isolated. The second configuration archetype is disordered linear arrays assembled with medium and high surface coverage. The simulation results establish the role of H-bonding, vdW π-stacking, and the influence of graphene surface towards the self-assembly. The ability to regulate the assembly into well-defined patterns can aid in the design of self-assembled nanostructures for the next-generation DNA based biosensors and nanoelectronic devices.

  1. DNA-assisted assembly of carbon nanotubes and MnO2 nanospheres as electrodes for high-performance asymmetric supercapacitors.

    Science.gov (United States)

    Guo, Chun Xian; Chitre, Amey Anil; Lu, Xianmao

    2014-03-14

    A DNA-assisted assembly approach is developed to fabricate a capacitor-type electrode material, DNA-functionalized carbon nanotubes (CNTs@DNA), and a battery-type electrode material, DNA@CNTs-bridged MnO2 spheres (CNTs@DNA-MnO2), for asymmetric supercapacitors. An energy density of 11.6 W h kg(-1) is achieved at a power density of 185.5 W kg(-1) with a high MnO2 mass loading of 4.2 mg cm(-2). It is found that DNA assembly plays a critical role in the enhanced supercapacitor performance. This is because while DNA molecules functionalize carbon nanotubes (CNTs) via π-π stacking, their hydrophilic sugar-phosphate backbones also promote the dispersion of CNTs. The resultant CNTs@DNA chains can link multiple MnO2 spheres to form a networked architecture that facilitates charge transfer and effective MnO2 utilization. The improved performance of the asymmetric supercapacitors indicates that DNA-assisted assembly offers a promising approach to the fabrication of high-performance energy storage devices.

  2. Self-Assembly in the Ferritin Nano-Cage Protein Superfamily

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    2011-08-01

    Full Text Available Protein self-assembly, through specific, high affinity, and geometrically constraining protein-protein interactions, can control and lead to complex cellular nano-structures. Establishing an understanding of the underlying principles that govern protein self-assembly is not only essential to appreciate the fundamental biological functions of these structures, but could also provide a basis for their enhancement for nano-material applications. The ferritins are a superfamily of well studied proteins that self-assemble into hollow cage-like structures which are ubiquitously found in both prokaryotes and eukaryotes. Structural studies have revealed that many members of the ferritin family can self-assemble into nano-cages of two types. Maxi-ferritins form hollow spheres with octahedral symmetry composed of twenty-four monomers. Mini-ferritins, on the other hand, are tetrahedrally symmetric, hollow assemblies composed of twelve monomers. This review will focus on the structure of members of the ferritin superfamily, the mechanism of ferritin self-assembly and the structure-function relations of these proteins.

  3. Ultrafine luminescent structures through nanoparticle self-assembly

    International Nuclear Information System (INIS)

    Prabhakaran, K; Goetzinger, S; Shafi, K V P M; Mazzei, A; Schietinger, S; Benson, O

    2006-01-01

    We report the fabrication of ultrafine structures consisting of regular arrays of nanoemitters through the self-assembly of luminescent nanoparticles on a silicon wafer. Nanoparticles of yttrium aluminium garnet (YAG) doped with Eu 3+ ions were synthesized by a sonochemical technique. These particles, suspended in ethanol, are introduced onto a pre-patterned silicon wafer, covered with a thin oxide layer. On annealing the sample in an ultrahigh-vacuum chamber, the nanoparticles self-assemble along the pattern. We demonstrate this 'chemical lithography' by assembling the nanoparticles along a variety of patterns. We believe that such self-organized nanopatterning of functional structures is important for the realization of nanodevices

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

    Science.gov (United States)

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

    2017-08-01

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

  5. Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerization

    International Nuclear Information System (INIS)

    Mu Bin; Zhao Mingfei; Liu Peng

    2008-01-01

    Halloysite nanotubes (HNTs) grafted hyperbranched polymers were prepared by the self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl)oxy)ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization of n-butyl acrylate (BA) and BAEA with BAEA as inimer (AB*) respectively, from the surfaces of the 2-bromoisobutyric acid modified halloysite nanotubes (HNTs-Br) via atom transfer radical polymerization (ATRP) technique. The halloysite nanotubes grafted hyperbranched polymer (HNTs-HP) and the halloysite nanotubes grafted hyperbranched copolymer (HNTs-HCP) were characterized by elemental analysis (EA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscope (TEM). The grafted hyperbranched polymers were characterized with Nuclear magnetic resonance (NMR) and the molecular ratio between the inimer AB* and BA in the grafted hyperbranched copolymers was found to be 3:2, calculated from the TGA and EA results

  6. Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Mu Bin; Zhao Mingfei; Liu Peng [Lanzhou University, State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering (China)], E-mail: pliu@lzu.edu.cn

    2008-05-15

    Halloysite nanotubes (HNTs) grafted hyperbranched polymers were prepared by the self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl)oxy)ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization of n-butyl acrylate (BA) and BAEA with BAEA as inimer (AB*) respectively, from the surfaces of the 2-bromoisobutyric acid modified halloysite nanotubes (HNTs-Br) via atom transfer radical polymerization (ATRP) technique. The halloysite nanotubes grafted hyperbranched polymer (HNTs-HP) and the halloysite nanotubes grafted hyperbranched copolymer (HNTs-HCP) were characterized by elemental analysis (EA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscope (TEM). The grafted hyperbranched polymers were characterized with Nuclear magnetic resonance (NMR) and the molecular ratio between the inimer AB* and BA in the grafted hyperbranched copolymers was found to be 3:2, calculated from the TGA and EA results.

  7. Hierarchical self-assembly of heparin-PEG end-capped porous silica as a redox sensitive nanocarrier for doxorubicin delivery

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Thi, Thu Thao; Tran, Tuong Vi; Tran, Ngoc Quyen [Institute of Research and Development, Duy Tan University, Da Nang City 550000 (Viet Nam); Institute of Applied Materials Science, Vietnam Academy of Science and Technology, Ho Chi Minh City 70000 (Viet Nam); Nguyen, Cuu Khoa [Institute of Applied Materials Science, Vietnam Academy of Science and Technology, Ho Chi Minh City 70000 (Viet Nam); Nguyen, Dai Hai, E-mail: nguyendaihai0511@gmail.com [Institute of Applied Materials Science, Vietnam Academy of Science and Technology, Ho Chi Minh City 70000 (Viet Nam)

    2017-01-01

    Porous nanosilica (PNS) has been attracting a great attention in fabrication carriers for drug delivery system (DDS). However, unmodified PNS-based carriers exhibited the initial burst release of loaded bioactive molecules, which may limit their potential clinical application. In this study, the surface of PNS was conjugated with adamantylamine (A) via disulfide bonds (PNS-SS-A) which was functionalized with cyclodextrin-heparin-polyethylene glycol (CD-HPEG) for redox triggered doxorubicin (DOX) delivery. The modified PNS was successfully formed with spherical shape and diameter around 50 nm determined by transmission electron microscopy (TEM). DOX was efficiently trapped in the PNS-SS-A@CD-HPEG and slowly released in phosphate buffered saline (PBS) without any initial burst effect. Importantly, the release of DOX was triggered due to the cleavage of the disulfide bonds in the presence of dithiothreitol (DTT). In addition, the MTT assay data showed that PNS-SS-A@CD-HPEG was a biocompatible nanocarrier and reduced the toxicity of DOX. These results demonstrated that PNS-SS-A@CD-HPEG has great potential as a novel nanocarrier for anticancer drug in cancer therapy. - Graphic abstract: Hierarchical self-assembly of heparin-PEG end-capped mesoporous silica through host-guest interaction for trapping doxorubicin. The copolymer attached on PNS via disulfide bond which is rapidly cleaved in redox environment, and as a result a huge amount of doxorubicin will release. - Highlights: • Novel redox-responsive nanocarriers based on surface-modified porous nanosilica (PNS) were developed. • Spherical-shaped PNS nanoparticles with diameter around 50 nm were obtained. • Doxorubicin (DOX) was effectively loaded and released in a controlled manner without any initial burst release by surface modification of PNS. • The redox-responsive properties of the modified PNS were demonstrated due to reductive cleavage of disulfide bonds in dithiothreitol (DTT). • The

  8. 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.

  9. Crops: a green approach toward self-assembled soft materials.

    Science.gov (United States)

    Vemula, Praveen Kumar; John, George

    2008-06-01

    To date, a wide range of industrial materials such as solvents, fuels, synthetic fibers, and chemical products are being manufactured from petroleum resources. However, rapid depletion of fossil and petroleum resources is encouraging current and future chemists to orient their research toward designing safer chemicals, products, and processes from renewable feedstock with an increased awareness of environmental and industrial impact. Advances in genetics, biotechnology, process chemistry, and engineering are leading to a new manufacturing concept for converting renewable biomass to valuable fuels and products, generally known as the biorefinery concept. The swift integration of crop-based materials synthesis and biorefinery manufacturing technologies offers the potential for new advances in sustainable energy alternatives and biomaterials that will lead to a new manufacturing paradigm. This Account presents a novel and emerging concept of generating various forms of soft materials from crops (an alternate feedstock). In future research, developing biobased soft materials will be a fascinating yet demanding practice, which will have direct impact on industrial applications as an economically viable alternative. Here we discuss some remarkable examples of glycolipids generated from industrial byproducts such as cashew nut shell liquid, which upon self-assembly produced soft nanoarchitectures including lipid nanotubes, twisted/helical nanofibers, low-molecular-weight gels, and liquid crystals. Synthetic methods applied to a "chiral pool" of carbohydrates using the selectivity of enzyme catalysis yield amphiphilic products derived from biobased feedstock including amygdalin, trehalose, and vitamin C. This has been achieved with a lipase-mediated regioselective synthetic procedure to obtain such amphiphiles in quantitative yields. Amygdalin amphiphiles showed unique gelation behavior in a broad range of solvents such as nonpolar hexanes to polar aqueous solutions

  10. Preparation and self-assembly of amphiphilic polylysine dendrons

    DEFF Research Database (Denmark)

    Mirsharghi, Sahar; Knudsen, Kenneth D.; Bagherifam, Shahla

    2016-01-01

    Polylysine dendrons with lipid tails prepared by divergent solid-phase synthesis showed self-assembling properties in aqueous solutions., Herein, we present the synthesis of new amphiphilic polylysine dendrons with variable alkyl chain lengths (C1–C18) at the C-terminal. The dendrons were...... synthesized in moderate to quantitative yields by divergent solid-phase synthesis (SPS) employing an aldehyde linker. The self-assembling properties of the dendrons in aqueous solutions were studied by small angle neutron scattering (SANS) and dynamic light scattering (DLS). The self-assembling properties...... were influenced by the length of the alkyl chain and the generation number (Gn). Increasing the temperature and concentration did not have significant impact on the hydrodynamic diameter, but the self-assembling properties were influenced by the pH value. This demonstrated the need for positively...

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

    Science.gov (United States)

    Kim, Kyunghee; Pochan, Darrin

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

  12. Cooperative effects of fibronectin matrix assembly and initial cell-substrate adhesion strength in cellular self-assembly.

    Science.gov (United States)

    Brennan, James R; Hocking, Denise C

    2016-03-01

    The cell-dependent polymerization of intercellular fibronectin fibrils can stimulate cells to self-assemble into multicellular structures. The local physical cues that support fibronectin-mediated cellular self-assembly are largely unknown. Here, fibronectin matrix analogs were used as synthetic adhesive substrates to model cell-matrix fibronectin fibrils having different integrin-binding specificity, affinity, and/or density. We utilized this model to quantitatively assess the relationship between adhesive forces derived from cell-substrate interactions and the ability of fibronectin fibril assembly to induce cellular self-assembly. Results indicate that the strength of initial, rather than mature, cell-substrate attachments correlates with the ability of substrates to support fibronectin-mediated cellular self-assembly. The cellular response to soluble fibronectin was bimodal and independent of the integrin-binding specificity of the substrate; increasing soluble fibronectin levels above a critical threshold increased aggregate cohesion on permissive substrates. Once aggregates formed, continuous fibronectin polymerization was necessary to maintain cohesion. During self-assembly, soluble fibronectin decreased cell-substrate adhesion strength and induced aggregate cohesion via a Rho-dependent mechanism, suggesting that the balance of contractile forces derived from fibronectin fibrils within cell-cell versus cell-substrate adhesions controls self-assembly and aggregate cohesion. Thus, initial cell-substrate attachment strength may provide a quantitative basis with which to build predictive models of fibronectin-mediated microtissue fabrication on a variety of substrates. Cellular self-assembly is a process by which cells and extracellular matrix (ECM) proteins spontaneously organize into three-dimensional (3D) tissues in the absence of external forces. Cellular self-assembly can be initiated in vitro, and represents a potential tool for tissue engineers to

  13. Self-assembling segmented coiled tubing

    Science.gov (United States)

    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.

  14. Sub-nanometer-resolution imaging of peptide nanotubes in water using frequency modulation atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sugihara, Tomoki; Hayashi, Itsuho; Onishi, Hiroshi [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Kimura, Kenjiro, E-mail: kimura@gold.kobe-u.ac.jp [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Tamura, Atsuo [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan)

    2013-06-20

    Highlights: ► Peptide nanotubes were aligned on highly oriented pyrolytic graphite surface. ► We visualized sub-nanometer-scale structure on peptide nanotube surface in water. ► We observed hydration structure at a peptide nanotube/water interface. - Abstract: Peptide nanotubes are self-assembled fibrous materials composed of cyclic polypeptides. Recently, various aspects of peptide nanotubes have been studied, in particular the utility of different methods for making peptide nanotubes with diverse designed functions. In order to investigate the relationship between formation, function and stability, it is essential to analyze the precise structure of peptide nanotubes. Atomic-scale surface imaging in liquids was recently achieved using frequency modulation atomic force microscopy with improved force sensing. Here we provide a precise surface structural analysis of peptide nanotubes in water without crystallizing them obtained by imaging the nanotubes at the sub-nanometer scale in water. In addition, the local hydration structure around the peptide nanotubes was observed at the nanotube/water interface.

  15. Simulation studies on structural and thermal properties of alkane thiol capped gold nanoparticles.

    Science.gov (United States)

    Devi, J Meena

    2017-06-01

    The structural and thermal properties of the passivated gold nanoparticles were explored employing molecular dynamics simulation for the different surface coverage densities of the self-assembled monolayer (SAM) of alkane thiol. The structural properties of the monolayer protected gold nanoparticles such us overall shape, organization and conformation of the capping alkane thiol chains were found to be influenced by the capping density. The structural order of the thiol capped gold nanoparticles enhances with the increase in the surface coverage density. The specific heat capacity of the alkane thiol capped gold nanoparticles was found to increase linearly with the thiol coverage density. This may be attributed to the enhancement in the lattice vibrational energy. The present simulation results suggest, that the structural and thermal properties of the alkane thiol capped gold nanoparticles may be modified by the suitable selection of the SAM coverage density. Copyright © 2017 Elsevier Inc. All rights reserved.

  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. 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.

  18. Understanding emergent functions in self-assembled fibrous networks

    Science.gov (United States)

    Sinko, Robert; Keten, Sinan

    2015-09-01

    Understanding self-assembly processes of nanoscale building blocks and characterizing their properties are both imperative for designing new hierarchical, network materials for a wide range of structural, optoelectrical, and transport applications. Although the characterization and choices of these material building blocks have been well studied, our understanding of how to precisely program a specific morphology through self-assembly still must be significantly advanced. In the recent study by Xie et al (2015 Nanotechnology 26 205602), the self-assembly of end-functionalized nanofibres is investigated using a coarse-grained molecular model and offers fundamental insight into how to control the structural morphology of nanofibrous networks. Varying nanoscale networks are observed when the molecular interaction strength is changed and the findings suggest that self-assembly through the tuning of molecular interactions is a key strategy for designing nanostructured networks with specific topologies.

  19. Tunneling Nanotubes are Novel Cellular Structures That Communicate Signals Between Trabecular Meshwork Cells.

    Science.gov (United States)

    Keller, Kate E; Bradley, John M; Sun, Ying Ying; Yang, Yong-Feng; Acott, Ted S

    2017-10-01

    The actin cytoskeleton of trabecular meshwork (TM) cells plays a role in regulating aqueous humor outflow. Many studies have investigated stress fibers, but F-actin also assembles into other supramolecular structures including filopodia. Recently, specialized filopodia called tunneling nanotubes (TNTs) have been described, which communicate molecular signals and organelles directly between cells. Here, we investigate TNT formation by TM cells. Human TM cells were labeled separately with the fluorescent dyes, DiO and DiD, or with mitochondrial dye. Fixed or live TM cells were imaged using confocal microscopy. Image analysis software was used to track fluorescent vesicles and count the number and length of filopodia. The number of fluorescently labeled vesicles transferred between cells was counted in response to specific inhibitors of the actin cytoskeleton. Human TM tissue was stained with phalloidin. Live-cell confocal imaging of cultured TM cells showed transfer of fluorescently labeled vesicles and mitochondria via TNTs. In TM tissue, a long (160 μm) actin-rich cell process bridged an intertrabecular space and did not adhere to the substratum. Treatment of TM cells with CK-666, an Arp2/3 inhibitor, significantly decreased the number and length of filopodia, decreased transfer of fluorescently labeled vesicles and induced thick stress fibers compared to vehicle control. Conversely, inhibiting stress fibers using Y27632 increased transfer of vesicles and induced long cell processes. Identification of TNTs provides a means by which TM cells can directly communicate with each other over long distances. This may be particularly important to overcome limitations of diffusion-based signaling in the aqueous humor fluid environment.

  20. Influence of ionic strength and surfactant concentration on electrostatic surfacial assembly of cetyltrimethylammonium bromide-capped gold nanorods on fully immersed glass.

    Science.gov (United States)

    Ferhan, Abdul Rahim; Guo, Longhua; Kim, Dong-Hwan

    2010-07-20

    The effect of ionic strength as well as surfactant concentration on the surface assembly of cetyltrimethylammonium bromide (CTAB)-capped gold nanorods (GNRs) has been studied. Glass substrates were modified to yield a net negative charge through electrostatic coating of polystyrenesulfonate (PSS) over a self-assembled monolayer (SAM) of positively charged aminopropyltriethoxysilane (APTS). The substrates were then fully immersed in GNR solutions at different CTAB concentrations and ionic strengths. Under slightly excess CTAB concentrations, it was observed that the density of GNRs immobilized on a substrate was predictably tunable through the adjustment of NaCl concentration over a wide range. Motivated by the experimental observation, we hypothesize that electrostatic shielding of charges around the GNRs affects the density of GNR immobilization. This model ultimately explains that at moderate to high CTAB concentrations a second electrostatic shielding effect contributed by excess CTAB molecules occurs, resulting in a parabolic trend of nanorod surface density when ionic strength is continually increased. In contrast, at a low CTAB concentration, the effect of ionic strength becomes much less significant due to insufficient CTAB molecules to provide for the second electrostatic shielding effect. The tunability of electrostatic-based surface assembly of GNRs enables the attainment of a dense surface assembly of nanorods without significant removal of CTAB or any other substituted stabilizing agent, both of which could compromise the stability and morphology of GNRs in solution. An additional study performed to investigate the robustness of such electrostatic-based surface assembly also proved its reliability to be used as biosensing platforms.

  1. Self-assembly and omniphobic property of fluorinated unit end-functionalized poly(methyl methacrylate)

    Science.gov (United States)

    Junyan, Liang; Pingdi, Xu; Jingxian, Bao; Ling, He; Nan, Zhu

    2018-03-01

    The self-assembly behavior of fluorinated unit end-functionalized poly(methyl methacrylate) (PDFHM-ef-PMMA) in solution and its influence on the surface microstructure, elemental composition and omniphobic property of cast film was investigated in this work. Specifically, three mixed solutions of tetrahydrofuran (THF)/methanol (MeOH), THF/H2O and THF/H2O/MeOH in various compositions were employed separately as the selective solvents. In THF/MeOH solution, the aggregate morphologies of PDFHM-ef-PMMA changed gradually from core-shell spheres to worm, and then to elliptical vesicles as MeOH content increased. In THF/H2O solution, spherical and bowl-shaped aggregates with significantly larger sizes than those in THF/MeOH solution were favored despite lower H2O content. The further addition of MeOH to THF/H2O mixture could reduce the size of aggregate but hardly change original aggregate morphology. During the film formation process, those self-assembled aggregates in THF/MeOH solution fused with one another to form a smooth surface. When such surface was fully covered by fluorinated segments, the outstanding hexadecane and water slide-off properties and ink-resistant property required for antifouling application were demonstrated. Instead, the aggregates formed in THF/H2O/MeOH mixture were subjected to secondary aggregation of PDFHM-ef-PMMA chains during solvent evaporation, leading to the formation of a particulate film with poor adhesion towards glass plate and hexadecane-repellent property.

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

    Science.gov (United States)

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

    2015-04-08

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

  3. Three-Dimensional Self-Assembled Photonic Crystal Waveguide

    Science.gov (United States)

    Baek, Kang-Hyun

    Photonic crystals (PCs), two- or three-dimensionally periodic, artificial, and dielectric structures, have a specific forbidden band for electromagnetic waves, referred to as photonic bandgap (PBG). The PBG is analogous to the electronic bandgap in natural crystal structures with periodic atomic arrangement. A well-defined and embedded planar, line, or point defect within the PCs causes a break in its structural periodicity, and introduces a state in the PBG for light localization. It offers various applications in integrated optics and photonics including optical filters, sharp bending light guides and very low threshold lasers. Using nanofabrication processes, PCs of the 2-D slab-type and 3-D layer-by-layer structures have been investigated widely. Alternatively, simple and low-cost self-assembled PCs with full 3-D PBG, inverse opals, have been suggested. A template with face centered cubic closed packed structure, opal, may initially be built by self-assembly of colloidal spheres, and is selectively removed after infiltrating high refractive index materials into the interstitials of spheres. In this dissertation, the optical waveguides utilizing the 3-D self-assembled PCs are discussed. The waveguides were fabricated by microfabrication technology. For high-quality colloidal silica spheres and PCs, reliable synthesis, self-assembly, and characterization techniques were developed. Its theoretical and experimental demonstrations are provided and correlated. They suggest that the self-assembled PCs with PBG are feasible for the applications in integrated optics and photonics.

  4. CMS end-cap yoke at the detector's assembly site.

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    The magnetic flux generated by the superconducting coil in the CMS detector is returned via an iron yoke comprising three end-cap discs at each end (end-cap yoke) and five concentric cylinders (barrel yoke). This picture shows the first of three end-cap discs (red) seen through the outer cylinder of the vacuum tank which will house the superconducting coil.

  5. Self-Assembled Hierarchical Formation of Conjugated 3D Cobalt Oxide Nanobead-CNT-Graphene Nanostructure Using Microwaves for High-Performance Supercapacitor Electrode.

    Science.gov (United States)

    Kumar, Rajesh; Singh, Rajesh Kumar; Dubey, Pawan Kumar; Singh, Dinesh Pratap; Yadav, Ram Manohar

    2015-07-15

    Here we report the electrochemical performance of a interesting three-dimensional (3D) structures comprised of zero-dimensional (0D) cobalt oxide nanobeads, one-dimensional (1D) carbon nanotubes and two-dimensional (2D) graphene, stacked hierarchically. We have synthesized 3D self-assembled hierarchical nanostructure comprised of cobalt oxide nanobeads (Co-nb), carbon nanotubes (CNTs), and graphene nanosheets (GNSs) for high-performance supercapacitor electrode application. This 3D self-assembled hierarchical nanostructure Co3O4 nanobeads-CNTs-GNSs (3D:Co-nb@CG) is grown at a large scale (gram) through simple, facile, and ultrafast microwave irradiation (MWI). In 3D:Co-nb@CG nanostructure, Co3O4 nanobeads are attached to the CNT surfaces grown on GNSs. Our ultrafast, one-step approach not only renders simultaneous growth of cobalt oxide and CNTs on graphene nanosheets but also institutes the intrinsic dispersion of carbon nanotubes and cobalt oxide within a highly conductive scaffold. The 3D:Co-nb@CG electrode shows better electrochemical performance with a maximum specific capacitance of 600 F/g at the charge/discharge current density of 0.7A/g in KOH electrolyte, which is 1.56 times higher than that of Co3O4-decorated graphene (Co-np@G) nanostructure. This electrode also shows a long cyclic life, excellent rate capability, and high specific capacitance. It also shows high stability after few cycles (550 cycles) and exhibits high capacitance retention behavior. It was observed that the supercapacitor retained 94.5% of its initial capacitance even after 5000 cycles, indicating its excellent cyclic stability. The synergistic effect of the 3D:Co-nb@CG appears to contribute to the enhanced electrochemical performances.

  6. Confinement of hydrogen at high pressure in carbon nanotubes

    Science.gov (United States)

    Lassila, David H [Aptos, CA; Bonner, Brian P [Livermore, CA

    2011-12-13

    A high pressure hydrogen confinement apparatus according to one embodiment includes carbon nanotubes capped at one or both ends thereof with a hydrogen-permeable membrane to enable the high pressure confinement of hydrogen and release of the hydrogen therethrough. A hydrogen confinement apparatus according to another embodiment includes an array of multi-walled carbon nanotubes each having first and second ends, the second ends being capped with palladium (Pd) to enable the high pressure confinement of hydrogen and release of the hydrogen therethrough as a function of palladium temperature, wherein the array of carbon nanotubes is capable of storing hydrogen gas at a pressure of at least 1 GPa for greater than 24 hours. Additional apparatuses and methods are also presented.

  7. Hollow inorganic nanospheres and nanotubes with tunable wall thicknesses by atomic layer deposition on self-assembled polymeric templates

    NARCIS (Netherlands)

    Ras, Robin H. A.; Kemell, Marianna; de Wit, Joost; Ritala, Mikko; ten Brinke, Gerrit; Leskela, Markku; Ikkala, Olli; Leskelä, Markku

    2007-01-01

    The construction of inorganic nanostructures with hollow interiors is demonstrated by coating self-assembled polymeric nano-objects with a thin Al2O3 layer by atomic layer deposition (ALD), followed by removal of the polymer template upon heating. The morphology of the nano-object (i.e., spherical

  8. Self-assembled structures and pKa value of oleic acid in systems of biological relevance.

    Science.gov (United States)

    Salentinig, Stefan; Sagalowicz, Laurent; Glatter, Otto

    2010-07-20

    In the human digestion process, triglycerides are hydrolyzed by lipases to monoglycerides and the corresponding fatty acids. Here we report the self-assembly of structures in biologically relevant, emulsified oleic acid-monoolein mixtures at various pH values and oleic acid concentrations. Small-angle X-ray scattering, cryogenic transmission electron microscopy, and dynamic light scattering were used to investigate the structures formed, and to follow their transitions while these factors were varied. The addition of oleic acid to monoolein-based cubosomes was found to increase the critical packing parameter in the system. Structural transitions from bicontinuous cubosomes through hexosomes and micellar cubosomes (Fd3m symmetry) to emulsified microemulsions occur with increasing oleic acid concentration. At sufficiently high oleic acid concentration, the internal particle structure was also found to strongly depend on the pH of the aqueous phase: transformations from emulsified microemulsion through micellar cubosomes, hexosomes, and bicontinuous cubosomes to vesicles can be observed as a function of increasing pH. The reversible transition from liquid crystals to vesicles occurs at intestinal pH values (between pH 7 and 8). The hydrodynamic radius of the particles decreases from around 120 nm for internally structured particles to around 60 nm for vesicles. All transitions with pH are reversible. Finally, the apparent pK(a) for oleic acid in monoolein could be determined from the change of structure with pH. This value is within the physiological pH range of the intestine and depends somewhat on composition.

  9. Bioinspired synthesis and self-assembly of hybrid organic–inorganic nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Honghu [Iowa State Univ., Ames, IA (United States)

    2016-12-17

    Nature is replete with complex organic–inorganic hierarchical materials of diverse yet specific functions. These materials are intricately designed under physiological conditions through biomineralization and biological self-assembly processes. Tremendous efforts have been devoted to investigating mechanisms of such biomineralization and biological self-assembly processes as well as gaining inspiration to develop biomimetic methods for synthesis and self-assembly of functional nanomaterials. In this work, we focus on the bioinspired synthesis and self-assembly of functional inorganic nanomaterials templated by specialized macromolecules including proteins, DNA and polymers. The in vitro biomineralization process of the magnetite biomineralizing protein Mms6 has been investigated using small-angle X-ray scattering. Templated by Mms6, complex magnetic nanomaterials can be synthesized on surfaces and in the bulk. DNA and synthetic polymers have been exploited to construct macroscopic two- and three-dimensional (2D and 3D) superlattices of gold nanocrystals. Employing X-ray scattering and spectroscopy techniques, the self-assembled structures and the self-assembly mechanisms have been studied, and theoretical models have been developed. Our results show that specialized macromolecules including proteins, DNA and polymers act as effective templates for synthesis and self-assembly of nanomaterials. These bottom-up approaches provide promising routes to fabricate hybrid organic–inorganic nanomaterials with rationally designed hierarchical structures, targeting specific functions.

  10. Enhanced endothelial cell functions on rosette nanotube-coated titanium vascular stents

    Directory of Open Access Journals (Sweden)

    Eli Fine

    2009-04-01

    Full Text Available Eli Fine1, Lijie Zhang1, Hicham Fenniri2, Thomas J Webster1 1Department of Engineering, Brown University, Providence, RI, USA; 2National Institute for Nanotechnology and Department of Chemistry, University of Alberta, Edmonton, AB, CanadaAbstract: One of the main problems with current vascular stents is a lack of endothelial cell interactions, which if sufficient, would create a uniform healthy endothelium masking the underlying foreign metal from inflammatory cell interference. Moreover, if endothelial cells from the arterial wall do not adhere to the stent, the stent can become loose and dislodge. Therefore, the objective of this in vitro study was to design a novel biomimetic nanostructured coating (that does not contain drugs on conventional vascular stent materials (specifically, titanium for improving vascular stent applications. Rosette nanotubes (RNTs are a new class of biomimetic nanotubes that self-assemble from DNA base analogs and have been shown in previous studies to sufficiently coat titanium and enhance osteoblast cell functions. RNTs have many desirable properties for use as vascular stent coatings including spontaneous self-assembly in body fluids, tailorable surface chemistry for specific implant applications, and nanoscale dimensions similar to those of the natural vascular extracellular matrix. Importantly, the results of this study provided the first evidence that RNTs functionalized with lysine (RNT–K, even at low concentrations, significantly increase endothelial cell density over uncoated titanium. Specifically, 0.01 mg/mL RNT–K coated titanium increased endothelial cell density by 37% and 52% compared to uncoated titanium after 4 h and three days, respectively. The excellent cytocompatibility properties of RNTs (as demonstrated here for the first time for endothelial cells suggest the need for the further exploration of these novel nanostructured materials for vascular stent applications.Keywords: stents

  11. 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.

  12. Self-assembly of silica microparticles in magnetic multiphase flows: Experiment and simulation

    Science.gov (United States)

    Li, Xiang; Niu, Xiao-Dong; Li, You; Chen, Mu-Feng

    2018-04-01

    Dynamic self-assembly, especially self-assembly under magnetic field, is vital not only for its marvelous phenomenon but also for its mechanisms. Revealing the underlying mechanisms is crucial for a deeper understanding of self-assembly. In this paper, several magnetic induced self-assembly experiments by using the mixed magnetic multiphase fluids comprised of silica microspheres were carried out. The relations of the strength of external magnetic field, the inverse magnetorheological effect, and the structures of self-assembled particles were investigated. In addition, a momentum-exchanged immersed boundary-based lattice Boltzmann method (MEIB-LBM) for modeling multi-physical coupling multiphase flows was employed to numerically study the magnetic induced self-assembly process in detail. The present work showed that the external magnetic field can be used to control the form of self-assembly of nonmagnetic microparticles in a chain-like structure, and the self-assembly process can be classified into four stages with magnetic hysteresis, magnetization of nonmagnetic microparticles, self-assembly in chain-like structures, and the stable chain state. The combination of experimental and numerical results could offer a method to control the self-assembled nonmagnetic microparticles, which can provide the technical and theoretical support for the design and fabrication of micro/nanomaterials.

  13. Self-assembling electroactive hydrogels for flexible display technology

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Scott L; Wong, Kok Hou; Ladouceur, Francois [School of Electrical Engineering and Telecommunications, University of NSW, Sydney, NSW, 2052 (Australia); Thordarson, Pall, E-mail: f.ladouceur@unsw.edu.a [School of Chemistry, University of NSW, Sydney, NSW, 2052 (Australia)

    2010-12-15

    We have assessed the potential of self-assembling hydrogels for use in conformal displays. The self-assembling process can be used to alter the transparency of the material to all visible light due to scattering by fibres. The reversible transition is shown to be of low energy by differential scanning calorimetry. For use in technology it is imperative that this transition is controlled electrically. We have thus synthesized novel self-assembling hydrogelator molecules which contain an electroactive group. The well-known redox couple of anthraquinone/anthrahydroquinone has been used as the hydrophobic component for a series of small molecule gelators. They are further functionalized with peptide combinations of L-phenylalanine and glycine to provide the hydrophilic group to complete 'head-tail' models of self-assembling gels. The gelation and electroactive characteristics of the series were assessed. Cyclic voltammetry shows the reversible redox cycle to be only superficially altered by functionalization. Additionally, spectroelectrochemical measurements show a reversible transparency and colour change induced by the redox process.

  14. Self-assembling electroactive hydrogels for flexible display technology

    International Nuclear Information System (INIS)

    Jones, Scott L; Wong, Kok Hou; Ladouceur, Francois; Thordarson, Pall

    2010-01-01

    We have assessed the potential of self-assembling hydrogels for use in conformal displays. The self-assembling process can be used to alter the transparency of the material to all visible light due to scattering by fibres. The reversible transition is shown to be of low energy by differential scanning calorimetry. For use in technology it is imperative that this transition is controlled electrically. We have thus synthesized novel self-assembling hydrogelator molecules which contain an electroactive group. The well-known redox couple of anthraquinone/anthrahydroquinone has been used as the hydrophobic component for a series of small molecule gelators. They are further functionalized with peptide combinations of L-phenylalanine and glycine to provide the hydrophilic group to complete 'head-tail' models of self-assembling gels. The gelation and electroactive characteristics of the series were assessed. Cyclic voltammetry shows the reversible redox cycle to be only superficially altered by functionalization. Additionally, spectroelectrochemical measurements show a reversible transparency and colour change induced by the redox process.

  15. DNA-Based Self-Assembly of Fluorescent Nanodiamonds.

    Science.gov (United States)

    Zhang, Tao; Neumann, Andre; Lindlau, Jessica; Wu, Yuzhou; Pramanik, Goutam; Naydenov, Boris; Jelezko, Fedor; Schüder, Florian; Huber, Sebastian; Huber, Marinus; Stehr, Florian; Högele, Alexander; Weil, Tanja; Liedl, Tim

    2015-08-12

    As a step toward deterministic and scalable assembly of ordered spin arrays we here demonstrate a bottom-up approach to position fluorescent nanodiamonds (NDs) with nanometer precision on DNA origami structures. We have realized a reliable and broadly applicable surface modification strategy that results in DNA-functionalized and perfectly dispersed NDs that were then self-assembled in predefined geometries. With optical studies we show that the fluorescence properties of the nitrogen-vacancy color centers in NDs are preserved during surface modification and DNA assembly. As this method allows the nanoscale arrangement of fluorescent NDs together with other optically active components in complex geometries, applications based on self-assembled spin lattices or plasmon-enhanced spin sensors as well as improved fluorescent labeling for bioimaging could be envisioned.

  16. Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

    Science.gov (United States)

    Wen, Li; Lin, Zhonghua; Gu, Pingying; Zhou, Jianzhang; Yao, Bingxing; Chen, Guoliang; Fu, Jinkun

    2009-02-01

    Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 °C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (gold nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01.

  17. Self-assembly from milli- to nanoscales: methods and applications

    International Nuclear Information System (INIS)

    Mastrangeli, M; Celis, J-P; Abbasi, S; Varel, C; Böhringer, K F; Van Hoof, C

    2009-01-01

    The design and fabrication techniques for microelectromechanical systems (MEMS) and nanodevices are progressing rapidly. However, due to material and process flow incompatibilities in the fabrication of sensors, actuators and electronic circuitry, a final packaging step is often necessary to integrate all components of a heterogeneous microsystem on a common substrate. Robotic pick-and-place, although accurate and reliable at larger scales, is a serial process that downscales unfavorably due to stiction problems, fragility and sheer number of components. Self-assembly, on the other hand, is parallel and can be used for device sizes ranging from millimeters to nanometers. In this review, the state-of-the-art in methods and applications for self-assembly is reviewed. Methods for assembling three-dimensional (3D) MEMS structures out of two-dimensional (2D) ones are described. The use of capillary forces for folding 2D plates into 3D structures, as well as assembling parts onto a common substrate or aggregating parts to each other into 2D or 3D structures, is discussed. Shape matching and guided assembly by magnetic forces and electric fields are also reviewed. Finally, colloidal self-assembly and DNA-based self-assembly, mainly used at the nanoscale, are surveyed, and aspects of theoretical modeling of stochastic assembly processes are discussed. (topical review)

  18. 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...

  19. Self-recognition in the coordination driven self-assembly of 2-D polygons.

    Science.gov (United States)

    Addicott, Chris; Das, Neeladri; Stang, Peter J

    2004-08-23

    Self-recognition in the transition-metal-mediated self-assembly of some 2-D polygons is presented. Prolonged heating of two or three organoplatinum reagents with 4,4'-dipyridyl in aqueous acetone results in the predominant formation of a rectangle, triangle, and/or square. All mixtures are characterized with NMR and electrospray ionization mass spectrometry (ESIMS). Despite the potential for ill-defined oligomeric products, these mixed ligand systems prefer to self-assemble into discrete species.

  20. 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.

  1. Atomic-resolution structure of the CAP-Gly domain of dynactin on polymeric microtubules determined by magic angle spinning NMR spectroscopy.

    Science.gov (United States)

    Yan, Si; Guo, Changmiao; Hou, Guangjin; Zhang, Huilan; Lu, Xingyu; Williams, John Charles; Polenova, Tatyana

    2015-11-24

    Microtubules and their associated proteins perform a broad array of essential physiological functions, including mitosis, polarization and differentiation, cell migration, and vesicle and organelle transport. As such, they have been extensively studied at multiple levels of resolution (e.g., from structural biology to cell biology). Despite these efforts, there remain significant gaps in our knowledge concerning how microtubule-binding proteins bind to microtubules, how dynamics connect different conformational states, and how these interactions and dynamics affect cellular processes. Structures of microtubule-associated proteins assembled on polymeric microtubules are not known at atomic resolution. Here, we report a structure of the cytoskeleton-associated protein glycine-rich (CAP-Gly) domain of dynactin motor on polymeric microtubules, solved by magic angle spinning NMR spectroscopy. We present the intermolecular interface of CAP-Gly with microtubules, derived by recording direct dipolar contacts between CAP-Gly and tubulin using double rotational echo double resonance (dREDOR)-filtered experiments. Our results indicate that the structure adopted by CAP-Gly varies, particularly around its loop regions, permitting its interaction with multiple binding partners and with the microtubules. To our knowledge, this study reports the first atomic-resolution structure of a microtubule-associated protein on polymeric microtubules. Our approach lays the foundation for atomic-resolution structural analysis of other microtubule-associated motors.

  2. Enabling complex nanoscale pattern customization using directed self-assembly.

    Science.gov (United States)

    Doerk, Gregory S; Cheng, Joy Y; Singh, Gurpreet; Rettner, Charles T; Pitera, Jed W; Balakrishnan, Srinivasan; Arellano, Noel; Sanders, Daniel P

    2014-12-16

    Block copolymer directed self-assembly is an attractive method to fabricate highly uniform nanoscale features for various technological applications, but the dense periodicity of block copolymer features limits the complexity of the resulting patterns and their potential utility. Therefore, customizability of nanoscale patterns has been a long-standing goal for using directed self-assembly in device fabrication. Here we show that a hybrid organic/inorganic chemical pattern serves as a guiding pattern for self-assembly as well as a self-aligned mask for pattern customization through cotransfer of aligned block copolymer features and an inorganic prepattern. As informed by a phenomenological model, deliberate process engineering is implemented to maintain global alignment of block copolymer features over arbitrarily shaped, 'masking' features incorporated into the chemical patterns. These hybrid chemical patterns with embedded customization information enable deterministic, complex two-dimensional nanoscale pattern customization through directed self-assembly.

  3. Evaluation of dose dependent antimicrobial activity of self-assembled chitosan, nano silver and chitosan-nano silver composite against several pathogens.

    Science.gov (United States)

    Tareq, Foysal Kabir; Fayzunnesa, Mst; Kabir, Md Shahariar; Nuzat, Musrat

    2018-01-01

    The aim of this investigation to preparation of silver nanoparticles organized chitosan nano polymer, which effective against microbial and pathogens, when apply to liquid medium and edible food products surface, will rescue the growth of microbes. Self-assembly approach used to synthesis of silver nanoparticles and silver nanoparticles organized chitosan nano polymer. Silver nanoparticles and silver nanoparticles organized chitosan nano polymer and film characterized using Ultra-violate visible spectrometer (UV-vis), X-ray diffraction (X-ray), and Scanning electronic microscope (SEM). The crystalline structured protein capped nano silver successfully synthesized at range of 12 nm-29 nm and organized into chitosan nano polymer. Antimicrobial ingredient in liquid medium and food product surface provide to rescue oxidative change and growth of microorganism to provide higher safety. The silver nanoparticles organized chitosan nano polymer caused the death of microorganism. The materials in nano scale synthesized successfully using self-assembly method, which showed good antimicrobial properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Nanomaterial processing using self-assembly-bottom-up chemical and biological approaches

    International Nuclear Information System (INIS)

    Thiruvengadathan, Rajagopalan; Gangopadhyay, Keshab; Gangopadhyay, Shubhra; Korampally, Venumadhav; Ghosh, Arkasubhra; Chanda, Nripen

    2013-01-01

    Nanotechnology is touted as the next logical sequence in technological evolution. This has led to a substantial surge in research activities pertaining to the development and fundamental understanding of processes and assembly at the nanoscale. Both top-down and bottom-up fabrication approaches may be used to realize a range of well-defined nanostructured materials with desirable physical and chemical attributes. Among these, the bottom-up self-assembly process offers the most realistic solution toward the fabrication of next-generation functional materials and devices. Here, we present a comprehensive review on the physical basis behind self-assembly and the processes reported in recent years to direct the assembly of nanoscale functional blocks into hierarchically ordered structures. This paper emphasizes assembly in the synthetic domain as well in the biological domain, underscoring the importance of biomimetic approaches toward novel materials. In particular, two important classes of directed self-assembly, namely, (i) self-assembly among nanoparticle–polymer systems and (ii) external field-guided assembly are highlighted. The spontaneous self-assembling behavior observed in nature that leads to complex, multifunctional, hierarchical structures within biological systems is also discussed in this review. Recent research undertaken to synthesize hierarchically assembled functional materials have underscored the need as well as the benefits harvested in synergistically combining top-down fabrication methods with bottom-up self-assembly. (review article)

  5. Chemical modifications to vesicle forming diblock copolymers: Development of smart functional polymersome membranes

    Science.gov (United States)

    Katz, Joshua S.

    2011-07-01

    A major limitation to current treatment regimens for diseases is the inability to adequately deliver therapeutics. Many routes to encapsulation of these materials have been explored to improve biodistribution and better protect encapsulants from harsh biological conditions. One vehicle particularly attractive for encapsulation of such materials is the polymersome. While promising for translation to clinical use, there are still limitations in polymer chemistry and resulting polymersome behavior that will slow their adaptation. This thesis addresses several of these limitations. The first major limitation to polymersomes is lack of control over their release rate. Release is generally by simple diffusion, leading to a burst. To address this burst, Aim 1 proposes a route to stabilizing polymersome membranes through their polymerization. PCL-PEG copolymers were terminally acrylated and the acrylates polymerized in the membrane following vesicle assembly. Polymerization enhanced mechanical robustness of the membranes and reduced diffusion of encapsulated contents. To ultimately trigger release, Aim 2 presents a novel route to synthesizing diblock copolymers, enabling insertion of a functional group at the blocks' junction. To facilitate triggering of release, we inserted UV-cleavable 2-nitrophenylalanine. Polymersomes assembled from this polymer collapse upon exposure to light and molecules release. Demonstrating further utility of this synthetic route, fluorescent vesicles were prepared using fluorescent lysine as the joining molecule. These vesicles labeled dendritic cells, providing a novel route to cell labeling and tracking. The second limitation to vesicles promising for biomedical applications (made of PCL-PEG) is their solid membranes. Aim 3 demonstrates partial (or full) replacement of the PCL block with a caprolactone analogue, TOSUO, which is non-crystalline and assembles into soft, deformable vesicles. Increasing TOSUO content in the copolymer leads to

  6. The effect of different thickness alumina capping layers on the final morphology of dewet thin Ni films

    Science.gov (United States)

    White, Benjamin C.; Behbahanian, Amir; Stoker, T. McKay; Fowlkes, Jason D.; Hartnett, Chris; Rack, Phillip D.; Roberts, Nicholas A.

    2018-03-01

    Nanoparticles on a substrate have numerous applications in nanotechnology, from enhancements to solar cell efficiency to improvements in carbon nanotube growth. Producing nanoparticles in a cost effective fashion with control over size and spacing is desired, but difficult to do. This work presents a scalable method for altering the radius and pitch distributions of nickel nanoparticles. The introduction of alumina capping layers to thin nickel films during a pulsed laser-induced dewetting process has yielded reductions in the mean and standard deviation of radii and pitch for dewet nanoparticles with no noticeable difference in final morphology with increased capping layer thickness. The differences in carbon nanotube mats grown, on the uncapped sample and one of the capped samples, is also presented here, with a more dense mat being present for the capped case.

  7. Morphology and Pattern Control of Diphenylalanine Self-Assembly via Evaporative Dewetting.

    Science.gov (United States)

    Chen, Jiarui; Qin, Shuyu; Wu, Xinglong; Chu, And Paul K

    2016-01-26

    Self-assembled peptide nanostructures have unique physical and biological properties and promising applications in electrical devices and functional molecular recognition. Although solution-based peptide molecules can self-assemble into different morphologies, it is challenging to control the self-assembly process. Herein, controllable self-assembly of diphenylalanine (FF) in an evaporative dewetting solution is reported. The fluid mechanical dimensionless numbers, namely Rayleigh, Marangoni, and capillary numbers, are introduced to control the interaction between the solution and FF molecules in the self-assembly process. The difference in the film thickness reflects the effects of Rayleigh and Marangoni convection, and the water vapor flow rate reveals the role of viscous fingering in the emergence of aligned FF flakes. By employing dewetting, various FF self-assembled patterns, like concentric and spokelike, and morphologies, like strips and hexagonal tubes/rods, can be produced, and there are no significant lattice structural changes in the FF nanostructures.

  8. Self-assembly of charged microclusters of CdSe/ZnS core/shell nanodots and nanorods into hierarchically ordered colloidal arrays

    International Nuclear Information System (INIS)

    Sukhanova, Alyona; Baranov, Alexander V; Klinov, Dmitriy; Oleinikov, Vladimir; Berwick, Kevin; Cohen, Jacques H M; Pluot, Michel; Nabiev, Igor

    2006-01-01

    A thermodynamically driven self-organization of microclusters of semiconductor nanocrystals with a narrow size distribution into periodic two-dimensional (2D) arrays is an attractive low-cost technique for the fabrication of 2D photonic crystals. We have found that CdSe/ZnS core/shell quantum dots or quantum rods, transferred in aqueous phase after capping with the bifunctional surface-active agent DL-cysteine, form on a poly-L-lysine coated surface homogeneously sized micro-particles, droplet-like spheroid clusters and hexagon-like colloidal crystals self-organized into millimetre-sized 2D hexagonal assemblies. The presence of an organic molecular layer around the micro-particles prevents immediate contact between them, forming an interstitial space which may be varied in thickness by changing the origin of the molecular layer capping nanocrystals. Due to the high refractive index of CdSe and the low refractive index of the interstitial spaces, these structures are expected to have deep gaps in their photonic band, forming hierarchically ordered 2D arrays of potentially photonic materials

  9. Layer-by-layer cell membrane assembly

    Science.gov (United States)

    Matosevic, Sandro; Paegel, Brian M.

    2013-11-01

    Eukaryotic subcellular membrane systems, such as the nuclear envelope or endoplasmic reticulum, present a rich array of architecturally and compositionally complex supramolecular targets that are as yet inaccessible. Here we describe layer-by-layer phospholipid membrane assembly on microfluidic droplets, a route to structures with defined compositional asymmetry and lamellarity. Starting with phospholipid-stabilized water-in-oil droplets trapped in a static droplet array, lipid monolayer deposition proceeds as oil/water-phase boundaries pass over the droplets. Unilamellar vesicles assembled layer-by-layer support functional insertion both of purified and of in situ expressed membrane proteins. Synthesis and chemical probing of asymmetric unilamellar and double-bilayer vesicles demonstrate the programmability of both membrane lamellarity and lipid-leaflet composition during assembly. The immobilized vesicle arrays are a pragmatic experimental platform for biophysical studies of membranes and their associated proteins, particularly complexes that assemble and function in multilamellar contexts in vivo.

  10. Double capping of molecular beam epitaxy grown InAs/InP quantum dots studied by cross-sectional scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Ulloa, J. M.; Koenraad, P. M.; Gapihan, E.; Letoublon, A.; Bertru, N.

    2007-01-01

    Cross-sectional scanning tunneling microscopy was used to study at the atomic scale the double capping process of self-assembled InAs/InP quantum dots (QDs) grown by molecular beam epitaxy on a (311)B substrate. The thickness of the first capping layer is found to play a mayor role in determining the final results of the process. For first capping layers up to 3.5 nm, the height of the QDs correspond to the thickness of the first capping layer. Nevertheless, for thicknesses higher than 3.5 nm, a reduction in the dot height compared to the thickness of the first capping layer is observed. These results are interpreted in terms of a transition from a double capping to a classical capping process when the first capping layer is thick enough to completely cover the dots

  11. Water self-diffusion through narrow oxygenated carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Striolo, Alberto [School of Chemical Biological and Materials Engineering, University of Oklahoma, Norman, OK 73019 (United States)

    2007-11-28

    The hydrophobic interior of carbon nanotubes, which is reminiscent of ion channels in cellular membranes, has inspired scientific research directed towards the production of, for example, membranes for water desalination, drug-delivery devices, and nanosyringes. To develop these technologies it is crucial to understand and predict the equilibrium and transport properties of confined water. We present here a series of molecular dynamics simulation results conducted to understand the extent to which the presence of a few oxygenated active sites, modeled as carbonyls, affects the transport properties of confined water. The model for the carbon nanotube is not intended to be realistic. Its only purpose is to allow us to understand the effect of a few oxygenated sites on the transport properties of water confined in a narrow cylindrical pore, which is otherwise hydrophobic. At low hydration levels we found little, if any, water diffusion. The diffusion, which appears to be of the Fickian type for sufficiently large hydration levels, becomes faster as the number of confined water molecules increases, reaches a maximum, and slows as water fills the carbon nanotubes. We explain our findings on the basis of two collective motion mechanisms observed from the analysis of sequences of simulation snapshots. We term the two mechanisms 'cluster-breakage' and 'cluster-libration' mechanisms. We observe that the cluster-breakage mechanism produces longer displacements for the confined water molecules than the cluster-libration one, but deactivates as water fills the carbon nanotube. From a practical point of view, our results are particularly important for two reasons: (1) at low hydration levels the presence of only eight carbonyl groups can prevent the diffusion of water through (8, 8) carbon nanotubes; and (2) the extremely fast self-diffusion coefficients observed for water within narrow carbon nanotubes are significantly decreased in the presence of only a

  12. Water self-diffusion through narrow oxygenated carbon nanotubes

    International Nuclear Information System (INIS)

    Striolo, Alberto

    2007-01-01

    The hydrophobic interior of carbon nanotubes, which is reminiscent of ion channels in cellular membranes, has inspired scientific research directed towards the production of, for example, membranes for water desalination, drug-delivery devices, and nanosyringes. To develop these technologies it is crucial to understand and predict the equilibrium and transport properties of confined water. We present here a series of molecular dynamics simulation results conducted to understand the extent to which the presence of a few oxygenated active sites, modeled as carbonyls, affects the transport properties of confined water. The model for the carbon nanotube is not intended to be realistic. Its only purpose is to allow us to understand the effect of a few oxygenated sites on the transport properties of water confined in a narrow cylindrical pore, which is otherwise hydrophobic. At low hydration levels we found little, if any, water diffusion. The diffusion, which appears to be of the Fickian type for sufficiently large hydration levels, becomes faster as the number of confined water molecules increases, reaches a maximum, and slows as water fills the carbon nanotubes. We explain our findings on the basis of two collective motion mechanisms observed from the analysis of sequences of simulation snapshots. We term the two mechanisms 'cluster-breakage' and 'cluster-libration' mechanisms. We observe that the cluster-breakage mechanism produces longer displacements for the confined water molecules than the cluster-libration one, but deactivates as water fills the carbon nanotube. From a practical point of view, our results are particularly important for two reasons: (1) at low hydration levels the presence of only eight carbonyl groups can prevent the diffusion of water through (8, 8) carbon nanotubes; and (2) the extremely fast self-diffusion coefficients observed for water within narrow carbon nanotubes are significantly decreased in the presence of only a few oxygenated active

  13. Construction of Supramolecular Architectures via Self-assembly

    Institute of Scientific and Technical Information of China (English)

    Takeharu; Haino

    2007-01-01

    1 Results In this paper we report supramolecular polymeric nano networks formed by the molecular-recognition-directed self-assembly between a calix[5]arene and C60[1]. Covalently-linked double-calix[5]arenes take up C60 into their cavities[2]. This complementary interaction creates a strong non-covalent bonding; thus,the iterative self-assembly between dumbbell fullerene 1 and ditopic host 2 can produce the supramolecular polymer networks (See Fig.1).

  14. Sequential bottom-up assembly of mechanically stabilized synthetic cells by microfluidics

    Science.gov (United States)

    Weiss, Marian; Frohnmayer, Johannes Patrick; Benk, Lucia Theresa; Haller, Barbara; Janiesch, Jan-Willi; Heitkamp, Thomas; Börsch, Michael; Lira, Rafael B.; Dimova, Rumiana; Lipowsky, Reinhard; Bodenschatz, Eberhard; Baret, Jean-Christophe; Vidakovic-Koch, Tanja; Sundmacher, Kai; Platzman, Ilia; Spatz, Joachim P.

    2018-01-01

    Compartments for the spatially and temporally controlled assembly of biological processes are essential towards cellular life. Synthetic mimics of cellular compartments based on lipid-based protocells lack the mechanical and chemical stability to allow their manipulation into a complex and fully functional synthetic cell. Here, we present a high-throughput microfluidic method to generate stable, defined sized liposomes termed `droplet-stabilized giant unilamellar vesicles (dsGUVs)’. The enhanced stability of dsGUVs enables the sequential loading of these compartments with biomolecules, namely purified transmembrane and cytoskeleton proteins by microfluidic pico-injection technology. This constitutes an experimental demonstration of a successful bottom-up assembly of a compartment with contents that would not self-assemble to full functionality when simply mixed together. Following assembly, the stabilizing oil phase and droplet shells are removed to release functional self-supporting protocells to an aqueous phase, enabling them to interact with physiologically relevant matrices.

  15. Quantitative self-assembly prediction yields targeted nanomedicines

    Science.gov (United States)

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

    2018-02-01

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

  16. Structural Polymorphism in a Self-Assembled Tri-Aromatic Peptide System.

    Science.gov (United States)

    Brown, Noam; Lei, Jiangtao; Zhan, Chendi; Shimon, Linda J W; Adler-Abramovich, Lihi; Wei, Guanghong; Gazit, Ehud

    2018-04-24

    Self-assembly is a process of key importance in natural systems and in nanotechnology. Peptides are attractive building blocks due to their relative facile synthesis, biocompatibility, and other unique properties. Diphenylalanine (FF) and its derivatives are known to form nanostructures of various architectures and interesting and varied characteristics. The larger triphenylalanine peptide (FFF) was found to self-assemble as efficiently as FF, forming related but distinct architectures of plate-like and spherical nanostructures. Here, to understand the effect of triaromatic systems on the self-assembly process, we examined carboxybenzyl-protected diphenylalanine (z-FF) as a minimal model for such an arrangement. We explored different self-assembly conditions by changing solvent compositions and peptide concentrations, generating a phase diagram for the assemblies. We discovered that z-FF can form a variety of structures, including nanowires, fibers, nanospheres, and nanotoroids, the latter were previously observed only in considerably larger or co-assembly systems. Secondary structure analysis revealed that all assemblies possessed a β-sheet conformation. Additionally, in solvent combinations with high water ratios, z-FF formed rigid and self-healing hydrogels. X-ray crystallography revealed a "wishbone" structure, in which z-FF dimers are linked by hydrogen bonds mediated by methanol molecules, with a 2-fold screw symmetry along the c-axis. All-atom molecular dynamics (MD) simulations revealed conformations similar to the crystal structure. Coarse-grained MD simulated the assembly of the peptide into either fibers or spheres in different solvent systems, consistent with the experimental results. This work thus expands the building block library for the fabrication of nanostructures by peptide self-assembly.

  17. Macroscopic magnetic Self assembly

    NARCIS (Netherlands)

    Löthman, Per Arvid

    2018-01-01

    Exploring the macroscopic scale's similarities to the microscale is part and parcel of this thesis as reflected in the research question: what can we learn about the microscopic scale by studying the macroscale? Investigations of the environment in which the self-assembly takes place, and the

  18. Single-wall carbon nanotube chemical attachment at platinum electrodes

    International Nuclear Information System (INIS)

    Rosario-Castro, Belinda I.; Contes-de-Jesus, Enid J.; Lebron-Colon, Marisabel; Meador, Michael A.; Scibioh, M. Aulice; Cabrera, Carlos R.

    2010-01-01

    Self-assembled monolayer (SAM) techniques were used to adsorb 4-aminothiophenol (4-ATP) on platinum electrodes in order to obtain an amino-terminated SAM as the base for the chemical attachment of single-wall carbon nanotubes (SWCNTs). A physico-chemical, morphological and electrochemical characterizations of SWCNTs attached onto the modified Pt electrodes was done by using reflection-absorption infrared spectroscopy (RAIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and cyclic voltammetry (CV) techniques. The SWNTs/4-ATP/Pt surface had regions of small, medium, and large thickness of carbon nanotubes with heights of 100-200 nm, 700 nm to 1.5 μm, and 1.0-3.0 μm, respectively. Cyclic voltammetries (CVs) in sulfuric acid demonstrated that attachment of SWNTs on 4-ATP/Pt is markedly stable, even after 30 potential cycles. CV in ruthenium hexamine was similar to bare Pt electrodes, suggesting that SWNTs assembly is similar to a closely packed microelectrode array.

  19. 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

  20. Fabrication of SWCNT-Ag nanoparticle hybrid included self-assemblies for antibacterial applications.

    Directory of Open Access Journals (Sweden)

    Sayanti Brahmachari

    Full Text Available The present article reports the development of soft nanohybrids comprising of single walled carbon nanotube (SWCNT included silver nanoparticles (AgNPs having superior antibacterial property. In this regard aqueous dispersing agent of carbon nanotube (CNT containing a silver ion reducing unit was synthesised by the inclusion of tryptophan and tyrosine within the backbone of the amphiphile. The dispersions were characterized spectroscopically and microscopically using TEM, AFM and Raman spectroscopy. The nanotube-nanoparticle conjugates were prepared by the in situ photoreduction of AgNO3. The phenolate residue and the indole moieties of tyrosine and tryptophan, respectively reduces the sliver ion as well as acts as stabilizing agents for the synthesized AgNPs. The nanohybrids were characterized using TEM and AFM. The antibacterial activity of the nanohybrids was studied against Gram-positive (Bacillus subtilis and Micrococcus luteus and Gram-negative bacteria (Escherichia coli and Klebsiella aerogenes. The SWCNT dispersions showed moderate killing ability (40-60% against Gram-positive bacteria however no antibacterial activity was observed against the Gram negative ones. Interestingly, the developed SWCNT-amphiphile-AgNP nanohybrids exhibited significant killing ability (∼90% against all bacteria. Importantly, the cell viability of these newly developed self-assemblies was checked towards chinese hamster ovarian cells and high cell viability was observed after 24 h of incubation. This specific killing of bacterial cells may have been achieved due to the presence of higher -SH containing proteins in the cell walls of the bacteria. The developed nanohybrids were subsequently infused into tissue engineering scaffold agar-gelatin films and the films similarly showed bactericidal activity towards both kinds of bacterial strains while allowing normal growth of eukaryotic cells on the surface of the films.

  1. Amphiphilic building blocks for self-assembly: from amphiphiles to supra-amphiphiles.

    Science.gov (United States)

    Wang, Chao; Wang, Zhiqiang; Zhang, Xi

    2012-04-17

    The process of self-assembly spontaneously creates well-defined structures from various chemical building blocks. Self-assembly can include different levels of complexity: it can be as simple as the dimerization of two small building blocks driven by hydrogen bonding or as complicated as a cell membrane, a remarkable supramolecular architecture created by a bilayer of phospholipids embedded with functional proteins. The study of self-assembly in simple systems provides a fundamental understanding of the driving forces and cooperativity behind these processes. Once the rules are understood, these guidelines can facilitate the research of highly complex self-assembly processes. Among the various components for self-assembly, an amphiphilic molecule, which contains both hydrophilic and hydrophobic parts, forms one of the most powerful building blocks. When amphiphiles are dispersed in water, the hydrophilic component of the amphiphile preferentially interacts with the aqueous phase while the hydrophobic portion tends to reside in the air or in the nonpolar solvent. Therefore, the amphiphiles aggregate to form different molecular assemblies based on the repelling and coordinating forces between the hydrophilic and hydrophobic parts of the component molecules and the surrounding medium. In contrast to conventional amphiphiles, supra-amphiphiles are constructed on the basis of noncovalent interactions or dynamic covalent bonds. In supra-amphiphiles, the functional groups can be attached to the amphiphiles by noncovalent synthesis, greatly speeding their construction. The building blocks for supra-amphiphiles can be either small organic molecules or polymers. Advances in the development of supra-amphiphiles will not only enrich the family of conventional amphiphiles that are based on covalent bonds but will also provide a new kind of building block for the preparation of complex self-assemblies. When polymers are used to construct supra-amphiphiles, the resulting

  2. 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.

  3. Constructing Asymmetric Polyion Complex Vesicles via Template Assembling Strategy: Formulation Control and Tunable Permeability

    Directory of Open Access Journals (Sweden)

    Junbo Li

    2017-11-01

    Full Text Available A strategy for constructing polyion complex vesicles (PICsomes with asymmetric structure is described. Poly(methylacrylic acid-block-poly(N-isopropylacrylamide modified gold nanoparticles (PMAA-b-PNIPAm-@-Au NPs were prepared and then assembled with poly(ethylene glycol-block-poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine] (PEG-b-PMMPImB via polyion complex of PMMA and PMMPImB. After removing the Au NPs template, asymmetric PICsomes composed of a PNIPAm inner-shell, PIC wall, and PEG outer-corona were obtained. These PICsomes have low protein absorption and thermally tunable permeability, provided by the PEG outer-corona and the PNIPAm inner-shell, respectively. Moreover, PICsome size can be tailored by using templates of predetermined sizes. This novel strategy for constructing asymmetric PICsomes with well-defined properties and controllable size is valuable for applications such as drug delivery, catalysis and monitoring of chemical reactions, and biomimetics.

  4. Self-assembling peptide-based building blocks in medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Acar, Handan; Srivastava, Samanvaya; Chung, Eun Ji; Schnorenberg, Mathew R.; Barrett, John C.; LaBelle, James L.; Tirrell, Matthew

    2017-02-01

    Peptides and peptide-conjugates, comprising natural and synthetic building blocks, are an increasingly popular class of biomaterials. Self-assembled nanostructures based on peptides and peptide-conjugates offer advantages such as precise selectivity and multifunctionality that can address challenges and limitations in the clinic. In this review article, we discuss recent developments in the design and self-assembly of various nanomaterials based on peptides and peptide-conjugates for medical applications, and categorize them into two themes based on the driving forces of molecular self-assembly. First, we present the self-assembled nanostructures driven by the supramolecular interactions between the peptides, with or without the presence of conjugates. The studies where nanoassembly is driven by the interactions between the conjugates of peptide-conjugates are then presented. Particular emphasis is given to in vivo studies focusing on therapeutics, diagnostics, immune modulation and regenerative medicine. Finally, challenges and future perspectives are presented.

  5. Watching Nanoscale Self-Assembly Kinetics of Gold Prisms in Liquids

    Science.gov (United States)

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

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

  6. Facile preparation of a cationic poly(amino acid) vesicle for potential drug and gene co-delivery

    Science.gov (United States)

    Ding, Jianxun; Xiao, Chunsheng; He, Chaoliang; Li, Mingqiang; Li, Di; Zhuang, Xiuli; Chen, Xuesi

    2011-12-01

    A novel pH-responsive poly(amino acid) grafted with oligocation was prepared through the combination of ring-opening polymerization (ROP) and subsequent atom transfer radical polymerization (ATRP). Firstly, poly(γ-2-chloroethyl-L-glutamate) (PCELG) with a pendent 2-chloroethyl group was synthesized through ROP of γ-2-chloroethyl-L-glutamate N-carboxyanhydride (CELG NCA) using n-hexylamine as the initiator. Then, PCELG was used to initiate the ARTP of 2-aminoethyl methacrylate hydrochloride (AMA), yielding poly(L-glutamate)-graft-oligo(2-aminoethyl methacrylate hydrochloride) (PLG-g-OAMA). The pKa of PLG-g-OAMA was 7.3 established by the acid-base titration method. The amphiphilic poly(amino acid) could directly self-assemble into a vesicle in PBS. The vesicle was characterized by TEM and DLS. Hydrophilic DOX·HCl was loaded into the hollow core of the vesicle. The in vitro release behavior of DOX·HCl from the vesicle in PBS could be adjusted by the solution pH. In vitro cell experiments revealed that the vesicle could reduce the toxicity of the DOX·HCl. In addition, the preliminary gel retardation assay displayed that PLG-g-OAMA could efficiently bind DNA at a PLG-g-OAMA/DNA weight ratio of 0.3 or above, indicating its potential use as a gene carrier. More in-depth studies of the PLG-g-OAMA vesicle for drug and gene co-delivery in vitro and in vivo are in progress.

  7. Opal-like Multicolor Appearance of Self-Assembled Photonic Array.

    Science.gov (United States)

    Arnon, Zohar A; Pinotsi, Dorothea; Schmidt, Matthias; Gilead, Sharon; Guterman, Tom; Sadhanala, Aditya; Ahmad, Shahab; Levin, Aviad; Walther, Paul; Kaminski, Clemens F; Fändrich, Marcus; Kaminski Schierle, Gabriele S; Adler-Abramovich, Lihi; Shimon, Linda J W; Gazit, Ehud

    2018-06-20

    Molecular self-assembly of short peptide building blocks leads to the formation of various material architectures that may possess unique physical properties. Recent studies had confirmed the key role of biaromaticity in peptide self-assembly, with the diphenylalanine (FF) structural family as an archetypal model. Another significant direction in the molecular engineering of peptide building blocks is the use of fluorenylmethoxycarbonyl (Fmoc) modification, which promotes the assembly process and may result in nanostructures with distinctive features and macroscopic hydrogel with supramolecular features and nanoscale order. Here, we explored the self-assembly of the protected, noncoded fluorenylmethoxycarbonyl-β,β-diphenyl-Ala-OH (Fmoc-Dip) amino acid. This process results in the formation of elongated needle-like crystals with notable aromatic continuity. By altering the assembly conditions, arrays of spherical particles were formed that exhibit strong light scattering. These arrays display vivid coloration, strongly resembling the appearance of opal gemstones. However, unlike the Rayleigh scattering effect produced by the arrangement of opal, the described optical phenomenon is attributed to Mie scattering. Moreover, by controlling the solution evaporation rate, i.e., the assembly kinetics, we were able to manipulate the resulting coloration. This work demonstrates a bottom-up approach, utilizing self-assembly of a protected amino acid minimal building block, to create arrays of organic, light-scattering colorful surfaces.

  8. The Origin of Nanoscopic Grooving on Vesicle Walls in Submarine Basaltic Glass: Implications for Nanotechnology

    Directory of Open Access Journals (Sweden)

    Jason E. French

    2009-01-01

    Full Text Available Dendritic networks of nanoscopic grooves measuring 50–75 nm wide by <50 nm deep occur on the walls of vesicles in the glassy margins of mid-ocean ridge pillow basalts worldwide. Until now, their exact origin and significance have remained unclear. Here we document examples of such grooved patterns on vesicle walls in rocks from beneath the North Atlantic Ocean, and give a fluid mechanical explanation for how they formed. According to this model, individual nanogrooves represent frozen viscous fingers of magmatic fluid that were injected into a thin spheroidal shell of hot glass surrounding each vesicle. The driving mechanism for this process is provided by previous numerical predictions of tangential tensile stress around some vesicles in glassy rocks upon cooling through the glass transition. The self-assembling nature of the dendritic nanogrooves, their small size, and overall complexity in form, are interesting from the standpoint of exploring new applications in the field of nanotechnology. Replicating such structures in the laboratory would compete with state-of-the-art nanolithography techniques, both in terms of pattern complexity and size, which would be useful in the fabrication of a variety of grooved nanodevices. Dendritic nanogrooving in SiO2 glass might be employed in the manufacturing of integrated circuits.

  9. Construction of energy transfer pathways self-assembled from DNA-templated stacks of anthracene.

    Science.gov (United States)

    Iwaura, Rika; Yui, Hiroharu; Someya, Yuu; Ohnishi-Kameyama, Mayumi

    2014-01-05

    We describe optical properties of anthracene stacks formed from single-component self-assembly of thymidylic acid-appended anthracene 2,6-bis[5-(3'-thymidylic acid)pentyloxy] anthracene (TACT) and the binary self-assembly of TACT and complementary 20-meric oligoadenylic acid (TACT/dA20) in an aqueous buffer. UV-Vis and emission spectra for the single-component self-assembly of TACT and the binary self-assembly of TACT/dA20 were very consistent with stacked acene moieties in both self-assemblies. Interestingly, time-resolved fluorescence spectra from anthracene stacks exhibited very different features of the single-component and binary self-assemblies. In the single-component self-assembly of TACT, a dynamic Stokes shift (DSS) and relatively short fluorescence lifetime (τ=0.35ns) observed at around 450nm suggested that the anthracene moieties were flexible. Moreover, a broad emission at 530nm suggested the formation of an excited dimer (excimer). In the binary self-assembly of TACT/dA20, we detected a broad, red-shifted emission component at 534nm with a lifetime (τ=0.4ns) shorter than that observed in the TACT single-component self-assembly. Combining these results with the emission spectrum of the binary self-assembly of TACT/5'-HEX dA20, we concluded that the energy transfer pathway was constructed by columnar anthracene stacks formed from the DNA-templated self-assembly of TACT. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Controlling Self-Assembly in Al(110) Homoepitaxy

    Science.gov (United States)

    Tiwary, Yogesh; Fichthorn, Kristen

    2010-03-01

    Homoepitaxial growth on Al(110) exhibits nanoscale self-assembly into huts with well-defined (100) and (111) facets [1]. Although some of the diffusion mechanisms underlying this kinetic self-assembly were identified and incorporated into a two-dimensional model [2], we used density-functional theory (DFT) to identify many other mechanisms that are needed to describe the three-dimensional assembly seen experimentally [3]. We developed a three-dimensional kinetic Monte Carlo (KMC) model of Al(110) homoepitaxy. The inputs to the model were obtained from DFT [3,4]. Our model is in agreement with experimentally observed trends for this system. We used KMC to predict self-assembly under various growth conditions. To achieve precise placement of Al nanohuts, we simulated thermal-field-directed assembly [5]. Our results indicate that this technique can be used to create uniform arrays of nanostructures. [1] F. Buatier de Mongeot, W. Zhu, A. Molle, R. Buzio, C. Boragno, U. Valbusa, E. Wang, and Z. Zhang, Phys. Rev. Lett. 91, 016102 (2003). [2] W. Zhu, F. Buatier de Mongeot, U. Valbusa, E. G. Wang, and Z. Y. Zhang, Phys. Rev. Lett. 92, 106102 (2004). [3] Y. Tiwary and K. A. Fichthorn, submitted to Phys. Rev. B. [4] Y. Tiwary and K. A. Fichthorn, Phys. Rev. B 78, 205418 (2008). [5] C. Zhang and R. Kalyanaraman, Appl. Phys. Lett. 83, 4827 (2003).

  11. Electrodynamic tailoring of self-assembled three-dimensional electrospun constructs

    Science.gov (United States)

    Reis, Tiago C.; Correia, Ilídio J.; Aguiar-Ricardo, Ana

    2013-07-01

    The rational design of three-dimensional electrospun constructs (3DECs) can lead to striking topographies and tailored shapes of electrospun materials. This new generation of materials is suppressing some of the current limitations of the usual 2D non-woven electrospun fiber mats, such as small pore sizes or only flat shaped constructs. Herein, we pursued an explanation for the self-assembly of 3DECs based on electrodynamic simulations and experimental validation. We concluded that the self-assembly process is driven by the establishment of attractive electrostatic forces between the positively charged aerial fibers and the already collected ones, which tend to acquire a negatively charged network oriented towards the nozzle. The in situ polarization degree is strengthened by higher amounts of clustered fibers, and therefore the initial high density fibrous regions are the preliminary motifs for the self-assembly mechanism. As such regions increase their in situ polarization electrostatic repulsive forces will appear, favoring a competitive growth of these self-assembled fibrous clusters. Highly polarized regions will evidence higher distances between consecutive micro-assembled fibers (MAFs). Different processing parameters - deposition time, electric field intensity, concentration of polymer solution, environmental temperature and relative humidity - were evaluated in an attempt to control material's design.The rational design of three-dimensional electrospun constructs (3DECs) can lead to striking topographies and tailored shapes of electrospun materials. This new generation of materials is suppressing some of the current limitations of the usual 2D non-woven electrospun fiber mats, such as small pore sizes or only flat shaped constructs. Herein, we pursued an explanation for the self-assembly of 3DECs based on electrodynamic simulations and experimental validation. We concluded that the self-assembly process is driven by the establishment of attractive

  12. Completion of the first TRT End-cap

    CERN Multimedia

    Catinaccio, A; Rohne, O

    On July 1, the first end-cap of the ATLAS Transition Radiation Tracker (TRT) was successfully completed in terms of the integration of the wheels assembled in Russia with their front-end electronics. The two groups of the detector, fully assembled and equipped with front-end electronics, were rotated from their horizontal position during stacking to their nominal vertical position, in which they will be integrated with the corresponding end-cap silicon-strip (SCT) detector towards the end of 2005, before installation into ATLAS in spring 2006. After starting the assembly in the SR building one year ago, the TRT team reached this important milestone, which marks the final realization and validation of the engineering concept developed by the CERN DT1 (ex-TA1) and ATT teams. A TRT end-cap consists of two sets of identical and independent wheels. The first type of wheels (type A, 12 wheels, positioned closest to the primary interaction point) contains 6144 radial straws positioned in eight successive layers s...

  13. Self-Assembly of Colloidal Particles

    Indian Academy of Sciences (India)

    is self-assembly where one engineers interaction between nanoscopic building blocks so ..... big question in the field how this microscopic chirality of the virus gets translated ... shape emerges due to a competition between the surface tension.

  14. Balancing the intermolecular forces in peptide amphiphiles for controlling self-assembly transitions.

    Science.gov (United States)

    Buettner, C J; Wallace, A J; Ok, S; Manos, A A; Nicholl, M J; Ghosh, A; Tweedle, M F; Goldberger, J E

    2017-06-21

    While the influence of alkyl chain length and headgroup size on self-assembly behaviour has been well-established for simple surfactants, the rational control over the pH- and concentration-dependent self-assembly behaviour in stimuli responsive peptides remains an elusive goal. Here, we show that different amphiphilic peptides can have similar self-assembly phase diagrams, providing the relative strengths of the attractive and repulsive forces are balanced. Using palmitoyl-YYAAEEEEK(DO3A:Gd)-NH 2 and palmitoyl-YAAEEEEK(DO3A:Gd)-NH 2 as controls, we show that reducing hydrophobic attractive forces through fewer methylene groups in the alkyl chain will lead to a similar self-assembly phase diagram as increasing the electrostatic repulsive forces via the addition of a glutamic acid residue. These changes allow creation of self-assembled MRI vehicles with slightly different micelle and nanofiber diameters but with minimal changes in the spin-lattice T 1 relaxivity. These findings reveal a powerful strategy to design self-assembled vehicles with different sizes but with similar self-assembly profiles.

  15. Self-assembled domain structures: From micro- to nanoscale

    Directory of Open Access Journals (Sweden)

    Vladimir Shur

    2015-06-01

    Full Text Available The recent achievements in studying the self-assembled evolution of micro- and nanoscale domain structures in uniaxial single crystalline ferroelectrics lithium niobate and lithium tantalate have been reviewed. The results obtained by visualization of static domain patterns and kinetics of the domain structure by different methods from common optical microscopy to more sophisticated scanning probe microscopy, scanning electron microscopy and confocal Raman microscopy, have been discussed. The kinetic approach based on various nucleation processes similar to the first-order phase transition was used for explanation of the domain structure evolution scenarios. The main mechanisms of self-assembling for nonequilibrium switching conditions caused by screening ineffectiveness including correlated nucleation, domain growth anisotropy, and domain–domain interaction have been considered. The formation of variety of self-assembled domain patterns such as fractal-type, finger and web structures, broad domain boundaries, and dendrites have been revealed at each of all five stages of domain structure evolution during polarization reversal. The possible applications of self-assembling for micro- and nanodomain engineering were reviewed briefly. The review covers mostly the results published by our research group.

  16. Self-assembly of silver nanoparticles and bacteriophage

    Directory of Open Access Journals (Sweden)

    Santi Scibilia

    2016-03-01

    Full Text Available Biohybrid nanostructured materials, composed of both inorganic nanoparticles and biomolecules, offer prospects for many new applications in extremely diverse fields such as chemistry, physics, engineering, medicine and nanobiotechnology. In the recent years, Phage display technique has been extensively used to generate phage clones displaying surface peptides with functionality towards organic materials. Screening and selection of phage displayed material binding peptides has attracted great interest because of their use for development of hybrid materials with multiple functionalities. Here, we present a self-assembly approach for the construction of hybrid nanostructured networks consisting of M13 P9b phage clone, specific for Pseudomonas aeruginosa, selected by Phage display technology, directly assembled with silver nanoparticles (AgNPs, previously prepared by pulsed laser ablation. These networks are characterized by UV–vis optical spectroscopy, scanning/transmission electron microscopies and Raman spectroscopy. We investigated the influence of different ions and medium pH on self-assembly by evaluating different phage suspension buffers. The assembly of these networks is controlled by electrostatic interactions between the phage pVIII major capsid proteins and the AgNPs. The formation of the AgNPs-phage networks was obtained only in two types of tested buffers at a pH value near the isoelectric point of each pVIII proteins displayed on the surface of the clone. This systematic study allowed to optimize the synthesis procedure to assembly AgNPs and bacteriophage. Such networks find application in the biomedical field of advanced biosensing and targeted gene and drug delivery. Keywords: Phage display, Silver nanoparticles, Self-assembly, Hybrid architecture, Raman spectroscopy

  17. Kinetic Monte Carlo simulations and cross-sectional scanning tunneling microscopy as tools to investigate the heteroepitaxial capping of self-assembled quantum dots

    NARCIS (Netherlands)

    Keizer, J.G.; Koenraad, P.M.; Smereka, P.; Ulloa, J.M.; Guzman, A.; Hierro, A.

    2012-01-01

    In the last decade, an ever increasing understanding of heteroepitaxial growth has paved the way for the fabrication of a multitude of self-assembled nanostructures. Nowadays, nanostructures such as quantum rings,1 quantum wires,2 quantum dashes,3 quantum rods,4 and quantum dots (QDs)5 can be grown

  18. Driven self-assembly of hard nanoplates on soft elastic shells

    International Nuclear Information System (INIS)

    Zhang Yao-Yang; Hua Yun-Feng; Deng Zhen-Yu

    2015-01-01

    The driven self-assembly behaviors of hard nanoplates on soft elastic shells are investigated by using molecular dynamics (MD) simulation method, and the driven self-assembly structures of adsorbed hard nanoplates depend on the shape of hard nanoplates and the bending energy of soft elastic shells. Three main structures for adsorbed hard nanoplates, including the ordered aggregation structures of hard nanoplates for elastic shells with a moderate bending energy, the collapsed structures for elastic shells with a low bending energy, and the disordered aggregation structures for hard shells, are observed. The self-assembly process of adsorbed hard nanoplates is driven by the surface tension of the elastic shell, and the shape of driven self-assembly structures is determined on the basis of the minimization of the second moment of mass distribution. Meanwhile, the deformations of elastic shells can be controlled by the number of adsorbed rods as well as the length of adsorbed rods. This investigation can help us understand the complexity of the driven self-assembly of hard nanoplates on elastic shells. (paper)

  19. Strain engineering of quantum dots for long wavelength emission: Photoluminescence from self-assembled InAs quantum dots grown on GaAs(001) at wavelengths over 1.55 μm

    International Nuclear Information System (INIS)

    Shimomura, K.; Kamiya, I.

    2015-01-01

    Photoluminescence (PL) at wavelengths over 1.55 μm from self-assembled InAs quantum dots (QDs) grown on GaAs(001) is observed at room temperature (RT) and 4 K using a bilayer structure with thin cap. The PL peak has been known to redshift with decreasing cap layer thickness, although accompanying intensity decrease and peak broadening. With our strain-controlled bilayer structure, the PL intensity can be comparable to the ordinary QDs while realizing peak emission wavelength of 1.61 μm at 4 K and 1.73 μm at RT. The key issue lies in the control of strain not only in the QDs but also in the cap layer. By combining with underlying seed QD layer, we realize strain-driven bandgap engineering through control of strain in the QD and cap layers

  20. Strain engineering of quantum dots for long wavelength emission: Photoluminescence from self-assembled InAs quantum dots grown on GaAs(001) at wavelengths over 1.55 μm

    Energy Technology Data Exchange (ETDEWEB)

    Shimomura, K., E-mail: sd12502@toyota-ti.ac.jp; Kamiya, I., E-mail: kamiya@toyota-ti.ac.jp [Toyota Technological Institute 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

    2015-02-23

    Photoluminescence (PL) at wavelengths over 1.55 μm from self-assembled InAs quantum dots (QDs) grown on GaAs(001) is observed at room temperature (RT) and 4 K using a bilayer structure with thin cap. The PL peak has been known to redshift with decreasing cap layer thickness, although accompanying intensity decrease and peak broadening. With our strain-controlled bilayer structure, the PL intensity can be comparable to the ordinary QDs while realizing peak emission wavelength of 1.61 μm at 4 K and 1.73 μm at RT. The key issue lies in the control of strain not only in the QDs but also in the cap layer. By combining with underlying seed QD layer, we realize strain-driven bandgap engineering through control of strain in the QD and cap layers.

  1. Micellar Self-Assembly of Recombinant Resilin-/Elastin-Like Block Copolypeptides.

    Science.gov (United States)

    Weitzhandler, Isaac; Dzuricky, Michael; Hoffmann, Ingo; Garcia Quiroz, Felipe; Gradzielski, Michael; Chilkoti, Ashutosh

    2017-08-14

    Reported here is the synthesis of perfectly sequence defined, monodisperse diblock copolypeptides of hydrophilic elastin-like and hydrophobic resilin-like polypeptide blocks and characterization of their self-assembly as a function of structural parameters by light scattering, cryo-TEM, and small-angle neutron scattering. A subset of these diblock copolypeptides exhibit lower critical solution temperature and upper critical solution temperature phase behavior and self-assemble into spherical or cylindrical micelles. Their morphologies are dictated by their chain length, degree of hydrophilicity, and hydrophilic weight fraction of the ELP block. We find that (1) independent of the length of the corona-forming ELP block there is a minimum threshold in the length of the RLP block below which self-assembly does not occur, but that once that threshold is crossed, (2) the RLP block length is a unique molecular parameter to independently tune self-assembly and (3) increasing the hydrophobicity of the corona-forming ELP drives a transition from spherical to cylindrical morphology. Unlike the self-assembly of purely ELP-based block copolymers, the self-assembly of RLP-ELPs can be understood by simple principles of polymer physics relating hydrophilic weight fraction and polymer-polymer and polymer-solvent interactions to micellar morphology, which is important as it provides a route for the de novo design of desired nanoscale morphologies from first principles.

  2. Multicomponent and Dissipative Self-Assembly Approaches : Towards functional materials

    NARCIS (Netherlands)

    Boekhoven, J.

    2012-01-01

    The use of self-assembly has proven to be a powerful approach to create smart and functional materials and has led to a vast variety of successful examples. However, the full potential of self-assembly has not been reached. Despite the number of successful artificial materials based on

  3. DNA nanotubes for NMR structure determination of membrane proteins.

    Science.gov (United States)

    Bellot, Gaëtan; McClintock, Mark A; Chou, James J; Shih, William M

    2013-04-01

    Finding a way to determine the structures of integral membrane proteins using solution nuclear magnetic resonance (NMR) spectroscopy has proved to be challenging. A residual-dipolar-coupling-based refinement approach can be used to resolve the structure of membrane proteins up to 40 kDa in size, but to do this you need a weak-alignment medium that is detergent-resistant and it has thus far been difficult to obtain such a medium suitable for weak alignment of membrane proteins. We describe here a protocol for robust, large-scale synthesis of detergent-resistant DNA nanotubes that can be assembled into dilute liquid crystals for application as weak-alignment media in solution NMR structure determination of membrane proteins in detergent micelles. The DNA nanotubes are heterodimers of 400-nm-long six-helix bundles, each self-assembled from a M13-based p7308 scaffold strand and >170 short oligonucleotide staple strands. Compatibility with proteins bearing considerable positive charge as well as modulation of molecular alignment, toward collection of linearly independent restraints, can be introduced by reducing the negative charge of DNA nanotubes using counter ions and small DNA-binding molecules. This detergent-resistant liquid-crystal medium offers a number of properties conducive for membrane protein alignment, including high-yield production, thermal stability, buffer compatibility and structural programmability. Production of sufficient nanotubes for four or five NMR experiments can be completed in 1 week by a single individual.

  4. SYNTHESIS OF pH-RESPONSIVE AMPHIPHILIC DIBLOCK COPOLYMERS CONTAINING POLYISOBUTYLENE via OXYANION-INITIATED POLYMERIZATION AND THEIR MULTIPLE SELF-ASSEMBLY MORPHOLOGIES

    Institute of Scientific and Technical Information of China (English)

    Huai-chao Wang; Ming-zu Zhang; Pei-hong Ni; Jin-lin He; Ying Hao; Yi-xian Wu

    2013-01-01

    Two pH-responsive amphiphilic diblock copolymers,namely polyisobutylene-block-poly[2-(N,N-dimethylamino)ethyl methacrylate] (PIB-b-PDMAEMA) and polyisobutylene-block-poly(metharylic acid) (PIB-b-PMAA),were synthesized via oxyanion-initiated polymerization,and their multiple self-assembly behaviors have been studied.An exo-o1efin-terminated highly reactive polyisobutylene (HRPIB) was first changed to hydroxyl-terminated PIB (PIB-OH) via hydroboration-oxidation of C=C double bond in the chain end,and then reacted with KH to yield a potassium alcoholate of PIB (PIB-O-K+).PIB-O-K+ was immediately used as a macroinitiator to polymerize DMAEMA monomer,resulting in a cationic diblock copolymer PIB-b-PDMAEMA.With the similar synthesis procedure,the anionic diblock copolymer PIB-b-PMAA could be prepared via a combination of oxyanion-initiated polymerization of tert-butyl methacrylate (tBMA) and subsequent hydrolysis of tert-butyl ester groups in PtBMA block.The functional PIB and block copolymers have been fully characterized by 1H-NMR,FT-IR spectroscopy,and gel permeation chromatography (GPC).These samples allowed us to systematically investigate the effects of block composition on the pH responsivity and various self-assembled morphologies of the copolymers in THF/water mixed solvent.Transmission electron microscopy (TEM) images revealed that these diblock copolymers containing small amount of original PIB without exo-olefin-terminated group are able to self-assemble into micelles,vesicles with different particle sizes and cylindrical aggregates,depending on various factors including block copolymer composition,solvent polarity and pH value.

  5. Carbon nanotube transistors scaled to a 40-nanometer footprint.

    Science.gov (United States)

    Cao, Qing; Tersoff, Jerry; Farmer, Damon B; Zhu, Yu; Han, Shu-Jen

    2017-06-30

    The International Technology Roadmap for Semiconductors challenges the device research community to reduce the transistor footprint containing all components to 40 nanometers within the next decade. We report on a p-channel transistor scaled to such an extremely small dimension. Built on one semiconducting carbon nanotube, it occupies less than half the space of leading silicon technologies, while delivering a significantly higher pitch-normalized current density-above 0.9 milliampere per micrometer at a low supply voltage of 0.5 volts with a subthreshold swing of 85 millivolts per decade. Furthermore, we show transistors with the same small footprint built on actual high-density arrays of such nanotubes that deliver higher current than that of the best-competing silicon devices under the same overdrive, without any normalization. We achieve this using low-resistance end-bonded contacts, a high-purity semiconducting carbon nanotube source, and self-assembly to pack nanotubes into full surface-coverage aligned arrays. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  6. Effects of Lateral and Terminal Chains of X-Shaped Bolapolyphiles with Oligo(phenylene ethynylene Cores on Self-Assembly Behavior. Part 2: Domain Formation by Self-Assembly in Lipid Bilayer Membranes

    Directory of Open Access Journals (Sweden)

    Stefan Werner

    2017-09-01

    Full Text Available Supramolecular self-assembly of membrane constituents within a phospholipid bilayer creates complex functional platforms in biological cells that operate in intracellular signaling, trafficking and membrane remodeling. Synthetic polyphilic compounds of macromolecular or small size can be incorporated into artificial phospholipid bilayers. Featuring three or four moieties of different philicities, they reach beyond ordinary amphiphilicity and open up avenues to new functions and interaction concepts. Here, we have incorporated a series of X-shaped bolapolyphiles into DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine bilayers of giant unilamellar vesicles. The bolapolyphiles consist of a rod-like oligo(phenylene ethynylene (OPE core, hydrophilic glycerol-based headgroups with or without oligo(ethylene oxide expansions at both ends and two lateral alkyl chains attached near the center of the OPE core. In the absence of DPPC and water, the compounds showed thermotropic liquid-crystalline behavior with a transition between polyphilic and amphiphilic assembly (see part 1 in this issue. In DPPC membranes, various trends in the domain morphologies were observed upon structure variations, which entailed branched alkyl chains of various sizes, alkyl chain semiperfluorination and size expansion of the headgroups. Observed effects on domain morphology are interpreted in the context of the bulk behavior (part 1 and of a model that was previously developed based on spectroscopic and physicochemical data.

  7. 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

  8. Homochiral Evolution in Self-Assembled Chiral Polymers and Block Copolymers.

    Science.gov (United States)

    Wen, Tao; Wang, Hsiao-Fang; Li, Ming-Chia; Ho, Rong-Ming

    2017-04-18

    The significance of chirality transfer is not only involved in biological systems, such as the origin of homochiral structures in life but also in man-made chemicals and materials. How the chiral bias transfers from molecular level (molecular chirality) to helical chain (conformational chirality) and then to helical superstructure or phase (hierarchical chirality) from self-assembly is vital for the chemical and biological processes in nature, such as communication, replication, and enzyme catalysis. In this Account, we summarize the methodologies for the examination of homochiral evolution at different length scales based on our recent studies with respect to the self-assembly of chiral polymers and chiral block copolymers (BCPs*). A helical (H*) phase to distinguish its P622 symmetry from that of normal hexagonally packed cylinder phase was discovered in the self-assembly of BCPs* due to the chirality effect on BCP self-assembly. Enantiomeric polylactide-containing BCPs*, polystyrene-b-poly(l-lactide) (PS-PLLA) and polystyrene-b-poly(d-lactide) (PS-PDLA), were synthesized for the examination of homochiral evolution. The optical activity (molecular chirality) of constituted chiral repeating unit in the chiral polylactide is detected by electronic circular dichroism (ECD) whereas the conformational chirality of helical polylactide chain can be explicitly determined by vibrational circular dichroism (VCD). The H* phases of the self-assembled polylactide-containing BCPs* can be directly visualized by 3D transmission electron microscopy (3D TEM) technique at which the handedness (hierarchical chirality) of the helical nanostructure is thus determined. The results from the ECD, VCD, and 3D TEM for the investigated chirality at different length scales suggest the homochiral evolution in the self-assembly of the BCPs*. For chiral polylactides, twisted lamellae in crystalline banded spherulite can be formed by dense packing scheme and effective interactions upon helical

  9. Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

    International Nuclear Information System (INIS)

    Wen Li; Lin Zhonghua; Gu Pingying; Zhou Jianzhang; Yao Bingxing; Chen Guoliang; Fu Jinkun

    2009-01-01

    Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 o C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01.

  10. Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

    Energy Technology Data Exchange (ETDEWEB)

    Wen Li [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China); Lin Zhonghua [Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces (China); Gu Pingying [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China); Zhou Jianzhang [Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces (China); Yao Bingxing [Xiamen University, School of Life Sciences (China); Chen Guoliang; Fu Jinkun, E-mail: wenli_1976@163.co [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China)

    2009-02-15

    Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 {sup o}C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold nanoparticles capped with thiol of 1.9 {+-} 0.8 nm size were formed by using Bacillus megatherium D01.

  11. Self-assembled three-dimensional chiral colloidal architecture

    Science.gov (United States)

    Ben Zion, Matan Yah; He, Xiaojin; Maass, Corinna C.; Sha, Ruojie; Seeman, Nadrian C.; Chaikin, Paul M.

    2017-11-01

    Although stereochemistry has been a central focus of the molecular sciences since Pasteur, its province has previously been restricted to the nanometric scale. We have programmed the self-assembly of micron-sized colloidal clusters with structural information stemming from a nanometric arrangement. This was done by combining DNA nanotechnology with colloidal science. Using the functional flexibility of DNA origami in conjunction with the structural rigidity of colloidal particles, we demonstrate the parallel self-assembly of three-dimensional microconstructs, evincing highly specific geometry that includes control over position, dihedral angles, and cluster chirality.

  12. Identification of Factors Promoting HBV Capsid Self-Assembly by Assembly-Promoting Antivirals.

    Science.gov (United States)

    Rath, Soumya Lipsa; Liu, Huihui; Okazaki, Susumu; Shinoda, Wataru

    2018-02-26

    Around 270 million individuals currently live with hepatitis B virus (HBV) infection. Heteroaryldihydropyrimidines (HAPs) are a family of antivirals that target the HBV capsid protein and induce aberrant self-assembly. The capsids formed resemble the native capsid structure but are unable to propagate the virus progeny because of a lack of RNA/DNA. Under normal conditions, self-assembly is initiated by the viral genome. The mode of action of HAPs, however, remains largely unknown. In this work, using molecular dynamics simulations, we attempted to understand the action of HAP by comparing the dynamics of capsid proteins with and without HAPs. We found that the inhibitor is more stable in higher oligomers. It retains its stability in the hexamer throughout 1 μs of simulation. Our results also show that the inhibitor might help in stabilizing the C-terminus, the HBc 149-183 arginine-rich domain of the capsid protein. The C-termini of dimers interact with each other, assisted by the HAP inhibitor. During capsid assembly, the termini are supposed to directly interact with the viral genome, thereby suggesting that the viral genome might work in a similar way to stabilize the capsid protein. Our results may help in understanding the underlying molecular mechanism of HBV capsid self-assembly, which should be crucial for exploring new drug targets and structure-based drug design.

  13. Facile fabrication of self-assembled polyaniline nanotubes doped with D-tartaric acid for high-performance supercapacitors

    Science.gov (United States)

    Mu, Jingjing; Ma, Guofu; Peng, Hui; Li, Jiajia; Sun, Kanjun; Lei, Ziqiang

    2013-11-01

    Polyaniline (PANI) nanotubes with outstanding electrochemical properties have been successfully synthesized via a simple chemical template-free method in the presence of D-tartaric acid (D-TA) as the dopant, and ammonium persulfate ((NH4)2S2O8) as the oxidant. The morphologies and structures of PANI-(D-TA) with different [D-TA]/[aniline] molar ratios are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) and X-ray diffraction (XRD). To assess the electrochemical properties of PANI-(D-TA) materials, cyclic voltammetry (CV) and galvanostatic charging-discharging measurements are performed. The PANI-(D-TA) nanotubes electrode, with [D-TA]/[aniline] molar ratio of 1:1, exhibits larger specific capacitance (as high as 625 F g-1 at 1 A g-1) and higher capacitance retention (77% of its initial capacitance after 500 cycles) in 1 M H2SO4 aqueous solution. The remarkable electrochemical characteristics of PANI-(D-TA) are mainly attributed to their unique nanotubular structures, which provide a high electrode/electrolyte contact area and short ions diffusion path. These novel PANI-(D-TA) nanotubes will be promising electrode materials for high-performance supercapacitors.

  14. Explosive decomposition of a melamine-cyanuric acid supramolecular assembly for fabricating defect-rich nitrogen-doped carbon nanotubes with significantly promoted catalysis.

    Science.gov (United States)

    Zhao, Zhongkui; Dai, Yitao; Ge, Guifang; Wang, Guiru

    2015-05-26

    A facile and scalable approach for fabricating structural defect-rich nitrogen-doped carbon nanotubes (MCSA-CNTs) through explosive decomposition of melamine-cyanuric acid supramolecular assembly is presented. In comparison to pristine carbon nanotubes, MCSA-CNT exhibits significantly enhanced catalytic performance in oxidant- and steam-free direct dehydrogenation of ethylbenzene, demonstrating the potential for metal-free clean and energy-saving styrene production. This finding also opens a new horizon for preparing highly-efficient carbocatalysts rich in structural defect sites for diverse transformations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. 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

  16. Crystal-Structure-Guided Design of Self-Assembling RNA Nanotriangles.

    Science.gov (United States)

    Boerneke, Mark A; Dibrov, Sergey M; Hermann, Thomas

    2016-03-14

    RNA nanotechnology uses RNA structural motifs to build nanosized architectures that assemble through selective base-pair interactions. Herein, we report the crystal-structure-guided design of highly stable RNA nanotriangles that self-assemble cooperatively from short oligonucleotides. The crystal structure of an 81 nucleotide nanotriangle determined at 2.6 Å resolution reveals the so-far smallest circularly closed nanoobject made entirely of double-stranded RNA. The assembly of the nanotriangle architecture involved RNA corner motifs that were derived from ligand-responsive RNA switches, which offer the opportunity to control self-assembly and dissociation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. The cervical cap (image)

    Science.gov (United States)

    The cervical cap is a flexible rubber cup-like device that is filled with spermicide and self-inserted over the cervix ... left in place several hours after intercourse. The cap is a prescribed device fitted by a health ...

  18. Supramolecular ribbons from amphiphilic trisamides self-assembly.

    Science.gov (United States)

    García, Fátima; Buendía, Julia; Sánchez, Luis

    2011-08-05

    Two amphiphilic C(3)-symmetric OPE-based trisamides have been synthesized and their self-assembling features investigated in solution and on surface. Variable-temperature UV-vis experiments demonstrate the cooperative supramolecular polymerization of these trisamides that self-assemble by the operation of triple C═O···H-N H-bonding arrays between the amide functional groups and π-π stacking between the aromatic units. The helical organization of the aggregates has been demonstrated by circular dichroism at a concentration as low as 1 × 10(-4) M in acetonitrile. In the reported trisamides, the large hydrophobic aromatic core acts as a solvophobic module impeding the interaction between the polar TEG chains and the amide H-bonds. This strategy makes unnecessary the separation of the amide functional groups to the polar tri(ethylene glycol) chains by paraffinic fragments. Achiral trisamide 1 self-assembles into flat ribbon-like structures that experience an amplification of chirality by the addition of a small amount of chiral 2 that generates twisted stripes.

  19. ZnO nanotube-based dye-sensitized solar cell and its application in self-powered devices

    Energy Technology Data Exchange (ETDEWEB)

    Han Jingbin; Fan Fengru; Xu Chen; Lin Shisheng; Wang Zhonglin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Wei Min; Duan Xue, E-mail: zhong.wang@mse.gatech.edu, E-mail: weimin@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2010-10-08

    High-density vertically aligned ZnO nanotube arrays were fabricated on FTO substrates by a simple and facile chemical etching process from electrodeposited ZnO nanorods. The nanotube formation was rationalized in terms of selective dissolution of the (001) polar face. The morphology of the nanotubes can be readily controlled by electrodeposition parameters for the nanorod precursor. By employing the 5.1 {mu}m-length nanotubes as the photoanode for a dye-sensitized solar cell (DSSC), a full-sun conversion efficiency of 1.18% was achieved. Furthermore, we show that the DSSC unit can serve as a robust power source to drive a humidity sensor, with a potential for self-powered devices.

  20. ZnO nanotube-based dye-sensitized solar cell and its application in self-powered devices

    KAUST Repository

    Han, Jingbin

    2010-09-10

    Abstract High-density vertically aligned ZnO nanotube arrays were fabricated on FTO substrates by a simple and facile chemical etching process from electrodeposited ZnO nanorods. The nanotube formation was rationalized in terms of selective dissolution of the (001) polar face. The morphology of the nanotubes can be readily controlled by electrodeposition parameters for the nanorod precursor. By employing the 5.1 μm-length nanotubes as the photoanode for a dye-sensitized solar cell (DSSC), a full-sun conversion efficiency of 1.18% was achieved. Furthermore, we show that the DSSC unit can serve as a robust power source to drive a humidity sensor, with a potential for self-powered devices. © 2010 IOP Publishing Ltd.

  1. Supramolecular assembled three-dimensional graphene hybrids: Synthesis and applications in supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Lubin [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, Jiangsu (China); Zhang, Wang [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, Jiangsu (China); Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 151-742 (Korea, Republic of); Wu, Zhen; Sun, Chunyu; Cai, Yin; Yang, Guang; Chen, Ming [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, Jiangsu (China); Piao, Yuanzhe, E-mail: parkat9@snu.ac.kr [Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 151-742 (Korea, Republic of); Diao, Guowang, E-mail: gwdiao@yzu.edu.cn [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, Jiangsu (China)

    2017-02-28

    Graphical abstract: Supramolecular assembled three-dimensdional graphene-based architectures were built by host-guest interactions of β-cyclodextrin polymers(β-CDPs) with adamantine end-capped poly(ethylene oxide) polymer linker (PEG-AD), exhibit significantly improved electrochemical performances of supercapacitor in terms of high specific capacitance, remarkable rate capability, and excellent cycling stability compared to pristine reduced graphene oxide. - Highlights: • Supramolecular assembled three-Dimensional (3D) graphene was first fabricated by host-guest interactions of β-CDPs with PEG-AD linkers. • The incorporation of PEG-AD linker into rGO sheets can provide efficient 3D electron transfer pathways and ion diffusion channels. • The 3D self-assembled graphene exhibits high specific capacitance, remarkable rate capability, and excellent cycling stability. • This study shed new lights to design 3D self-assembled graphene materials and their urgent applications in energy storage. - Abstract: Graphene-based materials have received worldwide attention in the focus of forefront energy storage investigations. Currently, the design of novel three-dimensional (3D) graphene structures with high energy capability, superior electron and ion conductivity, and robust mechanical flexibility is still a great challenge. Herein, we have successfully demonstrated a novel approach to fabricate 3D assembled graphene through the supramolecular interactions of β-cyclodextrin polymers (β-CDP) with an adamantine end-capped poly(ethylene oxide) polymer linker (PEG-AD). The incorporation of PEG-AD linker into rGO sheets increased the interlayer spacing of rGO sheets to form 3D graphene materials, which can provide efficient 3D electron transfer pathways and ion diffusion channels, and facilitate the infiltration of gel electrolyte. The as-prepared 3D self-assembled graphene materials exhibit significantly improved electrochemical performances of supercapacitor in terms

  2. Supramolecular assembled three-dimensional graphene hybrids: Synthesis and applications in supercapacitors

    International Nuclear Information System (INIS)

    Ni, Lubin; Zhang, Wang; Wu, Zhen; Sun, Chunyu; Cai, Yin; Yang, Guang; Chen, Ming; Piao, Yuanzhe; Diao, Guowang

    2017-01-01

    Graphical abstract: Supramolecular assembled three-dimensdional graphene-based architectures were built by host-guest interactions of β-cyclodextrin polymers(β-CDPs) with adamantine end-capped poly(ethylene oxide) polymer linker (PEG-AD), exhibit significantly improved electrochemical performances of supercapacitor in terms of high specific capacitance, remarkable rate capability, and excellent cycling stability compared to pristine reduced graphene oxide. - Highlights: • Supramolecular assembled three-Dimensional (3D) graphene was first fabricated by host-guest interactions of β-CDPs with PEG-AD linkers. • The incorporation of PEG-AD linker into rGO sheets can provide efficient 3D electron transfer pathways and ion diffusion channels. • The 3D self-assembled graphene exhibits high specific capacitance, remarkable rate capability, and excellent cycling stability. • This study shed new lights to design 3D self-assembled graphene materials and their urgent applications in energy storage. - Abstract: Graphene-based materials have received worldwide attention in the focus of forefront energy storage investigations. Currently, the design of novel three-dimensional (3D) graphene structures with high energy capability, superior electron and ion conductivity, and robust mechanical flexibility is still a great challenge. Herein, we have successfully demonstrated a novel approach to fabricate 3D assembled graphene through the supramolecular interactions of β-cyclodextrin polymers (β-CDP) with an adamantine end-capped poly(ethylene oxide) polymer linker (PEG-AD). The incorporation of PEG-AD linker into rGO sheets increased the interlayer spacing of rGO sheets to form 3D graphene materials, which can provide efficient 3D electron transfer pathways and ion diffusion channels, and facilitate the infiltration of gel electrolyte. The as-prepared 3D self-assembled graphene materials exhibit significantly improved electrochemical performances of supercapacitor in terms

  3. 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...

  4. Assembly of MreB filaments on liposome membranes: a synthetic biology approach.

    Science.gov (United States)

    Maeda, Yusuke T; Nakadai, Tomoyoshi; Shin, Jonghyeon; Uryu, Kunihiro; Noireaux, Vincent; Libchaber, Albert

    2012-02-17

    The physical interaction between the cytoskeleton and the cell membrane is essential in defining the morphology of living organisms. In this study, we use a synthetic approach to polymerize bacterial MreB filaments inside phospholipid vesicles. When the proteins MreB and MreC are expressed inside the liposomes, the MreB cytoskeleton structure develops at the inner membrane. Furthermore, when purified MreB is used inside the liposomes, MreB filaments form a 4-10 μm rigid bundle structure and deform the lipid vesicles in physical contact with the vesicle inner membrane. These results indicate that the fibrillation of MreB filaments can take place either in close proximity of deformable lipid membrane or in the presence of associated protein. Our finding might be relevant for the self-assembly of cytoskeleton filaments toward the construction of artificial cell systems.

  5. Combing and self-assembly phenomena in dry films of Taxol-stabilized microtubules

    Directory of Open Access Journals (Sweden)

    Rose Franck

    2007-01-01

    Full Text Available AbstractMicrotubules are filamentous proteins that act as a substrate for the translocation of motor proteins. As such, they may be envisioned as a scaffold for the self-assembly of functional materials and devices. Physisorption, self-assembly and combing are here investigated as a potential prelude to microtubule-templated self-assembly. Dense films of self-assembled microtubules were successfully produced, as well as patterns of both dendritic and non-dendritic bundles of microtubules. They are presented in the present paper and the mechanism of their formation is discussed.

  6. Self-assembly of subwavelength nanostructures with symmetry breaking in solution

    Science.gov (United States)

    Tian, Xiang-Dong; Chen, Shu; Zhang, Yue-Jiao; Dong, Jin-Chao; Panneerselvam, Rajapandiyan; Zhang, Yun; Yang, Zhi-Lin; Li, Jian-Feng; Tian, Zhong-Qun

    2016-01-01

    Nanostructures with symmetry breaking can allow the coupling between dark and bright plasmon modes to induce strong Fano resonance. However, it is still a daunting challenge to prepare bottom-up self-assembled subwavelength asymmetric nanostructures with appropriate gaps between the nanostructures especially below 5 nm in solution. Here we present a viable self-assembly method to prepare symmetry-breaking nanostructures consisting of Ag nanocubes and Au nanospheres both with tunable size (90-250 nm for Au nanospheres; 100-160 nm for Ag nanocubes) and meanwhile control the nanogaps through ultrathin silica shells of 1-5 nm thickness. The Raman tag of 4-mercaptobenzoic acid (MBA) assists the self-assembly process and endows the subwavelength asymmetric nanostructures with surface-enhanced Raman scattering (SERS) activity. Moreover, thick silica shells (above 50 nm thickness) can be coated on the self-assembled nanostructures in situ to stabilize the whole nanostructures, paving the way toward bioapplications. Single particle scattering spectroscopy with a 360° polarization resolution is performed on individual Ag nanocube and Au nanosphere dimers, correlated with high-resolution TEM characterization. The asymmetric dimers exhibit strong configuration and polarization dependence Fano resonance properties. Overall, the solution-based self-assembly method reported here is opening up new opportunities to prepare diverse multicomponent nanomaterials with optimal performance.Nanostructures with symmetry breaking can allow the coupling between dark and bright plasmon modes to induce strong Fano resonance. However, it is still a daunting challenge to prepare bottom-up self-assembled subwavelength asymmetric nanostructures with appropriate gaps between the nanostructures especially below 5 nm in solution. Here we present a viable self-assembly method to prepare symmetry-breaking nanostructures consisting of Ag nanocubes and Au nanospheres both with tunable size (90-250 nm

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

    Science.gov (United States)

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

    2008-09-01

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

  8. Structure and interactions in biomaterials based on membrane-biopolymer self-assembly

    Science.gov (United States)

    Koltover, Ilya

    Physical and chemical properties of artificial pure lipid membranes have been extensively studied during the last two decades and are relatively well understood. However, most real membrane systems of biological and biotechnological importance incorporate macromolecules either embedded into the membranes or absorbed onto their surfaces. We have investigated three classes of self-assembled membrane-biopolymer biomaterials: (i) Structure, interactions and stability of the two-dimensional crystals of the integral membrane protein bacteriorhodopsin (bR). We have conducted a synchrotron x-ray diffraction study of oriented bR multilayers. The important findings were as follows: (1) the protein 2D lattice exhibited diffraction patterns characteristic of a 2D solid with power-law decay of in-plane positional correlations, which allowed to measure the elastic constants of protein crystal; (2) The crystal melting temperature was a function of the multilayer hydration, reflecting the effect of inter-membrane repulsion on the stability of protein lattice; (3) Preparation of nearly perfect (mosaicity gene therapy applications. We have established that DNA complexes with cationic lipid (DOTAP) and a neutral lipid (DOPC) have a compact multilayer liquid crystalline structure ( L ca ) with DNA intercalated between the lipid bilayers in a periodic 2D smectic phase. Furthermore, a different 2D columnar phase of complexes was found in mixtures with a transfectionen-hancing lipid DOPE. This structure ( HcII ) derived from synchrotron x-ray diffraction consists of DNA coated by cationic lipid monolayers and arranged on a two-dimensional hexagonal lattice. Optical microscopy revealed that the L ca complexes bind stably to anionic vesicles (models of cellular membranes), whereas the more transfectant HcII complexes are unstable, rapidly fusing and releasing DNA upon adhering to anionic vesicles.

  9. Self-assembly of a [Ni8] carbonate cube incorporating four μ4-carbonato linkers through fixation of atmospheric CO2 by ligated [Ni2] complexes.

    Science.gov (United States)

    Ghosh, Aloke Kumar; Pait, Moumita; Shatruk, Michael; Bertolasi, Valerio; Ray, Debashis

    2014-02-07

    The communication reports the synthesis, characterization, and magnetic behavior of a novel μ4-carbonato supported and imidazole capped ligated nickel cage [Ni8(μ-H2bpmp)4(μ4-CO3)4(ImH)8](NO3)4·2H2O (1) through self-assembly of ligand bound ferromagnetic Ni2 building blocks. Structural analysis indicates newer geometrical features for the coordination cage formation and dominant interdimer antiferromagnetic coupling resulting in a diamagnetic ground state.

  10. Integrative self-assembly of functional hybrid nanoconstructs by inorganic wrapping of single biomolecules, biomolecule arrays and organic supramolecular assemblies.

    Science.gov (United States)

    Patil, Avinash J; Li, Mei; Mann, Stephen

    2013-08-21

    Synthesis of functional hybrid nanoscale objects has been a core focus of the rapidly progressing field of nanomaterials science. In particular, there has been significant interest in the integration of evolutionally optimized biological systems such as proteins, DNA, virus particles and cells with functional inorganic building blocks to construct mesoscopic architectures and nanostructured materials. However, in many cases the fragile nature of the biomolecules seriously constrains their potential applications. As a consequence, there is an on-going quest for the development of novel strategies to modulate the thermal and chemical stabilities, and performance of biomolecules under adverse conditions. This feature article highlights new methods of "inorganic molecular wrapping" of single or multiple protein molecules, individual double-stranded DNA helices, lipid bilayer vesicles and self-assembled organic dye superstructures using inorganic building blocks to produce bio-inorganic nanoconstructs with core-shell type structures. We show that spatial isolation of the functional biological nanostructures as "armour-plated" enzyme molecules or polynucleotide strands not only maintains their intact structure and biochemical properties, but also enables the fabrication of novel hybrid nanomaterials for potential applications in diverse areas of bionanotechnology.

  11. Integrative self-assembly of functional hybrid nanoconstructs by inorganic wrapping of single biomolecules, biomolecule arrays and organic supramolecular assemblies

    Science.gov (United States)

    Patil, Avinash J.; Li, Mei; Mann, Stephen

    2013-07-01

    Synthesis of functional hybrid nanoscale objects has been a core focus of the rapidly progressing field of nanomaterials science. In particular, there has been significant interest in the integration of evolutionally optimized biological systems such as proteins, DNA, virus particles and cells with functional inorganic building blocks to construct mesoscopic architectures and nanostructured materials. However, in many cases the fragile nature of the biomolecules seriously constrains their potential applications. As a consequence, there is an on-going quest for the development of novel strategies to modulate the thermal and chemical stabilities, and performance of biomolecules under adverse conditions. This feature article highlights new methods of ``inorganic molecular wrapping'' of single or multiple protein molecules, individual double-stranded DNA helices, lipid bilayer vesicles and self-assembled organic dye superstructures using inorganic building blocks to produce bio-inorganic nanoconstructs with core-shell type structures. We show that spatial isolation of the functional biological nanostructures as ``armour-plated'' enzyme molecules or polynucleotide strands not only maintains their intact structure and biochemical properties, but also enables the fabrication of novel hybrid nanomaterials for potential applications in diverse areas of bionanotechnology.

  12. Size and shape tunability of self-assembled InAs/GaAs nanostructures through the capping rate

    NARCIS (Netherlands)

    Utrilla, Antonio D.; Grossi, Davide F.; Reyes, Daniel F.; Gonzalo, Alicia; Braza, Verónica; Ben, Teresa; González, David; Guzman, Alvaro; Hierro, Adrian; Koenraad, Paul M.; Ulloa, Jose M.

    2018-01-01

    The practical realization of epitaxial quantum dot (QD) nanocrystals led before long to impressive experimental advances in optoelectronic devices, as well as to the emergence of new technological fields. However, the necessary capping process is well-known to hinder a precise control of the QD

  13. A self-propagation high-temperature synthesis and annealing route to synthesis of wave-like boron nitride nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jilin; Zhang, Laiping [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, Hubei, 430073 (China); Gu, Yunle, E-mail: ncm@mail.wit.edu.cn [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, Hubei, 430073 (China); Pan, Xinye; Zhao, Guowei; Zhang, Zhanhui [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, Hubei, 430073 (China)

    2013-03-15

    Highlights: ► Large quantities of wave-like BN nanotubes were synthesized by SHS-annealing method. ► The catalytic boron-containing porous precursor was produced by self-propagation high-temperature synthesis method. ► Three growth models were proposed to explain the growth mechanism of the wave-like BN nanotubes. - Abstract: Large quantities of boron nitride (BN) nanotubes were synthesized by annealing a catalytic boron-containing porous precursor in flowing NH{sub 3} gas at 1180 °C. The porous precursor was prepared by self-propagation high-temperature synthesis (SHS) method at 800 °C using Mg, B{sub 2}O{sub 3} and amorphous boron powder (α-B) as the starting materials. The porous precursor played an important role in large quantities synthesis of BN nanotubes. The as-synthesized product was characterized by X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), Raman, Scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), Transmission electron microscopy (TEM) and High-resolution transmission electron microscopy (HRTEM). Characterization results indicated that the BN nanotubes displayed wave-like inner structures with diameters in the range of 50–300 nm and average lengths of more than 10 μm. The possible growth mechanism of the BN nanotubes was also discussed.

  14. Self-assembled peptide-based nanostructures: Smart nanomaterials toward targeted drug delivery.

    Science.gov (United States)

    Habibi, Neda; Kamaly, Nazila; Memic, Adnan; Shafiee, Hadi

    2016-02-01

    Self-assembly of peptides can yield an array of well-defined nanostructures that are highly attractive nanomaterials for many biomedical applications such as drug delivery. Some of the advantages of self-assembled peptide nanostructures over other delivery platforms include their chemical diversity, biocompatibility, high loading capacity for both hydrophobic and hydrophilic drugs, and their ability to target molecular recognition sites. Furthermore, these self-assembled nanostructures could be designed with novel peptide motifs, making them stimuli-responsive and achieving triggered drug delivery at disease sites. The goal of this work is to present a comprehensive review of the most recent studies on self-assembled peptides with a focus on their "smart" activity for formation of targeted and responsive drug-delivery carriers.

  15. Proteins evolve on the edge of supramolecular self-assembly

    Science.gov (United States)

    Garcia-Seisdedos, Hector; Empereur-Mot, Charly; Elad, Nadav; Levy, Emmanuel D.

    2017-08-01

    The self-association of proteins into symmetric complexes is ubiquitous in all kingdoms of life. Symmetric complexes possess unique geometric and functional properties, but their internal symmetry can pose a risk. In sickle-cell disease, the symmetry of haemoglobin exacerbates the effect of a mutation, triggering assembly into harmful fibrils. Here we examine the universality of this mechanism and its relation to protein structure geometry. We introduced point mutations solely designed to increase surface hydrophobicity among 12 distinct symmetric complexes from Escherichia coli. Notably, all responded by forming supramolecular assemblies in vitro, as well as in vivo upon heterologous expression in Saccharomyces cerevisiae. Remarkably, in four cases, micrometre-long fibrils formed in vivo in response to a single point mutation. Biophysical measurements and electron microscopy revealed that mutants self-assembled in their folded states and so were not amyloid-like. Structural examination of 73 mutants identified supramolecular assembly hot spots predictable by geometry. A subsequent structural analysis of 7,471 symmetric complexes showed that geometric hot spots were buffered chemically by hydrophilic residues, suggesting a mechanism preventing mis-assembly of these regions. Thus, point mutations can frequently trigger folded proteins to self-assemble into higher-order structures. This potential is counterbalanced by negative selection and can be exploited to design nanomaterials in living cells.

  16. Tunable controlled release of molecular species from Halloysite nanotubes

    Science.gov (United States)

    Elumalai, Divya Narayan

    Encouraged by potential applications in rust coatings, self-healing composites, selective delivery of drugs, and catalysis, the transport of molecular species through Halloysite nanotubes (HNTs), specifically the storage and controlled release of these molecules, has attracted strong interest in recent years. HNTs are a naturally occurring biocompatible nanomaterial that are abundantly and readily available. They are alumosilicate based tubular clay nanotubes with an inner lumen of 15 nm and a length of 600-900 nm. The size of the inner lumen of HNTs may be adjusted by etching. The lumen can be loaded with functional agents like antioxidants, anticorrosion agents, flame-retardant agents, drugs, or proteins, allowing for a sustained release of these agents for hours. The release times can be further tuned for days and months by the addition of tube end-stoppers. In this work a three-dimensional, time-quantified Monte Carlo model that efficiently describes diffusion through and from nanotubes is implemented. Controlled delivery from Halloysite Nanotubes (HNT) is modeled based on interactions between the HNT's inner wall and the nanoparticles (NP) and among NPs themselves. The model was validated using experimental data published in the literature. The validated model is then used to study the effect of multiple parameters like HNT diameter and length, particle charge, ambient temperature and the creation of smart caps at the tube ends on the release of encapsulated NPs. The results show that release profiles depend on the size distribution of the HNT batch used for the experiment, as delivery is sensitive to HNT lumen and length. The effect of the addition of end-caps to the HNTs, on the rate of release of encapsulated NPs is also studied here. The results show that the release profiles are significantly affected by the addition of end caps to the HNTs and is sensitive to the end-cap pore lumen. A very good agreement with the experiment is observed when a weight

  17. First Wheel of the Hadronic EndCap Calorimeter Completed

    CERN Multimedia

    Oram, C.J.

    2002-01-01

    With the LAr calorimeters well advanced in module production, the attention is turning to Batiment 180 where the calorimeter modules are formed into complete detectors and inserted into their respective cryostats. For the Hadronic End Cap (HEC) Group the task in B180 is to assemble the wheels, rotate them into their final orientation, and put them onto the cradle in front of the End Cap Cryostat. These tasks have been completed for the first HEC wheel in the B180 End Cap Clean Room. Given that this wheel weighs 70 tons the group is very relieved to have established that these gymnastics with the wheel proceed in a routine fashion. To assemble a wheel we take modules that have already been cold tested, do the final electrical testing and locate them onto the HEC wheel assembly table. Four wheels are required in total, each consisting of 32 modules. Wheel assembly is done in the horizontal position, creating a doughnut-like object sitting on the HEC table. The first picture shows the last module being added ...

  18. A self-assembled monolayer-assisted surface microfabrication and release technique

    NARCIS (Netherlands)

    Kim, B.J.; Liebau, M.; Huskens, Jurriaan; Reinhoudt, David; Brugger, J.P.

    2001-01-01

    This paper describes a method of thin film and MEMS processing which uses self-assembled monolayers as ultra-thin organic surface coating to enable a simple removal of microfabricated devices off the surface without wet chemical etching. A 1.5-nm thick self-assembled monolayer of

  19. Effects of High Pressure on Internally Self-Assembled Lipid Nanoparticles

    DEFF Research Database (Denmark)

    Kulkarni, Chandrashekhar V; Yaghmur, Anan; Steinhart, Milos

    2016-01-01

    We present the first report on the effects of hydrostatic pressure on colloidally stabilized lipid nanoparticles enveloping inverse nonlamellar self-assemblies in their interiors. These internal self-assemblies were systematically tuned into bicontinuous cubic (Pn3m and Im3m), micellar cubic (Fd3...... the tolerance of lipid nanoparticles [cubosomes, hexosomes, micellar cubosomes, and emulsified microemulsions (EMEs)] for high pressures, confirming their robustness for various technological applications.......We present the first report on the effects of hydrostatic pressure on colloidally stabilized lipid nanoparticles enveloping inverse nonlamellar self-assemblies in their interiors. These internal self-assemblies were systematically tuned into bicontinuous cubic (Pn3m and Im3m), micellar cubic (Fd3m......), hexagonal (H2), and inverse micellar (L2) phases by regulating the lipid/oil ratio as the hydrostatic pressure was varied from atmospheric pressure to 1200 bar and back to atmospheric pressure. The effects of pressure on these lipid nanoparticles were compared with those on their equilibrium bulk...

  20. 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.

  1. Influence of surface chemistry on inkjet printed carbon nanotube films

    International Nuclear Information System (INIS)

    Hopkins, Alan R.; Straw, David C.; Spurrell, Kathryn C.

    2011-01-01

    Carbon nanotube ink chemistry and the proper formulation are crucial for direct-write printing of nanotubes. Moreover, the correct surface chemistry of the self-assembled monolayers that assist the direct deposition of carbon nanotubes onto the substrate is equally important to preserve orientation of the printed carbon nanotubes. We report that the successful formulation of two single walled carbon nanotube (SWNT) inks yields a consistent, homogenous printing pattern possessing the requisite viscosities needed for flow through the microcapillary nozzles of the inkjet printer with fairly modest drying times. The addition of an aqueous sodium silicate allows for a reliable method for forming a uniform carbon nanotube network deposited directly onto unfunctionalized surfaces such as glass or quartz via inkjet deposition. Furthermore, this sodium silicate ingredient helps preserve applied orientation to the printed SWNT solution. Sheet resistivity of this carbon nanotube ink formula printed on quartz decreases as a function of passes and is independent of the substrate. SWNTs were successfully patterned on Au. This amine-based surface chemistry dramatically helps improve the isolation stabilization of the printed SWNTs as seen in the atomic force microscopy (AFM) image. Lastly, using our optimized SWNT ink formula and waveform parameters in the Fuji materials printer, we are able to directly write/print SWNTs into 2D patterns. Dried ink pattern expose and help orient roped carbon nanotubes that are suspended in ordered arrays across the cracks.

  2. Self-assembly strategies for the synthesis of functional nanostructured materials

    Science.gov (United States)

    Perego, M.; Seguini, G.

    2016-06-01

    Self-assembly is the autonomous organization of components into patterns or structures without human intervention. This is the approach followed by nature to generate living cells and represents one of the practical strategies to fabricate ensembles of nanostructures. In static self-assembly the formation of ordered structures could require energy but once formed the structures are stable. The introduction of additional regular features in the environment could be used to template the self-assembly guiding the organization of the components and determining the final structure they form. In this regard self-assembly of block copolymers represents a potent platform for fundamental studies at the nanoscale and for application-driven investigation as a tool to fabricate functional nanostructured materials. Block copolymers can hierarchically assemble into chemically distinct domains with size and periodicity on the order of 10nm or below, offering a potentially inexpensive route to generate large-area nanostructured materials. The final structure characteristics of these materials are dictated by the properties of the elementary block copolymers, like chain length, volume fraction or degree of block incompatibility. Modern synthetic chemistry offers the possibility to design these macromolecules with very specific length scales and geometries, directly embodying in the block copolymers the code that drives their self- assembling process. The understanding of the kinetics and thermodynamics of the block copolymer self-assembly process in the bulk phase as well as in thin films represents a fundamental prerequisite toward the exploitation of these materials. Incorporating block copolymer into device fabrication procedures or directly into devices, as active elements, will lead to the development of a new generation of devices fabricated using the fundamental law of nature to our advantage in order to minimize cost and power consumption in the fabrication process

  3. 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.

  4. Strong piezoelectricity in bioinspired peptide nanotubes.

    Science.gov (United States)

    Kholkin, Andrei; Amdursky, Nadav; Bdikin, Igor; Gazit, Ehud; Rosenman, Gil

    2010-02-23

    We show anomalously strong shear piezoelectric activity in self-assembled diphenylalanine peptide nanotubes (PNTs), indicating electric polarization directed along the tube axis. Comparison with well-known piezoelectric LiNbO(3) and lateral signal calibration yields sufficiently high effective piezoelectric coefficient values of at least 60 pm/V (shear response for tubes of approximately 200 nm in diameter). PNTs demonstrate linear deformation without irreversible degradation in a broad range of driving voltages. The results open up a wide avenue for developing new generations of "green" piezoelectric materials and piezonanodevices based on bioactive tubular nanostructures potentially compatible with human tissue.

  5. The magneto-elastica: from self-buckling to self-assembly

    KAUST Repository

    Vella, D.; du Pontavice, E.; Hall, C. L.; Goriely, A.

    2013-01-01

    Spherical neodymium-iron-boron magnets are permanent magnets that can be assembled into a variety of structures owing to their high magnetic strength. A one-dimensional chain of these magnets responds to mechanical loadings in a manner reminiscent of an elastic rod. We investigate the macroscopic mechanical properties of assemblies of ferromagnetic spheres by considering chains, rings and chiral cylinders of magnets. Based on energy estimates and simple experiments, we introduce an effective magnetic bending stiffness for a chain of magnets and show that, used in conjunction with classic results for elastic rods, it provides excellent estimates for the buckling and vibration dynamics of magnetic chains. We then use this estimate to understand the dynamic self-assembly of a cylinder from an initially straight chain of magnets.

  6. The magneto-elastica: from self-buckling to self-assembly

    KAUST Repository

    Vella, D.

    2013-12-04

    Spherical neodymium-iron-boron magnets are permanent magnets that can be assembled into a variety of structures owing to their high magnetic strength. A one-dimensional chain of these magnets responds to mechanical loadings in a manner reminiscent of an elastic rod. We investigate the macroscopic mechanical properties of assemblies of ferromagnetic spheres by considering chains, rings and chiral cylinders of magnets. Based on energy estimates and simple experiments, we introduce an effective magnetic bending stiffness for a chain of magnets and show that, used in conjunction with classic results for elastic rods, it provides excellent estimates for the buckling and vibration dynamics of magnetic chains. We then use this estimate to understand the dynamic self-assembly of a cylinder from an initially straight chain of magnets.

  7. Microscopic and Macroscopic Structures of Carbon Nanotubes Produced by Pyrolysis of Iron Phthalocyanine

    International Nuclear Information System (INIS)

    Huang Shaoming; Dai Liming

    2002-01-01

    By pyrolysis of iron phthalocyanine (FePc), either in a patterned or non-patterned fashion, under an Ar/H 2 atmosphere, we have demonstrated the large-scale production of aligned carbon nanotubes perpendicular to the substrate surface useful for building devices with three-dimensional structures. Depending on the particular pyrolytic conditions used, carbon nanotubes with a wide range of microscopic structures having curved, helical, coiled, branched, and tube-within-tube shapes have also been prepared by the pyrolysis of FePc. This, coupled with several microfabrication methods (photolithography, soft-lithography, self-assembling, micro-contact transfer, etc.), has enabled us to produce carbon nanotube arrays of various macroscopic architectures including polyhedral, flower-like, dendritic, circular, multilayered, and micropatterned geometries. In this article, we summarize our work on the preparation of FePc-generated carbon nanotubes with the large variety of microscopic and macroscopic structures and give a brief overview on the perspectives of making carbon nanotubes with tailor-made microscopic/macroscopic structures, and hence well-defined physicochemical properties, for specific applications

  8. Self-assembled containers based on extended tetrathiafulvalene.

    Science.gov (United States)

    Bivaud, Sébastien; Goeb, Sébastien; Croué, Vincent; Dron, Paul I; Allain, Magali; Sallé, Marc

    2013-07-10

    Two original self-assembled containers constituted each by six electroactive subunits are described. They are synthesized from a concave tetratopic π-extended tetrathiafulvalene ligand bearing four pyridyl units and cis-M(dppf)(OTf)2 (M = Pd or Pt; dppf = 1,1'-bis(diphenylphosphino)ferrocene; OTf = trifluoromethane-sulfonate) complexes. Both fully characterized assemblies present an oblate spheroidal cavity that can incorporate one perylene molecule.

  9. 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.

  10. Self assembly of amphiphilic C60 fullerene derivatives into nanoscale supramolecular structures

    Directory of Open Access Journals (Sweden)

    Casscells S Ward

    2007-08-01

    Full Text Available Abstract Background The amphiphilic fullerene monomer (AF-1 consists of a "buckyball" cage to which a Newkome-like dendrimer unit and five lipophilic C12 chains positioned octahedrally to the dendrimer unit are attached. In this study, we report a novel fullerene-based liposome termed 'buckysome' that is water soluble and forms stable spherical nanometer sized vesicles. Cryogenic electron microscopy (Cryo-EM, transmission electron microscopy (TEM, and dynamic light scattering (DLS studies were used to characterize the different supra-molecular structures readily formed from the fullerene monomers under varying pH, aqueous solvents, and preparative conditions. Results Electron microscopy results indicate the formation of bilayer membranes with a width of ~6.5 nm, consistent with previously reported molecular dynamics simulations. Cryo-EM indicates the formation of large (400 nm diameter multilamellar, liposome-like vesicles and unilamellar vesicles in the size range of 50–150 nm diameter. In addition, complex networks of cylindrical, tube-like aggregates with varying lengths and packing densities were observed. Under controlled experimental conditions, high concentrations of spherical vesicles could be formed. In vitro results suggest that these supra-molecular structures impose little to no toxicity. Cytotoxicity of 10–200 μM buckysomes were assessed in various cell lines. Ongoing studies are aimed at understanding cellular internalization of these nanoparticle aggregates. Conclusion In this current study, we have designed a core platform based on a novel amphiphilic fullerene nanostructure, which readily assembles into supra-molecular structures. This delivery vector might provide promising features such as ease of preparation, long-term stability and controlled release.

  11. Sponge-like reduced graphene oxide/silicon/carbon nanotube composites for lithium ion batteries

    Science.gov (United States)

    Fang, Menglu; Wang, Zhao; Chen, Xiaojun; Guan, Shiyou

    2018-04-01

    Three-dimensional sponge-like reduced graphene oxide/silicon/carbon nanotube composites were synthesized by one-step hydrothermal self-assembly using silicon nanoparticles, graphene oxide and amino modified carbon nanotubes to develop high-performance anode materials of lithium ion batteries. Scanning electron microscopy and transmission electron microscopy images show the structure of composites that Silicon nanoparticles are coated with reduced graphene oxide while amino modified carbon nanotubes wrap around the reduced graphene oxide in the composites. When applied to lithium ion battery, these composites exhibit high initial specific capacity of 2552 mA h/g at a current density of 0.05 A/g. In addition, reduced graphene oxide/silicon/carbon nanotube composites also have better cycle stability than bare Silicon nanoparticles electrode with the specific capacity of 1215 mA h/g after 100 cycles. The three-dimension sponge-like structure not only ensures the electrical conductivity but also buffers the huge volume change, which has broad potential application in the field of battery.

  12. Drying induced upright sliding and reorganization of carbon nanotube arrays

    International Nuclear Information System (INIS)

    Li Qingwen; De Paula, Raymond; Zhang Xiefei; Zheng Lianxi; Arendt, Paul N; Mueller, Fred M; Zhu, Y T; Tu Yi

    2006-01-01

    Driven by capillary force, wet carbon nanotube (CNT) arrays have been found to reorganize into cellular structures upon drying. During the reorganization process, individual CNTs are firmly attached to the substrate and have to lie down on the substrate at cell bottoms, forming closed cells. Here we demonstrate that by modifying catalyst structures, the adhesion of CNTs to the substrate can be weakened. Upon drying such CNT arrays, CNTs may slide away from their original sites on the surface and self-assemble into cellular patterns with bottoms open. It is also found that the sliding distance of CNTs increases with array height, and drying millimetre tall arrays leads to the sliding of CNTs over a few hundred micrometres and the eventual self-assembly into discrete islands. By introducing regular vacancies in CNT arrays, CNTs may be manipulated into different patterns

  13. Periodic-cylinder vesicle with minimal energy

    International Nuclear Information System (INIS)

    Xiao-Hua, Zhou

    2010-01-01

    We give some details about the periodic cylindrical solution found by Zhang and Ou-Yang in [1996 Phys. Rev. E 53 4206] for the general shape equation of vesicle. Three different kinds of periodic cylindrical surfaces and a special closed cylindrical surface are obtained. Using the elliptic functions contained in mathematic, we find that this periodic shape has the minimal total energy for one period when the period–amplitude ratio β ≈ 1.477, and point out that it is a discontinuous deformation between plane and this periodic shape. Our results also are suitable for DNA and multi-walled carbon nanotubes (MWNTs). (cross-disciplinary physics and related areas of science and technology)

  14. 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.

  15. Numerical Study on Self-Cleaning Canister Filter With Add-On Filter Cap

    Directory of Open Access Journals (Sweden)

    Mohammed Akmal Nizam

    2017-01-01

    Full Text Available Filtration in a turbo machinery system such as a gas turbine will ensure that the air entering the inlet is free from contaminants that could bring damage to the main system. Self-cleaning filter systems for gas turbines are designed for continuously efficient flow filtration. A good filter would be able to maintain its effectiveness over a longer time period, prolonging the duration between filter replacements and providing lower pressure drop over its operating lifetime. With this goal in mind, the current study is focused on the difference in pressure loss of the benchmark Salutary Avenue Self-cleaning filter in comparison to a new design with an add-on filter cap. Geometry for the add-on filter cap will be based from Salutary Avenue Manufacturing Sdn.Bhd. SOLIDWORKS software was used to model the geometry of the filter, while simulation analysis on the flow through the filter was done using Computational Fluid Dynamic (CFD software. The simulations are based on a low velocity condition, in which the parameter for the inlet velocity are set at 0.032 m/s, 0.063 m/s, 0.094 m/s and 0.126 m/s respectively. From the simulation data obtained for the inlet velocities considered, the pressure drop reduction of the modified filter compared to the benchmark was found to be between 7.59% and 30.18%. All in all, the modification of the filter cap produced a lower pressure drop in comparison with the benchmark filter; an improvement of 27.02% for the total pressure drop was obtained.

  16. Self-Assembly of Colloidal Spheres into One, Two, and Three Dimensional Structures

    NARCIS (Netherlands)

    Guo, Y.

    2017-01-01

    The main goal of this thesis is to increase our understanding of colloidal self-assembly processes and develop new strategies to assemble colloidal building blocks into more sophisticated and well-defined super-structures. Self-assembly is a spontaneous process in which a disordered system of

  17. Multigeometry Nanoparticle Engineering via Kinetic Control through Multistep assembly

    Science.gov (United States)

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

    2014-03-01

    Organization of block copolymers into complicated multicompartment (MCM) and multigeometry (MGM) nanostructures is of increasing interest. Multistep, co-assembly methods resulting in kinetic control processing was used to produce complex nanoparticles that are not obtained via other assembly methods. Vesicle-cylinder, separate vesicle and cylinder, disk-cylinder, and mixed vesicle nanoparticles were constructed by binary blends of distinct diblock copolymers. Initially, the vesicle former polyacrylic acid-polyisoprene and cylinder former polyacrylic acid-polystyrene which share the same hydrophilic domain but immiscible hydrophobic domain were blended in THF. Secondly, dimaine molecules are added to associate with the common hydrophilic PAA. Importantly, and lastly, by tuning the kinetic addition rate of selective, miscible solvent water, the unlike hydrophobic blocks are kinetically trapped into one particle and eventually nanophase separate to form multiple compartments and multigeometries. The effective bottom-up multistep assembly strategies can be applied in other binary/ternary blends, in which new vesicle-sphere, disk-disk and cylinder-cylinder MCM/MGM nanoparticles were programed. We are grateful for the financial support from the National Science Funding DMR-0906815 (D.J.P. and K.L.W.) and NIST METROLOGY POCHAN 2012.

  18. Synthesis and Self-Assembly of Triangulenium Salts

    DEFF Research Database (Denmark)

    Shi, Dong

    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....... Addition of soft counter ion into the nanosheets solution could induce gluing of the nanosheets. The solid thin film formed from the formed nanosheets after water evaporation showed crystalline patterning order as revealed by x-ray diffraction (XRD) measurements. Chpater 5 reports the counter ion effect...

  19. Simultaneous detection of multiple DNA targets by integrating dual-color graphene quantum dot nanoprobes and carbon nanotubes.

    Science.gov (United States)

    Qian, Zhaosheng; Shan, Xiaoyue; Chai, Lujing; Chen, Jianrong; Feng, Hui

    2014-12-01

    Simultaneous detection of multiple DNA targets was achieved based on a biocompatible graphene quantum dots (GQDs) and carbon nanotubes (CNTs) platform through spontaneous assembly between dual-color GQD-based probes and CNTs and subsequently self-recognition between DNA probes and targets. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. The effect of amine protonation on the electrical properties of spin-assembled single-walled carbon nanotube networks

    Energy Technology Data Exchange (ETDEWEB)

    Opatkiewicz, Justin P; LeMieux, Melburne C; Bao Zhenan [Department of Chemical Engineering, Stanford University, Stanford, CA 94305 (United States); Patil, Nishant P; Wei Hai; Mitra, Subhasish, E-mail: zbao@stanford.edu [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)

    2011-03-25

    Amine-terminated self-assembled monolayers (SAMs) have been shown to selectively adsorb semiconducting single-walled carbon nanotubes (sc-SWNTs). Previous studies have shown that when deposited by spin coating, the resulting nanotube networks (SWNTnts) can be strongly influenced by the charge state of the amine (primary, secondary, and tertiary). When the amine surfaces were exposed to varying pH solutions, the conductivity and overall quality of the resulting fabricated networks were altered. Atomic force microscopy (AFM) topography had shown that the density of the SWNTnts was reduced as the amine protonation decreased, indicating that the electrostatic attraction between the SWNTs in solution and the surface influenced the adsorption. Simultaneously, {mu}-Raman analysis had suggested that when exposed to more basic conditions, the resulting networks were enhanced with sc-SWNTs. To directly confirm this enhancement, Ti/Pd contacts were deposited and devices were tested in air. Key device characteristics were found to match the enhancement trends previously observed by spectroscopy. For the primary and secondary amines, on/off current ratios were commensurate with the Raman trends in metallic contribution, while no trends were observed on the tertiary amine (due to weaker interactions). Finally, differing SWNT solution volumes were used to compensate for adsorption differences and yielded identical SWNTnt densities on the various pH-treated samples to eliminate the influence of network density. These results further the understanding of the amine-SWNT interaction during the spin coating process. Overall, we provide a convenient route to provide SWNT-based TFTs with highly tunable electronic charge transport through better understanding of the influence of these specific interactions.

  1. The effect of amine protonation on the electrical properties of spin-assembled single-walled carbon nanotube networks

    International Nuclear Information System (INIS)

    Opatkiewicz, Justin P; LeMieux, Melburne C; Bao Zhenan; Patil, Nishant P; Wei Hai; Mitra, Subhasish

    2011-01-01

    Amine-terminated self-assembled monolayers (SAMs) have been shown to selectively adsorb semiconducting single-walled carbon nanotubes (sc-SWNTs). Previous studies have shown that when deposited by spin coating, the resulting nanotube networks (SWNTnts) can be strongly influenced by the charge state of the amine (primary, secondary, and tertiary). When the amine surfaces were exposed to varying pH solutions, the conductivity and overall quality of the resulting fabricated networks were altered. Atomic force microscopy (AFM) topography had shown that the density of the SWNTnts was reduced as the amine protonation decreased, indicating that the electrostatic attraction between the SWNTs in solution and the surface influenced the adsorption. Simultaneously, μ-Raman analysis had suggested that when exposed to more basic conditions, the resulting networks were enhanced with sc-SWNTs. To directly confirm this enhancement, Ti/Pd contacts were deposited and devices were tested in air. Key device characteristics were found to match the enhancement trends previously observed by spectroscopy. For the primary and secondary amines, on/off current ratios were commensurate with the Raman trends in metallic contribution, while no trends were observed on the tertiary amine (due to weaker interactions). Finally, differing SWNT solution volumes were used to compensate for adsorption differences and yielded identical SWNTnt densities on the various pH-treated samples to eliminate the influence of network density. These results further the understanding of the amine-SWNT interaction during the spin coating process. Overall, we provide a convenient route to provide SWNT-based TFTs with highly tunable electronic charge transport through better understanding of the influence of these specific interactions.

  2. Impact of cationic surfactant on the self-assembly of sodium caseinate.

    Science.gov (United States)

    Vinceković, Marko; Curlin, Marija; Jurašin, Darija

    2014-08-27

    The impact of a cationic surfactant, dodecylammonium chloride (DDACl), on the self-assembly of sodium caseinate (SC) has been investigated by light scattering, zeta potential, and rheological measurements as well as by microscopy (transmission electron and confocal laser scanning microscopy). In SC dilute solutions concentration-dependent self-assembly proceeds through the formation of spherical associates and their aggregation into elongated structures composed of connected spheres. DDACl interacts with SC via its hydrophilic and hydrophobic groups, inducing changes in SC self-assembled structures. These changes strongly depend on the surfactant aggregation states (monomeric or micellar) as well as concentration ratio of both components, leading to the formation of soluble and insoluble complexes of nano- to microdimensions. DDACl monomers interact with SC self-assembled entities in a different way compared to their micelles. Surfactant monomers form soluble complexes (similar to surfactant mixed micelles) at lower SC concentration but insoluble gelatinous complexes at higher SC concentration. At surfactant micellar concentration soluble complexes with casein chains wrapped around surfactant micelles are formed. This study suggests that the use of proper cationic surfactant concentration will allow modification and control of structural changes of SC self-assembled entities.

  3. Directed self-assembly of nanogold using a chemically modified nanopatterned surface

    Science.gov (United States)

    Nidetz, Robert; Kim, Jinsang

    2012-02-01

    Electron-beam lithography (EBL) was used to define an aminosilane nanopatterned surface in order to electrostatically self-assemble gold nanoparticles (Au NPs). The chemically modified nanopatterned surfaces were immersed into a Au NP solution to allow the Au NPs to self-assemble. Equilibrium self-assembly was achieved in only 20 min. The number of Au NPs that self-assembled on an aminosilane dot was controlled by manipulating the diameters of both the Au NPs and the dots. Adding salt to the Au NP solution enabled the Au NPs to self-assemble in greater numbers on the same sized dot. However, the preparation of the Au NP solution containing salt was sensitive to spikes in the salt concentration. These spikes led to aggregation of the Au NPs and non-specific deposition of Au NPs on the substrate. The Au NP patterned surfaces were immersed in a sodium hydroxide solution in order to lift-off the patterned Au NPs, but no lift-off was observed without adequate physical agitation. The van der Waals forces are too strong to allow for lift-off despite the absence of electrostatic forces.

  4. Directed self-assembly of nanogold using a chemically modified nanopatterned surface

    International Nuclear Information System (INIS)

    Nidetz, Robert; Kim, Jinsang

    2012-01-01

    Electron-beam lithography (EBL) was used to define an aminosilane nanopatterned surface in order to electrostatically self-assemble gold nanoparticles (Au NPs). The chemically modified nanopatterned surfaces were immersed into a Au NP solution to allow the Au NPs to self-assemble. Equilibrium self-assembly was achieved in only 20 min. The number of Au NPs that self-assembled on an aminosilane dot was controlled by manipulating the diameters of both the Au NPs and the dots. Adding salt to the Au NP solution enabled the Au NPs to self-assemble in greater numbers on the same sized dot. However, the preparation of the Au NP solution containing salt was sensitive to spikes in the salt concentration. These spikes led to aggregation of the Au NPs and non-specific deposition of Au NPs on the substrate. The Au NP patterned surfaces were immersed in a sodium hydroxide solution in order to lift-off the patterned Au NPs, but no lift-off was observed without adequate physical agitation. The van der Waals forces are too strong to allow for lift-off despite the absence of electrostatic forces. (paper)

  5. Light-assisted, templated self-assembly using a photonic-crystal slab.

    Science.gov (United States)

    Jaquay, Eric; Martínez, Luis Javier; Mejia, Camilo A; Povinelli, Michelle L

    2013-05-08

    We experimentally demonstrate the technique of light-assisted, templated self-assembly (LATS). We excite a guided-resonance mode of a photonic-crystal slab with 1.55 μm laser light to create an array of optical traps. We demonstrate assembly of a square lattice of 520 nm diameter polystyrene particles spaced by 860 nm. Our results demonstrate how LATS can be used to fabricate reconfigurable structures with symmetries different from traditional colloidal self-assembly, which is limited by free energetic constraints.

  6. Narcissistic self-sorting in self-assembled cages of rare Earth metals and rigid ligands.

    Science.gov (United States)

    Johnson, Amber M; Wiley, Calvin A; Young, Michael C; Zhang, Xing; Lyon, Yana; Julian, Ryan R; Hooley, Richard J

    2015-05-04

    Highly selective, narcissistic self-sorting can be achieved in the formation of self-assembled cages of rare earth metals with multianionic salicylhydrazone ligands. The assembly process is highly sensitive to the length of the ligand and the coordination geometry. Most surprisingly, high-fidelity sorting is possible between ligands of identical coordination angle and geometry, differing only in a single functional group on the ligand core, which is not involved in the coordination. Supramolecular effects allow discrimination between pendant functions as similar as carbonyl or methylene groups in a complex assembly process. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Templated synthesis of metal nanorods in silica nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Yadong; Gao, Chuanbo

    2018-04-10

    A method of preparing a metal nanorod. The method includes seeding a metal nanoparticle within the lumen of a nanotube, and growing a metal nanorod from the seeded metal nanoparticle to form a metal nanorod-nanotube composite. In some cases, the nanotube includes metal binding ligands attached to the inner surface. Growing of the metal nanorod includes incubating the seeded nanotube in a solution that includes: a metal source for the metal in the metal nanorod, the metal source including an ion of the metal; a coordinating ligand that forms a stable complex with the metal ion; a reducing agent for reducing the metal ion, and a capping agent that stabilizes atomic monomers of the metal. Compositions derived from the method are also provided.

  8. Sambot II: A self-assembly modular swarm robot

    Science.gov (United States)

    Zhang, Yuchao; Wei, Hongxing; Yang, Bo; Jiang, Cancan

    2018-04-01

    The new generation of self-assembly modular swarm robot Sambot II, based on the original generation of self-assembly modular swarm robot Sambot, adopting laser and camera module for information collecting, is introduced in this manuscript. The visual control algorithm of Sambot II is detailed and feasibility of the algorithm is verified by the laser and camera experiments. At the end of this manuscript, autonomous docking experiments of two Sambot II robots are presented. The results of experiments are showed and analyzed to verify the feasibility of whole scheme of Sambot II.

  9. 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......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...

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

    Science.gov (United States)

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

    2016-10-01

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

  11. Self-assembling peptide hydrogels immobilized on silicon surfaces

    International Nuclear Information System (INIS)

    Franchi, Stefano; Battocchio, Chiara; Galluzzi, Martina; Navisse, Emanuele; Zamuner, Annj; Dettin, Monica; Iucci, Giovanna

    2016-01-01

    The hydrogels of self-assembling ionic complementary peptides have collected in the scientific community increasing consensus as mimetics of the extracellular matrix that can offer 3D supports for cell growth or be vehicles for the delivery of stem cells or drugs. Such scaffolds have also been proposed as bone substitutes for small defects as they promote beneficial effects on human osteoblasts. In this context, our research deals with the introduction of a layer of self-assembling peptides on a silicon surface by covalent anchoring and subsequent physisorption. In this work, we present a spectroscopic investigation of the proposed bioactive scaffolds, carried out by surface-sensitive spectroscopic techniques such as XPS (X-ray photoelectron spectroscopy) and RAIRS (Reflection Absorption Infrared Spectroscopy) and by state-of-the-art synchrotron radiation methodologies such as angle dependent NEXAFS (Near Edge X-ray Absorption Fine Structure). XPS studies confirmed the change in the surface composition in agreement with the proposed enrichments, and led to assess the self-assembling peptide chemical stability. NEXAFS spectra, collected in angular dependent mode at the N K-edge, allowed to investigate the self-assembling behavior of the macromolecules, as well as to determine their molecular orientation on the substrate. Furthermore, Infrared Spectroscopy measurements demonstrated that the peptide maintains its secondary structure (β-sheet anti-parallel) after deposition on the silicon surface. The complementary information acquired by means of XPS, NEXAFS and RAIRS lead to hypothesize a “layer-by-layer” arrangement of the immobilized peptides, giving rise to an ordered 3D nanostructure. - Highlights: • A self-assembling peptide (SAP) was covalently immobilized of on a flat silicon surface. • A physisorbed SAP layer was grown on top of the covalently immobilized peptide layer. • Molecular order and orientation of the peptide overlayer on the flat silicon

  12. Self-assembling peptide hydrogels immobilized on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Franchi, Stefano; Battocchio, Chiara; Galluzzi, Martina; Navisse, Emanuele [Department of Sciences, University “Roma Tre”, Via della Vasca Navale 79, Roma, 00146 (Italy); Zamuner, Annj; Dettin, Monica [Department of Industrial Engineering, University of Padua, Via Marzolo, 9, Padua, 35131 (Italy); Iucci, Giovanna, E-mail: giovanna.iucci@uniroma3.it [Department of Sciences, University “Roma Tre”, Via della Vasca Navale 79, Roma, 00146 (Italy)

    2016-12-01

    The hydrogels of self-assembling ionic complementary peptides have collected in the scientific community increasing consensus as mimetics of the extracellular matrix that can offer 3D supports for cell growth or be vehicles for the delivery of stem cells or drugs. Such scaffolds have also been proposed as bone substitutes for small defects as they promote beneficial effects on human osteoblasts. In this context, our research deals with the introduction of a layer of self-assembling peptides on a silicon surface by covalent anchoring and subsequent physisorption. In this work, we present a spectroscopic investigation of the proposed bioactive scaffolds, carried out by surface-sensitive spectroscopic techniques such as XPS (X-ray photoelectron spectroscopy) and RAIRS (Reflection Absorption Infrared Spectroscopy) and by state-of-the-art synchrotron radiation methodologies such as angle dependent NEXAFS (Near Edge X-ray Absorption Fine Structure). XPS studies confirmed the change in the surface composition in agreement with the proposed enrichments, and led to assess the self-assembling peptide chemical stability. NEXAFS spectra, collected in angular dependent mode at the N K-edge, allowed to investigate the self-assembling behavior of the macromolecules, as well as to determine their molecular orientation on the substrate. Furthermore, Infrared Spectroscopy measurements demonstrated that the peptide maintains its secondary structure (β-sheet anti-parallel) after deposition on the silicon surface. The complementary information acquired by means of XPS, NEXAFS and RAIRS lead to hypothesize a “layer-by-layer” arrangement of the immobilized peptides, giving rise to an ordered 3D nanostructure. - Highlights: • A self-assembling peptide (SAP) was covalently immobilized of on a flat silicon surface. • A physisorbed SAP layer was grown on top of the covalently immobilized peptide layer. • Molecular order and orientation of the peptide overlayer on the flat silicon

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

    NARCIS (Netherlands)

    de Nijs, B.

    2014-01-01

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

  14. Supramolecule-to-supramolecule transformations of coordination-driven self-assembled polygons.

    Science.gov (United States)

    Zhao, Liang; Northrop, Brian H; Stang, Peter J

    2008-09-10

    Two types of supramolecular transformations, wherein a self-assembled Pt(II)-pyridyl metal-organic polygon is controllably converted into an alternative polygon, have been achieved through the reaction between cobalt carbonyl and the acetylene moiety of a dipyridyl donor ligand. A [6 + 6] hexagon is transformed into two [3 + 3] hexagons, and a triangle-square mixture is converted into [2 + 2] rhomboids. 1H and 31P NMR spectra are used to track the transformation process and evaluate the yield of new self-assembled polygons. Such transformed species are identified by electrospray ionization (ESI) mass spectrometry. This new kind of supramolecule-to-supramolecule transformations provides a viable means for constructing, and then converting, new self-assembled polygons.

  15. The self-assembling process and applications in tissue engineering

    Science.gov (United States)

    Lee, Jennifer K.; Link, Jarrett M.; Hu, Jerry C. Y.; Athanasiou, Kyriacos A.

    2018-01-01

    Tissue engineering strives to create neotissues capable of restoring function. Scaffold-free technologies have emerged that can recapitulate native tissue function without the use of an exogenous scaffold. This chapter will survey, in particular, the self-assembling and self-organization processes as scaffold-free techniques. Characteristics and benefits of each process are described, and key examples of tissues created using these scaffold-free processes are examined to provide guidance for future tissue engineering developments. This chapter aims to explore the potential of self-assembly and self-organization scaffold-free approaches, detailing the recent progress in the in vitro tissue engineering of biomimetic tissues with these methods, toward generating functional tissue replacements. PMID:28348174

  16. DNA assisted self-assembly of PAMAM dendrimers.

    Science.gov (United States)

    Mandal, Taraknath; Kumar, Mattaparthi Venkata Satish; Maiti, Prabal K

    2014-10-09

    We report DNA assisted self-assembly of polyamidoamine (PAMAM) dendrimers using all atom Molecular Dynamics (MD) simulations and present a molecular level picture of a DNA-linked PAMAM dendrimer nanocluster, which was first experimentally reported by Choi et al. (Nano Lett., 2004, 4, 391-397). We have used single stranded DNA (ssDNA) to direct the self-assembly process. To explore the effect of pH on this mechanism, we have used both the protonated (low pH) and nonprotonated (high pH) dendrimers. In all cases studied here, we observe that the DNA strand on one dendrimer unit drives self-assembly as it binds to the complementary DNA strand present on the other dendrimer unit, leading to the formation of a DNA-linked dendrimer dimeric complex. However, this binding process strongly depends on the charge of the dendrimer and length of the ssDNA. We observe that the complex with a nonprotonated dendrimer can maintain a DNA length dependent inter-dendrimer distance. In contrast, for complexes with a protonated dendrimer, the inter-dendrimer distance is independent of the DNA length. We attribute this observation to the electrostatic complexation of a negatively charged DNA strand with the positively charged protonated dendrimer.

  17. Self-assembled nanomaterials based on beta (β"3) tetrapeptides

    International Nuclear Information System (INIS)

    Seoudi, Rania S; Hinds, Mark G; Wilson, David J D; Adda, Christopher G; Mechler, Adam; Del Borgo, Mark; Aguilar, Marie-Isabel; Perlmutter, Patrick

    2016-01-01

    β "3-amino acid based polypeptides offer a unique starting material for the design of self-assembled nanostructures such as fibres and hierarchical dendritic assemblies, due to their well-defined helical geometry in which the peptide side chains align at 120° due to the 3.0–3.1 residue pitch of the helix. In a previous work we have described the head-to-tail self-assembly of N-terminal acetylated β "3-peptides into infinite helical nanorods that was achieved by designing a bioinspired supramolecular self-assembly motif. Here we describe the effect of consecutively more polar side chains on the self-assembly characteristics of β "3-tetrapeptides Ac-β "3Ala-β "3Leu-β "3Ile-β "3Ala (Ac-β"3[ALIA]), Ac-β "3Ser-β "3Leu-β "3Ile-β "3Ala (Ac-β"3[SLIA]) and Ac-β "3Lys-β "3Leu-β "3Ile-β "3Glu (Ac-β"3[KLIE]). β "3-tetrapeptides complete 1 1/3 turns of the helix: thus in the oligomeric form the side chain positions shift 120° with each added monomer, forming a regular periodic pattern along the nanorod. Dynamic light scattering (DLS) measurements confirmed that these peptides self-assemble even in highly polar solvents such as water and DMSO, while diffusion-ordered NMR spectroscopy revealed the presence of a substantial monomeric population. Temperature dependence of the size distribution in DLS measurements suggests a dynamic equilibrium between monomers and oligomers. Solution casting produced distinct fibrillar deposits after evaporating the solvent. In the case of the apolar Ac-β "3[ALIA] the longitudinal helix morphology gives rise to geometrically defined (∼70°) junctions between fibres, forming a mesh that opens up possibilities for applications e.g. in tissue scaffolding. The deposits of polar Ac-β "3[SLIA] and Ac-β "3[KLIE] exhibit fibres in regular parallel alignment over surface areas in the order of 10 μm. (paper)

  18. Kinetic partitioning between aggregation and vesicle permeabilization by modified ADan

    DEFF Research Database (Denmark)

    Nesgaard, Lise W.; Vad, Brian; Christiansen, Gunna

    2009-01-01

    The neurodegenerative illness Familial Danish Dementia (FDD) is linked to formation and aggregation of the 34-residue ADan peptide, whose cytotoxicity may be mediated by membrane interactions. Here we characterize the derived peptide SerADan, in which the two cysteines found in ADan have been....... Aggregation is prevented at neutral/acidic pH and low ionic strength by anionic lipid vesicles. These vesicles are permeabilized by monomeric SerADan assembling on the membrane to form stable beta-sheet structures which are different from the solution aggregates. In contrast, solution ageing of SerADan first...

  19. 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....

  20. Self-assembly of patchy colloidal dumbbells

    NARCIS (Netherlands)

    Avvisati, Guido|info:eu-repo/dai/nl/407630198; Vissers, Teun|info:eu-repo/dai/nl/304829943; Dijkstra, Marjolein|info:eu-repo/dai/nl/123538807

    2015-01-01

    We employ Monte Carlo simulations to investigate the self-assembly of patchy colloidal dumbbells interacting via a modified Kern-Frenkel potential by probing the system concentration and dumbbell shape. We consider dumbbells consisting of one attractive sphere with diameter sigma(1) and one

  1. Fluorescent Self-Assembled Polyphenylene Dendrimer Nanofibers

    NARCIS (Netherlands)

    Liu, Daojun; Feyter, Steven De; Cotlet, Mircea; Wiesler, Uwe-Martin; Weil, Tanja; Herrmann, Andreas; Müllen, Klaus; Schryver, Frans C. De

    2003-01-01

    A second-generation polyphenylene dendrimer 1 self-assembles into nanofibers on various substrates such as HOPG, silicon, glass, and mica from different solvents. The investigation with noncontact atomic force microscopy (NCAFM) and scanning electron microscopy (SEM) shows that the morphology of the

  2. 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.

  3. Bioprinting synthetic self-assembling peptide hydrogels for biomedical applications

    International Nuclear Information System (INIS)

    Loo, Yihua; Hauser, Charlotte A E

    2016-01-01

    Three-dimensional (3D) bioprinting is a disruptive technology for creating organotypic constructs for high-throughput screening and regenerative medicine. One major challenge is the lack of suitable bioinks. Short synthetic self-assembling peptides are ideal candidates. Several classes of peptides self-assemble into nanofibrous hydrogels resembling the native extracellular matrix. This is a conducive microenvironment for maintaining cell survival and physiological function. Many peptides also demonstrate stimuli-responsive gelation and tuneable mechanical properties, which facilitates extrusion before dispensing and maintains the shape fidelity of the printed construct in aqueous media. The inherent biocompatibility and biodegradability bodes well for in vivo applications as implantable tissues and drug delivery matrices, while their short length and ease of functionalization facilitates synthesis and customization. By applying self-assembling peptide inks to bioprinting, the dynamic complexity of biological tissue can be recreated, thereby advancing current biomedical applications of peptide hydrogel scaffolds. (paper)

  4. Actinide Sequestration Using Self-Assembled Monolayers on Mesoporous Supports

    International Nuclear Information System (INIS)

    Fryxell, Glen E.; Lin, Yuehe; Fiskum, Sandra K.; Birnbaum, Jerome C.; Wu, Hong; Kemner, K. M.; Kelly, Shelley

    2005-01-01

    Surfactant templated synthesis of mesoporous ceramics provides a versatile foundation upon which to create high efficiency environmental sorbents. These nanoporous ceramic oxides condense a huge amount of surface area into a very small volume. The ceramic oxide interface is receptive to surface functionalization through molecular self-assembly. The marriage of mesoporous ceramics with self-assembled monolayer chemistry creates a powerful new class of environmental sorbent materials called self-assembled monolayers on mesoporous supports (SAMMS). These SAMMS materials are highly efficient sorbents, whose interfacial chemistry can be fine-tuned to selectively sequester a specific target species, such as heavy metals, tetrahedral oxometallate anions and radionuclides. Details addressing the design, synthesis and characterization of SAMMS materials specifically designed to sequester actinides, of central importance to the environmental clean-up necessary after 40 years of weapons grade plutonium production, as well as evaluation of their binding affinities and kinetics are presented

  5. Self-assembly of Archimedean tilings with enthalpically and entropically patchy polygons.

    Science.gov (United States)

    Millan, Jaime A; Ortiz, Daniel; van Anders, Greg; Glotzer, Sharon C

    2014-03-25

    Considerable progress in the synthesis of anisotropic patchy nanoplates (nanoplatelets) promises a rich variety of highly ordered two-dimensional superlattices. Recent experiments of superlattices assembled from nanoplates confirm the accessibility of exotic phases and motivate the need for a better understanding of the underlying self-assembly mechanisms. Here, we present experimentally accessible, rational design rules for the self-assembly of the Archimedean tilings from polygonal nanoplates. The Archimedean tilings represent a model set of target patterns that (i) contain both simple and complex patterns, (ii) are comprised of simple regular shapes, and (iii) contain patterns with potentially interesting materials properties. Via Monte Carlo simulations, we propose a set of design rules with general applicability to one- and two-component systems of polygons. These design rules, specified by increasing levels of patchiness, correspond to a reduced set of anisotropy dimensions for robust self-assembly of the Archimedean tilings. We show for which tilings entropic patches alone are sufficient for assembly and when short-range enthalpic interactions are required. For the latter, we show how patchy these interactions should be for optimal yield. This study provides a minimal set of guidelines for the design of anisostropic patchy particles that can self-assemble all 11 Archimedean tilings.

  6. Assessing the effects of a "personal effectiveness" training on psychological capital, assertiveness and self-awareness using self-other agreement

    NARCIS (Netherlands)

    Demerouti, E.; Eeuwijk, van E.; Snelder, M.; Wild, U.

    2011-01-01

    Purpose: This study seeks to examine the effects of a "personal effectiveness" training on both assertiveness and Psychological Capital (PsyCap) that were monitored before and after the training. Design/methodology/approach: In addition to self-ratings, other-ratings were assembled to explore two

  7. Fabrication of DNA nanotubes with an array of exterior magnetic nanoparticles.

    Science.gov (United States)

    Rafati, Adele; Zarrabi, Ali; Gill, Pooria

    2017-10-01

    Described here a methodology for arraying of magnetic nanoparticles (MNPs) on the surface of DNA nanotubes (DNTs). Positioning of magnetic nanoparticles at exterior surface of DNTs were shaped after self-assembling of oligonucleotide staples within an M13mp18 DNA scaffold via an origami process. The staples were partially labeled with biotin to be arrayed at the surface of DNTs. Gel retardation assay of the DNTs carrying magnetic nanoparticles indicated a reversely behavioral electrophoretic movement in comparison to the nanotubes have been demonstrated previously. Also, high resolution transmission electron microscopy confirmed positioning magnetic nanoparticles at the exterior surface of DNTs, correctly. Ultrastructural characteristics of these DNA nanotubes using atomic force microscopy demonstrated topographic heights on their surfaces formed through positioning of magnetic nanoparticles outside the tubules. This nanoarchitecture would be potential for multiple arraying of nanoparticles that those be useful as functionalized chimeric nanocarriers for developing novel nanodrugs and nanobiosensors. Copyright © 2017. Published by Elsevier B.V.

  8. 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

  9. Modulating β-lactoglobulin nanofibril self-assembly at pH 2 using glycerol and sorbitol.

    Science.gov (United States)

    Dave, Anant C; Loveday, Simon M; Anema, Skelte G; Jameson, Geoffrey B; Singh, Harjinder

    2014-01-13

    β-Lactoglobulin (β-lg) forms fibrils when heated at 80 °C, pH 2, and low ionic strength (sorbitol (0-50% w/v) on β-lg self-assembly at pH 2. Glycerol and sorbitol stabilize native protein structure and modulate protein functionality by preferential exclusion. In our study, both polyols decreased the rate of β-lg self-assembly but had no effect on the morphology of fibrils. The mechanism of these effects was studied using circular dichroism spectroscopy and SDS-PAGE. Sorbitol inhibited self-assembly by stabilizing β-lg against unfolding and hydrolysis, resulting in fewer fibrillogenic species, whereas glycerol inhibited nucleation without inhibiting hydrolysis. Both polyols increased the viscosity of the solutions, but viscosity appeared to have little effect on fibril assembly, and we believe that self-assembly was not diffusion-limited under these conditions. This is in agreement with previous reports for other proteins assembling under different conditions. The phenomenon of peptide self-assembly can be decoupled from protein hydrolysis using glycerol.

  10. Linear self-assembly and grafting of gold nanorods into arrayed micrometer-long nanowires on a silicon wafer via a combined top-down/bottom-up approach.

    Science.gov (United States)

    Lestini, Elena; Andrei, Codrin; Zerulla, Dominic

    2018-01-01

    Macroscopically long wire-like arrangements of gold nanoparticles were obtained by controlled evaporation and partial coalescence of an aqueous colloidal solution of capped CTAB-Au nanorods onto a functionalised 3-mercaptopropyl trimethoxysilane (MPTMS) silicon substrate, using a removable, silicon wafer with a hydrophobic surface that serves as a "handrail" for the initial nanorods' linear self-assembly. The wire-like structures display a quasi-continuous pattern by thermal annealing of the gold nanorods when the solvent (i.e. water) is evaporated at temperatures rising from 20°C to 140°C. Formation of both single and self-replicating parallel 1D-superstructures consisting of two or even three wires is observed and explained under such conditions.

  11. Self-assembled magnetic filter for highly efficient immunomagnetic separation.

    Science.gov (United States)

    Issadore, David; Shao, Huilin; Chung, Jaehoon; Newton, Andita; Pittet, Mikael; Weissleder, Ralph; Lee, Hakho

    2011-01-07

    We have developed a compact and inexpensive microfluidic chip, the self-assembled magnetic filter, to efficiently remove magnetically tagged cells from suspension. The self-assembled magnetic filter consists of a microfluidic channel built directly above a self-assembled NdFeB magnet. Micrometre-sized grains of NdFeB assemble to form alternating magnetic dipoles, creating a magnetic field with a very strong magnitude B (from the material) and field gradient ▽B (from the configuration) in the microfluidic channel. The magnetic force imparted on magnetic beads is measured to be comparable to state-of-the-art microfabricated magnets, allowing for efficient separations to be performed in a compact, simple device. The efficiency of the magnetic filter is characterized by sorting non-magnetic (polystyrene) beads from magnetic beads (iron oxide). The filter enriches the population of non-magnetic beads to magnetic beads by a factor of >10(5) with a recovery rate of 90% at 1 mL h(-1). The utility of the magnetic filter is demonstrated with a microfluidic device that sorts tumor cells from leukocytes using negative immunomagnetic selection, and concentrates the tumor cells on an integrated membrane filter for optical detection.

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

    Science.gov (United States)

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

    2016-08-01

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

  13. In situ microscopy of the self-assembly of branched nanocrystals in solution

    Science.gov (United States)

    Sutter, Eli; Sutter, Peter; Tkachenko, Alexei V.; Krahne, Roman; de Graaf, Joost; Arciniegas, Milena; Manna, Liberato

    2016-04-01

    Solution-phase self-assembly of nanocrystals into mesoscale structures is a promising strategy for constructing functional materials from nanoscale components. Liquid environments are key to self-assembly since they allow suspended nanocrystals to diffuse and interact freely, but they also complicate experiments. Real-time observations with single-particle resolution could have transformative impact on our understanding of nanocrystal self-assembly. Here we use real-time in situ imaging by liquid-cell electron microscopy to elucidate the nucleation and growth mechanism and properties of linear chains of octapod-shaped nanocrystals in their native solution environment. Statistical mechanics modelling based on these observations and using the measured chain-length distribution clarifies the relative importance of dipolar and entropic forces in the assembly process and gives direct access to the interparticle interaction. Our results suggest that monomer-resolved in situ imaging combined with modelling can provide unprecedented quantitative insight into the microscopic processes and interactions that govern nanocrystal self-assembly in solution.

  14. Formation of layer-by-layer assembled titanate nanotubes filled coating on flexible polyurethane foam with improved flame retardant and smoke suppression properties.

    Science.gov (United States)

    Pan, Haifeng; Wang, Wei; Pan, Ying; Song, Lei; Hu, Yuan; Liew, Kim Meow

    2015-01-14

    A fire blocking coating made from chitosan, titanate nanotubes and alginate was deposited on a flexible polyurethane (FPU) foam surface by a layer-by-layer assembly technique in an effort to reduce its flammability. First, titanate nanotubes were prepared by a hydrothermal method. And then the coating growth was carried out by alternately submerging FPU foams into chitosan solution, titanate nanotubes suspension and alginate solution. The mass gain of coating on the surface of FPU foams showed dependency on the concentration of titanate nanotubes suspension and the trilayers's number. Scanning electron microscopy indicated that titanate nanotubes were distributed well on the entire surface of FPU foam and showed a randomly oriented and entangled network structure. The cone calorimeter result indicated that the coated FPU foams showed reduction in the peak heat release rate (peak HRR), peak smoke production rate (peak SPR), total smoke release (TSR) and peak carbon monoxide (CO) production compared with those of the control FPU foam. Especially for the FPU foam with only 5.65 wt % mass gain, great reduction in peak HRR (70.2%), peak SPR (62.8%), TSR (40.9%) and peak CO production (63.5%) could be observed. Such a significant improvement in flame retardancy and the smoke suppression property for FPU foam could be attributed to the protective effect of titanate nanotubes network structure formed, including insulating barrier effect and adsorption effect.

  15. Nondeterministic self-assembly of two tile types on a lattice.

    Science.gov (United States)

    Tesoro, S; Ahnert, S E

    2016-04-01

    Self-assembly is ubiquitous in nature, particularly in biology, where it underlies the formation of protein quaternary structure and protein aggregation. Quaternary structure assembles deterministically and performs a wide range of important functions in the cell, whereas protein aggregation is the hallmark of a number of diseases and represents a nondeterministic self-assembly process. Here we build on previous work on a lattice model of deterministic self-assembly to investigate nondeterministic self-assembly of single lattice tiles and mixtures of two tiles at varying relative concentrations. Despite limiting the simplicity of the model to two interface types, which results in 13 topologically distinct single tiles and 106 topologically distinct sets of two tiles, we observe a wide variety of concentration-dependent behaviors. Several two-tile sets display critical behaviors in the form of a sharp transition from bound to unbound structures as the relative concentration of one tile to another increases. Other sets exhibit gradual monotonic changes in structural density, or nonmonotonic changes, while again others show no concentration dependence at all. We catalog this extensive range of behaviors and present a model that provides a reasonably good estimate of the critical concentrations for a subset of the critical transitions. In addition, we show that the structures resulting from these tile sets are fractal, with one of two different fractal dimensions.

  16. Lipid-bilayer-assisted two-dimensional self-assembly of DNA origami nanostructures

    Science.gov (United States)

    Endo, Masayuki; Sugiyama, Hiroshi

    2015-01-01

    Self-assembly is a ubiquitous approach to the design and fabrication of novel supermolecular architectures. Here we report a strategy termed ‘lipid-bilayer-assisted self-assembly' that is used to assemble DNA origami nanostructures into two-dimensional lattices. DNA origami structures are electrostatically adsorbed onto a mica-supported zwitterionic lipid bilayer in the presence of divalent cations. We demonstrate that the bilayer-adsorbed origami units are mobile on the surface and self-assembled into large micrometre-sized lattices in their lateral dimensions. Using high-speed atomic force microscopy imaging, a variety of dynamic processes involved in the formation of the lattice, such as fusion, reorganization and defect filling, are successfully visualized. The surface modifiability of the assembled lattice is also demonstrated by in situ decoration with streptavidin molecules. Our approach provides a new strategy for preparing versatile scaffolds for nanofabrication and paves the way for organizing functional nanodevices in a micrometer space. PMID:26310995

  17. Lipid-bilayer-assisted two-dimensional self-assembly of DNA origami nanostructures

    Science.gov (United States)

    Suzuki, Yuki; Endo, Masayuki; Sugiyama, Hiroshi

    2015-08-01

    Self-assembly is a ubiquitous approach to the design and fabrication of novel supermolecular architectures. Here we report a strategy termed `lipid-bilayer-assisted self-assembly' that is used to assemble DNA origami nanostructures into two-dimensional lattices. DNA origami structures are electrostatically adsorbed onto a mica-supported zwitterionic lipid bilayer in the presence of divalent cations. We demonstrate that the bilayer-adsorbed origami units are mobile on the surface and self-assembled into large micrometre-sized lattices in their lateral dimensions. Using high-speed atomic force microscopy imaging, a variety of dynamic processes involved in the formation of the lattice, such as fusion, reorganization and defect filling, are successfully visualized. The surface modifiability of the assembled lattice is also demonstrated by in situ decoration with streptavidin molecules. Our approach provides a new strategy for preparing versatile scaffolds for nanofabrication and paves the way for organizing functional nanodevices in a micrometer space.

  18. Vortex pinning in superconductors laterally modulated by nanoscale self-assembled arrays

    DEFF Research Database (Denmark)

    Vanacken, J.; Vinckx, W.; Moshchalkov, V.V.

    2008-01-01

    Being the exponent of the so-called "bottom-up" approach, self-assembled structures are now-a-days attracting a lot of attention in the fields of science and technology. In this work, we show that nanoscale self-assembled arrays used as templates can provide periodic modulation in superconducting...

  19. Self-lubricating fluid bearing assembly

    International Nuclear Information System (INIS)

    Kapich, D.D.

    1981-01-01

    A sealed self-lubricating fluid bearing assembly is described for circulating fluid in the form of a gas coolant in a nuclear reactor, the power for the circulator being provided by a shaft located within the primary containment vessel. In such a system the reactor coolant is isolated from the fluid region at the far end of the drive shaft. (U.K.)

  20. Extracellular Vesicles in Brain Tumors and Neurodegenerative Diseases

    Directory of Open Access Journals (Sweden)

    Federica Ciregia

    2017-08-01

    Full Text Available Extracellular vesicles (EVs can be classified into apoptotic bodies, microvesicles (MVs, and exosomes, based on their origin or size. Exosomes are the smallest and best characterized vesicles which derived from the endosomal system. These vesicles are released from many different cell types including neuronal cells and their functions in the nervous system are investigated. They have been proposed as novel means for intercellular communication, which takes part not only to the normal neuronal physiology but also to the transmission of pathogenic proteins. Indeed, exosomes are fundamental to assemble and transport proteins during development, but they can also transfer neurotoxic misfolded proteins in pathogenesis. The present review will focus on their roles in neurological diseases, specifically brain tumors, such as glioblastoma (GBM, neuroblastoma (NB, medulloblastoma (MB, and metastatic brain tumors and chronic neurodegenerative diseases, such as Alzheimer, Parkinson, multiple sclerosis (MS, amyotrophic lateral sclerosis (ALS, Huntington, and Prion diseseases highlighting their involvement in spreading neurotoxicity, in therapeutics, and in pathogenesis.