Sample records for expanded self-assembled capsules

  1. Advantages of Catalysis in Self-Assembled Molecular Capsules. (United States)

    Catti, Lorenzo; Zhang, Qi; Tiefenbacher, Konrad


    Control over the local chemical environment of a molecule can be achieved by encapsulation in supramolecular host systems. In supramolecular catalysis, this control is used to gain advantages over classical homogeneous catalysis in bulk solution. Two of the main advantages concern influencing reactions in terms of substrate and product selectivity. Due to size and/or shape recognition, substrate selective conversion can be realized. Additionally, noncovalent interactions with the host environment facilitate alternative reaction pathways and can yield unusual products. This Concept article discusses and highlights literature examples utilizing self-assembled molecular capsules to achieve catalytic transformations displaying a high degree of substrate and/or product selectivity. Furthermore, the advantage of supramolecular hosts in multicatalyst tandem reactions is covered. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Dynamic formation of hybrid peptidic capsules by chiral self-sorting and self-assembly. (United States)

    Jędrzejewska, Hanna; Wierzbicki, Michał; Cmoch, Piotr; Rissanen, Kari; Szumna, Agnieszka


    Owing to their versatility and biocompatibility, peptide-based self-assembled structures constitute valuable targets for complex functional designs. It is now shown that artificial capsules based on β-barrel binding motifs can be obtained by means of dynamic covalent chemistry (DCC) and self-assembly. Short peptides (up to tetrapeptides) are reversibly attached to resorcinarene scaffolds. Peptidic capsules are thus selectively formed in either a heterochiral or a homochiral way by simultaneous and spontaneous processes, involving chiral sorting, tautomerization, diastereoselective induction of inherent chirality, and chiral self-assembly. Self-assembly is shown to direct the regioselectivity of reversible chemical reactions. It is also responsible for shifting the tautomeric equilibrium for one of the homochiral capsules. Two different tautomers (keto-enamine hemisphere and enol-imine hemisphere) are observed in this capsule, allowing the structure to adapt for self-assembly. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Particle-stabilized oscillating diver: a self-assembled responsive capsule

    DEFF Research Database (Denmark)

    Tavacoli, Joe; Thijssen, Job H. J.; Clegg, Paul S.


    We report the experimental discovery of a self-assembled capsule, with density set by interfacial glass beads and an internal bubble, that automatically performs regular oscillations up and down a vial in response to a temperature gradient. Similar composites featuring interfacial particles...

  4. Control of stilbene conformation and fluorescence in self-assembled capsules (United States)

    Ams, Mark R; Ajami, Dariush; Craig, Stephen L; Yang, Jye-Shane


    Summary The extensively studied trans-stilbene molecule is known to give only weak fluorescence in solution and inside loosely-fitting synthetic capsules. However, trans-stilbene has been recently studied in the context of antibody interiors, where binding results in strong blue fluorescence. The present research was undertaken to understand the spatial factors that influence stilbene fluorescence. trans-Stilbene was encapsulated in the snug, self-assembled complex 1.1 and exhibited fluorescence quenching due to the distortion of its ground-state geometry. When the complex is elongated by incorporating glycouril spacers, trans-stilbene is allowed to adapt a fully coplanar arrangement and fluorescence returns. PMID:20300499

  5. Self-Assembling Molecular Capsules Based on α,γ-Cyclic Peptides. (United States)

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


    A new capsule based on a β-sheet self-assembling cyclic peptide with the ability to recognize and release several guests is described. The host structure is composed of two self-complementary α,γ-cyclic peptides bearing a Zn porphyrin cap that is used for the selective recognition of the guest. The two components are linked through two dynamic covalent bonds. The combination of binding forces, including hydrogen bonding, metal coordination, and dynamic hydrazone bonds, allows the reversible recognition of long bipyridine guests. The affinity for these ligands showed a strong dependence on the guest length. Delivery of the encapsulated ligand can be achieved by hydrolysis of hydrazones to disrupt the sandwich complex structure.

  6. Self-assembly of amphiphilic janus particles into monolayer capsules for enhanced enzyme catalysis in organic media. (United States)

    Cao, Wei; Huang, Renliang; Qi, Wei; Su, Rongxin; He, Zhimin


    Encapsulation of enzymes during the creation of an emulsion is a simple and efficient route for enhancing enzyme catalysis in organic media. Herein, we report a capsule with a shell comprising a monolayer of silica Janus particles (JPs) (referred to as a monolayer capsule) and a Pickering emulsion for the encapsulation of enzyme molecules for catalysis purposes in organic media using amphiphilic silica JPs as building blocks. We demonstrate that the JP capsules had a monolayer shell consisting of closely packed silica JPs (270 nm). The capsules were on average 5-50 μm in diameter. The stability of the JP capsules (Pickering emulsion) was investigated with the use of homogeneous silica nanoparticles as a control. The results show that the emulsion stabilized via amphiphilic silica JPs presented no obvious changes in physical appearance after 15 days, indicating the high stability of the emulsions and JP capsules. Furthermore, the lipase from Candida sp. was chosen as a model enzyme for encapsulation within the JP capsules during their formation. The catalytic performance of lipase was evaluated according to the esterification of 1-hexanol with hexanoic acid. It was found that the specific activity of the encapsulated enzymes (28.7 U mL(-1)) was more than 5.6 times higher than that of free enzymes in a biphasic system (5.1 U mL(-1)). The enzyme activity was further increased by varying the volume ratio of water to oil and the JPs loadings. The enzyme-loaded capsule also exhibited high stability during the reaction process and good recyclability. In particular, the jellification of agarose in the JP capsules further enhanced their operating stability. We believe that the monolayer structure of the JP capsules, together with their high stability, rendered the capsules to be ideal enzyme carriers and microreactors for enzyme catalysis in organic media because they created a large interfacial area and had low mass transfer resistance through the monolayer shell.

  7. Characterization of the Capsule Surrounding Smooth and Textured Tissue Expanders and Correlation with Contracture

    Directory of Open Access Journals (Sweden)

    Erika Kuriyama, MD


    Full Text Available Background:. Capsular contracture is a common complication after breast augmentation surgery. This study pathologically evaluated the soft-tissue response to surface modifications in both smooth and textured tissue expander prostheses. Methods:. Smooth tissue expanders and textured tissue expanders in 5 cases each were used for breast reconstruction after mastectomy. Histological samples were harvested from the capsules when the tissue expanders were replaced by silicone implants. Collagen orientation and cellular responses were assessed histologically. Capsular contracture was evaluated using the Baker classification 6 months and 2 years after the removal of the tissue expander. Results:. The capsules surrounding the smooth tissue expanders tended to produce more contracture than those surrounding the textured tissue expanders. The collagen architecture of the capsules of the smooth tissue expanders showed random orientation with fragmentation. Conversely, the capsules of the textured tissue expanders showed parallel orientation with collagen bundles of almost normal structure. Significantly more fibrils of elastin and myofibroblasts were found in the capsules surrounding the smooth tissue than in those surrounding the textured ones. Conclusions:. The collagen fibers surrounding the smooth tissue expanders could be cracked during expansion, which may lead to scarring and contracture. Conversely, the collagen orientation surrounding the textured tissue expanders was excellent. Moreover, the increase in elastic fibers and myofibroblasts in the capsules surrounding the smooth tissue expanders may be associated with in vivo contraction patterns. Therefore, the surface type of tissue expanders affects capsular contraction after replacement with definitive implants.

  8. Self-assembled nanostructures

    CERN Document Server

    Zhang, Jin Z; Liu, Jun; Chen, Shaowei; Liu, Gang-yu


    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.

  9. Photovoltaic self-assembly.

    Energy Technology Data Exchange (ETDEWEB)

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


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

  10. Microtubule Self- Assembly (United States)

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


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

  11. Self-assembly of self-assembled molecular triangles

    Indian Academy of Sciences (India)

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

  12. Reactivity within a confined self-assembled nanospace

    NARCIS (Netherlands)

    Koblenz, T.S.; Wassenaar, J.; Reek, J.N.H.


    Confined nanospaces in which reactions can take place, have been created by various approaches such as molecular capsules, zeolites and micelles. In this tutorial review we focus on the application of self-assembled nanocapsules with well-defined cavities as nanoreactors for organic and metal

  13. Designing self-assembling 3D structures of microcapsules (United States)

    Li, Like; Shum, Henry; Shklyaev, Oleg; Yashin, Victor; Balazs, Anna

    Self-assembly of complex, three-dimensional structures is commonly achieved by biological cells but difficult to realize in synthetic systems with micron-scale or larger components. Some previous modeling studies have considered only the planar self-assembly of microcapsules on a substrate. In this work, nanoparticles released from the capsules bind to the substrate and to the shells of nearby capsules. The non-uniform nanoparticle deposition on a capsule's surface leads to adhesion gradients, which drive the capsules to effectively ``climb'' on top of one another and self-organize in the vertical direction. We determine conditions that favor this structural organization. In particular, we study how the vertical structuring depends on the background fluid flow, the topography of the microcapsules and the underlying surface, the capsule-capsule interaction and that between the capsules and the substrate. The findings can provide design rules for the autonomous creation of novel nanocomposites, where the layers are formed from nanoparticle-containing and nanoparticle-decorated microcapsules.

  14. Peptide amphiphile self-assembly (United States)

    Iscen, Aysenur; Schatz, George C.


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

  15. Self-assembly of cyclodextrins

    DEFF Research Database (Denmark)

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


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

  16. Coded nanoscale self-assembly

    Indian Academy of Sciences (India)

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

  17. A self-assembled ionophore (United States)

    Tirumala, Sampath K.


    Ionophores are compounds that bind and transport ions. Ion binding and transport are fundamental to many biological and chemical processes. In this thesis we detail the structural characterization and cation binding properties of a self-assembled ionophore built from an isoguanosine (isoG) derivative, 5sp'-t-butyldimethylsilyl-2sp',3sp'-isopropylidene isoG 30. We begin with a summary of the themes that facilitate ionophore design and the definitions of "self-assembly" and "self-assembled ionophore" in Chapter 1. In Chapter 2, we describe the structural characterization of the isoG 30 self-assembly. IsoG possesses complementary hydrogen bond donor and acceptor sites suitable to form a Csb4-symmetric tetramer, (isoG)sb4 51, that is stable even in high dielectric organic solvents such as CDsb3CN and dsb6-acetone. The isoG tetramer 51 has been characterized by vapor phase osmometry, UV spectroscopy, and by 1D and 2D NMR spectroscopy. The isoG tetramer 51 organizes by hydrogen bonding between the Watson-Crick face of one isoG base and the complementary bottom edge of another purine. The tetramer 51 is stabilized by an inner and outer ring of hydrogen bonds. The inner ring forms between the imino NH1 proton of one monomer and the C2 carbonyl oxygen of an adjacent monomer, while the outer ring is made up of four NH6-N3 hydrogen bonds. The isoG tetramer 51 is thermodynamically stable, with an equilibrium constant (Ksba) of ca. 10sp9-10sp{10} Msp{-3} at room temperature, and a DeltaGsp° of tetramer formation of -12.5 kcal molsp{-1} in dsb6-acetone at 25sp°C. The van't Hoff plots indicated that the thermodynamic parameters for tetramer formation were DeltaHsp° = -18.2 ± 0.87 kcal molsp{-1} and DeltaSsp°sb{298} = -19.1 ± 5.45 eu. In Chapter 3, we describe the cation binding properties of isoG tetramer 51. The isoG tetramer 51 has a central cavity, containing four oxygen atoms, that is suitable for cation coordination. Depending on the cation, the resulting iso

  18. Self-assembled nanostructured metamaterials (United States)

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


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

  19. Design principles for nonequilibrium self-assembly. (United States)

    Nguyen, Michael; Vaikuntanathan, Suriyanarayanan


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

  20. Molecular self-assembly advances and applications

    CERN Document Server

    Dequan, Alex Li


    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

  1. Self-assembled nanomaterials for photoacoustic imaging. (United States)

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


    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.

  2. Recovery and redispersion of gold nanoparticles using the self-assembly of a pH sensitive zwitterionic amphiphile. (United States)

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


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

  3. Self-assembling enzymes and the origins of the cytoskeleton (United States)

    Barry, Rachael; Gitai, Zemer


    The bacterial cytoskeleton is composed of a complex and diverse group of proteins that self-assemble into linear filaments. These filaments support and organize cellular architecture and provide a dynamic network controlling transport and localization within the cell. Here, we review recent discoveries related to a newly appreciated class of self-assembling proteins that expand our view of the bacterial cytoskeleton and provide potential explanations for its evolutionary origins. Specifically, several types of metabolic enzymes can form structures similar to established cytoskeletal filaments and, in some cases, these structures have been repurposed for structural uses independent of their normal role. The behaviors of these enzymes suggest that some modern cytoskeletal proteins may have evolved from dual-role proteins with catalytic and structural functions. PMID:22014508

  4. Directed Self-Assembly of Nanodispersions

    Energy Technology Data Exchange (ETDEWEB)

    Furst, Eric M [University of Delaware


    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

  5. Biocatalytic Self-Assembly on Magnetic Nanoparticles. (United States)

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


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

  6. Mechanical Self-Assembly Science and Applications

    CERN Document Server


    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 at the Colloidal Scale (United States)

    Zhong, Xiao

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

  8. Buckling Instability of Self-Assembled Colloidal Columns (United States)

    Swan, James W.; Vasquez, Paula A.; Furst, Eric M.


    Suspended, slender self-assembled domains of magnetically responsive colloids are observed to buckle in microgravity. Upon cessation of the magnetic field that drives their assembly, these columns expand axially and buckle laterally. This phenomenon resembles the buckling of long beams due to thermal expansion; however, linear stability analysis predicts that the colloidal columns are inherently susceptible to buckling because they are freely suspended in a Newtonian fluid. The dominant buckling wavelength increases linearly with column thickness and is quantitatively described using an elastohydrodynamic model and the suspension thermodynamic equation of state.

  9. Self-assembly of nanocomposite materials (United States)

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


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

  10. Self-Assembly Modularity and Physical Complexity (United States)

    Ahnert, S. E.


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

  11. S-Layer Protein Self-Assembly (United States)

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


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

  12. Nondeterministic self-assembly with asymmetric interactions (United States)

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


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

  13. Self-assembling segmented coiled tubing

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, David W.


    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. Stabilization of Self-Assembled Alumina Mesophases

    NARCIS (Netherlands)

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


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

  15. Self-assembly of hyperbranched spheres

    NARCIS (Netherlands)

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


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

  16. Self-assembled nanogaps for molecular electronics

    DEFF Research Database (Denmark)

    Tang, Qingxin; Tong, Yanhong; Jain, Titoo


    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...

  17. Self-Assembly and Nanotechnology: Real-Time, Hands-On, and Safe Experiments for K-12 Students (United States)

    Bagaria, Hitesh G.; Dean, Michelle R.; Nichol, Carolyn A.; Wong, Michael S.


    What students and teachers often ask is, how are nano-sized materials made when they are so small? One answer is through the process of self-assembly in which molecules, polymers, and nanoparticles connect to form larger objects of a defined structure and shape. Two hands-on experiments are presented in which students prepare capsules in real time…

  18. Self-assembly between biomacromolecules and lipids (United States)

    Liang, Hongjun

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

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

    Indian Academy of Sciences (India)

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

  20. 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.


    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

  1. Ternary self-assemblies in water

    DEFF Research Database (Denmark)

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


    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...

  2. Programming protein self assembly with coiled coils

    Energy Technology Data Exchange (ETDEWEB)

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


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

  3. Self-assembling membranes and related methods thereof (United States)

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


    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).

  4. Self-assembled Nanomaterials for Chemotherapeutic Applications (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

  5. Biological Nanoplatforms for Self-Assembled Electronics (United States)


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

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

    Indian Academy of Sciences (India)


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

  7. Smart Self-Assembled Hybrid Hydrogel Biomaterials


    Kopeček, Jindřich; Yang, Jiyuan


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

  8. Polycaps: Reversibly formed polymeric capsules (United States)

    Castellano, Ronald K.; Rudkevich, Dmitry M.; Rebek, Julius


    Described are assemblies consisting of polymeric capsules, “polycaps,” formed from two calix[4]arene tetraureas covalently connected at their lower rims. In these structures self-assembly leads to reversibly formed capsule sites along a chain, reminiscent of beads on a string. Their dynamic behavior is characterized by 1H NMR spectroscopy through encapsulation of guest species, reversible polymerization, and the formation of sharply defined hybrid capsules. PMID:11038556

  9. Self-assembled monolayers in organic electronics. (United States)

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


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

  10. Self-assembly of polar food lipids. (United States)

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


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

  11. Self-Assembly of Nanoparticle Surfactants (United States)

    Lombardo, Michael T.

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

  12. Self-Assembly of Large Amyloid Fibers (United States)

    Ridgley, Devin M.

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

  13. Self-assembled biomimetic nanoreactors I: Polymeric template (United States)

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


    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.

  14. Ionic self-assembly for functional hierarchical nanostructured materials. (United States)

    Faul, Charl F J


    CONSPECTUS: The challenge of constructing soft functional materials over multiple length scales can be addressed by a number of different routes based on the principles of self-assembly, with the judicious use of various noncovalent interactions providing the tools to control such self-assembly processes. It is within the context of this challenge that we have extensively explored the use of an important approach for materials construction over the past decade: exploiting electrostatic interactions in our ionic self-assembly (ISA) method. In this approach, cooperative assembly of carefully chosen charged surfactants and oppositely charged building blocks (or tectons) provides a facile noncovalent route for the rational design and production of functional nanostructured materials. Generally, our research efforts have developed with an initial focus on establishing rules for the construction of novel noncovalent liquid-crystalline (LC) materials. We found that the use of double-tailed surfactant species (especially branched double-tailed surfactants) led to the facile formation of thermotropic (and, in certain cases, lyotropic) phases, as demonstrated by extensive temperature-dependent X-ray and light microscopy investigations. From this core area of activity, research expanded to cover issues beyond simple construction of anisotropic materials, turning to the challenge of inclusion and exploitation of switchable functionality. The use of photoactive azobenzene-containing ISA materials afforded opportunities to exploit both photo-orientation and surface relief grating formation. The preparation of these anisotropic LC materials was of interest, as the aim was the facile production of disposable and low-cost optical components for display applications and data storage. However, the prohibitive cost of the photo-orientation processes hampered further exploitation of these materials. We also expanded our activities to explore ISA of biologically relevant tectons

  15. Self-assembled nanostructures on vicinal surfaces (United States)

    Petrovykh, Dmitri Yourievich


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

  16. Heterogeneous self-assembled media for biopolymerization

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain


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

  17. Nanoscale spirals by directed self-assembly (United States)

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


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

  18. Self-assembly of colloidal surfactants (United States)

    Kegel, Willem


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

  19. Controllable self-assembly of RNA dendrimers. (United States)

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


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

  20. Peptide Self-Assembled Nanostructures for Drug Delivery Applications

    Directory of Open Access Journals (Sweden)

    Taotao Fan


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

  1. Self-Assembly of Human Serum Albumin: A Simplex Phenomenon (United States)

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


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

  2. Magnetic self-assembly of small parts (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

  3. Self-assembled software and method of overriding software execution (United States)

    Bouchard, Ann M.; Osbourn, Gordon C.


    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.

  4. Self-assembled monolayers on silicon oxide

    Energy Technology Data Exchange (ETDEWEB)

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


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

  5. Self-Assembling Brush Polymers Bearing Multisaccharides. (United States)

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


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

  6. Self-assembling multimeric nucleic acid constructs (United States)

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


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

  7. Smart self-assembled hybrid hydrogel biomaterials. (United States)

    Kopeček, Jindřich; Yang, Jiyuan


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

  8. Self assembled structures for 3D integration (United States)

    Rao, Madhav

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

  9. Self-assembly of granular crystals (United States)

    Shattuck, Mark


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

  10. Shape Restoration by Active Self-Assembly

    Directory of Open Access Journals (Sweden)

    D. Arbuckle


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

  11. Polymer-mediated nanorod self-assembly predicted by dissipative particle dynamics simulations. (United States)

    Khani, Shaghayegh; Jamali, Safa; Boromand, Arman; Hore, Michael J A; Maia, Joao


    Self-assembly of nanoparticles in polymer matrices is an interesting and growing subject in the field of nanoscience and technology. We report herein on modelling studies of the self-assembly and phase behavior of nanorods in a homopolymer matrix, with the specific goal of evaluating the role of deterministic entropic and enthalpic factors that control the aggregation/dispersion in such systems. Grafting polymer brushes from the nanorods is one approach to control/impact their self-assembly capabilities within a polymer matrix. From an energetic point of view, miscible interactions between the brush and the matrix are required for achieving a better dispersibility; however, grafting density and brush length are the two important parameters in dictating the morphology. Unlike in previous computational studies, the present Dissipative Particle Dynamics (DPD) simulation framework is able to both predict dispersion or aggregation of nanorods and determine the self-assembled structure, allowing for the determination of a phase diagram, which takes all of these factors into account. Three types of morphologies are predicted: dispersion, aggregation and partial aggregation. Moreover, favorable enthalpic interactions between the brush and the matrix are found to be essential for expanding the window for achieving a well-dispersed morphology. A three-dimensional phase diagram is mapped on which all the afore-mentioned parameters are taken into account. Additionally, in the case of immiscibility between brushes and the matrix, simulations predict the formation of some new and tunable structures.

  12. Directed Self-Assembly of Hierarchical Supramolecular Block Copolymer Thin Films on Chemical Patterns

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Guang-Peng [MOE Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 China; Liu, Xiaoying [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Chen, Xuanxuan [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Suh, Hyo Seon [Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue Argonne IL 60439 USA; Li, Xiao [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Ren, Jiaxing [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Arges, Christopher G. [Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue Argonne IL 60439 USA; Li, Faxue [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Jiang, Zhang [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue Argonne IL 60439 USA; Nealey, Paul F. [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue Argonne IL 60439 USA


    A long-range ordered lamellae-within-lamellae hierarchical structure is reported for the first time through the directed self-assembly of supramolecular polymer-surfactant thin films on chemical patterns with density multiplication. The coassembly of supramolecular system with gold nanoparticles is further achieved to create a hybrid material with well-organized nanoparticle arrays, expanding the palette of morphologies and structures available for nanoscale fabrication.

  13. Mechanochemical Encapsulation of Fullerenes in Peptidic Containers Prepared by Dynamic Chiral Self-Sorting and Self-Assembly. (United States)

    Szymański, Marek; Wierzbicki, Michał; Gilski, Mirosław; Jędrzejewska, Hanna; Sztylko, Marcin; Cmoch, Piotr; Shkurenko, Aleksander; Jaskólski, Mariusz; Szumna, Agnieszka


    Molecular capsules composed of amino acid or peptide derivatives connected to resorcin[4]arene scaffolds through acylhydrazone linkers have been synthesized using dynamic covalent chemistry (DCC) and hydrogen-bond-based self-assembly. The dynamic character of the linkers and the preference of the peptides towards self-assembly into β-barrel-type motifs lead to the spontaneous amplification of formation of homochiral capsules from mixtures of different substrates. The capsules have cavities of around 800 Å(3) and exhibit good kinetic stability. Although they retain their dynamic character, which allows processes such as chiral self-sorting and chiral self-assembly to operate with high fidelity, guest complexation is hindered in solution. However, the quantitative complexation of even very large guests, such as fullerene C60 or C70 , is possible through the utilization of reversible covalent bonds or the application of mechanochemical methods. The NMR spectra show the influence of the chiral environment on the symmetry of the fullerene molecules, which results in the differentiation of diastereotopic carbon atoms for C70 , and the X-ray structures provide unique information on the modes of peptide-fullerene interactions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. 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.


    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

  15. Self-assembled Nanomaterials for Hybrid Electronic and Photonic Systems (United States)


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

  16. Combinatoric and mean field analysis of heterogeneous self assembly (United States)


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

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

    NARCIS (Netherlands)

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


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

  18. Scalable Directed Self-Assembly Using Ultrasound Waves (United States)


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

  19. Self-Assembly of Magnetic Colloids in Soft Confinement

    NARCIS (Netherlands)

    Liu, P.


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

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

    NARCIS (Netherlands)

    Graveland-Bikker, Johanna Frederike


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

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

    Indian Academy of Sciences (India)

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

  2. RNA self-assembly and RNA nanotechnology. (United States)

    Grabow, Wade W; Jaeger, Luc


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

  3. Solvent mediated self-assembly of solids

    Energy Technology Data Exchange (ETDEWEB)

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


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

  4. Self-assembly of polyamines as a facile approach to fabricate permeability tunable polymeric shells for biomolecular encapsulation. (United States)

    Jianhao, Bai; Sebastian, Beyer; Yein, Toh Soo; Dieter, Trau


    In this article, the self-assembly of polyamines as a facile approach to fabricate permeability tunable polymeric shells for encapsulation of relatively low molecular weight (LM(w)) hydrophilic biomacromolecules (M(w) ≈ 4000 Da) is presented. The entire process is performed in organic solvents within 2 to 4 h to allow for nearly 100% encapsulation yield. The polymeric shells are fabricated by a two-step process: 1) The self-assembly of polyamines (nonionized poly(allylamine) (niPA) or branched nonionized polyethyleneimine (niPEI)) within porous agarose microbeads via an inwards buildup self-assembly process. 2) Stabilization of assembled polyamines either via covalent (cross-linkers) or ionic bonding (complex with nonionized poly(styrene sulfonic acid) (niPSS)). Stable and distinct polymeric shells are formed in both cases. The shell thickness is demonstrated to be tunable within a range of 1 to 14 μm; and as the inwards buildup self-assembly technique is not a self-limiting process, shells with broader thicknesses can be achieved. Also, it is demonstrated that the polymer density of the shell can be tuned. Depending on the fabrication parameters, the resulting polymeric shells have been demonstrated to have different permeability characteristics for relatively LM(W) dextran (M(W) ≈ 4000 Da). For example, niPEI shells are observed to have a higher permeability than niPA shells. Therefore, polymeric capsules can be fabricated via this facile approach for either retention of relatively LM(w) hydrophilic biomacromolecules or designed to passively or responsively release the biomacromolecule payload. This two-step shell fabrication process represent an alternative and facile approach for the fabrication of self-assembled polymeric shells in the fields of capsule-based reactors/sensors and drugs/gene delivery where relatively LM(w) macromolecules are concerned.

  5. Manipulating fluids: Advances in micro-fluidics, opto-fluidics and fluidic self assembly (United States)

    Vyawahare, Saurabh

    materials like quantum dots and solvent resistant elastomers along with 3-D fabrication and methods of self assembly, provide a new set of tools that significantly expand our control over fluids.

  6. Initial condition of stochastic self-assembly. (United States)

    Davis, Jason K; Sindi, Suzanne S


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

  7. Functional Self-Assembled Nanofibers by Electrospinning (United States)

    Greiner, A.; Wendorff, J. H.

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

  8. What promotes derected self assembly (DSA)?

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, S.T.


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

  9. Electrostatic self-assembly of biomolecules (United States)

    Olvera de La Cruz, Monica


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

  10. Self-assembly programming of DNA polyominoes. (United States)

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


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

  11. Optical orientation in self assembled quantum dots

    CERN Document Server

    Stevens, G C


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

  12. Self-assembled biomimetic superhydrophobic hierarchical arrays. (United States)

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


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

  13. Self-assembly models for lipid mixtures (United States)

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


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

  14. Enzyme-assisted self-assembly under thermodynamic control. (United States)

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


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

  15. Anisotropic Self-Assembly of Organic–Inorganic Hybrid Microtoroids

    KAUST Repository

    Al-Rehili, Safa’a


    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.

  16. Multiband theory of multi-exciton complexes in self-assembled quantum dots (United States)

    Sheng, Weidong; Cheng, Shun-Jen; Hawrylak, Pawel


    We report on a multiband microscopic theory of many-exciton complexes in self-assembled quantum dots. The single particle states are obtained by three methods: single-band effective-mass approximation, the multiband k•p method, and the tight-binding method. The electronic structure calculations are coupled with strain calculations via Bir-Pikus Hamiltonian. The many-body wave functions of N electrons and N valence holes are expanded in the basis of Slater determinants. The Coulomb matrix elements are evaluated using statically screened interaction for the three different sets of single particle states and the correlated N -exciton states are obtained by the configuration interaction method. The theory is applied to the excitonic recombination spectrum in InAs/GaAs self-assembled quantum dots. The results of the single-band effective-mass approximation are successfully compared with those obtained by using the of k•p and tight-binding methods.

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

    CERN Document Server

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


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

  18. Magnetic manipulation of self-assembled colloidal asters.

    Energy Technology Data Exchange (ETDEWEB)

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


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

  19. Functional self-assembled lipidic systems derived from renewable resources. (United States)

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


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

  20. Functionalized fullerenes in self-assembled monolayers. (United States)

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


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

  1. Self-Assembling Wireless Autonomous Reconfigurable Modules (SWARM) Project (United States)

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

  2. DNA Self-assembly Catalyzed by Artificial Agents. (United States)

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


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

  3. A review on self-assembly in microfluidic devices (United States)

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


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

  4. Enzymatic self-assembly of nanostructures for theranostics. (United States)

    Chen, Yue; Liang, Gaolin


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

  5. Self-assembling Venturi-like peptide nanotubes. (United States)

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


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

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

    Directory of Open Access Journals (Sweden)

    Xiang Sun


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

  7. Multiresponsive self-assembled liquid crystals with azobenzene groups. (United States)

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


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

  8. Self-Assembled Nanostructured Health Monitoring Sensors Project (United States)

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

  9. RT Self-assembly of Silica Nanoparticles on Optical Fibres

    DEFF Research Database (Denmark)

    Canning, John; Lindoy, Lachlan; Huyang, George


    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....

  10. Mesoscopic Self-Assembly: A Shift to Complexity

    Directory of Open Access Journals (Sweden)

    Massimo eMastrangeli


    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.

  11. Self-assembly of graphene nanostructures on nanotubes. (United States)

    Patra, Niladri; Song, Yuanbo; Král, Petr


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

  12. Enzymatic Self-Assembly of Nanostructures for Theranostics


    Yue Chen, Gaolin Liang


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

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

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


    Kulkarni, C


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

  15. Self-assembled tunable networks of sticky colloidal particles

    Energy Technology Data Exchange (ETDEWEB)

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


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

  16. Self-Assembly of Colloidal Nanocrystals: From Intricate Structures to Functional Materials. (United States)

    Boles, Michael A; Engel, Michael; Talapin, Dmitri V


    Chemical methods developed over the past two decades enable preparation of colloidal nanocrystals with uniform size and shape. These Brownian objects readily order into superlattices. Recently, the range of accessible inorganic cores and tunable surface chemistries dramatically increased, expanding the set of nanocrystal arrangements experimentally attainable. In this review, we discuss efforts to create next-generation materials via bottom-up organization of nanocrystals with preprogrammed functionality and self-assembly instructions. This process is often driven by both interparticle interactions and the influence of the assembly environment. The introduction provides the reader with a practical overview of nanocrystal synthesis, self-assembly, and superlattice characterization. We then summarize the theory of nanocrystal interactions and examine fundamental principles governing nanocrystal self-assembly from hard and soft particle perspectives borrowed from the comparatively established fields of micrometer colloids and block copolymer assembly. We outline the extensive catalog of superlattices prepared to date using hydrocarbon-capped nanocrystals with spherical, polyhedral, rod, plate, and branched inorganic core shapes, as well as those obtained by mixing combinations thereof. We also provide an overview of structural defects in nanocrystal superlattices. We then explore the unique possibilities offered by leveraging nontraditional surface chemistries and assembly environments to control superlattice structure and produce nonbulk assemblies. We end with a discussion of the unique optical, magnetic, electronic, and catalytic properties of ordered nanocrystal superlattices, and the coming advances required to make use of this new class of solids.

  17. Self-assembly of nanoparticles into biomimetic capsid-like nanoshells (United States)

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


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

  18. Self-assembled gelatin-ι-carrageenan encapsulation structures for intestinal-targeted release applications. (United States)

    Gómez-Mascaraque, Laura G; Llavata-Cabrero, Beatriz; Martínez-Sanz, Marta; Fabra, María José; López-Rubio, Amparo


    In this work, natural biopolymeric encapsulation structures were developed through the self-assembly of gelatin and ι-carrageenan in aqueous solutions. The interactions of this binary system and of a ternary system containing a polyphenol-rich extract were deeply explored for the development of intestinal delivery systems. The processing of the structures (extrusion vs. freeze-drying) greatly influenced release properties, explained by the specific interactions between gelatin and polyphenols, thus allowing for tuning the processing conditions depending on the desired target application. Release was further controlled by incorporating a divalent salt, giving raise to extract-loaded ι-carrageenan/gelatin capsules with adequate release profiles for intestinal targeted delivery. These results demonstrate the potential of exploiting biopolymer interactions for designing bioactive delivery systems using environmentally friendly processes which do not involve the use of toxic or harsh solvents or cross-linkers. Copyright © 2018 Elsevier Inc. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  20. Regulating DNA Self-assembly by DNA-Surface Interactions. (United States)

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


    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.

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

    Directory of Open Access Journals (Sweden)

    Katja Petkau-Milroy


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

  2. Associative Pattern Recognition Through Macro-molecular Self-Assembly (United States)

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


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

  3. Self-Assembly in Biosilicification and Biotemplated Silica Materials

    Directory of Open Access Journals (Sweden)

    Francisco M. Fernandes


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

  4. Self-Assembly in Biosilicification and Biotemplated Silica Materials. (United States)

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


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

  5. Self-assembly of hydrofluorinated Janus graphene monolayer

    DEFF Research Database (Denmark)

    Jin, Yakang; Xue, Qingzhong; Zhu, Lei


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

  6. Scratch Drive Actuator Driven Self-assembled Variable Optical Attenuator (United States)

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


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

  7. Self-assembly of model proteins into virus capsids (United States)

    Wołek, Karol; Cieplak, Marek


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

  8. Self-Assembling Ability Determines the Activity of Enzyme-Instructed Self-Assembly for Inhibiting Cancer Cells. (United States)

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


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

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

    Directory of Open Access Journals (Sweden)

    Øystein Stakkestad


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

  10. Hydrazine-mediated construction of nanocrystal self-assembly materials. (United States)

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


    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.

  11. Leveraging symmetry to predict self-assembly of multiple polymers (United States)

    Lin, Milo M.


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

  12. Self-Assembled Hydrogel Nanoparticles for Drug Delivery Applications

    Directory of Open Access Journals (Sweden)

    Miguel Gama


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  14. Self-assembly patterning of organic molecules on a surface (United States)

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


    The embodiments disclosed herein include all-electron control over a chemical attachment and the subsequent self-assembly of an organic molecule into a well-ordered three-dimensional monolayer on a metal surface. The ordering or assembly of the organic molecule may be through electron excitation. Hot-electron and hot-hole excitation enables tethering of the organic molecule to a metal substrate, such as an alkyne group to a gold surface. All-electron reactions may allow a direct control over the size and shape of the self-assembly, defect structures and the reverse process of molecular disassembly from single molecular level to mesoscopic scale.

  15. Self-assembly of active amphiphilic Janus particles (United States)

    Mallory, S. A.; Alarcon, F.; Cacciuto, A.; Valeriani, C.


    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.

  16. Two dimensional self-assembly of inverse patchy colloids


    K, Remya Ann Mathews; Mani, Ethayaraja


    We report on the self-assembly of inverse patchy colloids (IPC) using Monte Carlo simulations in two-dimensions. The IPC model considered in this work corresponds to either bipolar colloids or colloids decorated with complementary DNA on their surfaces, where only patch and non-patch parts attract. The patch coverage is found to be a dominant factor in deciding equilibrium self-assembled structures. In particular, both regular square and triangular crystals are found to be stable at 0.5 patch...

  17. Nano-engineering by optically directed self-assembly.

    Energy Technology Data Exchange (ETDEWEB)

    Furst, Eric (University of Delaware, Newark, DE); Dunn, Elissa (Yale University, New Haven, CT); Park, Jin-Gyu (Yale University, New Haven, CT); Brinker, C. Jeffrey; Sainis, Sunil (Yale University, New Haven, CT); Merrill, Jason (Yale University, New Haven, CT); Dufresne, Eric (Yale University, New Haven, CT); Reichert, Matthew D.; Brotherton, Christopher M.; Bogart, Katherine Huderle Andersen; Molecke, Ryan A.; Koehler, Timothy P.; Bell, Nelson Simmons; Grillet, Anne Mary; Gorby, Allen D.; Singh, John (University of Delaware, Newark, DE); Lele, Pushkar (University of Delaware, Newark, DE); Mittal, Manish (University of Delaware, Newark, DE)


    Lack of robust manufacturing capabilities have limited our ability to make tailored materials with useful optical and thermal properties. For example, traditional methods such as spontaneous self-assembly of spheres cannot generate the complex structures required to produce a full bandgap photonic crystals. The goal of this work was to develop and demonstrate novel methods of directed self-assembly of nanomaterials using optical and electric fields. To achieve this aim, our work employed laser tweezers, a technology that enables non-invasive optical manipulation of particles, from glass microspheres to gold nanoparticles. Laser tweezers were used to create ordered materials with either complex crystal structures or using aspherical building blocks.

  18. Host-guest complexation driven dynamic supramolecular self-assembly. (United States)

    Zhang, Huacheng; Nguyen, Kim Truc; Ma, Xing; Yan, Hong; Guo, Junfei; Zhu, Liangliang; Zhao, Yanli


    Host-guest complexation between pillararene trimer 1 and biviologen 2 was used to fabricate the dynamic supramolecular self-assembly, which exhibits a reversible multidimensional transformation from 0D to 3D upon concentration changes. As a comparison, assemblies built by the complexation between 1,4-dimethoxypillar[5]arene and 2 only show spherical morphology under similar conditions.

  19. Photoinduced self-assembly of nanostructure in glass

    Directory of Open Access Journals (Sweden)

    Shimotsuma Y.


    Full Text Available Ultrashort-pulsed laser direct writing can be useful for a 3D material processing. Especially the localized form-birefringence originated from self-assembled nanostructure in isotropic material (i.e. SiO2 and GeO2 glass was demonstrated.

  20. Electronic functionalization of organic semiconductors with self-assembled monolayers (United States)

    Podzorov, Vitaly


    Self-assembled monolayers (SAM) are widely used in a variety of emerging applications for surface modification of metals and oxides. Here, we demonstrate a new type of molecular self-assembly: the growth of organosilane SAMs at the surface of organic semiconductors. Remarkably, SAM growth results in a pronounced increase of surface conductivity of organic materials, which can be very large for SAMs with a strong electron withdrawing ability. For example, the conductivity induced by perfluorinated alkyl silanes in organic molecular crystals approaches 10̂-5 S per square, two orders of magnitude greater than the maximum conductivity typically achieved in organic field-effect transistors (OFETs). The observed large electronic effect opens new opportunities for nanoscale surface functionalization of organic semiconductors with molecular self-assembly. In particular, SAM-induced conductivity exhibits sensitivity to different molecular species present in the environment, which makes this system very attractive for chemical sensing applications [1]. [1]. M. F. Calhoun, J. Sanchez, D. Olaya, M. E. Gershenson and V. Podzorov, ``Electronic functionalization of the surface of organic semiconductors with self-assembled monolayers'', Nature Materials, Nov. 18, (2007).

  1. Self-assembling biomolecular catalysts for hydrogen production. (United States)

    Jordan, Paul C; Patterson, Dustin P; Saboda, Kendall N; Edwards, Ethan J; Miettinen, Heini M; Basu, Gautam; Thielges, Megan C; Douglas, Trevor


    The chemistry of highly evolved protein-based compartments has inspired the design of new catalytically active materials that self-assemble from biological components. A frontier of this biodesign is the potential to contribute new catalytic systems for the production of sustainable fuels, such as hydrogen. Here, we show the encapsulation and protection of an active hydrogen-producing and oxygen-tolerant [NiFe]-hydrogenase, sequestered within the capsid of the bacteriophage P22 through directed self-assembly. We co-opted Escherichia coli for biomolecular synthesis and assembly of this nanomaterial by expressing and maturing the EcHyd-1 hydrogenase prior to expression of the P22 coat protein, which subsequently self assembles. By probing the infrared spectroscopic signatures and catalytic activity of the engineered material, we demonstrate that the capsid provides stability and protection to the hydrogenase cargo. These results illustrate how combining biological function with directed supramolecular self-assembly can be used to create new materials for sustainable catalysis.

  2. Tetrahymena dynamin related protein 6 self assembles independent ...

    Indian Academy of Sciences (India)

    eluted as small oligomeric forms. Absence of any peak in the void volume suggests that human dynamin 1 does not form self-assembled structure under high ionic strength condition. Supplementary figure 3: Size exclusion chromatography profile of Drp6-R414A. His6-Drp6-. R414A expressed and purified from bacteria ...

  3. Covalently stabilized self-assembled chlorophyll nanorods by olefin metathesis. (United States)

    Sengupta, Sanchita; Würthner, Frank


    A new chlorophyll derivative with peripheral olefinic chains has been synthesised and its self-assembly properties have been studied, revealing formation of well-defined nanorods. These nanorods were stabilized and rigidified by olefin metathesis reaction as confirmed by spectroscopic and microscopic methods.

  4. Functional materials derived from block copolymer self-assembly

    DEFF Research Database (Denmark)

    Li, Tao

    The main objective of this project is to explore block copolymer self-assembly for generating functional materials with well-defined morphology on sub-20 nanometer length scale, which can be utilized in many important applications such as solar cells and nanolithography. One of the specific targe...

  5. Tailoring self-assembled monolayers at the electrochemical interface

    Indian Academy of Sciences (India)

    The main focus of this review is to illustrate the amenability of self-assembled monolayers (SAMs) for functionalisation with different receptors, catalytic materials, biomolecules, enzymes, antigen-antibody, etc for various applications. The review discusses initially about the preparation and characterization of SAMs and ...

  6. Electrostatic Self-Assembly of Polysaccharides into Nanofibers

    DEFF Research Database (Denmark)

    Mendes, Ana Carina Loureiro; Strohmenger, Timm; Goycoolea, Francisco


    In this study, the anionic polysaccharide Xanthan gum (X) was mixed with positively charged Chitosan oligomers (ChO), and used as building blocks, to generate novel nanofibers by electrostatic self-assembly in aqueous conditions. Different concentrations, ionic strength and order of mixing of both...

  7. Multiphonon capture processes in self-assembled quantum dots

    DEFF Research Database (Denmark)

    Magnúsdóttir, Ingibjörg; Uskov, A.; Bischoff, Svend


    We investigate capture of carriers from states in the continuous part of the energy spectrum into the discrete states of self-assembled InAs/GaAs QDs via emission of one or two phonons. We are not aware of any other investigations of two-phonon mediated capture processes in QDs, but we show that ...

  8. Self-Assembled Microwires of Terephthalic Acid and Melamine

    Directory of Open Access Journals (Sweden)

    Hong Wang


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

  9. Complex Colloidal Structures by Self-assembly in Electric Fields

    NARCIS (Netherlands)

    Vutukuri, H.R.


    The central theme of this thesis is exploiting the directed self-assembly of both isotropic and anisotropic colloidal particles to achieve the fabrication of one-, two-, and three-dimensional complex colloidal structures using external electric fields and/or a simple in situ thermal annealing

  10. Synthesis, characterization and self-assembly of Co complexes ...

    Indian Academy of Sciences (India)

    (H-bonded) assemblies and afford inclusion complexes with solvents serving as the guest molecules.12 Self- assembly of phenolic compounds show that the ...... Board (SERB), Govt. of India for the generous financial support and CIF-USIC of this university for the instru- mental facilities. AA and DB thank University Grant.

  11. Critical Self-assembly Concentration of Bolaamphiphilic Peptides ...

    African Journals Online (AJOL)

    The study of the self-assembly properties of peptides and proteins is important for the understanding of molecular recognition processes and for the rational design of functional biomaterials. Novel bolaamphiphilic peptides and peptide hybrids incorporating non-natural aminoacids were designed around a model ...

  12. Tuning of metal work functions with self-assembled monolayers

    NARCIS (Netherlands)

    de Boer, B; Hadipour, A; Mandoc, MM; van Woudenbergh, T; Blom, PWM


    Work functions of gold and silver are varied by over 1.4 and 1.7 eV, respectively, by using self-assembled monolayers. Using these modified electrodes, the hole current in a poly(2-methoxy-5-(2'-ethylhexyloxy)- 1,4-phenylene vinylene) light-emitting diode is tuned by more than six orders of

  13. Tetrahymena dynamin-related protein 6 self-assembles ...

    Indian Academy of Sciences (India)

    Usha P Kar


    Dec 30, 2017 ... Self-assembly on target membranes is one of the important properties of all dynamin family proteins. Drp6, a dynamin- related protein in Tetrahymena, controls nuclear remodelling and undergoes cycles of assembly/disassembly on the nuclear envelope. To elucidate the mechanism of Drp6 function, we ...

  14. Chirality controlled responsive self-assembled nanotubes in water

    NARCIS (Netherlands)

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


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

  15. Polymer Self-Assembled Nanostructures as Innovative Drug Nanocarrier Platforms. (United States)

    Pippa, Natassa; Pispas, Stergios; Demetzos, Costas


    Polymer self-assembled nanostructures are used in pharmaceutical sciences as bioactive molecules' delivery systems for therapeutic and diagnostic purposes. Micelles, polyelectrolyte complexes, polymersomes, polymeric nanoparticles, nanogels and polymer grafted liposomes represent delivery vehicles that are marketed and/or under clinical development, as drug formulations. In this mini-review, these, recently appeared in the literature, innovative polymer drug nanocarrier platforms are discussed, starting from their technological development in the laboratory to their potential clinical use, through studies of their biophysics, thermodynamics, physical behavior, morphology, bio-mimicry, therapeutic efficacy and safety. The properties of an ideal drug delivery system are the structural control over size and shape of drug or imaging agent cargo/domain, biocompatibility, nontoxic polymer/ pendant functionality and the precise, nanoscale container and/or scaffolding properties with high drug or imaging agent capacity features. Self-assembled polymer nanostructures exhibit all these properties and could be considered as ideal drug nanocarriers through control of their size, structure and morphology, with the aid of a large variety of parameters, in vitro and in vivo. These modern trends reside at the interface of soft matter self-assembly and pharmaceutical sciences and the technologies for health. Great advantages related to basic science and applications are expected by understanding the self-assembly behavior of these polymeric nanotechnological drug delivery systems, created through bio-inspiration and biomimicry and have potential utilization into clinical applications.

  16. Applications of self-assembled monolayers in materials chemistry

    Indian Academy of Sciences (India)

    Self-assembly provides a simple route to organise suitable organic molecules on noble metal and selected nanocluster surfaces by using monolayers of long chain organic molecules with various functionalities like -SH, -COOH, -NH2, silanes etc. These surfaces can be effectively used to build-up interesting nano level ...

  17. Long lived coherence in self-assembled quantum dots

    DEFF Research Database (Denmark)

    Birkedal, Dan; Leosson, Kristjan; Hvam, Jørn Märcher


    We report measurements of ultralong coherence in self-assembled quantum dots. Transient four-wave mixing experiments at 5 K show an average dephasing time of 372 ps, corresponding to a homogeneous linewidth of 3.5 mu eV, which is significantly smaller than the linewidth observed in single-dot lum...

  18. Hierarchical self-assembly: Self-organized nanostructures in a nematically ordered matrix of self-assembled polymeric chains (United States)

    Mubeena, Shaikh; Chatterji, Apratim


    We report many different nanostructures which are formed when model nanoparticles of different sizes (diameter σn) are allowed to aggregate in a background matrix of semiflexible self-assembled polymeric wormlike micellar chains. The different nanostructures are formed by the dynamical arrest of phase-separating mixtures of micellar monomers and nanoparticles. The different morphologies obtained are the result of an interplay of the available free volume, the elastic energy of deformation of polymers, the density (chemical potential) of the nanoparticles in the polymer matrix, and, of course, the ratio of the size of self-assembling nanoparticles and self-avoidance diameter of polymeric chains. We have used a hybrid semi-grand-canonical Monte Carlo simulation scheme to obtain the (nonequilibrium) phase diagram of the self-assembled nanostructures. We observe rodlike structures of nanoparticles which get self-assembled in the gaps between the nematically ordered chains, as well as percolating gel-like network of conjoined nanotubes. We also find a totally unexpected interlocked crystalline phase of nanoparticles and monomers, in which each crystal plane of nanoparticles is separated by planes of perfectly organized polymer chains. We identified the condition which leads to such interlocked crystal structure. We suggest experimental possibilities of how the results presented in this paper could be used to obtain different nanostructures in the laboratory.

  19. Nanoengineered polymeric S-layers based capsules with targeting activity. (United States)

    Habibi, Neda; Pastorino, Laura; Soumetz, Federico Caneva; Sbrana, Francesca; Raiteri, Roberto; Ruggiero, Carmelina


    Nanostructured polymeric capsules are regarded as highly promising systems with different potential applications ranging from drug delivery, biosensing and artificial cells. To fully exploit this potential, it is required to produce bio-activated stable and biocompatible capsules. To this purpose, in present work we proposed the combination of the layer-by-layer self assembly method with bacterial S-layer technology to fabricate stable and biocompatible polymeric capsules having a well defined arrangement of functional groups allowing the covalent attachment of antibody molecules. Hollow microcapsules were obtained by the layer-by-layer self assembly of oppositely charged polyelectrolytes onto colloidal particles, followed by removal of the cores at acidic pH. S-layers were crystallized onto the shell of the obtained capsules. Quartz crystal microbalance was used to characterize the crystallization process onto planar surfaces. S-layer containing capsules were investigated by atomic force microscopy. Immunoenzymatic tests were performed to assess the effective modification of the S-layer with antibody molecules both on planar surfaces and on hollow capsules. Fluorescent microscopy was employed to visualize the presence of the antibody molecules onto the capsule shell and immunological tests used to assess the bioactivity of the immobilized antibodies. Finally, the in vitro cytotoxicity of fabricated S-layer containing capsules was studied. The obtained results demonstrated the possibility to fabricate bio-activated S-layer containing capsules with improved features in terms of biocompatibility. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Predicting supramolecular self-assembly on reconstructed metal surfaces (United States)

    Roussel, Thomas J.; Barrena, Esther; Ocal, Carmen; Faraudo, Jordi


    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

  1. A Case Study of the Likes and Dislikes of DNA and RNA in Self-Assembly. (United States)

    Zuo, Hua; Wu, Siyu; Li, Mo; Li, Yulin; Jiang, Wen; Mao, Chengde


    Programmed self-assembly of nucleic acids (DNA and RNA) is an active research area as it promises a general approach for nanoconstruction. Whereas DNA self-assembly has been extensively studied, RNA self-assembly lags much behind. One strategy to boost RNA self-assembly is to adapt the methods of DNA self-assembly for RNA self-assembly because of the chemical and structural similarities of DNA and RNA. However, these two types of molecules are still significantly different. To enable the rational design of RNA self-assembly, a thorough examination of their likes and dislikes in programmed self-assembly is needed. The current work begins to address this task. It was found that similar, two-stranded motifs of RNA and DNA lead to similar, but clearly different nanostructures. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Protein-directed self-assembly of a fullerene crystal (United States)

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


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

  3. Self-assembled carboxylate complexes of zinc, nickel and copper (United States)

    Deka, Kaustavmoni; Barooah, Nilotpal; Sarma, Rupam Jyoti; Baruah, Jubaraj B.


    A metallo-organic hybrid acid namely tetra-aquo bis-4-carboxy- N-phthaloylglycinato zinc(II) dihydrate is prepared and characterised. In this complex the hydrogen bonding by free carboxylic acid group and π-π interactions between the rings in crystal lattice contributes to the formation of self-assembled structure. A monomeric nickel complex from 2-carbomethoxy benzoic acid ( L2H) and pyridine [Ni( L2)(py) 3(H 2O) 2] L2 is prepared (where py = pyridine). This complex has ionic as well as monodentate carboxylates. It forms self-assembly by C-H⋯π as well as hydrogen-bonding interactions. The 2-carbomethoxy benzoic acid ( L2H) forms dimeric copper complex [Cu 2( L2) 4(H 2O) 2]2H 2O which has an extended chain structure through hydrogen-bond interactions.

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

    Directory of Open Access Journals (Sweden)

    Chandrashekhar V. Kulkarni


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

  5. Self-Assembly and Hydrogelation of Peptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Wahyudi Priyono Suwarso


    Full Text Available Seven peptide amphiphiles were successfully synthesized using solid phase peptide synthesis method. Peptide amphiphiles were characterized using matrix assisted laser desorption/ionization (MALDI. Atomic force microscopy (AFM study showed that peptide amphiphiles having glycine, valine, or proline as linker, self-assembled into 100-200 nm nanofibers structure. According to our research, both peptide amphiphile with positive and negative charges bear similar self-assembly properties. Peptide amphiphile also showed its capability as low molecular weight gelator (LMWG. Peptide amphiphiles bearing C-16 and C-12 as alkyl showed better hydrogelation properties than C-8 alkyl. Five out of seven peptide amphiphiles have minimum gelation concentration (MGC lower than 1% (w/v.

  6. Dynamic covalent chemistry in aid of peptide self-assembly. (United States)

    Sadownik, Jan W; Ulijn, Rein V


    Self-assembled peptide systems have been widely studied in the context of gaining understanding of the rules that govern biomolecular processes and increasingly as new bio-inspired nanomaterials. Such materials may be designed to be highly dynamic, displaying adaptive and self-healing properties. This review focuses on recent approaches, which exploit reversible covalent and noncovalent chemistry in combination with peptide-based self-assembly. Selected examples of recent advances include sulphur and nitrogen-based reversible reactions, metal-ligand coordination and enzyme-assisted transamidation that lead to structures such as catenanes, nanofibres, β-hairpins and coiled-coil assemblies. It is demonstrated that these structures give rise to nanomaterials with emergent properties that are highly sensitive and adaptive to external conditions and may allow for in vitro evolution of novel peptide nanostructures via templating or self-recognition. Copyright © 2010 Elsevier Ltd. All rights reserved.

  7. Programmed self-assembly of a quadruplex DNA nanowire. (United States)

    Hessari, Nason Ma'ani; Spindler, Lea; Troha, Tinkara; Lam, Wan-Chi; Drevenšek-Olenik, Irena; da Silva, Mateus Webba


    The ability to produce, reproducibly and systematically, well-defined quadruplex DNA nanowires through controlled rational design is poorly understood despite potential utility in structural nanotechnology. The programmed hierarchical self-assembly of a long four-stranded DNA nanowire through cohesive self-assembly of GpC and CpG "sticky" ends is reported. The encoding of bases within the quadruplex stem allows for an uninterrupted π-stacking system with rectilinear propagation for hundreds of nanometers in length. The wire is mechanically stable and features superior nuclease resistance to double-stranded DNA. The study indicates the feasibility for programmed assembly of uninterrupted quadruplex DNA nanowires. This is fundamental to the systematic investigation of well-defined DNA nanostructures for uses in optoelectronic and electronic devices as well as other structural nanotechnology applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Synthesis and Self-Assembly of Triangulenium Salts

    DEFF Research Database (Denmark)

    Shi, Dong

    This thesis describes the design and synthesis of asymmetrically substituted amphiphilic tis(dialkylamino)trioxiatriangulenium (ATOTA+) salts with different counter ions. Attention was focused on exploring the assembling properties of the ATOTA+ salts in aqueous media. A direct vortexing-processed...... in influencing the assembling process and morphology of the assembled nanostructures. Tailoring the ATOTA+ system with alkyl chains of different length showed large effect on the final morphology of assembled supramolecular structures. The first two chapters give a brief introduction to molecular self......, highly ordered, and free-floating bilayer nanosheets through prolonged vigorous shaking. In this study, a mechanism for the self-assembly process agitated by prolonged vigorous shaking is proposed. It is proposed that the self-assembly is realized via a intermediated monolayer formed at the dynamic air...

  9. Thermomechanical Response of Self-Assembled Nanoparticle Membranes

    Energy Technology Data Exchange (ETDEWEB)

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


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

  10. Molecular Gels Materials with Self-Assembled Fibrillar Networks

    CERN Document Server

    Weiss, Richard G


    Molecular gels and fibrillar networks – a comprehensive guide to experiment and theory Molecular Gels: Materials with Self-Assembled Fibrillar Networks provides a comprehensive treatise on gelators, especially low molecular-mass gelators (LMOGs), and the properties of their gels. The structures and modes of formation of the self-assembled fibrillar networks (SAFINs) that immobilize the liquid components of the gels are discussed experimentally and theoretically. The spectroscopic, rheological, and structural features of the different classes of LMOGs are also presented. Many examples of the application of the principal analytical techniques for investigation of molecular gels (including SANS, SAXS, WAXS, UV-vis absorption, fluorescence and CD spectroscopies, scanning electron, transmission electron and optical microscopies, and molecular modeling) are presented didactically and in-depth, as are several of the theories of the stages of aggregation of individual LMOG molecules leading to SAFINs. Several actua...

  11. Optical nanoimaging for block copolymer self-assembly. (United States)

    Yan, Jie; Zhao, Ling-Xi; Li, Chong; Hu, Zhe; Zhang, Guo-Feng; Chen, Ze-Qiang; Chen, Tao; Huang, Zhen-Li; Zhu, Jintao; Zhu, Ming-Qiang


    One approach toward optical nanoimaging involves sequential molecular localization of photoswitchable fluorophores to achieve high resolution beyond optical limit of diffraction. Block copolymer micelles assembled from polystryrene-block-poly(ethylene oxide) block copolymers (PSt-b-PEO) are visualized in optical nanoimaging by staining the polystyrene blocks with spiropyrans (SPs). SPs localized in hydrophobic phase of block copolymer micelles exhibit reversible fluorescence on-off switching at alternating irradiation of UV and visible light. Phase-selective distribution of SPs in block copolymer micelles enables optical nanoimaging of microphase structures of block copolymer self-assembly at 50-nm resolution. To date, this is the sturdiest realization of optical nanoimaging with subdiffraction resolution for solution self-assembly of block copolymers.

  12. Catalysis of Transesterification Reactions by a Self-Assembled Nanosystem

    Directory of Open Access Journals (Sweden)

    Davide Zaramella


    Full Text Available Histidine-containing peptides self-assemble on the surface of monolayer protected gold nanoparticles to form a catalytic system for transesterification reactions. Self-assembly is a prerequisite for catalysis, since the isolated peptides do not display catalytic activity by themselves. A series of catalytic peptides and substrates are studied in order to understand the structural parameters that are of relevance to the catalytic efficiency of the system. It is shown that the distance between the His-residue and the anionic tail does not affect the catalytic activity. On the other hand, the catalytic His-residue is sensitive to the chemical nature of the flanking amino acid residues. In particular, the presence of polar Ser-residues causes a significant increase in activity. Finally, kinetic studies of a series of substrates reveal that substrates with a hydrophobic component are very suitable for this catalytic system.

  13. Artificial Photosynthesis at Dynamic Self-Assembled Interfaces in Water. (United States)

    Hansen, Malte; Troppmann, Stefan; König, Burkhard


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

  14. J-aggregation of cyanine dyes by self-assembly. (United States)

    Steiger, Rolf; Pugin, Raphaël; Heier, Jakob


    The importance of highly ordered surfaces, containing adsorptive surface states, is discussed for J-aggregation by self-assembly. Such nucleating surfaces are nanometer-sized edges and corners of cubic AgBr microcrystals, or surface iodide-clusters located along edges and corners of AgBr:I microcrystals. Of particular interest are dendrimers, monoatomic steps on terraced silver halide microcrystals and fullerene derivatives as nucleating surfaces. Molecular organisation into J-aggregates by self-assembly was realized using aprotic, apolar solvents for fullerenes, and polar solvents for dendrimers and monoatomic surface steps. By using dendrimers as nucleating agents in mesopores of metal oxide nanoparticle coatings, size-controlled and stable J-aggregates with high optical densities and strong fluorescence were obtained reproducibly. Such films may be useful for sensors, opto-electronics, lighting and photovoltaics.

  15. Self-assembly of hyperbranched polymers and its biomedical applications. (United States)

    Zhou, Yongfeng; Huang, Wei; Liu, Jinyao; Zhu, Xinyuan; Yan, Deyue


    Hyperbranched polymers (HBPs) are highly branched macromolecules with a three-dimensional dendritic architecture. Due to their unique topological structure and interesting physical/chemical properties, HBPs have attracted wide attention from both academia and industry. In this paper, the recent developments in HBP self-assembly and their biomedical applications have been comprehensively reviewed. Many delicate supramolecular structures from zero-dimension (0D) to three-dimension (3D), such as micelles, fibers, tubes, vesicles, membranes, large compound vesicles and physical gels, have been prepared through the solution or interfacial self-assembly of amphiphilic HBPs. In addition, these supramolecular structures have shown promising applications in the biomedical areas including drug delivery, protein purification/detection/delivery, gene transfection, antibacterial/antifouling materials and cytomimetic chemistry. Such developments promote the interdiscipline researches among surpramolecular chemistry, biomedical chemistry, nano-technology and functional materials.

  16. Self-Assembled Monolayers of CdSe Nanocrystals on Doped GaAs Substrates

    DEFF Research Database (Denmark)

    Marx, E.; Ginger, D.S.; Walzer, Karsten


    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...

  17. STM visualisation of counterions and the effect of charges on self-assembled monolayers of macrocycles

    NARCIS (Netherlands)

    Kudernac, Tibor; Shabelina, Natalia; Mamdouh, Wael; Höger, Sigurd; De Feyter, Steven


    Despite their importance in self-assembly processes, the influence of charged counterions on the geometry of self-assembled organic monolayers and their direct localisation within the monolayers has been given little attention. Recently, various examples of self-assembled monolayers composed of

  18. Carbonate linkage bearing naphthalenediimides: self-assembly and photophysical properties. (United States)

    Kulkarni, Chidambar; George, Subi J


    Self-assembly of carbonate linkage bearing naphthalene diimides (NDI) showed unusually red-shifted excimer emission at approximately 560 nm. On the other hand, the ether linkers showed usual excimers at around 520 nm, highlighting the role of the carbonate group in tuning the molecular organization and the resultant photophysical properties of NDI. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Coherence and dephasing in self-assembled quantum dots

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Leosson, K.; Birkedal, Dan


    We measured dephasing times in InGaAl/As self-assembled quantum dots at low temperature using degenerate four-wave mixing. At 0K, the coherence time of the quantum dots is lifetime limited, whereas at finite temperatures pure dephasing by exciton-phonon interactions governs the quantum dot...... coherence. The inferred homogeneous line widths are significantly smaller than the line widths usually observed in the photoluminescence from single quantum dots indicating an additional inhomogeneours broadening mechanism in the latter....

  20. Spin State As a Probe of Vesicle Self-Assembly


    Kim, Sanghoon; Bellouard, Christine; Eastoe, Julian; Canilho, Nadia; Rogers, Sarah E; Ihiawakrim, Dris; Ersen, Ovidiu; Pasc, Andreea


    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...

  1. Spin State As a Probe of Vesicle Self-Assembly. (United States)

    Kim, Sanghoon; Bellouard, Christine; Eastoe, Julian; Canilho, Nadia; Rogers, Sarah E; Ihiawakrim, Dris; Ersen, Ovidiu; Pasc, Andreea


    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.

  2. Molecular Self-Assembly into One-Dimensional Nanostructures


    Palmer, Liam C.; Stupp, Samuel I.


    Self-assembly of small molecules into one-dimensional nanostructures offers many potential applications in electronically and biologically active materials. The recent advances discussed in this Account demonstrate how researchers can use the fundamental principles of supramolecular chemistry to craft the size, shape, and internal structure of nanoscale objects. In each system described here, we used atomic force microscopy (AFM) and transmission electron microscopy (TEM) to study the assembl...

  3. Biocompatible and Biomimetic Self-Assembly of Functional Nanostructures (United States)


    and C. J. Brinker, "Photoresponsive nanocomposite formed by self-assembly of an azobenzene -modified silane," Angew. Chem.-Int. Edit. 42 (15), 1731...Responsive Materials: Azobenzene Containing Polymers and Liquid Crystals,U Yue Zhao and Tomiki Ikeda, eds., John Wiley & Sons, Inc., Hoboken, NJ...phagocyte- derived oxidants: New role for the NADPH oxidase in host defense. Proc Natl Acad Sci U S A. 101, 13867-13872 (2004). xviii. Iler, R.K

  4. Microtubule dynamics. II. Kinetics of self-assembly

    DEFF Research Database (Denmark)

    Flyvbjerg, H.; Jobs, E.


    dependence on initial conditions-except it is known to be impossible for equilibrium reactions. This article presents a case study of a far-from-equilibrium reaction: it presents a systematic phenomenological analysis of experimental time series for the amount of final product, a biopolymer, formed from...... to analyze the self-assembly of microtubules from tubulin are general, and many other reactions and processes may be studied as inverse problems with these methods when enough experimental data are available....

  5. Algorithmic self-assembly of DNA Sierpinski triangles.

    Directory of Open Access Journals (Sweden)

    Paul W K Rothemund


    Full Text Available Algorithms and information, fundamental to technological and biological organization, are also an essential aspect of many elementary physical phenomena, such as molecular self-assembly. Here we report the molecular realization, using two-dimensional self-assembly of DNA tiles, of a cellular automaton whose update rule computes the binary function XOR and thus fabricates a fractal pattern--a Sierpinski triangle--as it grows. To achieve this, abstract tiles were translated into DNA tiles based on double-crossover motifs. Serving as input for the computation, long single-stranded DNA molecules were used to nucleate growth of tiles into algorithmic crystals. For both of two independent molecular realizations, atomic force microscopy revealed recognizable Sierpinski triangles containing 100-200 correct tiles. Error rates during assembly appear to range from 1% to 10%. Although imperfect, the growth of Sierpinski triangles demonstrates all the necessary mechanisms for the molecular implementation of arbitrary cellular automata. This shows that engineered DNA self-assembly can be treated as a Turing-universal biomolecular system, capable of implementing any desired algorithm for computation or construction tasks.

  6. Probabilistic inverse design for self-assembling materials (United States)

    Jadrich, R. B.; Lindquist, B. A.; Truskett, T. M.


    One emerging approach for the fabrication of complex architectures on the nanoscale is to utilize particles customized to intrinsically self-assemble into a desired structure. Inverse methods of statistical mechanics have proven particularly effective for the discovery of interparticle interactions suitable for this aim. Here we evaluate the generality and robustness of a recently introduced inverse design strategy [B. A. Lindquist et al., J. Chem. Phys. 145, 111101 (2016)] by applying this simulation-based machine learning method to optimize for interparticle interactions that self-assemble particles into a variety of complex microstructures as follows: cluster fluids, porous mesophases, and crystalline lattices. Using the method, we discover isotropic pair interactions that lead to the self-assembly of each of the desired morphologies, including several types of potentials that were not previously understood to be capable of stabilizing such systems. One such pair potential led to the assembly of the highly asymmetric truncated trihexagonal lattice and another produced a fluid containing spherical voids, or pores, of designed size via purely repulsive interactions. Through these examples, we demonstrate several advantages inherent to this particular design approach including the use of a parametrized functional form for the optimized interparticle interactions, the ability to constrain the range of said parameters, and compatibility of the inverse design strategy with a variety of simulation protocols (e.g., positional restraints).

  7. Self-assembly of inorganic nanoparticles: Ab ovo (United States)

    Kotov, Nicholas A.


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

  8. Molecular Effects on Coacervate-Driven Block Copolymer Self Assembly (United States)

    Lytle, Tyer; Radhakrishna, Mithun; Sing, Charles

    Two oppositely charged polymers can undergo associative phase separation in a salt solution in a process known as \\x98complex coacervation. Recent work has used this as a motif to control the self-assembly behavior of a mixture of oppositely-charged block copolymers which form nanoscale structures. The materials formed from these complex coacervate-block copolymers (BCPs) have potential use as drug delivery systems, gels, and sensors. We have developed a hybrid Monte Carlo-Single Chain in a Mean Field (MC-SCMF) simulation method that is able to determine morphological phase diagrams for BCPs. This technique is an efficient way to calculate morphological phase diagrams and provides a clear link between molecular level features and self-assembly behaviors. Morphological phase diagrams showing the effects of polymer concentration, salt concentration, chain length, and charge-block fraction at large charge densities on self-assembly behavior have been determined. An unexpected phase transition from disorder to hexagonal packing at large salt concentrations has been observed for charge-block fractions equal to and larger than 0.5. This is attributed to the salt filling space stabilizing the morphology of the BCP.

  9. Evolutionary dynamics in a simple model of self-assembly (United States)

    Johnston, Iain G.; Ahnert, Sebastian E.; Doye, Jonathan P. K.; Louis, Ard A.


    We investigate the evolutionary dynamics of an idealized model for the robust self-assembly of two-dimensional structures called polyominoes. The model includes rules that encode interactions between sets of square tiles that drive the self-assembly process. The relationship between the model’s rule set and its resulting self-assembled structure can be viewed as a genotype-phenotype map and incorporated into a genetic algorithm. The rule sets evolve under selection for specified target structures. The corresponding complex fitness landscape generates rich evolutionary dynamics as a function of parameters such as the population size, search space size, mutation rate, and method of recombination. Furthermore, these systems are simple enough that in some cases the associated model genome space can be completely characterized, shedding light on how the evolutionary dynamics depends on the detailed structure of the fitness landscape. Finally, we apply the model to study the emergence of the preference for dihedral over cyclic symmetry observed for homomeric protein tetramers.

  10. Molecular Motions in Functional Self-Assembled Nanostructures

    Directory of Open Access Journals (Sweden)

    Jean-Marc Saiter


    Full Text Available The construction of “smart” materials able to perform specific functions at the molecular scale through the application of various stimuli is highly attractive but still challenging. The most recent applications indicate that the outstanding flexibility of self-assembled architectures can be employed as a powerful tool for the development of innovative molecular devices, functional surfaces and smart nanomaterials. Structural flexibility of these materials is known to be conferred by weak intermolecular forces involved in self-assembly strategies. However, some fundamental mechanisms responsible for conformational lability remain unexplored. Furthermore, the role played by stronger bonds, such as coordination, ionic and covalent bonding, is sometimes neglected while they can be employed readily to produce mechanically robust but also chemically reversible structures. In this review, recent applications of structural flexibility and molecular motions in self-assembled nanostructures are discussed. Special focus is given to advanced materials exhibiting significant performance changes after an external stimulus is applied, such as light exposure, pH variation, heat treatment or electromagnetic field. The crucial role played by strong intra- and weak intermolecular interactions on structural lability and responsiveness is highlighted.

  11. Self-assembly of lipopolysaccharide layers on allantoin crystals. (United States)

    Vagenende, Vincent; Ching, Tim-Jang; Chua, Rui-Jing; Jiang, Qiu Zhen; Gagnon, Pete


    Self-assembly of lipopolysaccharides (LPS) on solid surfaces is important for the study of bacterial membranes, but has not been possible due to technical difficulties and the lack of suitable solid supports. Recently we found that crystals of the natural compound allantoin selectively bind pure LPS with sub-nanomolar affinity. The physicochemical origins of this selectivity and the adsorption mode of LPS on allantoin crystals remain, however, unknown. In this study we present evidence that LPS adsorption on allantoin crystals is initiated through hydrogen-bond attachment of hydrophilic LPS regions. Hydrophobic interactions between alkyl chains of adjacently adsorbed LPS molecules subsequently promote self-assembly of LPS layers. The essential role of hydrogen-bond interactions is corroborated by our finding that allantoin crystals bind to practically any hydrophilic surface chemistry. Binding contributions of hydrophobic interactions between LPS alkyl chains are evidenced by the endothermic nature of the adsorption process and explain why the binding affinity for LPS is several orders of magnitude higher than for proteins (lysozyme, BSA and IgG) and polysaccharides. Self-assembly of LPS layers via hydrogen-bond attachment on allantoin crystals emerges as a novel binding mechanism and could be considered as a practical method for preparing biomimetic membranes on a solid support. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Organization of the interior of molecular capsules by hydrogen bonding. (United States)

    Atwood, Jerry L; Barbour, Leonard J; Jerga, Agoston


    The enclosure of functional entities within a protective boundary is an essential feature of biological systems. On a molecular scale, free-standing capsules with an internal volume sufficiently large to house molecular species have been synthesized and studied for more than a decade. These capsules have been prepared by either covalent synthesis or self-assembly, and the internal volumes have ranged from 200 to 1,500 A(3). Although biological systems possess a remarkable degree of order within the protective boundaries, to date only steric constraints have been used to order the guests within molecular capsules. In this article we describe the synthesis and characterization of hexameric molecular capsules held together by hydrogen bonding. These capsules possess internal order of the guests brought about by hydrogen bond donors within, but not used by, the framework of the capsule. The basic building blocks of the hexameric capsules are tetrameric macrocycles related to resorcin[4]arenes and pyrogallol[4]arenes. The former contain four 1,3-dihydroxybenzene rings bridged together by -CHR- units, whereas the latter contain four 1,2,3-trihydroxybenzene rings bridged together. We now report the synthesis of related mixed macrocycles, and the main focus is on the macrocycle composed of three 1,2,3-trihydroxybenzene rings and one 1,3-dihydroxybenzene ring bridged together. The mixed macrocycles self-assemble from a mixture of closely related compounds to form the hexameric capsule with internally ordered guests.

  13. A Two-Piece Derivative of a Group I Intron RNA as a Platform for Designing Self-Assembling RNA Templates to Promote Peptide Ligation

    Directory of Open Access Journals (Sweden)

    Takahiro Tanaka


    Full Text Available Multicomponent RNA-peptide complexes are attractive from the viewpoint of artificial design of functional biomacromolecular systems. We have developed self-folding and self-assembling RNAs that serve as templates to assist chemical ligation between two reactive peptides with RNA-binding capabilities. The design principle of previous templates, however, can be applied only to limited classes of RNA-binding peptides. In this study, we employed a two-piece derivative of a group I intron RNA from the Tetrahymena large subunit ribosomal RNA (LSU rRNA as a platform for new template RNAs. In this group I intron-based self-assembling platform, modules for the recognition of substrate peptides can be installed independently from modules holding the platform structure. The new self-assembling platform allows us to expand the repertoire of substrate peptides in template RNA design.

  14. Self-Assembly of Plasmonic Nanoclusters for Optical Metauids (United States)

    Schade, Nicholas Benjamin

    I discuss experimental progress towards developing a material with an isotropic, negative index of refraction at optical frequencies. The simplest way to make such a material is to create a metafluid, or a disordered collection of subwavelength, isotropic electromagnetic resonators. Small clusters of metal particles, such as tetrahedra, serve as these constituents. What is needed are methods for manufacturing these structures with high precision and in sufficient yield that their resonances are identical. Jonathan Fan et al. [Science, 328 (5982), 1135-1138, 2010] demonstrated that colloidal self-assembly is a means of preparing electromagnetic resonators from metal nanoparticles. However, the resonances are sensitive to the separation gaps between particles. Standard synthesis routes for metal nanoparticles yield crystals or nanoshells that are inadequate for metafluids due to polydispersity, faceting, and thermal instabilities. To ensure that the separation gaps and resonances are uniform, more monodisperse spherical particles are needed. An additional challenge is the self-assembly of tetrahedral clusters in high yield from these particles. In self-assembly approaches that others have examined previously, the yield of any particular type of cluster is low. In this dissertation I present solutions to several of these problems, developed in collaboration with my research group and others. We demonstrate that slow chemical etching can transform octahedral gold crystals into ultrasmooth, monodisperse nanospheres. The particles can serve as seeds for the growth of larger octahedra which can in turn be etched. The size of the gold nanospheres can therefore be adjusted as desired. We further show that in colloidal mixtures of two sphere species that strongly bind to one another, the sphere size ratio determines the size distribution of self-assembled clusters. At a critical size ratio, tetrahedral clusters assemble in high yield. We explain the experimentally observed

  15. Nanoscale click-reactive scaffolds from peptide self-assembly. (United States)

    Guttenplan, Alexander P M; Young, Laurence J; Matak-Vinkovic, Dijana; Kaminski, Clemens F; Knowles, Tuomas P J; Itzhaki, Laura S


    Due to their natural tendency to self-assemble, proteins and peptides are important components for organic nanotechnology. One particular class of peptides of recent interest is those that form amyloid fibrils, as this self-assembly results in extremely strong, stable quasi-one-dimensional structures which can be used to organise a wide range of cargo species including proteins and oligonucleotides. However, assembly of peptides already conjugated to proteins is limited to cargo species that do not interfere sterically with the assembly process or misfold under the harsh conditions often used for assembly. Therefore, a general method is needed to conjugate proteins and other molecules to amyloid fibrils after the fibrils have self-assembled. Here we have designed an amyloidogenic peptide based on the TTR105-115 fragment of transthyretin to form fibrils that display an alkyne functionality, important for bioorthogonal chemical reactions, on their surface. The fibrils were formed and reacted both with an azide-containing amino acid and with an azide-functionalised dye by the Huisgen cycloaddition, one of the class of "click" reactions. Mass spectrometry and total internal reflection fluorescence optical microscopy were used to show that peptides incorporated into the fibrils reacted with the azide while maintaining the structure of the fibril. These click-functionalised amyloid fibrils have a variety of potential uses in materials and as scaffolds for bionanotechnology. Although previous studies have produced peptides that can both form amyloid fibrils and undergo "click"-type reactions, this is the first example of amyloid fibrils that can undergo such a reaction after they have been formed. Our approach has the advantage that self-assembly takes place before click functionalization rather than pre-functionalised building blocks self-assembling. Therefore, the molecules used to functionalise the fibril do not themselves have to be exposed to harsh, amyloid

  16. Molecular self-assembly into one-dimensional nanostructures. (United States)

    Palmer, Liam C; Stupp, Samuel I


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

  17. A Theoretical and Experimental Study of DNA Self-assembly (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

  18. Capsule endoscopy

    DEFF Research Database (Denmark)

    Skovsen, Anders Peter; Burcharth, Jakob; Burgdorf, Stefan Kobbelgaard


    with ultrasound, MRI, and subsequently a capsule endoscopy. Six months later, the patient presented, and an abdominal CT-scan showed mechanical small bowel obstruction with suspicion of metallic foreign body and perforation. Laparotomy showed perforation, stenosis, and foreign body, approximately 5 cm from...... of capsule retention, especially in patients with known or suspected Crohn's disease, due to the propensity of Crohn's disease to form stenosis of the bowel. In cases where a stenosis is suspected, it is warranted to perform a patency capsule swallow before subjecting the patient to a capsule endoscopy....

  19. Monitoring of Enzymatic Proteolysis Using Self-Assembled Quantum Dot-Protein Substrate Sensors

    Directory of Open Access Journals (Sweden)

    Aaron R. Clapp


    Full Text Available We have previously utilized hybrid semiconductor quantum dot- (QD- peptide substrates for monitoring of enzymatic proteolysis. In this report, we expand on this sensing strategy to further monitor protein-protease interactions. We utilize QDs self-assembled with multiple copies of dye-labeled proteins as substrates for the sensing of protease activity. Detection of proteolysis is based on changes in the rate of fluorescence resonance energy transfer (FRET between the QDs and the proximal dye-labeled proteins following protein digestion by added enzyme. Our study focused on two representative proteolytic enzymes: the cysteine protease papain and the serine protease endoproteinase K. Analysis of the enzymatic digestion allowed us to estimate minimal values for the enzymatic activities of each enzyme used. Mechanisms of enzymatic inhibition were also inferred from the FRET data collected in the presence of inhibitors. Potential applications of this technology include drug discovery assays and in vivo cellular monitoring of enzymatic activity.

  20. Enhanced conductivity of thin film polyaniline by self-assembled transition metal complexes. (United States)

    Sarno, David M; Martin, Justin J; Hira, Steven M; Timpson, Cliff J; Gaffney, Jean P; Jones, Wayne E


    In a recent study, the transition metal complex, cis-dichlorobis(2-,2'-dipyridyl)ruthenium (II) (Ru(bpy)2Cl2), and the macrocycle Ru(TPP)CO (TPP:- tetraphenylporphine) were bound to pyridine terminated self-assembled monolayers on quartz. Following modification of the quartz surface with metal complexes, the conducting polymer polyaniline was deposited via in situ polymerization. The sheet conductivity (as measured by the four-probe method) of the resulting polyaniline films deposited onto Ru(bpy)2Cl2 and Ru(TPP)CO surfaces was significantly enhanced relative to films deposited onto unmodified quartz. It is postulated that either the macrocycle or the transition metal complex-modified surface interacts with the conducting polymer as it is forming, resulting in a more ordered expanded coil conformation for the polymer. The net result of such an interaction is a thin film possessing significantly greater electrical conductivity.

  1. Tolerance to structural disorder and tunable mechanical behavior in self-assembled superlattices of polymer-grafted nanocrystals (United States)

    Ye, Xingchen; Koshy, David M.; Vachhani, Shraddha; Hosemann, Peter; Alivisatos, A. Paul


    Large, freestanding membranes with remarkably high elastic modulus (>10 GPa) have been fabricated through the self-assembly of ligand-stabilized inorganic nanocrystals, even though these nanocrystals are connected only by soft organic ligands (e.g., dodecanethiol or DNA) that are not cross-linked or entangled. Recent developments in the synthesis of polymer-grafted nanocrystals have greatly expanded the library of accessible superlattice architectures, which allows superlattice mechanical behavior to be linked to specific structural features. Here, colloidal self-assembly is used to organize polystyrene-grafted Au nanocrystals at a fluid interface to form ordered solids with sub-10-nm periodic features. Thin-film buckling and nanoindentation are used to evaluate the mechanical behavior of polymer-grafted nanocrystal superlattices while exploring the role of polymer structural conformation, nanocrystal packing, and superlattice dimensions. Superlattices containing 3–20 vol % Au are found to have an elastic modulus of ∼6–19 GPa, and hardness of ∼120–170 MPa. We find that rapidly self-assembled superlattices have the highest elastic modulus, despite containing significant structural defects. Polymer extension, interdigitation, and grafting density are determined to be critical parameters that govern superlattice elastic and plastic deformation. PMID:28242704

  2. Tolerance to structural disorder and tunable mechanical behavior in self-assembled superlattices of polymer-grafted nanocrystals (United States)

    Gu, X. Wendy; Ye, Xingchen; Koshy, David M.; Vachhani, Shraddha; Hosemann, Peter; Alivisatos, A. Paul


    Large, freestanding membranes with remarkably high elastic modulus (>10 GPa) have been fabricated through the self-assembly of ligand-stabilized inorganic nanocrystals, even though these nanocrystals are connected only by soft organic ligands (e.g., dodecanethiol or DNA) that are not cross-linked or entangled. Recent developments in the synthesis of polymer-grafted nanocrystals have greatly expanded the library of accessible superlattice architectures, which allows superlattice mechanical behavior to be linked to specific structural features. Here, colloidal self-assembly is used to organize polystyrene-grafted Au nanocrystals at a fluid interface to form ordered solids with sub-10-nm periodic features. Thin-film buckling and nanoindentation are used to evaluate the mechanical behavior of polymer-grafted nanocrystal superlattices while exploring the role of polymer structural conformation, nanocrystal packing, and superlattice dimensions. Superlattices containing 3-20 vol % Au are found to have an elastic modulus of ˜6-19 GPa, and hardness of ˜120-170 MPa. We find that rapidly self-assembled superlattices have the highest elastic modulus, despite containing significant structural defects. Polymer extension, interdigitation, and grafting density are determined to be critical parameters that govern superlattice elastic and plastic deformation.

  3. Development of self-assembling nanowires containing electronically active oligothiophenes (United States)

    Tsai, Wei-Wen

    This dissertation discusses the development of conductive one-dimensional nanowires from self-assembling oligothiophene molecules. Self-assembly has been demonstrated to be a promising alternative approach towards high performance, solution processable, and low-cost organic electronics. One of the many challenges in this field is the control of supramolecular morphologies of ordered structures containing pi-conjugated moieties. This research demonstrated several successful strategies to achieve self assembly of conductive nanowires using synergistic interactions combining pi stacking and hydrogen bonding. The first approach used was to develop a hairpin-shaped sexithiophene molecule, which features two arms of the conjugated structure. The diamidocyclohexyl headgroup of this molecule successfully directs the self-assembly from hydrogen bonding among the amides, forming high-aspect-ratio one-dimensional nanowires with well-defined diameters of 3.0 +/- 0.3 nm. The molecular orientation in the nanostructures promotes formation of sexithiophene H and J aggregates that facilitate efficient charge transport. Organic field-effect transistors were fabricated to reveal improved intrinsic hole mobility from films of the nanostructures, 3.46 x 10-6 cm2V-1s-1, which is one order of magnitude higher than films cast from unassembled molecules. Bulk heterojunction solar cells were developed from this molecule and fullerenes utilizing solution-phase fabrication methods. Intimate mix of the molecule and phenyl-C61-butyric acid methyl ester creates structured interfaces for efficient exciton splitting. The charge carrier mobilities of each material are improved by self-assembly in solution and thermal-energy assisted phase separation.The photovoltaic devices achieved the highest open-circuit voltage of 0.62 V, short-circuit current of 1.79 mA/cm2, fill factor of 35%, and power conversion efficiency of 0.48%. Another strategy to one-dimensional nanowires studied here involved the

  4. Preface: Special Topic on Supramolecular Self-Assembly at Surfaces (United States)

    Bartels, Ludwig; Ernst, Karl-Heinz; Gao, Hong-Jun; Thiel, Patricia A.


    Supramolecular self-assembly at surfaces is one of the most exciting and active fields in Surface Science today. Applications can take advantage of two key properties: (i) versatile pattern formation over a broad length scale and (ii) tunability of electronic structure and transport properties, as well as frontier orbital alignment. It provides a new frontier for Chemical Physics as it uniquely combines the versatility of Organic Synthesis and the Physics of Interfaces. The Journal of Chemical Physics is pleased to publish this Special Topic Issue, showcasing recent advances and new directions.

  5. Directed Formation of DNA Nanoarrays through Orthogonal Self-Assembly

    Directory of Open Access Journals (Sweden)

    Eugen Stulz


    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.

  6. Nanoscale Nitrogen Doping in Silicon by Self-Assembled Monolayers


    Bin Guan; Hamidreza Siampour; Zhao Fan; Shun Wang; Xiang Yang Kong; Abdelmadjid Mesli; Jian Zhang; Yaping Dan


    International audience; This Report presents a nitrogen-doping method by chemically forming self-assembled monolayers on silicon. Van der Pauw technique, secondary-ion mass spectroscopy and low temperature Hall effect measurements are employed to characterize the nitrogen dopants. The experimental data show that the diffusion coefficient of nitrogen dopants is 3.66 × 10−15 cm2 s−1, 2 orders magnitude lower than that of phosphorus dopants in silicon. It is found that less than 1% of nitrogen d...

  7. Exploring the properties and possibilities of self-assembling

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Castillo, Jaime


    The study (and potential application) of diphenylalanine peptide nanotubes is a popular topic that in recent years has experienced a boost in activity. This activity has been propelled forward by new articles continuously being published presenting even more spectacular properties of the nanotube...... and exciting possibilities. The major driving forces supporting the interest in the peptide nanotubes is the fast and simple assembly process combined with their remarkable stability towards alcohols, organic solvents, and biological analytes that was presented shortly after the self-assembling properties...

  8. Directed self-assembly graphoepitaxy template generation with immersion lithography (United States)

    Ma, Yuansheng; Lei, Junjiang; Andres Torres, J.; Hong, Le; Word, James; Fenger, Germain; Tritchkov, Alexander; Lippincott, George; Gupta, Rachit; Lafferty, Neal; He, Yuan; Bekaert, Joost; Vanderberghe, Geert


    We present an optimization methodology for the template designs of subresolution contacts using directed self-assembly (DSA) with graphoepitaxy and immersion lithography. We demonstrate the flow using a 60-nm-pitch contact design in doublet with Monte Carlo simulations for DSA. We introduce the notion of template error enhancement factor (TEEF) to gauge the sensitivity of DSA printing infidelity to template printing infidelity and evaluate optimized template designs with TEEF metrics. Our data show that source mask optimization and inverse lithography technology are critical to achieve sub-80 nm non-L0 pitches for DSA patterns using 193i.

  9. Photobleaching-activated micropatterning on self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Scrimgeour, Jan; Kodali, Vamsi K; Kovari, Daniel T; Curtis, Jennifer E, E-mail: jennifer.curtis@physics.gatech.ed [School of Physics and Petit Institute for Bioengineering and Biosciences (IBB), Georgia Institute of Technology, 837 State St, Atlanta, GA 30332 (United States)


    Functional chemical micropatterns were fabricated by exploiting the photobleaching of dye-coupled species near methacrylate self-assembled monolayers. Using this approach we have demonstrated that multiple chemistries can be coupled to the monolayer using a standard fluorescence microscope. The surface bound functional groups remain active and patterns with feature sizes down to 3 {mu}m can be readily achieved with excellent signal-to-noise ratio. Control over the ligand binding density was demonstrated to illustrate the convenient route provided by this platform for fabricating complex spatial gradients in ligand density.

  10. Exploiting non-equilibrium phase separation for self-assembly. (United States)

    Grünwald, Michael; Tricard, Simon; Whitesides, George M; Geissler, Phillip L


    Demixing can occur in systems of two or more particle species that experience different driving forces, e.g., mixtures of self-propelled active particles or of oppositely charged colloids subject to an electric field. Here we show with macroscopic experiments and computer simulations that the forces underlying such non-equilibrium segregation can be used to control the self-assembly of particles that lack attractive interactions. We demonstrate that, depending on the direction, amplitude and frequency of a periodic external force acting on one particle species, the structures formed by a second, undriven species can range from compact clusters to elongated, string-like patterns.

  11. Self-assembled manganese oxide structures through direct oxidation

    KAUST Repository

    Zhao, Chao


    The morphology and phase of self-assembled manganese oxides during different stages of thermal oxidation were studied. Very interesting morphological patterns of Mn oxide films were observed. At the initial oxidation stage, the surface was characterized by the formation of ring-shaped patterns. As the oxidation proceeded to the intermediate stage, concentric plates formed to relax the compressive stress. Our experimental results gave a clear picture of the evolution of the structures. We also examined the properties of the structures. © 2012 Elsevier B.V.

  12. Preface: Special Topic on Supramolecular Self-Assembly at Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, Ludwig [Department of Chemistry and the Materials Science and Engineering Program, University of California - Riverside, Riverside, California 92521 (United States); Ernst, Karl-Heinz [EMPA, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dubendorf (Switzerland); Gao, Hong-Jun [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,Chinese Academy of Sciences, Beijing 100190 (China); Thiel, Patricia A. [Department of Chemistry, Department of Materials Science and Engineering, Ames Laboratory,Iowa State University, Ames, Iowa 50011 (United States)


    Supramolecular self-assembly at surfaces is one of the most exciting and active fields in Surface Science today. Applications can take advantage of two key properties: (i) versatile pattern formation over a broad length scale and (ii) tunability of electronic structure and transport properties, as well as frontier orbital alignment. It provides a new frontier for Chemical Physics as it uniquely combines the versatility of Organic Synthesis and the Physics of Interfaces. The Journal of Chemical Physics is pleased to publish this Special Topic Issue, showcasing recent advances and new directions.

  13. A 3D Optical Metamaterial Made by Self-Assembly

    KAUST Repository

    Vignolini, Silvia


    Optical metamaterials have unusual optical characteristics that arise from their periodic nanostructure. Their manufacture requires the assembly of 3D architectures with structure control on the 10-nm length scale. Such a 3D optical metamaterial, based on the replication of a self-assembled block copolymer into gold, is demonstrated. The resulting gold replica has a feature size that is two orders of magnitude smaller than the wavelength of visible light. Its optical signature reveals an archetypal Pendry wire metamaterial with linear and circular dichroism. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Self-assembly of free-standing RNA membranes (United States)

    Han, Daehoon; Park, Yongkuk; Kim, Hyejin; Lee, Jong Bum


    RNA has emerged as a promising material for nanostructure and microstructure engineering. Although rare, some macroscopic RNA structures have also been constructed using lipid or polymer materials. Here, we report the first example of an enzymatically generated RNA membrane. This robust and free-standing RNA membrane has a macroscopic structure and is generated without any polymer support or complexation. Our RNA membrane is fabricated following two sequential processes, complementary rolling circle transcription and evaporation-induced self-assembly, and its structural and functional properties are rationally controlled by adjusting RNA base pairing. In this study, three types of RNA membranes are fabricated and are used to demonstrate potential applications.

  15. Purification of ethanol for highly sensitive self-assembly experiments

    Directory of Open Access Journals (Sweden)

    Kathrin Barbe


    Full Text Available Ethanol is the preferred solvent for the formation of self-assembled monolayers (SAMs of thiolates on gold. By applying a thin film sensor system, we could demonstrate that even the best commercial qualities of ethanol contain surface-active contaminants, which can compete with the desired thiolates for surface sites. Here we present that gold nanoparticles deposited onto zeolite X can be used to remove these contaminants by chemisorption. This nanoparticle-impregnated zeolite does not only show high capacities for surface-active contaminants, such as thiols, but can be fully regenerated via a simple pyrolysis protocol.

  16. Self-Assembled Supramolecular Architectures Lyotropic Liquid Crystals

    CERN Document Server

    Garti, Nissim


    This book will describe fundamentals and recent developments in the area of Self-Assembled Supramolecular Architecture and their relevance to the  understanding of the functionality of  membranes  as delivery systems for active ingredients. As the heirarchial architectures determine their performance capabilities, attention will be paid to theoretical and design aspects related to the construction of lyotropic liquid crystals: mesophases such as lamellar, hexagonal, cubic, sponge phase micellosomes. The book will bring to the reader mechanistic aspects, compositional c

  17. Self-assembled organic microfibers for nonlinear optics. (United States)

    Xu, Jialiang; Semin, Sergey; Niedzialek, Dorota; Kouwer, Paul H J; Fron, Eduard; Coutino, Eduardo; Savoini, Matteo; Li, Yuliang; Hofkens, Johan; Uji-I, Hiroshi; Beljonne, David; Rasing, Theo; Rowan, Alan E


    While highly desired in integrated optical circuits, multiresponsive and tunable nonlinear optical (NLO) active 1D (sub)wavelength scale superstructures from organic materials are rarely reported due to the strong tendency of organic molecules to self-assembly in centrosymmetric modes. Here a solution-processed assembly approach is reported to generate non-centrosymmetric single-crystalline organic microfibers with a cumulative dipole moment for anisotropic combined second- and third-order NLO. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Switching properties of self-assembled ferroelectric memory cells (United States)

    Alexe, M.; Gruverman, A.; Harnagea, C.; Zakharov, N. D.; Pignolet, A.; Hesse, D.; Scott, J. F.


    In this letter, we report on the switching properties of an ordered system of Bi4Ti3O12 ferroelectric memory cells of an average lateral size of 0.18 μm formed via a self-assembling process. The ferroelectricity of these cells has been measured microscopically and it has been demonstrated that an individual cell of 0.18 μm size is switching. Switching of single nanoelectrode cells was achieved via scanning force microscopy working in piezoresponse mode.

  19. Equation of State for Phospholipid Self-Assembly

    DEFF Research Database (Denmark)

    Marsh, Derek


    concentration at a single temperature suffices to define an effective heat capacity according to the model. Agreement with the experimental temperature dependence of the critical micelle concentration is then good. The predictive powers should extend also to amphiphile partitioning and the kinetics of lipid...... 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...

  20. The self assembly of thymine at Au(110)/liquid interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Molina Contreras, J.R. [Departamento de Ingenieria Electrica y Electronica, Instituto Tecnologico de Aguascalientes, Mexico (Mexico); Smith, C.I.; Bowfield, A.; Weightman, P. [Physics Department, University of Liverpool (United Kingdom); Tillner, F. [Fachbereich Physik, Universitaet Konstanz (Germany)


    We show that thymine self-assembles into an ordered structure when adsorbed at a Au(110)/liquid interface. Reflection anisotropy spectroscopy (RAS) shows that as found for cytosine and adenine the adsorbed thymine molecules are oriented essentially vertically on the Au(110) surface with the molecule aligned along one of the principal axes of the Au(110) surface. Simulations of the RA spectra to an empirical model indicates that as found for adsorbed cytosine and adenine, thymine is aligned along the [1 anti 10] direction on the Au(110) surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Long coherence times in self-assembled semiconductor quantum dots

    DEFF Research Database (Denmark)

    Birkedal, Dan; Leosson, K.; Hvam, Jørn Märcher


    We report measurements of ultra-long coherence in self-assembled quantum dots. Transient four-wave mixing experiments at 5 K show an average dephasing time of 372 ps, corresponding to a homogeneous linewidth of 3.5 mueV, which is significantly smaller than the linewidth observed in single-dot...... luminescence. Time-resolved luminescence measurements show a lifetime of the dot ground state of 800 ps demonstrating the presence of pure dephasing at finite temperature. The homogeneous width is lifetime limited only at temperatures approaching 0 K....

  2. Self-assembled organogels formed by monochain derivatives of ethylenediamine. (United States)

    Luo, Xuzhong; Li, Zengfu; Xiao, Wei; Wang, Qiong; Zhong, Jinlian


    A family of low molecular weight organogelators (LMOG) based on monochain derivatives of ethylenediamine were investigated. The monochain derivatives of ethylenediamine show strong gelation ability in a number of organic solvents, including polar solvents and non-polar solvents. In gel state, molecules of monochain ethylenediamine derivatives self-assemble into ordered aggregates, which are juxtaposed and interlocked to form three-dimensional networks of fiber bundles as confirmed by scanning electron microscopy (SEM). The Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) studies demonstrate that intermolecular hydrogen bonds between neighboring molecules are critical factor in the process of organogelation.

  3. 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:; Cabrerizo-Vílchez, Miguel A.


    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.

  4. Protein-directed self-assembly of a fullerene crystal (United States)

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


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

  5. Probabilistic Performance Guarantees for Distributed Self-Assembly

    KAUST Repository

    Fox, Michael J.


    In distributed self-assembly, a multitude of agents seek to form copies of a particular structure, modeled here as a labeled graph. In the model, agents encounter each other in spontaneous pairwise interactions and decide whether or not to form or sever edges based on their two labels and a fixed set of local interaction rules described by a graph grammar. The objective is to converge on a graph with a maximum number of copies of a given target graph. Our main result is the introduction of a simple algorithm that achieves an asymptotically maximum yield in a probabilistic sense. Notably, agents do not need to update their labels except when forming or severing edges. This contrasts with certain existing approaches that exploit information propagating rules, effectively addressing the decision problem at the level of subgraphs as opposed to individual vertices. We are able to obey more stringent locality requirements while also providing smaller rule sets. The results can be improved upon if certain requirements on the labels are relaxed. We discuss limits of performance in self-assembly in terms of rule set characteristics and achievable maximum yield.

  6. Self assembled monolayers on silicon for molecular electronics. (United States)

    Aswal, D K; Lenfant, S; Guerin, D; Yakhmi, J V; Vuillaume, D


    We present an overview of various aspects of the self-assembly of organic monolayers on silicon substrates for molecular electronics applications. Different chemical strategies employed for grafting the self-assembled monolayers (SAMs) of alkanes having different chain lengths on native oxide of Si or on bare Si have been reviewed. The utility of different characterization techniques in determination of the thickness, molecular ordering and orientation, surface coverage, growth kinetics and chemical composition of the SAMs has been discussed by choosing appropriate examples. The metal counterelectrodes are an integral part of SAMs for measuring their electrical properties as well as using them for molecular electronic devices. A brief discussion on the variety of options available for the deposition of metal counterelectrodes, that is, soft metal contacts, vapor deposition and soft lithography, has been presented. Various theoretical models, namely, tunneling (direct and Fowler-Nordheim), thermionic emission, Poole-Frenkel emission and hopping conduction, used for explaining the electronic transport in dielectric SAMs have been outlined and, some experimental data on alkane SAMs have been analyzed using these models. It has been found that short alkyl chains show excellent agreement with tunneling models; while more experimental data on long alkyl chains are required to understand their transport mechanism(s). Finally, the concepts and realization of various molecular electronic components, that is, diodes, resonant tunnel diodes, memories and transistors, based on appropriate architecture of SAMs comprising of alkyl chains (sigma- molecule) and conjugated molecules (pi-molecule) have been presented.

  7. Interfacial rheological properties of self-assembling biopolymer microcapsules. (United States)

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


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

  8. Physical principles of filamentous protein self-assembly kinetics (United States)

    Michaels, Thomas C. T.; Liu, Lucie X.; Meisl, Georg; Knowles, Tuomas P. J.


    The polymerization of proteins and peptides into filamentous supramolecular structures is an elementary form of self-organization of key importance to the functioning biological systems, as in the case of actin biofilaments that compose the cellular cytoskeleton. Aberrant filamentous protein self-assembly, however, is associated with undesired effects and severe clinical disorders, such as Alzheimer’s and Parkinson’s diseases, which, at the molecular level, are associated with the formation of certain forms of filamentous protein aggregates known as amyloids. Moreover, due to their unique physicochemical properties, protein filaments are finding extensive applications as biomaterials for nanotechnology. With all these different factors at play, the field of filamentous protein self-assembly has experienced tremendous activity in recent years. A key question in this area has been to elucidate the microscopic mechanisms through which filamentous aggregates emerge from dispersed proteins with the goal of uncovering the underlying physical principles. With the latest developments in the mathematical modeling of protein aggregation kinetics as well as the improvement of the available experimental techniques it is now possible to tackle many of these complex systems and carry out detailed analyses of the underlying microscopic steps involved in protein filament formation. In this paper, we review some classical and modern kinetic theories of protein filament formation, highlighting their use as a general strategy for quantifying the molecular-level mechanisms and transition states involved in these processes.

  9. Synthesis and self-assembly of complex hollow materials

    KAUST Repository

    Zeng, Hua Chun


    Hollow materials with interiors or voids and pores are a class of lightweight nanostructured matters that promise many future technological applications, and they have received significant research attention in recent years. On the basis of well-known physicochemical phenomena and principles, for example, several solution-based protocols have been developed for the general preparation of these complex materials under mild reaction conditions. This article is thus a short introductory review on the synthetic aspects of this field of development. The synthetic methodologies can be broadly divided into three major categories: (i) template-assisted synthesis, (ii) self-assembly with primary building blocks, and (iii) induced matter relocations. In most cases, both synthesis and self-assembly are involved in the above processes. Further combinations of these methodologies appear to be very important, as they will allow one to prepare functional materials at a higher level of complexity and precision. The synthetic strategies are introduced through some simple case studies with schematic illustrations. Salient features of the methods developed have been summarized, and some urgent issues of this field have also been indicated. © 2011 The Royal Society of Chemistry.

  10. Electrostatic Force Microscopy of Self Assembled Peptide Structures

    DEFF Research Database (Denmark)

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


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

  11. Design of single peptides for self-assembled conduction channels

    Energy Technology Data Exchange (ETDEWEB)

    Yew, Sok Yee; Mhaisalkar, Subodh; Lam, Yeng Ming [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, 639798 (Singapore); Shekhawat, Gajendra; Dravid, Vinayak P [School of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL 60208 (United States); Wangoo, Nishima; Suri, C Raman, E-mail: [Institute of Microbial Technology (IMTECH), Sector 39 Chandigarh (India)


    Self-assembly of peptides provides the possibility of achieving relatively long range order on surfaces. These ordered peptides can also form channels that can be used as conduction channels. In the past, studies were focused on electron conduction through the secondary structure and amine bond of peptides and these restrict conduction of electrons over a short range (a few nanometers). In this work, we demonstrate the realization of electron conduction over a longer range of a few hundred nanometers via {pi}-{pi} stacking of the phenyl groups in the tyrosine residue of a single peptide. The peptide used in this work was designed with a phenyl ring for {pi}-{pi} stacking at one end and a carboxylic group at the other end for binding to aminopropyltriethoxysilane (APTES) treated silicon wafer. The distance between the peptides is controlled by a disulfide bond formed between neighboring cysteine residue and also by the amine groups of aminopropyltriethoxysilane. We demonstrate that the self-assembled peptide is conducting in the dry state over hundreds of nanometers, realizing the possibility of using peptide as a molecular wire.

  12. Silver nanoprisms self-assembly on differently functionalized silica surface (United States)

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


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

  13. Hierarchical Self-Assembly of Light Guided Spinning Microgears (United States)

    Aubret, Antoine; Youssef, Mena; Sacanna, Stefano; Palacci, Jeremie; Sacanna Group, NYU Team


    In this work, we demonstrate the self-assembly of microgears obtained from the guided construction of tailored self-propelled particles used as primary building blocks. The experiment relies on our control of phoretic phenomena: the migration of particles in a solute gradient. We activate a photocatalytic material, the hematite, and trigger the decomposition of hydrogen peroxide to set concentration gradient. We use this effect to engineer phototactic swimmers, attracted to the region of high illumination. We guide the swimmers to form robust and highly persistent microgears. They interact with each other through hydrodynamics and diffusiophoretically through the chemical clouds of fuel consumption. Multiple rotors are studied and we specifically address the dynamics of two rotors. We show that the microgears move collectively or synchronize thanks to the interaction of their chemical clouds. Increasing the number of microrotors (N = 2 - 7), we form an active crystal which can rotate, re-organize, change shape, and exhibit phase synchronization between its individual components. Such crystal made of non-equilibrium rotating gears at the microscale is unique. Our study paves the way for better understanding and control of emergent phenomena in collection of active spinning particles. It is a promising avenue for the creation of cutting-edge materials using emergent behavior from hierarchical self-assembly to unveil untapped functionalities. This work is supported by NSF CAREER DMR 1554724.

  14. Proteins evolve on the edge of supramolecular self-assembly (United States)

    Garcia-Seisdedos, Hector; Empereur-Mot, Charly; Elad, Nadav; Levy, Emmanuel D.


    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.

  15. Aerosol-Assisted Self-Assembly of Mesostructured Spherical Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Brinker, C.J.; Fan,; H.; Lu, Y.; Rieker, T.; Stump, A.; Ward, T.L.


    Nanostructured particles exhibiting well-defined pore sizes and pore connectivities (1-, 2-, or 3-dimensional) are of interest for catalysis, chromatography, controlled release, low dielectric constant fillers, and custom-designed pigments and optical hosts. During the last several years considerable progress has been made on controlling the macroscopic forms of mesoporous silicas prepared by surfactant and block copolymer liquid crystalline templating procedures. Typically interfacial phenomena are used to control the macroscopic form (particles, fibers, or films), while self-assembly of amphiphilic surfactants or polymers is used to control the mesostructure. To date, although a variety of spherical or nearly-spherical particles have been prepared, their extent of order is limited as is the range of attainable mesostructures. They report a rapid, aerosol process that results in solid, completely ordered spherical particles with stable hexagonal, cubic, or vesicular mesostructures. The process relies on evaporation-induced interfacial self-assembly (EISA) confined to a spherical aerosol droplet. The process is simple and generalizable to a variety of materials combinations. Additionally, it can be modified to provide the first aerosol route to the formation of ordered mesostructured films.

  16. Low-temperature photoluminescence in self-assembled diphenylalanine microtubes

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, T. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Kopyl, S. [Physics Department & CICECO – Materials Institute of Aveiro, University of Aveiro, 3810-193 Aveiro (Portugal); Shur, V.Ya. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Kopelevich, Y.V., E-mail: [Instituto de Fisica, UNICAMP, Campinas, São Paulo 13083-859 (Brazil); Kholkin, A.L., E-mail: [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Physics Department & CICECO – Materials Institute of Aveiro, University of Aveiro, 3810-193 Aveiro (Portugal)


    Bioinspired self-assembled structures are increasingly important for a variety of applications ranging from drug delivery to electronic and energy harvesting devices. An important class of these structures is diphenylalanine microtubes which are potentially important for optical applications including light emitting diodes and optical biomarkers. In this work we present the data on their photoluminescent properties at low temperatures (down to 12 K) and discuss the origin of the emission in the near ultraviolet (UV) range seen earlier in a number of reports. UV luminescence increases with decreasing temperature and exhibits several equidistant lines that are assigned to zero-phonon exciton emission line and its phonon replicas. We infer that the exciton is localized on the defect sites and significant luminescence decay is due to thermal quenching arising from the carrier excitation from these defects and non-radiative recombination. - Highlights: • Low-temperature luminescence is studied in bioinspired self-assembled FF peptide microtubes. • The mechanism of the optical emission is assigned to the luminescence of excitonic states localized at defects. • Luminescence in FF microtubes can be used as an absolute temperature probe at low temperature.

  17. Self-assembled single-phase perovskite nanocomposite thin films. (United States)

    Kim, Hyun-Suk; Bi, Lei; Paik, Hanjong; Yang, Dae-Jin; Park, Yun Chang; Dionne, Gerald F; Ross, Caroline A


    Thin films of perovskite-structured oxides with general formula ABO(3) have great potential in electronic devices because of their unique properties, which include the high dielectric constant of titanates, (1) high-T(C) superconductivity in cuprates, (2) and colossal magnetoresistance in manganites. (3) These properties are intimately dependent on, and can therefore be tailored by, the microstructure, orientation, and strain state of the film. Here, we demonstrate the growth of cubic Sr(Ti,Fe)O(3) (STF) films with an unusual self-assembled nanocomposite microstructure consisting of (100) and (110)-oriented crystals, both of which grow epitaxially with respect to the Si substrate and which are therefore homoepitaxial with each other. These structures differ from previously reported self-assembled oxide nanocomposites, which consist either of two different materials (4-7) or of single-phase distorted-cubic materials that exhibit two or more variants. (8-12) Moreover, an epitaxial nanocomposite SrTiO(3) overlayer can be grown on the STF, extending the range of compositions over which this microstructure can be formed. This offers the potential for the implementation of self-organized optical/ferromagnetic or ferromagnetic/ferroelectric hybrid nanostructures integrated on technologically important Si substrates with applications in magnetooptical or spintronic devices.

  18. Managing lifelike behavior in a dynamic self-assembled system (United States)

    Ropp, Chad; Bachelard, Nicolas; Wang, Yuan; Zhang, Xiang

    Self-organization can arise outside of thermodynamic equilibrium in a process of dynamic self-assembly. This is observed in nature, for example in flocking birds, but can also be created artificially with non-living entities. Such dynamic systems often display lifelike properties, including the ability to self-heal and adapt to environmental changes, which arise due to the collective and often complex interactions between the many individual elements. Such interactions are inherently difficult to predict and control, and limit the development of artificial systems. Here, we report a fundamentally new method to manage dynamic self-assembly through the direct external control of collective phenomena. Our system consists of a waveguide filled with mobile scattering particles. These particles spontaneously self-organize when driven by a coherent field, self-heal when mechanically perturbed, and adapt to changes in the drive wavelength. This behavior is governed by particle interactions that are completely mediated by coherent wave scattering. Compared to hydrodynamic interactions which lead to compact ordered structures, our system displays sinusoidal degeneracy and many different steady-state geometries that can be adjusted using the external field.

  19. Self-assembling and self-limiting monolayer deposition (United States)

    Foest, Rüdiger; Schmidt, Martin; Gargouri, Hassan


    Effects of spatial ordering of molecules on surfaces are commonly utilized to deposit ultra-thin films with a thickness of a few nm. In this review paper, several methods are discussed, that are distinguished from other thin film deposition processes by exactly these effects that lead to self-assembling and self-limiting layer growth and eventually to coatings with unique and fascinating properties and applications in micro-electronics, optics, chemistry, or biology. Traditional methods for the formation of self-assembled films of ordered organic molecules, such as the Langmuir-Blodgett technique along with thermal atomic layer deposition (ALD) of inorganic molecules are evaluated. The overview is complemented by more recent developments for the deposition of organic or hybrid films by molecular layer deposition. Particular attention is given to plasma assisted techniques, either as a preparative, supplementary step or as inherent part of the deposition as in plasma enhanced ALD or plasma assisted, repeated grafting deposition. The different methods are compared and their film formation mechanisms along with their advantages are presented from the perspective of a plasma scientist. The paper contains lists of established film compounds and a collection of the relevant literature is provided for further reading.

  20. Anisotropic Self-Assembly from Isotropic Colloidal Building Blocks. (United States)

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


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

  1. Self-assembly of dodecaphenyl POSS thin films (United States)

    Handke, Bartosz; Klita, Łukasz; Niemiec, Wiktor


    The self-assembly abilities of Dodecaphenyl Polyhedral Oligomeric Silsesquioxane thin films on Si(1 0 0) surfaces were studied. Due to their thermal properties - relatively low sublimation temperature and preservation of molecular structure - cage type silsesquioxanes are ideal material for the preparation of a thin films by Physical Vapor Deposition. The Ultra-High Vacuum environment and the deposition precision of the PVD method enable the study of early stages of thin film growth and its molecular organization. X-ray Reflectivity and Atomic Force Microscopy measurements allow to pursuit size-effects in the structure of thin films with thickness ranges from less than a single molecular layer up to several tens of layers. Thermal treatment of the thin films triggered phase change: from a poorly ordered polycrystalline film into a well-ordered multilayer structure. Self-assembly of the layers is the effect of the π-stacking of phenyl rings, which force molecules to arrange in a superlattice, forming stacks of alternating organic-inorganic layers.

  2. Free surface BCP self-assembly process characterization with CDSEM (United States)

    Levi, Shimon; Weinberg, Yakov; Adan, Ofer; Klinov, Michael; Argoud, Maxime; Claveau, Guillaume; Tiron, Raluca


    A simple and common practice to evaluate Block copolymers (BCP) self-assembly performances, is on a free surface wafer. With no guiding pattern the BCP designed to form line space pattern for example, spontaneously rearranges to form a random fingerprint type of a pattern. The nature of the rearrangement is dictated by the physical properties of the BCP moieties, wafer surface treatment and the self-assembly process parameters. Traditional CDSEM metrology algorithms are designed to measure pattern with predefined structure, like linespace or oval via holes. Measurement of pattern with expected geometry can reduce measurement uncertainty. Fingerprint type of structure explored in this dissertation, poses a challenge for CD-SEM measurement uncertainty and offers an opportunity to explore 2D metrology capabilities. To measure this fingerprints we developed a new metrology approach that combines image segmentation and edge detection to measure 2D pattern with arbitrary rearrangement. The segmentation approach enabled to quantify the quality of the BCP material and process, detecting 2D attributes such as: CD and CDU at one axis, and number of intersections, length and number of PS fragments, etched PMMA spaces and donut shapes numbers on the second axis. In this paper we propose a 2D metrology to measure arbitrary BCP pattern on a free surface wafer. We demonstrate experimental results demonstrating precision data, and characterization of PS-b-PMMA BCP, intrinsic period L0 = 38nm (Arkema), processed at different bake time and temperatures.

  3. Self-assembly of colloids with magnetic caps

    Energy Technology Data Exchange (ETDEWEB)

    Novak, E.V., E-mail: [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)


    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.

  4. Hidden geometries in networks arising from cooperative self-assembly. (United States)

    Šuvakov, Milovan; Andjelković, Miroslav; Tadić, Bosiljka


    Multilevel self-assembly involving small structured groups of nano-particles provides new routes to development of functional materials with a sophisticated architecture. Apart from the inter-particle forces, the geometrical shapes and compatibility of the building blocks are decisive factors. Therefore, a comprehensive understanding of these processes is essential for the design of assemblies of desired properties. Here, we introduce a computational model for cooperative self-assembly with the simultaneous attachment of structured groups of particles, which can be described by simplexes (connected pairs, triangles, tetrahedrons and higher order cliques) to a growing network. The model incorporates geometric rules that provide suitable nesting spaces for the new group and the chemical affinity of the system to accept excess particles. For varying chemical affinity, we grow different classes of assemblies by binding the cliques of distributed sizes. Furthermore, we characterize the emergent structures by metrics of graph theory and algebraic topology of graphs, and 4-point test for the intrinsic hyperbolicity of the networks. Our results show that higher Q-connectedness of the appearing simplicial complexes can arise due to only geometric factors and that it can be efficiently modulated by changing the chemical potential and the polydispersity of the binding simplexes.

  5. Self-Assembling Multifunctional Peptide Dimers for Gene Delivery Systems

    Directory of Open Access Journals (Sweden)

    Kitae Ryu


    Full Text Available Self-assembling multifunctional peptide was designed for gene delivery systems. The multifunctional peptide (MP consists of cellular penetrating peptide moiety (R8, matrix metalloproteinase-2 (MMP-2 specific sequence (GPLGV, pH-responsive moiety (H5, and hydrophobic moiety (palmitic acid (CR8GPLGVH5-Pal. MP was oxidized to form multifunctional peptide dimer (MPD by DMSO oxidation of thiols in terminal cysteine residues. MPD could condense pDNA successfully at a weight ratio of 5. MPD itself could self-assemble into submicron micelle particles via hydrophobic interaction, of which critical micelle concentration is about 0.01 mM. MPD showed concentration-dependent but low cytotoxicity in comparison with PEI25k. MPD polyplexes showed low transfection efficiency in HEK293 cells expressing low level of MMP-2 but high transfection efficiency in A549 and C2C12 cells expressing high level of MMP-2, meaning the enhanced transfection efficiency probably due to MMP-induced structural change of polyplexes. Bafilomycin A1-treated transfection results suggest that the transfection of MPD is mediated via endosomal escape by endosome buffering ability. These results show the potential of MPD for MMP-2 targeted gene delivery systems due to its multifunctionality.

  6. Stimuli-controlled self-assembly of diverse tubular aggregates from one single small monomer (United States)

    Shi, Qixun; Javorskis, Tomas; Bergquist, Karl-Erik; Ulčinas, Artūras; Niaura, Gediminas; Matulaitienė, Ieva; Orentas, Edvinas; Wärnmark, Kenneth


    The design and synthesis of new stimuli-responsive hydrogen-bonding monomers that display a diversity of self-assembly pathways is of central importance in supramolecular chemistry. Here we describe the aggregation properties of a simple, intrinsically C2-symmetric enantiopure bicyclic cavity compound bearing a terminally unsubstituted ureidopyrimidinone fragment fused with a pyrrole moiety in different solvents and in the absence and presence of C60 and C70 guests. The tetrameric cyclic aggregate is selectively obtained in chlorinated solvents, where only part of the available hydrogen bonding sites are utilized, whereas in toluene or upon addition of C70 guests, further aggregation into tubular supramolecular polymers is achieved. The open-end cyclic assemblies rearrange into a closed-shell capsule upon introduction of C60 with an accompanied symmetry breaking of the monomer. Our study demonstrates that a C60 switch can be used to simultaneously control the topology and occupancy of tubular assemblies resulting from the aggregation of small monomers.

  7. Engineered Bacterial Metal-binding Proteins for Nanoscale Self-assembly and heavy Metal Tolerance (United States)

    Hall Sedlak, Ruth Amanda

    Implementing biological principles in material synthesis and assembly is one way to expand our abilities to efficiently assemble nanoscale materials and devices. Specifically, recent advances in identifying peptides that bind inorganic materials with high affinity and specificity has spurred investigation of protein models for nanoscale inorganic assembly. This dissertation presents the results of my studies of several E. coli proteins engineered to bind inorganic materials through simple peptide motifs. I demonstrate that these proteins modulate the self-assembly of DNA-based nanostructures and can introduce heavy metal tolerance into metal-sensitive bacteria. Chapter 2 explores use of the engineered F plasmid DNA relaxase/helicase TraI for the self-assembly of complex DNA-protein-gold nanostructures. The full-length protein is engineered with a gold binding motif at an internal permissive site (TraI369GBP1-7x), while a truncated version of TraI is engineered with the same gold binding motif at the C-terminus (TraI361GBP1-7x). Both constructs bind gold nanoparticles while maintaining their DNA binding activity, and transmission electron microscopy reveals TraI369GBP1-7x utilizes its non-specific DNA binding activity to decorate single-stranded and double-stranded DNA with gold nanoparticles. The self assembly principles demonstrated in this work will be fundamental to constructing higher ordered hybrid nanostructures through DNA-protein-nanoparticle interactions. Chapter 3 studies the effects of expressing inorganic binding peptides within cells. I identified a silver binding peptide that, when fused to the periplasmic maltose binding protein, protects E. coli from silver toxicity in batch culture and reduces silver ions to silver nanoparticles within the bacterial periplasm. Engineered metal-ion tolerant microorganisms such as this E. coli could potentially be used in applications ranging from remediation to interrogation of biomolecule-metal interactions in vivo

  8. Guinea pigs as experimental model to evaluate the resistance of the tissue expander capsule Cobaias como modelo experimental para avaliar a resistência da cápsula do tecido expandido

    Directory of Open Access Journals (Sweden)

    Fábio Xerfan Nahas


    Full Text Available The purpose of this study is to report the use of guinea pigs as experimental model to study the resitance of the tissue expander capsule. Two groups were studied. In both groups a round 20 cc tissue expander, attached to a multiperforated catheter was inserted. The pocket housing was standardized. The skin over the expanded area was tattooed demarcating the area and arc, which were measured before and after each expansion. Every 4 days, a volume corresponding to 10% of the expander's total capacity was injected. Animals of the control group received 3 cc of saline through the catheter at the same time of expansion. Animals of the experimental group received 3 cc of the HBGF-1 diluted with saline. The intraluminal pressure of the expander was measured before and after the injection. After its total filling, the animals were sacrificed and 5 cc more were injected into each expander. The pressure was measured after each 1 cc injected. The capsule was examined histologically by immunofluorescence, trichrome and hematoxylin-eosin stains with the purpose of quantifying collagen and fibroblasts. The experimental model to study the resistance of the tissue expander's capsule showed to be feasible in guinea pigs.O objetivo deste estudo é relatar o uso de cobaias como modelo experimental para estudar a resistência da cápsula de expansores. Dois grupos foram estudados. Em ambos os grupos um expansor Redondo de 20 ml com um cateter multiperforado fixadoforam inseridos nos animais. A loja foi padronizada. A pele a ser expandida foi tatuada demarcando uma area e um arco que foram medidos a cada expansão. A cada 4 dias. Um volume correspondendo a 10 % da capacidade total do expansor foi injetado. Os animais do grupo controle receberam 3 ml de soro fisiológico pelo catéter de irrigação no mesmo momento da expansão. Os animais do grupo experimental receberam 3 ml de HBGF-1 diluido com soro fisiológico. A pressão intraluminal do expansor foi medida

  9. Self-assembly of designed precursors: A route to crystallographically aligned new materials with controlled nanoarchitecture

    Energy Technology Data Exchange (ETDEWEB)

    Westover, Richard, E-mail:; Atkins, Ryan A.; Falmbigl, Matthias; Ditto, Jeffrey J.; Johnson, David C.


    Modulated elemental reactants is a method by which new and complex intergrowth compounds can be synthesized by the self-assembly of designed precursors prepared by physical vapor deposition. Careful calibration of the composition and thickness of the precursors ensures the formation of the desired product by precise control of local composition and diffusion lengths. Superstructures of increasing complexity can be realized using binary and ternary systems as starting points. The synthesis of systems based on three different binary compounds, either alloyed together or separated into distinct layers, expands the number of possible superstructures that can be formed using this technique, but provides analytical challenges. The synthesis of [(SnSe){sub 1.15}]{sub 1}([Ta{sub x}V{sub 1−x}]Se{sub 2}){sub 1}[(SnSe){sub 1.15}]{sub 1}([V{sub y}Ta{sub 1−y}]Se{sub 2}){sub 1} compound is used to illustrate the preparation of precursors and the challenges in both measuring and limiting the interdiffusion of layers during self-assembly. Systematic changes in the electrical properties of (SnSe){sub 1+δ}(Ta{sub x}V{sub 1−x})Se{sub 2} alloys are observed as x is varied. The electrical resistivity of [(SnSe){sub 1.15}]{sub 1}([Ta{sub x}V{sub 1−x}]Se{sub 2}){sub 1}[(SnSe){sub 1.15}]{sub 1}([V{sub y}Ta{sub 1−y}]Se{sub 2}){sub 1} can be modeled as the two constituent layers in parallel.

  10. Tuning the Cavity Size and Chirality of Self-Assembling 3D DNA Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Chad R.; Zhang, Fei; MacCulloch, Tara; Fahmi, Noureddine; Stephanopoulos, Nicholas; Liu, Yan; Seeman, Nadrian C. [Department; Yan, Hao


    The foundational goal of structural DNA nanotechnology—the field that uses oligonucleotides as a molecular building block for the programmable self-assembly of nanostructured systems—was to use DNA to construct three-dimensional (3D) lattices for solving macromolecular structures. The programmable nature of DNA makes it an ideal system for rationally constructing self-assembled crystals and immobilizing guest molecules in a repeating 3D array through their specific stereospatial interactions with the scaffold. In this work, we have extended a previously described motif (4 × 5) by expanding the structure to a system that links four double-helical layers; we use a central weaving oligonucleotide containing a sequence of four six-base repeats (4 × 6), forming a matrix of layers that are organized and dictated by a series of Holliday junctions. In addition, we have assembled mirror image crystals (l-DNA) with the identical sequence that are completely resistant to nucleases. Bromine and selenium derivatives were obtained for the l- and d-DNA forms, respectively, allowing phase determination for both forms and solution of the resulting structures to 3.0 and 3.05 Å resolution. Both right- and left-handed forms crystallized in the trigonal space groups with mirror image 3-fold helical screw axes P32 and P31 for each motif, respectively. The structures reveal a highly organized array of discrete and well-defined cavities that are suitable for hosting guest molecules and allow us to dictate a priori the assembly of guest–DNA conjugates with a specified crystalline hand.

  11. Charge conduction and breakdown mechanisms in self-assembled nanodielectrics. (United States)

    DiBenedetto, Sara A; Facchetti, Antonio; Ratner, Mark A; Marks, Tobin J


    Developing alternative high dielectric constant (k) materials for use as gate dielectrics is essential for continued advances in conventional inorganic CMOS and organic thin film transistors (OTFTs). Thicker films of high-k materials suppress tunneling leakage currents while providing effective capacitances comparable to those of thin films of lower-k materials. Self-assembled monolayers (SAMs) and multilayers offer attractive options for alternative OTFT gate dielectrics. One class of materials, organosilane-based self-assembled nanodielectrics (SANDs), has been shown to form robust films with excellent insulating and surface passivation properties, enhancing both organic and inorganic TFT performance and lowering device operating voltages. Since gate leakage current through the dielectric is one factor limiting continued TFT performance improvements, we investigate here the current (voltage, temperature) (I (V,T)) transport characteristics of SAND types II (pi-conjugated layer) and III (sigma-saturated + pi-conjugated layers) in Si/native SiO(2)/SAND/Au metal-insulator-metal (MIS) devices over the temperature range -60 to +100 degrees C. It is found that the location of the pi-conjugated layer with respect to the Si/SiO(2) substrate surface in combination with a saturated alkylsilane tunneling barrier is crucial in controlling the overall leakage current through the various SAND structures. For small applied voltages, hopping transport dominates at all temperatures for the pi-conjugated system (type II). However, for type III SANDs, the sigma- and pi-monolayers dominate the transport in two different transport regimes: hopping between +25 degrees C and +100 degrees C, and an apparent switch to tunneling for temperatures below 25 degrees C. The sigma-saturated alkylsilane tunneling barrier functions to reduce type III current leakage by blocking injected electrons, and by enabling bulk-dominated (Poole-Frenkel) transport vs electrode-dominated (Schottky) transport

  12. Principles Governing the Self Assembly of Polypeptide Nanoparticles (United States)

    Wahome, Newton

    Self assembling systems on the nanometer scale afford the advantage of being able to control submicron level events. In this study, we focus on the self-assembling polypeptide nanoparticles (SAPN). The SAPN scaffold is made up of oligomerizing domains that align along the principle rotational axes of icosahedral symmetry. By aligning them along these axes, a particle with spherical geometry can be achieved. This particle can be utilized as a vaccine, as a drug delivery vehicle, or as a biomedical imaging device. This research will try to answer why the SAPN self-assembles into distinct molecular weight ranges while mostly maintaining a spherical morphology. The first means will be theoretical and computational, where we will utilize a mathematical formalism to find out how the packing of SAPN's monomeric units can occur within symmetric space. Then molecular dynamics will be run within this symmetric space to test the per amino acid residue susceptibility of SAPN towards becoming polymorphic in nature. Means for examining the aggregation propensity of SAPN will be also be tested. Specifically, the relationship of different sequences of SAPN with pH will be elucidated. Co-assembly of SAPN to reduce the surface density of an aggregation prone epitope will be tested. Also, aggregation reduction consisting of the exchange of an anionic denaturant with a positively charged suppressor in order to mitigate a priori peptide association and misfolding, will also be attempted. SAPN has been shown to be an immunogenic platform for the presentation of pathogen derived antigens. We will attempt to show the efficacy of presenting an antigen from HIV-1 which is structurally restrained to best match the native conformation on the virus. Immunological studies will be performed to test the effect of this approach, as well testing the antigenicity of the nanoparticle in the absence of adjuvant. Finally, the antigen presenting nanoparticles will undergo formulation testing, to measure

  13. Charge Conduction and Breakdown Mechanisms in Self-Assembled Nanodielectrics

    Energy Technology Data Exchange (ETDEWEB)

    DiBenedetto, S.; Facchetti, A; Ratner, M; Marks, T


    Developing alternative high dielectric constant (k) materials for use as gate dielectrics is essential for continued advances in conventional inorganic CMOS and organic thin film transistors (OTFTs). Thicker films of high-k materials suppress tunneling leakage currents while providing effective capacitances comparable to those of thin films of lower-k materials. Self-assembled monolayers (SAMs) and multilayers offer attractive options for alternative OTFT gate dielectrics. One class of materials, organosilane-based self-assembled nanodielectrics (SANDs), has been shown to form robust films with excellent insulating and surface passivation properties, enhancing both organic and inorganic TFT performance and lowering device operating voltages. Since gate leakage current through the dielectric is one factor limiting continued TFT performance improvements, we investigate here the current (voltage, temperature) (I (V,T)) transport characteristics of SAND types II ({Pi}-conjugated layer) and III ({sigma}-saturated + {Pi}-conjugated layers) in Si/native SiO{sub 2}/SAND/Au metal-insulator-metal (MIS) devices over the temperature range -60 to +100 C. It is found that the location of the {Pi}-conjugated layer with respect to the Si/SiO{sub 2} substrate surface in combination with a saturated alkylsilane tunneling barrier is crucial in controlling the overall leakage current through the various SAND structures. For small applied voltages, hopping transport dominates at all temperatures for the {Pi}-conjugated system (type II). However, for type III SANDs, the {sigma}- and {Pi}- monolayers dominate the transport in two different transport regimes: hopping between +25 C and +100 C, and an apparent switch to tunneling for temperatures below 25 C. The {sigma}-saturated alkylsilane tunneling barrier functions to reduce type III current leakage by blocking injected electrons, and by enabling bulk-dominated (Poole-Frenkel) transport vs electrode-dominated (Schottky) transport in

  14. Protective Coatings for Space System Components Fabricated Using Ionic Self Assembled Monolayer Processes

    National Research Council Canada - National Science Library

    Miler, Mike


    Self-assembled multilayer thin film fabrication methods offer unique opportunities to incorporate multiple functionalities into coatings for space system materials and structures as well as consumer products...

  15. Self Assembly of Nano Metric Metallic Particles for Realization of Photonic and Electronic Nano Transistors

    Directory of Open Access Journals (Sweden)

    Asaf Shahmoon


    Full Text Available In this paper, we present the self assembly procedure as well as experimental results of a novel method for constructing well defined arrangements of self assembly metallic nano particles into sophisticated nano structures. The self assembly concept is based on focused ion beam (FIB technology, where metallic nano particles are self assembled due to implantation of positive gallium ions into the insulating material (e.g., silica as in silicon on insulator wafers that acts as intermediary layer between the substrate and the negatively charge metallic nanoparticles.

  16. Self-assembly of "patchy" nanoparticles: a versatile approach to functional hierarchical materials

    National Research Council Canada - National Science Library

    Lunn, David J; Finnegan, John R; Manners, Ian


    The solution-phase self-assembly or "polymerization" of discrete colloidal building blocks, such as "patchy" nanoparticles and multicompartment micelles, is attracting growing attention with respect...

  17. Combing and self-assembly phenomena in dry films of Taxol-stabilized microtubules

    Directory of Open Access Journals (Sweden)

    Rose Franck


    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.

  18. Self-assembled fibre optoelectronics with discrete translational symmetry. (United States)

    Rein, Michael; Levy, Etgar; Gumennik, Alexander; Abouraddy, Ayman F; Joannopoulos, John; Fink, Yoel


    Fibres with electronic and photonic properties are essential building blocks for functional fabrics with system level attributes. The scalability of thermal fibre drawing approach offers access to large device quantities, while constraining the devices to be translational symmetric. Lifting this symmetry to create discrete devices in fibres will increase their utility. Here, we draw, from a macroscopic preform, fibres that have three parallel internal non-contacting continuous domains; a semiconducting glass between two conductors. We then heat the fibre and generate a capillary fluid instability, resulting in the selective transformation of the cylindrical semiconducting domain into discrete spheres while keeping the conductive domains unchanged. The cylindrical-to-spherical expansion bridges the continuous conducting domains to create ∼10 4 self-assembled, electrically contacted and entirely packaged discrete spherical devices per metre of fibre. The photodetection and Mie resonance dependent response are measured by illuminating the fibre while connecting its ends to an electrical readout.

  19. Self assembled silicon nanowire Schottky junction assisted by collagen (United States)

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


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

  20. Nanoscale Nitrogen Doping in Silicon by Self-Assembled Monolayers (United States)

    Guan, Bin; Siampour, Hamidreza; Fan, Zhao; Wang, Shun; Kong, Xiang Yang; Mesli, Abdelmadjid; Zhang, Jian; Dan, Yaping


    This Report presents a nitrogen-doping method by chemically forming self-assembled monolayers on silicon. Van der Pauw technique, secondary-ion mass spectroscopy and low temperature Hall effect measurements are employed to characterize the nitrogen dopants. The experimental data show that the diffusion coefficient of nitrogen dopants is 3.66 × 10-15 cm2 s-1, 2 orders magnitude lower than that of phosphorus dopants in silicon. It is found that less than 1% of nitrogen dopants exhibit electrical activity. The analysis of Hall effect data at low temperatures indicates that the donor energy level for nitrogen dopants is located at 189 meV below the conduction band, consistent with the literature value.

  1. Communication: Programmable self-assembly of thin-shell mesostructures (United States)

    Halverson, Jonathan D.; Tkachenko, Alexei V.


    We study numerically the possibility of programmable self-assembly of various thin-shell architectures. They include clusters isomorphic to fullerenes C20 and C60, finite and infinite sheets, tube-shaped and toroidal mesostructures. Our approach is based on the recently introduced directionally functionalized nanoparticle platform, for which we employ a hybrid technique of Brownian dynamics with stochastic bond formation. By combining a number of strategies, we were able to achieve a near-perfect yield of the desired structures with a reduced "alphabet" of building blocks. Among those strategies are the following: the use of bending rigidity of the interparticle bond as a control parameter, programming the morphology with a seed architecture, use of chirality-preserving symmetries for reduction of the particle alphabet, and the hierarchic approach.

  2. Phase Diagrams of Electrostatically Self-Assembled Amphiplexes

    Energy Technology Data Exchange (ETDEWEB)

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


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

  3. Controlled doping by self-assembled dendrimer-like macromolecules (United States)

    Wu, Haigang; Guan, Bin; Sun, Yingri; Zhu, Yiping; Dan, Yaping


    Doping via self-assembled macromolecules might offer a solution for developing single atom electronics by precisely placing individual dopants at arbitrary location to meet the requirement for circuit design. Here we synthesize dendrimer-like polyglycerol macromolecules with each carrying one phosphorus atom in the core. The macromolecules are immobilized by the coupling reagent onto silicon surfaces that are pre-modified with a monolayer of undecylenic acid. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) are employed to characterize the synthesized macromolecules and the modified silicon surfaces, respectively. After rapid thermal annealing, the phosphorus atoms carried by the macromolecules diffuse into the silicon substrate, forming dopants at a concentration of 1017 cm-3. Low-temperature Hall effect measurements reveal that the ionization process is rather complicated. Unlike the widely reported simple ionization of phosphorus dopants, nitrogen and carbon are also involved in the electronic activities in the monolayer doped silicon.

  4. Characterization of the Casein/Keratin Self-Assembly Nanomicelles

    Directory of Open Access Journals (Sweden)

    Su Xiao-Zhou


    Full Text Available Complex nanomicelles were made from casein and keratin through electrostatic self-assembly and transglutaminase fixation that was proved to be harmless and green. The complex nanomicelles were characterized by dynamic light scattering, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and steady-state florescence. The results show that the complex nanomcelles acquired at the neutral pH in the mass ratio of casein to keratin 4 : 1 exhibit an anomalous sphere shape with uniform size which the diameter is about 40–70 nm. The complex nanomicelles in solution possess excellent dilution and storage stability due to the fixation and their high ζ-potential (22.8 mV. The complex nanomicelles are relatively hydrophilic and have a good potential for industrial application.

  5. Patchy Particles: Directional Self-Assembly of Nanoparticles (United States)

    Zhang, Z. L.; Glotzer, S. C.


    Nanoparticles functionalized by organic molecules and biological ligands attached to their surfaces may provide a new route to directly engineer materials with specific functionality, such as wires, sheets, rings, and disks. We developed a molecular simulation model to study the self-assembly of patchy" particles, and present simulations to elucidate the effects of various surface patterns and topologies on the assembled structures. We demonstrate how particular surface interaction patterns conspire to produce chains, rings, sheets and more complex structures such as shells. Our initial computational studies predict that surface pattern and topology providing directional control and strongly influence the equilibrium structures. The proposed model may be a useful tool in exploring the complex behavior of synthetic and biological nanoparticle self-organization.

  6. Functional Molecular Junctions Derived from Double Self-Assembled Monolayers. (United States)

    Seo, Sohyeon; Hwang, Eunhee; Cho, Yunhee; Lee, Junghyun; Lee, Hyoyoung


    Information processing using molecular junctions is becoming more important as devices are miniaturized to the nanoscale. Herein, we report functional molecular junctions derived from double self-assembled monolayers (SAMs) intercalated between soft graphene electrodes. Newly assembled molecular junctions are fabricated by placing a molecular SAM/(top) electrode on another molecular SAM/(bottom) electrode by using a contact-assembly technique. Double SAMs can provide tunneling conjugation across the van der Waals gap between the terminals of each monolayer and exhibit new electrical functions. Robust contact-assembled molecular junctions can act as platforms for the development of equivalent contact molecular junctions between top and bottom electrodes, which can be applied independently to different kinds of molecules to enhance either the structural complexity or the assembly properties of molecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Self assembled monolayers of octadecyltrichlorosilane for dielectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijay, E-mail: [Centre for Nanoscience and Engineering, Indian Institute of Science-Bangalore (India); Mechanical Engineering Department, Birla Institute of Technology and Science-Pilani (India); Puri, Paridhi; Nain, Shivani [Mechanical Engineering Department, Birla Institute of Technology and Science-Pilani (India); Bhat, K. N. [Centre for Nanoscience and Engineering, Indian Institute of Science-Bangalore (India); Sharma, N. N. [Mechanical Engineering Department, Birla Institute of Technology and Science-Pilani (India); School of Automobile, Mechanical & Mechatronics, Manipal University-Jaipur (India)


    Treatment of surfaces to change the interaction of fluids with them is a critical step in constructing useful microfluidics devices, especially those used in biological applications. Selective modification of inorganic materials such as Si, SiO{sub 2} and Si{sub 3}N{sub 4} is of great interest in research and technology. We evaluated the chemical formation of OTS self-assembled monolayers on silicon substrates with different dielectric materials. Our investigations were focused on surface modification of formerly used common dielectric materials SiO{sub 2}, Si{sub 3}N{sub 4} and a-poly. The improvement of wetting behaviour and quality of monolayer films were characterized using Atomic force microscope, Scanning electron microscope, Contact angle goniometer, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) monolayer deposited oxide surface.

  8. Three-dimensional structures self-assembled from DNA bricks. (United States)

    Ke, Yonggang; Ong, Luvena L; Shih, William M; Yin, Peng


    We describe a simple and robust method to construct complex three-dimensional (3D) structures by using short synthetic DNA strands that we call "DNA bricks." In one-step annealing reactions, bricks with hundreds of distinct sequences self-assemble into prescribed 3D shapes. Each 32-nucleotide brick is a modular component; it binds to four local neighbors and can be removed or added independently. Each 8-base pair interaction between bricks defines a voxel with dimensions of 2.5 by 2.5 by 2.7 nanometers, and a master brick collection defines a "molecular canvas" with dimensions of 10 by 10 by 10 voxels. By selecting subsets of bricks from this canvas, we constructed a panel of 102 distinct shapes exhibiting sophisticated surface features, as well as intricate interior cavities and tunnels.

  9. Self-assembly of nematic liquid crystal elastomer filaments (United States)

    Wei, Wei-Shao; Xia, Yu; Yang, Shu; Yodh, A. G.

    In this work we investigate the self-assembly of nematic liquid crystal polymer (NLCP) filaments and their corresponding cross-linked elastomer structures. Specifically, by fine-tuning surfactant concentration, prepolymer chain length, and temperature within a background aqueous phase we can generate filaments composed of oligomerized LC monomers. Filaments with narrowly dispersed diameters ranging from one hundred nanometers to a few micrometers can be obtained. Using polarization optical microscopy, we show that the nematic LCs within the filaments have an escaped radial structure. After photo-cross-linking, nematic liquid crystal elastomer filaments are obtained with well-maintained directors and smooth surface structure. Since these materials are elastomers, the size and mechanical and optical response of the filaments can be ''tuned'' near the nematic to isotropic phase transition temperature. This work is supported by NSF DMR16-07378, PENN MRSEC Grant DMR11-20901, and NASA Grant NNX08AO0G.

  10. Supramolecular amplification of amyloid self-assembly by iodination (United States)

    Bertolani, Arianna; Pirrie, Lisa; Stefan, Loic; Houbenov, Nikolay; Haataja, Johannes S.; Catalano, Luca; Terraneo, Giancarlo; Giancane, Gabriele; Valli, Ludovico; Milani, Roberto; Ikkala, Olli; Resnati, Giuseppe; Metrangolo, Pierangelo


    Amyloid supramolecular assemblies have found widespread exploitation as ordered nanomaterials in a range of applications from materials science to biotechnology. New strategies are, however, required for understanding and promoting mature fibril formation from simple monomer motifs through easy and scalable processes. Noncovalent interactions are key to forming and holding the amyloid structure together. On the other hand, the halogen bond has never been used purposefully to achieve control over amyloid self-assembly. Here we show that single atom replacement of hydrogen with iodine, a halogen-bond donor, in the human calcitonin-derived amyloidogenic fragment DFNKF results in a super-gelator peptide, which forms a strong and shape-persistent hydrogel at 30-fold lower concentration than the wild-type pentapeptide. This is remarkable for such a modest perturbation in structure. Iodination of aromatic amino acids may thus develop as a general strategy for the design of new hydrogels from unprotected peptides and without using organic solvents.

  11. Fabrication of bioinspired nanostructured materials via colloidal self-assembly (United States)

    Huang, Wei-Han

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

  12. Toward Single Electron Nanoelectronics Using Self-Assembled DNA Structure. (United States)

    Tapio, Kosti; Leppiniemi, Jenni; Shen, Boxuan; Hytönen, Vesa P; Fritzsche, Wolfgang; Toppari, J Jussi


    DNA based structures offer an adaptable and robust way to develop customized nanostructures for various purposes in bionanotechnology. One main aim in this field is to develop a DNA nanobreadboard for a controllable attachment of nanoparticles or biomolecules to form specific nanoelectronic devices. Here we conjugate three gold nanoparticles on a defined size TX-tile assembly into a linear pattern to form nanometer scale isolated islands that could be utilized in a room temperature single electron transistor. To demonstrate this, conjugated structures were trapped using dielectrophoresis for current-voltage characterization. After trapping only high resistance behavior was observed. However, after extending the islands by chemical growth of gold, several structures exhibited Coulomb blockade behavior from 4.2 K up to room temperature, which gives a good indication that self-assembled DNA structures could be used for nanoelectronic patterning and single electron devices.

  13. Engineering self-assembled bioreactors from protein microcompartments

    Energy Technology Data Exchange (ETDEWEB)

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


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

  14. Protocols for self-assembly and imaging of DNA nanostructures. (United States)

    Sobey, Thomas L; Simmel, Friedrich C


    Programed molecular structures allow us to research and make use of physical, chemical, and biological effects at the nanoscale. They are an example of the "bottom-up" approach to nanotechnology, with structures forming through self-assembly. DNA is a particularly useful molecule for this purpose, and some of its advantages include parallel (as opposed to serial) assembly, naturally occurring "tools," such as enzymes and proteins for making modifications and attachments, and structural dependence on base sequence. This allows us to develop one, two, and three dimensional structures that are interesting for their fundamental physical and chemical behavior, and for potential applications such as biosensors, medical diagnostics, molecular electronics, and efficient light-harvesting systems. We describe five techniques that allow one to assemble and image such structures: concentration measurement by ultraviolet absorption, titration gel electrophoresis, thermal annealing, fluorescence microscopy, and atomic force microscopy in fluids.

  15. Self-assembly of rhodamine 6G on silver nanoparticles (United States)

    Deng, Hua; Yu, Hongtao


    Understanding interactions between nanoparticles and small molecules is of significance for design of nanoparticle-based materials. Each citrate-coated silver nanoparticle (AgNP, 24 nm) in solution attracts 210,000 rhodamine 6G (R6G) molecules to assemble on its surface to form 170 nm "micelle-like" structures, where the fluorescence of the R6G molecules is efficiently quenched. The "micelles" can form agglomerates of 370 nm at higher concentrations. The R6G-AgNP self-assembly does not occur at higher R6G concentrations (≥5 μM) or can be prevented if AgNP is coated with polymers such as polyethylene glycol or polyvinyl pyrrolidone.

  16. Limitations of Self-Assembly at Temperature One (extended abstract

    Directory of Open Access Journals (Sweden)

    Matthew J. Patitz


    Full Text Available We prove that if a subset X of the integer Cartesian plane weakly self-assembles at temperature 1 in a deterministic (Winfree tile assembly system satisfying a natural condition known as *pumpability*, then X is a finite union of doubly periodic sets. This shows that only the most simple of infinite shapes and patterns can be constructed using pumpable temperature 1 tile assembly systems, and gives strong evidence for the thesis that temperature 2 or higher is required to carry out general-purpose computation in a tile assembly system. Finally, we show that general-purpose computation *is* possible at temperature 1 if negative glue strengths are allowed in the tile assembly model.

  17. Spin-flip transitions in self-assembled quantum dots (United States)

    Stavrou, V. N.


    Detailed realistic calculations of the spin-flip time (T 1) for an electron in a self-assembled quantum dot (SAQD) due to emission of an acoustic phonon, using only bulk properties with no fitting parameters, are presented. Ellipsoidal lens shaped Inx Ga1-x As quantum dots, with electronic states calculated using 8-band strain dependent {k \\cdot p} theory, are considered. The phonons are treated as bulk acoustic phonons coupled to the electron by both deformation potential and piezoelectric interactions. The dependence of T 1 on the geometry of SAQD, on the applied external magnetic field and on the lattice temperature is highlighted. The theoretical results are close to the experimental measurements on the spin-flip times for a single electron in QD.

  18. Modelling the self-assembly of virus capsids (United States)

    Johnston, Iain G.; Louis, Ard A.; Doye, Jonathan P. K.


    We use computer simulations to study a model, first proposed by Wales (2005 Phil. Trans. R. Soc. A 363 357), for the reversible and monodisperse self-assembly of simple icosahedral virus capsid structures. The success and efficiency of assembly as a function of thermodynamic and geometric factors can be qualitatively related to the potential energy landscape structure of the assembling system. Even though the model is strongly coarse-grained, it exhibits a number of features also observed in experiments, such as sigmoidal assembly dynamics, hysteresis in capsid formation and numerous kinetic traps. We also investigate the effect of macromolecular crowding on the assembly dynamics. Crowding agents generally reduce capsid yields at optimal conditions for non-crowded assembly, but may increase yields for parameter regimes away from the optimum. Finally, we generalize the model to a larger triangulation number T = 3, and observe assembly dynamics more complex than that seen for the original T = 1 model.

  19. Self-assembly of ABA triblock copolymers under soft confinement (United States)

    Sheng, Yuping; An, Jian; Zhu, Yutian


    Using Monte Carlo method, the self-assembly of ABA triblock copolymers under soft confinement is investigated in this study. The soft confinement is achieved by a poor solvent environment for the polymer, which makes the polymer aggregate into a droplet. Various effects, including the block length ratio, the solvent quality for the blocks B, and the incompatibility between blocks A and B, on the micellar structures induced by soft confinement are examined. By increasing the solvent quality of B blocks, the micellar structure transforms from stacked lamella to bud-like structure, and then to onion-like structure for A5B8A5 triblock copolymers, while the inner micellar structure changes from spherical phase to various cylindrical phase, such as inner single helix, double helixes, stacked rings and cage-like structures, for A7B4A7 triblock copolymers. Moreover, the formation pathways of some typical aggregates are examined to illustrate their growth mechanisms.

  20. Self-Assembled PbSe Nanowire:Perovskite Hybrids

    KAUST Repository

    Yang, Zhenyu


    © 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.

  1. Mixed carboranethiol self-assembled monolayers on gold surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, Adem [Micro and Nanotechnology Department, Graduate School of Natural and Applied Science, Middle East Technical University, Ankara 06800 (Turkey); Sohrabnia, Nima [Department of Chemistry, Middle East Technical University, Ankara 06800 (Turkey); Yilmaz, Ayşen [Micro and Nanotechnology Department, Graduate School of Natural and Applied Science, Middle East Technical University, Ankara 06800 (Turkey); Department of Chemistry, Middle East Technical University, Ankara 06800 (Turkey); Danışman, M. Fatih, E-mail: [Micro and Nanotechnology Department, Graduate School of Natural and Applied Science, Middle East Technical University, Ankara 06800 (Turkey); Department of Chemistry, Middle East Technical University, Ankara 06800 (Turkey)


    Highlights: • M1 binds to the gold surface preferentially when co-deposited with M9 or O1. • Contact angles show similar trends regardless of the gold substrate roughness. • Contact angles were lower, with higher hysteresis, on template stripped gold. • Mixed carboranethiol SAMs have similar morphological properties regardless of mixing ratio. - Abstract: Carboranethiol self-assembled monolayers on metal surfaces have been shown to be very convenient systems for surface engineering. Here we have studied pure and mixed self-assembled monolayers (SAMs) of three different carboranethiol (CT) isomers on gold surfaces. The isomers were chosen with dipole moments pointing parallel to (m-1-carboranethiol, M1), out of (m-9-carboranethiol, M9) and into (o-1-carboranethiol, O1) the surface plane, in order to investigate the effect of dipole moment orientation on the film properties. In addition, influence of the substrate surface morphology on the film properties was also studied by using flame annealed (FA) and template stripped (TS) gold surfaces. Contact angle measurements indicate that in M1/M9 and M1/O1 mixed SAMs, M1 is the dominant species on the surface even for low M1 ratio in the growth solution. Whereas for O1/M9 mixed SAMs no clear evidence could be observed indicating dominance of one of the species over the other one. Though contact angle values were lower and hysteresis values were higher for SAMs grown on TS gold surfaces, the trends in the behavior of the contact angles with changing mixing ratio were identical for SAMs grown on both substrates. Atomic force microscopy images of the SAMs on TS gold surfaces indicate that the films have similar morphological properties regardless of mixing ratio.

  2. Self-assembly of silver nanoparticles and bacteriophage

    Directory of Open Access Journals (Sweden)

    Santi Scibilia


    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.

  3. Guided self-assembly of nanostructured titanium oxide (United States)

    Wang, Baoxiang; Rozynek, Zbigniew; Fossum, Jon Otto; Knudsen, Kenneth D.; Yu, Yingda


    A series of nanostructured titanium oxide particles were synthesized by a simple wet chemical method and characterized by means of small-angle x-ray scattering (SAXS)/wide-angle x-ray scattering (WAXS), atomic force microscope (AFM), scanning electron microscope (SEM), transmission electron microscope (TEM), thermal analysis, and rheometry. Tetrabutyl titanate (TBT) and ethylene glycol (EG) can be combined to form either TiOx nanowires or smooth nanorods, and the molar ratio of TBT:EG determines which of these is obtained. Therefore, TiOx nanorods with a highly rough surface can be obtained by hydrolysis of TBT with the addition of cetyl-trimethyl-ammonium bromide (CTAB) as surfactant in an EG solution. Furthermore, TiOx nanorods with two sharp ends can be obtained by hydrolysis of TBT with the addition of salt (LiCl) in an EG solution. The AFM results show that the TiOx nanorods with rough surfaces are formed by the self-assembly of TiOx nanospheres. The electrorheological (ER) effect was investigated using a suspension of titanium oxide nanowires or nanorods dispersed in silicone oil. Oil suspensions of titanium oxide nanowires or nanorods exhibit a dramatic reorganization when submitted to a strong DC electric field and the particles aggregate to form chain-like structures along the direction of applied electric field. Two-dimensional SAXS images from chains of anisotropically shaped particles exhibit a marked asymmetry in the SAXS patterns, reflecting the preferential self-assembly of the particles in the field. The suspension of rough TiOx nanorods shows stronger ER properties than that of the other nanostructured TiOx particles. We find that the particle surface roughness plays an important role in modification of the dielectric properties and in the enhancement of the ER effect.

  4. Self-assembling hybrid diamond-biological quantum devices (United States)

    Albrecht, A.; Koplovitz, G.; Retzker, A.; Jelezko, F.; Yochelis, S.; Porath, D.; Nevo, Y.; Shoseyov, O.; Paltiel, Y.; Plenio, M. B.


    The realization of scalable arrangements of nitrogen vacancy (NV) centers in diamond remains a key challenge on the way towards efficient quantum information processing, quantum simulation and quantum sensing applications. Although technologies based on implanting NV-centers in bulk diamond crystals or hybrid device approaches have been developed, they are limited by the achievable spatial resolution and by the intricate technological complexities involved in achieving scalability. We propose and demonstrate a novel approach for creating an arrangement of NV-centers, based on the self-assembling capabilities of biological systems and their beneficial nanometer spatial resolution. Here, a self-assembled protein structure serves as a structural scaffold for surface functionalized nanodiamonds, in this way allowing for the controlled creation of NV-structures on the nanoscale and providing a new avenue towards bridging the bio-nano interface. One-, two- as well as three-dimensional structures are within the scope of biological structural assembling techniques. We realized experimentally the formation of regular structures by interconnecting nanodiamonds using biological protein scaffolds. Based on the achievable NV-center distances of 11 nm, we evaluate the expected dipolar coupling interaction with neighboring NV-centers as well as the expected decoherence time. Moreover, by exploiting these couplings, we provide a detailed theoretical analysis on the viability of multiqubit quantum operations, suggest the possibility of individual addressing based on the random distribution of the NV intrinsic symmetry axes and address the challenges posed by decoherence and imperfect couplings. We then demonstrate in the last part that our scheme allows for the high-fidelity creation of entanglement, cluster states and quantum simulation applications.

  5. Self-Assembly and Crystallization of Conjugated Block Copolymers (United States)

    Davidson, Emily Catherine

    This dissertation demonstrates the utility of molecular design in conjugated polymers to create diblock copolymers that robustly self-assemble in the melt and confine crystallization upon cooling. This work leverages the model conjugated polymer poly(3-(2'-ethyl)hexylthiophene) (P3EHT), which features a branched side chain, resulting in a dramatically reduced melting temperature (Tm 80°C) relative to the widely-studied poly(3-hexylthiophene) (P3HT) (Tm 200°C). This reduced melting temperature permits an accessible melt phase, without requiring that the segregation strength (chiN) be dramatically increased. Thus, diblock copolymers containing P3EHT demonstrate robust diblock copolymer self-assembly in the melt over a range of compositions and morphologies. Furthermore, confined crystallization in the case of both glassy (polystyrene (PS) matrix block) and soft (polymethylacrylate (PMA) matrix block) confinement is studied, with the finding that even in soft confinement, crystallization is constrained within the diblock microdomains. This success demonstrates the strategy of leveraging molecular design to decrease the driving force for crystallization as a means to achieving robust self-assembly and confined crystallization in conjugated block copolymers. Importantly, despite the relatively flexible nature of P3EHT in the melt, the diblock copolymer phase behavior appears to be significantly impacted by the stiffness (persistence length of 3 nm) of the P3EHT chain compared to the coupled amorphous blocks (persistence length 0.7 nm). In particular, it is shown that the synthesized morphologies are dominated by a very large composition window for lamellar geometries (favored at high P3EHT volume fractions); cylindrical geometries are favored when P3EHT is the minority fraction. This asymmetry of the composition window is attributed to impact of conformational asymmetry (the difference in chain stiffness, as opposed to shape) between conjugated and amorphous blocks

  6. Construction of energy transfer pathways self-assembled from DNA-templated stacks of anthracene. (United States)

    Iwaura, Rika; Yui, Hiroharu; Someya, Yuu; Ohnishi-Kameyama, Mayumi


    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.

  7. Structural investigations of self-assembled monolayers for organic electronics: results from X-ray reflectivity. (United States)

    Khassanov, Artoem; Steinrück, Hans-Georg; Schmaltz, Thomas; Magerl, Andreas; Halik, Marcus


    Self-assembled monolayers (SAMs) have been established as crucial interlayers and electronically active layers in organic electronic devices, such as organic light emitting diodes (OLEDs), organic photovoltaics (OPVs), organic thin film transistors (OTFTs), and nonvolatile memories (NVMs). The use of self-assembling functionalized organic molecules is beneficial due to mainly three advantages compared with common thin film deposition approaches. (1) Molecular self-assembly occurs with surface selectivity, determined by the interaction between the functional anchor group of the organic molecules and the target surface. (2) The film thickness of the resulting layers is perfectly controllable on the angstrom scale, due to the self-terminating film formation to only a single molecular layer. And finally, (3) the wide variability in the chemical structure of such molecules enables different SAM functionalities for devices, ranging from electrical insulation to charge storage to charge transport. The SAM approach can be further expanded by employing several functionalized molecules to create mixed SAMs with consequently mixed properties. The function of SAMs in devices depends not only on the chemical structure of the molecules but also on their final arrangement and orientation on the surface. A reliable and nondestructive in-depth characterization of SAMs on nonconductive oxide surfaces is still challenging because of the very small thickness and the impracticality of methods such as scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). In this Account, we illustrate how X-ray reflectivity (XRR) provides analytical access to major questions of SAM composition, morphology, and even formation by means of investigations of pure and mixed SAMs based on phosphonic acids (PAs) of various chain structures on flat alumina (AlOx) surfaces. XRR is an analytical method that provides access to spatially averaged structural depth profiles over a relatively

  8. Urea-functionalized crystalline capsules for recognition and separation of tetrahedral oxoanions

    Energy Technology Data Exchange (ETDEWEB)

    Custelcean, Radu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division


    We reviewed the persistent ability of tripodal TREN-based tris-urea receptors (TREN = tris(2-aminoethyl)amine) to self-assemble with a variety of oxoanions into dimeric capsules upon crystallization. The capsule crystallization allows for charge-, shape-, and size-selective encapsulation of tetrahedral XO4n-anions (n = 2,3), and provides an effective way to separate these anions from competitive aqueous environments.

  9. Challenges and advances in the field of self-assembled membranes

    NARCIS (Netherlands)

    van Rijn, Patrick; Tutus, Murat; Kathrein, Christine; Zhu, Leilei; Wessling, Matthias; Schwaneberg, Ulrich; Boeker, Alexander


    Self-assembled membranes are of vital importance in biological systems e. g. cellular and organelle membranes, however, more focus is being put on synthetic self-assembled membranes not only as an alternative for lipid membranes but also as an alternative for lithographic methods. More

  10. Student Learning about Biomolecular Self-Assembly Using Two Different External Representations (United States)

    Host, Gunnar E.; Larsson, Caroline; Olson, Arthur; Tibell, Lena A. E.


    Self-assembly is the fundamental but counterintuitive principle that explains how ordered biomolecular complexes form spontaneously in the cell. This study investigated the impact of using two external representations of virus self-assembly, an interactive tangible three-dimensional model and a static two-dimensional image, on student learning…

  11. Metal-driven hierarchical self-assembled zigzag nanoarchitectures with electrical conductivity. (United States)

    Qiao, Yan; Lin, Yiyang; Liu, Song; Zhang, Shaofei; Chen, Huanfa; Wang, Yijie; Yan, Yun; Guo, Xuefeng; Huang, Jianbin


    Quasi-one-dimensional electroactive materials with zigzag shape are fabricated by supramolecular self-assembly of a tetrathiafulvalene (TTF) derivative and metal ions under mild conditions. This is the first time that self-assembled organic conductors with zigzag shape are reported.

  12. From self-organization to self-assembly: a new materialism? (United States)

    Vincent, Bernadette Bensaude


    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.

  13. Comparative self-assembly studies and self-sorting of two ...

    Indian Academy of Sciences (India)

    The propensity for self-assembly of NDI-1 was greater due to symmetrical placement of two amide groups on either arms of this chromophore which allowed -stacking in tandem with hydrogen-bonding, while NDI-2 formed thermally more stable self-assembled fibres possibly due to location of two amide groups in close ...

  14. The Self-Assembly Properties of a Benzene-1,3,5-tricarboxamide Derivative (United States)

    Stals, Patrick J. M.; Haveman, Jan F.; Palmans, Anja R. A.; Schenning, Albertus P. H. J.


    A series of experiments involving the synthesis and characterization of a benzene-1,3,5-tricarboxamide derivative and its self-assembly properties are reported. These laboratory experiments combine organic synthesis, self-assembly, and physical characterization and are designed for upper-level undergraduate students to introduce the topic of…

  15. STM visualisation of counterions and the effect of charges on self-assembled monolayers of macrocycles

    Directory of Open Access Journals (Sweden)

    Tibor Kudernac


    Full Text Available Despite their importance in self-assembly processes, the influence of charged counterions on the geometry of self-assembled organic monolayers and their direct localisation within the monolayers has been given little attention. Recently, various examples of self-assembled monolayers composed of charged molecules on surfaces have been reported, but no effort has been made to prove the presence of counterions within the monolayer. Here we show that visualisation and exact localisation of counterions within self-assembled monolayers can be achieved with scanning tunnelling microscopy (STM. The presence of charges on the studied shape-persistent macrocycles is shown to have a profound effect on the self-assembly process at the liquid–solid interface. Furthermore, preferential adsorption was observed for the uncharged analogue of the macrocycle on a surface.

  16. Lyotropic liquid crystal engineering-ordered nanostructured small molecule amphiphile self-assembly materials by design. (United States)

    Fong, Celesta; Le, Tu; Drummond, Calum J


    Future nanoscale soft matter design will be guided to a large extent by the teachings of amphiphile (lipid or surfactant) self-assembly. Ordered nanostructured lyotropic liquid crystalline mesophases may form in select mixtures of amphiphile and solvent. To reproducibly engineer the low energy amphiphile self-assembly of materials for the future, we must first learn the design principles. In this critical review we discuss the evolution of these design rules and in particular discuss recent key findings regarding (i) what drives amphiphile self-assembly, (ii) what governs the self-assembly structures that are formed, and (iii) how can amphiphile self-assembly materials be used to enhance product formulations, including drug delivery vehicles, medical imaging contrast agents, and integral membrane protein crystallisation media. We focus upon the generation of 'dilutable' lyotropic liquid crystal phases with two- and three-dimensional geometries from amphiphilic small molecules (225 references). This journal is © The Royal Society of Chemistry 2012

  17. Self-assembled peptide nanomaterials for biomedical applications: promises and pitfalls (United States)

    Sun, Linlin; Zheng, Chunli; Webster, Thomas J


    Over the last several decades, a great number of advances have been made in the area of self-assembled supramolecules for regenerative medicine. Such advances have involved the design, preparation, and characterization of brand new self-assembled peptide nanomaterials for a variety of applications. Among all biomolecules considered for self-assembly applications, peptides have attracted a great deal of attention as building blocks for bottom-up fabrication, due to their versatility, ease of manufacturing, low costs, tunable structures, and versatile properties. Herein, some of the more exciting new designs of self-assembled peptides and their associated unique features are reviewed and several promising applications of how self-assembled peptides are advancing drug delivery, tissue engineering, antibacterial therapy, and biosensor device applications are highlighted. PMID:28053525

  18. Layer-by-layer self-assembled carbon nanotube electrode for microbial fuel cells application. (United States)

    Roh, Sung-Hee


    Anodic material is usually a limiting factor in power generation in microbial fuel cell (MFC). A meditatorless two-chambered MFC was constructed using new type of carbon nanotube (CNT)-based electrode architecture by layer-by-layer (LBL) self-assembly to increase power density. Multi-walled carbon nanotube (MWNT) and polyeletrolyte polyethyleneimine (PEI) were employed to modify carbon paper (CP) electrode utilizing a LBL self-assembly technique, and the electrochemical properties and performance of the modified electrode as an anode in MFC were investigated. The CNT-based LBL self-assembled electrode showed a better electrochemical performance than that of unmodified CP electrode. The self-assembled MWNT/PEI onto CP produced the maximum power density of 480 mW/m2, which was 48% larger than that of the plain CP anode. The CNT-based LBL self-assembled electrode therefore offers good prospects for application in MFCs.

  19. Prodrugs as self-assembled hydrogels: a new paradigm for biomaterials. (United States)

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


    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.

  20. Fibrin self-assembly is adapted to oxidation. (United States)

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


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

  1. Directed self-assembly of mesoscopic components for led applications (United States)

    Tkachenko, Anton

    Light-emitting diodes (LEDs) constitute a rapidly evolving and fast growing technology that promises to replace incandescent bulbs and compact fluorescent lights in many illumination applications. Large-area LED luminaires have a capability to transform lighting by providing a venue for development of smart lighting systems with additional benefits, such as visible light communications, sensing, health and productivity improvement through color temperature control, capability of creating "virtual sky" ceiling, and many others. The objective of this work is to explore directed self-assembly (DSA) approaches suitable for cost-effective assembly of large amount of LEDs and other mesoscopic (i.e. millimeter and sub-millimeter) electronic components and thus to enable manufacturing of smart lighting luminaires. Existing alternative approaches for assembly of semiconductor dies are examined including transfer printing, laser-assisted die transfer, and various directed self-assembly approaches using shape-recognition, magnetic and capillary forces, etc. After comparing their advantages and limitations, we developed two approaches to magnetic force-assisted DSA of LEDs on a large-area substrate in liquid and air medium. The first approach involves pick-up of buoyant and magnetic dies from the liquid surface onto the flexible substrate in a roll-to-roll process. The possibility of high-speed assembly of LED dies is demonstrated, but with a low yield due to the influence of the capillary force of the carrier liquid and the difficulty in ensuring reliable supply of dies to the assembly interface. To overcome the aforementioned challenges this process was modified to assemble the dies by sinking them onto the receiving substrate with a stencil mask on top, demonstrating LED assembly with a very low error rate but at a lower speed. A solder-assisted self-alignment is used to further improve placement precision and to ensure the proper orientation of the dies. The second

  2. Self-Assembly of Small Molecules for Organic Photovoltaic Applications (United States)

    Aytun, Taner

    Organic photovoltaic (OPV) solar cells aim to provide efficient, flexible and lightweight photovoltaics (PV) with simple processing and low-cost. Advances in device optimization, structural and molecular design, as well as mechanistic understanding have helped increase device efficiency and performance. Within the framework of active layer optimization, systematically improving bulk heterojunction (BHJ) morphology could improve the power conversion efficiency of OPVs. However, most strategies aimed at improving morphology focus on annealing methods or the use of solvent additives. Rational approaches in supramolecular self-assembly can potentially offer additional control over the morphology of BHJ active layers and lead to improved power conversion efficiencies. In Chapter 2, the author explores the effect of molecular shape on the assembly of electron donating small molecules, and its ensuing effect on OPV performance. Two tripodal 'star-shaped' donor molecules with diketopyrrolopyrrole (DPP) side chains were used to generate solution-processed BHJ OPVs. It was found that the tripod molecules neither aggregate in solution nor form crystalline domains in thin films when a branched alkyl solubilizing group is used. On the other hand, linear alkyl chains promote the formation of one-dimensional (1D) nanowires and crystalline domains as well. This work demonstrated that the one-dimensional assembly of donor molecules enhances the performance of the corresponding solution-processed OPVs by 50%. This is attributed to the reduction of trap states in the 1D nanowires, resulting in a significant increase in the fill factor of the devices. In Chapter 3, experiments are described in which the electron donor is a hairpin-shaped molecule containing a trans-1,2-diamidocyclohexane core and two DPP conjugated segments, and a fullerene derivative as the electron acceptor. Self-assembly of the donor molecule is driven by the synergistic interaction between hydrogen bonds and pi

  3. opened capsule

    African Journals Online (AJOL)

    by the opened capsule method is bioequivalent to a proprietary formulation approved by regulatory agencies. In the future, paediatric fixed-drug combination (FDC) antiretroviral formulations will greatly accelerate the roll-out of antiretrovirals to children in rural resource-limited settings. However, no paediatric antiretroviral ...

  4. Self-assembly and interactions of biomimetic thin films (United States)

    Handa, Hitesh

    Bilayer lipid membranes create the natural environment for the immobilization of functional proteins and have been used as a model for understanding structure and properties of cell membranes. The development of biomimetic surfaces requires in depth knowledge of surface science, self-assembly, immobilization techniques, nanofabrication, biomolecular interactions and analytical techniques. This research is focused on synthesizing and characterizing biomimetic artificial surfaces for fundamental studies in membrane structure and better understanding of specific and non-specific interactions. The other main focus is on surface engineering of self-assembled, nanostructured interfaces that mimic cell membranes. These structures provide a powerful bottom-up approach to the studies of the structure and functionality of cell membranes and their interactions with other molecules. One of the advantages of this approach is that the complexity of the system can be controlled and gradually increased to add functionalities. This dissertation provides a first single molecule force measurement of the specific interactions between Salmonella typhimurium and P22 bacteriophage. This dissertation also provides a novel model system for the confined crystallization of drug molecules such as aspirin using the concept of phospholipid bilayer assembly at surfaces. The results will impact the development of biosensors and drug delivery. The defense will focus on the preparation and bio-recognition interactions between a monolayer of bacteriophage P22, covalently bound to glass substrates through a bifunctional cross linker 3-aminopropyltrimethoxysilane, and the outer membrane of Salmonella, lipopolysaccharides (LPS). The LPS bilayer was deposited on poly (ethylenimine)-modified mica from their sonicated unilamellar vesicle solution. The specific binding of Salmonella typhimurium to the phage monolayer was studied by enzyme-linked immunosorbent assay (ELISA) and atomic force microscopy (AFM

  5. Liquid-solid transitions with applications to self-assembly (United States)

    Keys, Aaron S.

    We study the thermodynamic and kinetic pathways by which liquids transform into solids, and their relation to the metastable states that commonly arise in self-assembly applications. As a case study in the formation of ordered metastable solids, we investigate the atomistic mechanism by which quasicrystals form. We show that the aperiodic growth of quasicrystals is controlled by the ability of the growing quasicrystal "nucleus" to incorporate kinetically trapped atoms into the solid phase with minimal rearrangement. In a related study, we propose a two-part mechanism for forming 3d dodecagonal quasicrystals by self-assembly. Our mechanism involves (1) attaching small mobile particles to the surface of spherical particles to encourage icosahedral packing and (2) allowing a subset of particles to deviate from the ideal spherical shape, to discourage close-packing In addition to studying metastable ordered solids, we investigate the phenomenology and mechanism of the glass transition. We report measurements of spatially heterogeneous dynamics in a system of air-driven granular beads approaching a jamming transition, and show that the dynamics in our granular system are quantitatively indistinguishable from those for a supercooled liquid approaching a glass transition. In a second study of the glass transition, we use transition path sampling to study the structure, statistics and dynamics of localized excitations for several model glass formers. We show that the excitations are sparse and localized, and their size is temperature-independent. We show that their equilibrium concentration is proportional to exp[- Ja (1/T-1/T o)], where Ja is the energy scale for irreversible particle displacements of length a, and T o is an onset temperature. We show that excitation dynamics is facilitated by the presence of other excitations, causing dynamics to slow in a hierarchical way as temperature is lowered. To supplement our studies of liquid-solid transitions, we introduce a

  6. Self-assembly studies of native and recombinant fibrous proteins (United States)

    Wilson, Donna Lucille

    The structure of silk proteins consists of alternating amorphous (glycine-rich) and ordered crystalline regions (poly(alanine) and poly(glycine-alanine) repeats), where the organized regions are typically beta-sheet assemblies. In collagen, the basic helical repeat (glycine-proline-hydroxyproline and variants on this repeat) drives hierarchical assembly. Three polypeptide chains form left-handed poly-proline II-like helices, these three chains then self-assemble to form a right-handed triple helix. The focus of this thesis is on these proteins and defined variations thereof to reveal features of fibrous protein self-assembly. The amino acid sequences of native silk and collagen and their respective assembly environments have been systematically manipulated. Spider silk protein, based on the consensus sequence of Nephila clavipes dragline-silk, was genetically engineered to include methionines flanking the beta-sheet forming polyalanine regions. These methionines could be selectively oxidized and reduced, altering the bulkiness and charge of a methionine-based sulfoxide group to control beta-sheet formation by steric hindrance. A second version of the sterical trigger included a recognition site for Protein Kinase A allowing for the selective phosphorylation of a serine. Patterning a monolayer of precursor "director" molecules on length scales ranging from nanometer- to micrometer-length scales simplifies the interpretation of supramolecular assembly. Utilizing the atomic force microscopy (AFM)-based technique of dip-pen nanolithography, thiolated collagen and a collagen-like peptide were patterned at 30--50 nm line widths on evaporated gold surfaces. These are the largest molecules thus far positively printed on a surface at such small-length scales. The method preserved the triple helical structure and biological activity of collagen and even fostered the formation of characteristic higher-levels of structural organization. Nanopatterns were also achieved for

  7. Investigation of functionalized silicon nanowires by self-assembled monolayer

    Energy Technology Data Exchange (ETDEWEB)

    Hemed, Nofar Mintz [Dept. of Physical Electronics, Eng. Faculty, and the University Res. Inst. for Nano Science and Nano-Technologies, Tel-Aviv University, Ramat-Aviv 69978 (Israel); Convertino, Annalisa [Istituto per la Microelettronica e i Microsistemi C.N.R.-Area della Ricerca di Roma, via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Shacham-Diamand, Yosi [Dept. of Physical Electronics, Eng. Faculty, and the University Res. Inst. for Nano Science and Nano-Technologies, Tel-Aviv University, Ramat-Aviv 69978 (Israel); The Department of Applied Chemistry, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan)


    Graphical abstract: - Highlights: • We characterize and verify the existence of self-assembled monolayer (SAM) on silicon nanowires and α-Si:H. • We define the term “electrical coverage” and find the formula for both cases. • The SAM's electrical coverage on silicon nanowires is found to be ∼63%. • The SAM's electrical coverage on α-Si:H is found to be ∼65 ± 3%. • The amount of SAM on the SiNWs is sufficient and it can serve as a linker to biological molecules. - Abstract: The functionalization using self assembled monolayer (SAM) of silicon nanowires (SiNW) fabricated by plasma enhanced chemical vapor deposition (PECVD) is reported here. The SAM is being utilized as the first building block in the functionalization process. The morphology of the SiNW comprises a polycrystalline core wrapped by an hydrogenated amorphous silicon (α-Si:H) shell. Since most of the available methods for SAM verification and characterization are suitable only for flat substrates; therefore, in addition to the SiNW α-Si:H on flat samples were produced in the same system as the SiNWs. First we confirmed the SAM's presence on the flat α-Si:H samples using the following methods: contact angle measurement to determine the change in surface energy; atomic force microscopy (AFM) to determine uniformity and molecular coverage. Spectroscopic ellipsometry and X-ray reflectivity (XRR) were performed to measure SAM layer thickness and density. X-ray photoelectron spectroscopy (XPS) was applied to study the chemical states of the surface. Next, SiNW/SAM were tested by electrochemical impedance spectroscopy (EIS), and the results were compared to α-Si:H/SAM. The SAM electrical coverage on SiNW and α-Si:H was found to be ∼37% and ∼65 ± 3%, respectively. A model, based on transmission line theory for the nanowires is presented to explain the disparity in results between the nanowires and flat surface of the same materials.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  9. Optimal efficiency of self-assembling light-harvesting arrays. (United States)

    Kim, Ji-Hyun; Cao, Jianshu


    Using a classical master equation that describes energy transfer over a given lattice, we explore how energy transfer efficiency along with the photon capturing ability depends on network connectivity, on transfer rates, and on volume fractions-the numbers and relative ratio of fluorescence chromophore components, e.g., donor (D), acceptor (A), and bridge (B) chromophores. For a one-dimensional AD array, the exact analytical expression (derived in Appendix A) for efficiency shows a steep increase with a D-to-A transfer rate when a spontaneous decay is sufficiently slow. This result implies that the introduction of B chromophores can be a useful method for improving efficiency for a two-component AD system with inefficient D-to-A transfer and slow spontaneous decay. Analysis of this one-dimensional system can be extended to higher-dimensional systems with chromophores arranged in structures such as a helical or stacked-disk rod, which models the self-assembling monomers of the tobacco mosaic virus coat protein. For the stacked-disk rod, we observe the following: (1) With spacings between sites fixed, a staggered conformation is more efficient than an eclipsed conformation. (2) For a given ratio of A and D chromophores, the uniform distribution of acceptors that minimizes the mean first passage time to acceptors is a key point to designing the optimal network for a donor-acceptor system with a relatively small D-to-A transfer rate. (3) For a three-component ABD system with a large B-to-A transfer rate, a key design strategy is to increase the number of the pathways in accordance with the directional energy flow from D to B to A chromophores. These conclusions are consistent with the experimental findings reported by Francis, Fleming, and their co-workers and suggest that synthetic architectures of self-assembling supermolecules and the distributions of AD or ABD chromophore components can be optimized for efficient light-harvesting energy transfer.

  10. Layer-by-layer self-assembled shells for drug delivery. (United States)

    Ariga, Katsuhiko; Lvov, Yuri M; Kawakami, Kohsaku; Ji, Qingmin; Hill, Jonathan P


    There are several requirements for the safe and effective delivery of therapeutic agents for human use. Direct injection of drugs may cause side effects due to their permeation to other, undiseased regions of the body so that concealment and targeting with appropriate materials is a critical consideration in the design of practical drug delivery systems. In particular, carriers with structures which can be flexibly controlled are more useful since functional structure units can be assembled in component-by-component and/or layer-by-layer fashion. In this review, we focus on preparation of layer-by-layer shells directed at drug delivery applications. After a description of the fundamentals of layer-by-layer (LbL) assembly, recent progress in the field of self-assembled microshells and nanoshells for drug delivery applications are summarized. In addition, concepts developed to solve current difficulties are also described. Encapsulation of insoluble drugs in nanoshells and their delivery can satisfy some of the demands of practical medical use. Thus, aqueous suspensions of insoluble drugs have been subjected to powerful ultrasonic treatment followed by sequential addition of polycations and polyanions to the particle solution leading to assembly of ultra-thin polyelectrolyte shells on the nano-sized drug particles. In another innovative example, stepwise release of drugs from LbL films of mesoporous capsules to the exterior in the absence of external stimuli was demonstrated. It can be regarded as stimuli-free auto-modulated material release. Copyright © 2011 Elsevier B.V. All rights reserved.


    Energy Technology Data Exchange (ETDEWEB)

    Monson, Peter [University of Massachusetts; Auerbach, Scott [University of Massachusetts


    This report describes progress on a collaborative project on the multiscale modeling of the assembly processes in the synthesis of nanoporous materials. Such materials are of enormous importance in modern technology with application in the chemical process industries, biomedicine and biotechnology as well as microelectronics. The project focuses on two important classes of materials: i) microporous crystalline materials, such as zeolites, and ii) ordered mesoporous materials. In the first case the pores are part of the crystalline structure, while in the second the structures are amorphous on the atomistic length scale but where surfactant templating gives rise to order on the length scale of 2 - 20 nm. We have developed a modeling framework that encompasses both these kinds of materials. Our models focus on the assembly of corner sharing silica tetrahedra in the presence of structure directing agents. We emphasize a balance between sufficient realism in the models and computational tractibility given the complex many-body phenomena. We use both on-lattice and off-lattice models and the primary computational tools are Monte Carlo simulations with sampling techniques and ensembles appropriate to specific situations. Our modeling approach is the first to capture silica polymerization, nanopore crystallization, and mesopore formation through computer-simulated self assembly.

  12. Silica biomineralization via the self-assembly of helical biomolecules. (United States)

    Liu, Ben; Cao, Yuanyuan; Huang, Zhehao; Duan, Yingying; Che, Shunai


    The biomimetic synthesis of relevant silica materials using biological macromolecules as templates via silica biomineralization processes attract rapidly rising attention toward natural and artificial materials. Biomimetic synthesis studies are useful for improving the understanding of the formation mechanism of the hierarchical structures found in living organisms (such as diatoms and sponges) and for promoting significant developments in the biotechnology, nanotechnology and materials chemistry fields. Chirality is a ubiquitous phenomenon in nature and is an inherent feature of biomolecular components in organisms. Helical biomolecules, one of the most important types of chiral macromolecules, can self-assemble into multiple liquid-crystal structures and be used as biotemplates for silica biomineralization, which renders them particularly useful for fabricating complex silica materials under ambient conditions. Over the past two decades, many new silica materials with hierarchical structures and complex morphologies have been created using helical biomolecules. In this review, the developments in this field are described and the recent progress in silica biomineralization templating using several classes of helical biomolecules, including DNA, polypeptides, cellulose and rod-like viruses is summarized. Particular focus is placed on the formation mechanism of biomolecule-silica materials (BSMs) with hierarchical structures. Finally, current research challenges and future developments are discussed in the conclusion. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Coarse-Grained Molecular Simulation of Lipid Self-Assembly (United States)

    Shinoda, Wataru


    The talk will review our recent work on understanding the behavior of lipid self-assembly using a coarse-grained (CG) force field model developed recently. The CG model is designed to reproduce experimental surface/interfacial properties as well as distribution functions from all-atom (AA) molecular dynamics (MD) simulations. A series of MD simulations has elucidated that the CG model reproduces the phase diagram reasonably and produces the membranes with reasonable elastic moduli, surface and line tensions. With a help of technical development of free energy computation, we have evaluated the stability of liposome. A comparison of CG-MD and a simple continuum theory for the free energy barrier to the vesicle-to-bicelle transformation reveals that the internal structural relaxation in the bilayer membrane plays an important role in lowering the free energy barrier in case of a small unilamellar vesicle. The effects of lipid components and additives are also discussed in this talk. Especially the effect of fullerenes on the membrane properties will be discussed in details. The behavior of fullerenes in the bilayer membrane and the resultant membrane properties depend on the size of fullerene and bilayer thickness quite sensitively. To discuss these details, we need a chemically accurate CG model constructed based on extensive AA-MD results.

  14. Surfaces Self-Assembly and Rapid Growth of Amyloid Fibrils (United States)

    Lin, Yichih; Petersson, E. James; Fakhraai, Zahra


    The mechanism of surface-mediated fibrillization has been considered as a key issue in understanding the origins of the neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. In vitro, amyloid proteins fold through nucleation-elongation process. There is a critical concentration for early nucleating stage. However, some studies indicate that surfaces can modulate the fibril's formation under physiological conditions, even when the concentration is much lower than the critical concentration. Here, we use a label-free procedure to monitor the growth of fibrils across many length scales. We show that near a surface, the fibrillization process appears to bypass the nucleation step and fibrils grow through a self-assembly mechanism instead. We control and measure the pre-fibrillar morphology at different stages of this process on various surfaces. The interplay between the surface concentration and diffusion constant can help identify the detailed mechanisms of surface-mediated fibril growth, which remains largely unexplored. Our works provide a new insight in designing new probes and therapies. Supported by the National Institute On Aging of the National Institutes of Health under Award Number P30AG010124.

  15. Directed colloidal self-assembly in toggled magnetic fields. (United States)

    Swan, James W; Bauer, Jonathan L; Liu, Yifei; Furst, Eric M


    Suspensions of paramagnetic colloids are driven to phase separate and self-assemble by a toggled magnetic field. Initially, all suspensions form network structures that span the sample cell. When the magnetic field is toggled, this network structure coarsens diffusively for a time that scales exponentially with frequency. Beyond this break through time, suspensions cease diffusive coarsening and undergo an apparent instability. The magnetic field drives suspensions to condense into dispersed, domains of bodycentered tetragonal crystals. Within these domains the crystalline order depends on the pulse frequency. Because the scaling of the break through time with respect to frequency is exponential, the steady state limit corresponding to an infinite pulse frequency is kinetically arrested and the equilibrium state is unreachable. These experiments show that there is an out-of-equilibrium pathway that can be used to escape a kinetically arrested state as well as a diverging time scale for phase separation as the critical frequency for condensation is approached. Rather than fine tuning the strength of the interactions among particles, a simple annealing scheme - toggling of the magnetic field - is used to create a broad envelope for assembly of ordered particle structures.

  16. Modular Design of Self-Assembling Peptide-Based Nanotubes. (United States)

    Burgess, Natasha C; Sharp, Thomas H; Thomas, Franziska; Wood, Christopher W; Thomson, Andrew R; Zaccai, Nathan R; Brady, R Leo; Serpell, Louise C; Woolfson, Derek N


    An ability to design peptide-based nanotubes (PNTs) rationally with defined and mutable internal channels would advance understanding of peptide self-assembly, and present new biomaterials for nanotechnology and medicine. PNTs have been made from Fmoc dipeptides, cyclic peptides, and lock-washer helical bundles. Here we show that blunt-ended α-helical barrels, that is, preassembled bundles of α-helices with central channels, can be used as building blocks for PNTs. This approach is general and systematic, and uses a set of de novo helical bundles as standards. One of these bundles, a hexameric α-helical barrel, assembles into highly ordered PNTs, for which we have determined a structure by combining cryo-transmission electron microscopy, X-ray fiber diffraction, and model building. The structure reveals that the overall symmetry of the peptide module plays a critical role in ripening and ordering of the supramolecular assembly. PNTs based on pentameric, hexameric, and heptameric α-helical barrels sequester hydrophobic dye within their lumens.

  17. Nanoscale patterning of ionic self-assembled multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Tulpar, Aysen; Jang, C-H; Ducker, William A [Department of Chemistry, Virginia Tech, Blacksburg, VA 24061 (United States); Wang Zhiyong [Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA 24061 (United States); Jain, Vaibhav [Macromolecular Science and Engineering, Virginia Tech, Blacksburg, VA 24061 (United States); Heflin, James R [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States)], E-mail:


    Films that are nanostructured in all three dimensions can be fabricated by the templated growth of ionic self-assembled multilayers (ISAMs) on solids that have been patterned by nanografting. Nanografting was used to controllably pattern -COOH surface groups on a background of -OH groups. Atomic force microscopy (AFM) confirms that ISAM bilayers grow selectively on the -COOH groups and not on the surrounding -OH groups. The patterned area clearly shows an increase in height with an increase in the number of bilayers. As compared with other methods of nanofabrication, nanografting with ISAM deposition provides fast and precise control over the size of the pattern region, which remains stable even after repeated washing. This combination allows the fabricated template to be altered in situ without the need of any kind of mask, expensive probe, or post-lithography processing/cleaning methods. We have demonstrated line widths of 75 nm. Ultimately the line width is limited by the width of the AFM tip that causes desorption of the thiol, which is typically about 25 nm. Smaller line widths should be possible with the use of sharper AFM tips.

  18. Electric Field Driven Self-Assembly of Colloidal Rods (United States)

    Juarez, Jaime; Chaudhary, Kundan; Chen, Qian; Granick, Steve; Lewis, Jennifer


    The ability to assemble anisotropic colloidal building blocks into ordered configurations is of both scientific and technological importance. We are studying how electric field-induced interactions guide the self-assembly of these blocks into well aligned microstructures. Specifically, we present observations of the assembly of colloidal silica rods (L/D ˜ 4) within planar electrode cells as a function of different electric field parameters. Results from video microscopy and image analysis demonstrate that aligned microstructures form due to the competition between equilibrium interactions of induced dipoles and non-equilibrium processes (i.e., electro-osmosis). Under the appropriate electric field conditions (˜ kHZ AC fields), aligned colloidal rod fluids form over large areas on the electrode surface. The superposition of a DC electric field to this aligned colloidal rod fluid initiates their condensation into a vertically oriented crystalline phase. Ongoing work is now focused on exploring how temporal changes to electric fields influence colloidal rod dynamics and, hence, the assembly kinetics of aligned colloidal monolayers.

  19. Membrane-targeted self-assembling cyclic peptide nanotubes. (United States)

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


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

  20. Nanophase Segregation of Self-Assembled Monolayers on Gold Nanoparticles. (United States)

    Meena, Santosh Kumar; Goldmann, Claire; Nassoko, Douga; Seydou, Mahamadou; Marchandier, Thomas; Moldovan, Simona; Ersen, Ovidiu; Ribot, François; Chanéac, Corinne; Sanchez, Clément; Portehault, David; Tielens, Frederik; Sulpizi, Marialore


    Nanophase segregation of a bicomponent thiol self-assembled monolayer is predicted using atomistic molecular dynamics simulations and experimentally confirmed. The simulations suggest the formation of domains rich in acid-terminated chains, on one hand, and of domains rich in amide-functionalized ethylene glycol oligomers, on the other hand. In particular, within the amide-ethylene glycol oligomers region, a key role is played by the formation of interchain hydrogen bonds. The predicted phase segregation is experimentally confirmed by the synthesis of 35 and 15 nm gold nanoparticles functionalized with several binary mixtures of ligands. An extensive study by transmission electron microscopy and electron tomography, using silica selective heterogeneous nucleation on acid-rich domains to provide electron contrast, supports simulations and highlights patchy nanoparticles with a trend toward Janus nano-objects depending on the nature of the ligands and the particle size. These results validate our computational platform as an effective tool to predict nanophase separation in organic mixtures on a surface and drive further exploration of advanced nanoparticle functionalization.

  1. Polypeptide Multilayer Self-Assembly Studied by Ellipsometry

    Directory of Open Access Journals (Sweden)

    Marina Craig


    Full Text Available A polypeptide nanofilm made by layer-by-layer (LbL self-assembly was built on a surface that mimics nonwoven, a material commonly used in wound dressings. Poly-L-lysine (PLL and poly-L-glutamic acid (PLGA are the building blocks of the nanofilm, which is intended as an enzymatically degradable lid for release of bactericides to chronic wounds. Chronic wounds often carry infection originating from bacteria such as Staphylococcus aureus and a release system triggered by the degree of infection is of interest. The dry nanofilm was studied with ellipsometry. The thickness of the nanofilm was 60% less in its dry state than in its wet state. The measurements showed that a primer was not necessary to build a stable nanofilm, which is practically important in our case because a nondegradable primer is highly unwanted in a wound care dressing. Added V8 (glutamyl endopeptidase enzymes only showed adsorption on the nanofilm at room temperature, indicating that the PLL/PLGA “lid” may remain intact until the dressing has been filled with wound exudate at the elevated temperature typical of that of the wound.

  2. Polypeptide multilayer self-assembly studied by ellipsometry. (United States)

    Craig, Marina; Holmberg, Krister; Le Ru, Eric; Etchegoin, Pablo


    A polypeptide nanofilm made by layer-by-layer (LbL) self-assembly was built on a surface that mimics nonwoven, a material commonly used in wound dressings. Poly-L-lysine (PLL) and poly-L-glutamic acid (PLGA) are the building blocks of the nanofilm, which is intended as an enzymatically degradable lid for release of bactericides to chronic wounds. Chronic wounds often carry infection originating from bacteria such as Staphylococcus aureus and a release system triggered by the degree of infection is of interest. The dry nanofilm was studied with ellipsometry. The thickness of the nanofilm was 60% less in its dry state than in its wet state. The measurements showed that a primer was not necessary to build a stable nanofilm, which is practically important in our case because a nondegradable primer is highly unwanted in a wound care dressing. Added V8 (glutamyl endopeptidase) enzymes only showed adsorption on the nanofilm at room temperature, indicating that the PLL/PLGA "lid" may remain intact until the dressing has been filled with wound exudate at the elevated temperature typical of that of the wound.

  3. Polymer based planar coupling of self-assembled bottle microresonators (United States)

    Grimaldi, I. A.; Berneschi, S.; Testa, G.; Baldini, F.; Nunzi Conti, G.; Bernini, R.


    The investigation of a simple and self-assembling method for realizing polymeric micro-bottle resonators is reported. By dispensing precise amounts of SU-8 onto a cleaved optical fiber, employed as mechanical support, bottle microcavities with different shapes and diameters are fabricated. The balancing of surface energy between glass fiber and polymeric microresonator with surface tension of SU-8 confers different shape to these microstructures. Planar single-mode SU-8 based waveguide, realized on polymethylmethacrylate, is chosen for exciting the micro-bottle resonators by evanescent wave. The reliability of the fabrication process and the shape of the bottle microcavities are investigated through optical analysis. We observe whispering gallery modes in these resonant microstructures by a robust coupling with single mode planar waveguides around 1.5 μm wavelength. The resonance spectra of micro-bottle resonators and the spectral characteristics, such as Quality-factor (Q factor) and free spectral range, are evaluated for all the realized microstructures. SU-8 micro-bottle resonators show high Q-factors up to 3.8 × 104 and present a good mechanical stability. These features make these microcavities attractive for sensing and/or lasing applications in a planar platform.

  4. Self-Assembly of Protein Nanostructures to Enhance Biosensor Sensitivity (United States)

    Olsen, Bradley; Dong, Xuehui; Obermeyer, Allie

    The Langmuir adsorption isotherm predicts that the number of bound species on a surface at a given concentration will be directly proportional to the number of binding sites on the surface. Therefore, the number of binding events in a biosensor may be increased at a given analyte concentration if the surface density of binding domains is increased. Here, we demonstrate the formation of block copolymers where one block is a human IgG antibody or a nanobody and self-assemble these molecules into nanostructured films with a high density of binding sites. The type of nanostructure formed and the rate of transport through the protein-polymer layers are explored as a function of coil fraction of the protein-polymer conjugate block copolymers, showing optima for transport and assembly that depend upon the identity of the protein. For small enough analytes, binding to the antibodies and nanobodies is linear with film thickness, indicating that the entire film is accessible. Consistent with the enhanced number of binding sites and the prediction of the Langmuir isotherm, the films improve sensitivity by several orders of magnitude relative to chemisorbed protein layers used in current sensor designs. Current research is integrating this new material technology into prototype sensors. Work supported by the Air Force Office of Scientific Reesearch (AFOSR).

  5. Stoichiometric control of DNA-grafted colloid self-assembly (United States)

    Vo, Thi; Kumar, Sanat; Srinivasan, Babji; Pal, Suchetan; Zhang, Yugang; Gang, Oleg


    There has been considerable interest in understanding the self-assembly of DNA-grafted nanoparticles into different crystal structures, e.g., CsCl, AlB2, and Cr3Si. Although there are important exceptions, a generally accepted view is that the right stoichiometry of the two building block colloids needs to be mixed to form the desired crystal structure. To incisively probe this issue, we combine experiments and theory on a series of DNA-grafted nanoparticles at varying stoichiometries, including noninteger values. We show that stoichiometry can couple with the geometries of the building blocks to tune the resulting equilibrium crystal morphology. As a concrete example, a stoichiometric ratio of 3:1 typically results in the Cr3Si structure. However, AlB2 can form when appropriate building blocks are used so that the AlB2 standard-state free energy is low enough to overcome the entropic preference for Cr3Si. These situations can also lead to an undesirable phase coexistence between crystal polymorphs. Thus, whereas stoichiometry can be a powerful handle for direct control of lattice formation, care must be taken in its design and selection to avoid polymorph coexistence. PMID:25848044

  6. White-Emissive Self-Assembled Organic Microcrystals. (United States)

    Li, Zhi Zhou; Liang, Feng; Zhuo, Ming Peng; Shi, Ying Li; Wang, Xue Dong; Liao, Liang Sheng


    Organic semiconductor micro-/nanocrystals with regular shapes have been demonstrated for many applications, such as organic field-effect transistors, organic waveguide devices, organic solid-state lasers, and therefore are inherently ideal building blocks for the key circuits in the next generation of miniaturized optoelectronics. In the study, blue-emissive organic molecules of 1,4-bis(2-methylstyryl)benzene (o-MSB) can assemble into rectangular microcrystals at a large scale via the room-temperature solution-exchange method. Because of the Förster resonance energy transfer, the energy of the absorbed photons by the host matrix organic molecules of o-MSB can directly transfer to the dopant organic molecules of tetracene or 1,2:8,9-dibenzopentacene (DBP), which then emit visible photons in different colors from blue to green, and to yellow. More impressively, by modulating the doping molar ratios of DBP to o-MSB, bright white-emissive organic microcrystals with well-preserved rectangular morphology can be successfully achieved with a low doping ratio of 1.5%. These self-assembled organic semiconductor microcrystals with multicolor emissions can be the white-light sources for the integrated optical circuits at micro-/nanoscale. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Versatility of cyclodextrins in self-assembly systems of amphiphiles. (United States)

    Jiang, Lingxiang; Yan, Yun; Huang, Jianbin


    Recently, cyclodextrins (CDs) were found to play important yet complicated (or even apparently opposite sometimes) roles in self-assembly systems of amphiphiles or surfactants. Herein, we try to review and clarify the versatility of CDs in surfactant assembly systems by 1) classifying the roles played by CDs into two groups (modulator and building unit) and four subgroups (destructive and constructive modulators, amphiphilic and unamphiphilic building units), 2) comparing these subgroups, and 3) analyzing mechanisms. As a modulator, although CDs by themselves do not participate into the final surfactant aggregates, they can greatly affect the aggregates in two ways. In most cases CDs will destroy the aggregates by depleting surfactant molecules from the aggregates (destructive), or in certain cases CDs can promote the aggregates to grow by selectively removing the less-aggregatable surfactant molecules from the aggregates (constructive). As an amphiphilic building unit, CDs can be chemically (by chemical bonds) or physically (by host-guest interaction) attached to a hydrophobic moiety, and the resultant compounds act as classic amphiphiles. As an unamphiphilic building unit, CD/surfactant complexes or even CDs on their own can assemble into aggregates in an unconventional, unamphiphilic manner driven by CD-CD H-bonds. Moreover, special emphasis is put on two recently appeared aspects: the constructive modulator and unamphiphilic building unit. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Functional self-assembling bolaamphiphilic polydiacetylenes as colorimetric sensor scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Song, Jie; Cisar, Justin S.; Bertozzi, Carolyn R.


    Conjugated polymers capable of responding to external stimuli by changes in optical, electrical or electrochemical properties can be used for the construction of direct sensing devices. Polydiacetylene-based systems are attractive for sensing applications due to their colorimetric response to changes in the local environment. Here we present the design, preparation and characterization of self-assembling functional bolaamphiphilic polydiacetylenes (BPDAs) inspired by Nature's strategy for membrane stabilization. We show that by placing polar headgroups on both ends of the diacetylene lipids in a transmembranic fashion, and altering the chemical nature of the polar surface residues, the conjugated polymers can be engineered to display a range of radiation-, thermal- and pH-induced colorimetric responses. We observed dramatic nanoscopic morphological transformations accompanying charge-induced chromatic transitions, suggesting that both side chain disordering and main chain rearrangement play important roles in altering the effective conjugation lengths of the poly(ene-yne). These results establish the foundation for further development of BPDA-based colorimetric sensors.

  9. Magnetic Actuation of Self-assembled Bacteria Inspired Nanoswimmers (United States)

    Ali, Jamel; Cheang, U. Kei; Martindale, James D.; Jabbarzadeh, Mehdi; Fu, Henry C.; Kim, Min Jun


    Currently, there is growing interest in developing nanoscale swimmers for biological and biomedical tasks. Of particular interest is the development of soft stimuli-responsive nanorobots to probe cellular and sub-cellular environments. While there have been a few reports of nanoscale robotic swimmers, which have shown potential to be used for these tasks, they often lack multifuctionality. In particular, no man-made soft nanoscale material has been able to match the ability of natural bacterial flagella to undergo rapid and reversible morphological changes in response to multiple forms of environmental stimuli. Towards this end, we report self-assembled stimuli-responsive nanoscale robotic swimmers composed of single or multiple bacterial flagella and attached to magnetic nanoparticles. We visualize the movement of flagella using high resolution fluorescence microscopy while controlling these swimmers via a magnetic control system. Differences in in propulsion before and after the change in flagellar form are observed. Furthermore, we demonstrate the ability to induce flagellar bundling in multiflagellated nanoswimmers. This work was funded by the National Science Foundation (DMR 1712061 and CMMI 1737682 to M.J.K. and DMR 1650970 and CBET 1651031 to H.C.F.), and the Korea Evaluation Institute of Industrial Technology (MOTIE) (NO. 10052980) award to M.J.K.

  10. Quantitative computational models of molecular self-assembly in systems biology. (United States)

    Thomas, Marcus; Schwartz, Russell


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  12. Quantitative computational models of molecular self-assembly in systems biology (United States)

    Thomas, Marcus; Schwartz, Russell


    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.

  13. Dynamic and programmable self-assembly of micro-rafts at the air-water interface. (United States)

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


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

  14. Control of Surface-Localized, Enzyme-Assisted Self-Assembly of Peptides through Catalyzed Oligomerization. (United States)

    Vigier-Carrière, Cécile; Wagner, Déborah; Chaumont, Alain; Durr, Baptiste; Lupattelli, Paolo; Lambour, Christophe; Schmutz, Marc; Hemmerlé, Joseph; Senger, Bernard; Schaaf, Pierre; Boulmedais, Fouzia; Jierry, Loïc


    Localized self-assembly allowing both spatial and temporal control over the assembly process is essential in many biological systems. This can be achieved through localized enzyme-assisted self-assembly (LEASA), also called enzyme-instructed self-assembly, where enzymes present on a substrate catalyze a reaction that transforms noninteracting species into self-assembling ones. Very few LEASA systems have been reported so far, and the control of the self-assembly process through the surface properties represents one essential step toward their use, for example, in artificial cell mimicry. Here, we describe a new type of LEASA system based on α-chymotrypsin adsorbed on a surface, which catalyzes the production of (KL)nOEt oligopeptides from a KLOEt (K: lysine; L: leucine; OEt ethyl ester) solution. When a critical concentration of the formed oligopeptides is reached near the surface, they self-assemble into β-sheets resulting in a fibrillar network localized at the interface that can extend over several micrometers. One significant feature of this process is the existence of a lag time before the self-assembly process starts. We investigate, in particular, the effect of the α-chymotrypsin surface density and KLOEt concentration on the self-assembly kinetics. We find that the lag time can be finely tuned through the surface density in α-chymotrypsin and KLOEt concentration. For a given surface enzyme concentration, a critical KLOEt concentration exists below which no self-assembly takes place. This concentration increases when the surface density in enzyme decreases.

  15. A parameter estimation technique for stochastic self-assembly systems and its application to human papillomavirus self-assembly (United States)

    Senthil Kumar, M.; Schwartz, Russell


    Virus capsid assembly has been a key model system for studies of complex self-assembly but it does pose some significant challenges for modeling studies. One important limitation is the difficulty of determining accurate rate parameters. The large size and rapid assembly of typical viruses make it infeasible to directly measure coat protein binding rates or deduce them from the relatively indirect experimental measures available. In this work, we develop a computational strategy to deduce coat-coat binding rate parameters for viral capsid assembly systems by fitting stochastic simulation trajectories to experimental measures of assembly progress. Our method combines quadratic response surface and quasi-gradient descent approximations to deal with the high computational cost of simulations, stochastic noise in simulation trajectories and limitations of the available experimental data. The approach is demonstrated on a light scattering trajectory for a human papillomavirus (HPV) in vitro assembly system, showing that the method can provide rate parameters that produce accurate curve fits and are in good concordance with prior analysis of the data. These fits provide an insight into potential assembly mechanisms of the in vitro system and give a basis for exploring how these mechanisms might vary between in vitro and in vivo assembly conditions.

  16. Synthesis and cell localization of self-assembled dinuclear lanthanide bioprobes. (United States)

    Chauvin, Anne-Sophie; Thomas, Frédéric; Song, Bo; Vandevyver, Caroline D B; Bünzli, Jean-Claude G


    Lanthanide bioprobes and bioconjugates are ideal luminescent stains in view of their low propensity to photobleaching, sharp emission lines and long excited state lifetimes permitting time-resolved detection for enhanced sensitivity. In this paper, we expand our previous work which demonstrated that self-assembled dinuclear triple-stranded helicates [Ln2(L(C2X))3] behave as excellent cell and tissue labels in immunocytochemical and immunohistochemical assays. The synthetic strategy of the hexadentate ditopic ligands incorporating dipicolinic acid, benzimidazole units and polyoxyethylene pendants is revisited in order to provide a more straightforward route and to give access to further functionalization of the polyoxyethylene arms by incorporating a terminal function X. Formation of the helicates [Ln2(L(C2X))3] (X=COOH, CH2OH, COEt, NH2, phthalimide) is ascertained by several experimental techniques and their stability tested against diethylenetriaminepentaacetate. Their photophysical properties (quantum yield, lifetime, radiative lifetime and sensitization efficiency) are presented and compared with those of the parent helicates [Ln2(L(C2))3]. Finally, the cellular uptake of five Eu(III) helicates is monitored by time-resolved luminescence microscopy and their localization in HeLa cells established by co-staining experiments.

  17. Self-assembly of diphenylalanine peptide with controlled polarization for power generation (United States)

    Nguyen, Vu; Zhu, Ren; Jenkins, Kory; Yang, Rusen


    Peptides have attracted considerable attention due to their biocompatibility, functional molecular recognition and unique biological and electronic properties. The strong piezoelectricity in diphenylalanine peptide expands its technological potential as a smart material. However, its random and unswitchable polarization has been the roadblock to fulfilling its potential and hence the demonstration of a piezoelectric device remains lacking. Here we show the control of polarization with an electric field applied during the peptide self-assembly process. Uniform polarization is obtained in two opposite directions with an effective piezoelectric constant d33 reaching 17.9 pm V-1. We demonstrate the power generation with a peptide-based power generator that produces an open-circuit voltage of 1.4 V and a power density of 3.3 nW cm-2. Devices enabled by peptides with controlled piezoelectricity provide a renewable and biocompatible energy source for biomedical applications and open up a portal to the next generation of multi-functional electronics compatible with human tissue.

  18. Safety and efficacy of self-assembling bubble carriers stabilized with sodium dodecyl sulfate for oral delivery of therapeutic proteins. (United States)

    Lin, Po-Yen; Chuang, Er-Yuan; Chiu, Yi-Hsuan; Chen, Hsin-Lung; Lin, Kun-Ju; Juang, Jyuhn-Huarng; Chiang, Ching-Hua; Mi, Fwu-Long; Sung, Hsing-Wen


    Sodium dodecyl sulfate (SDS) is generally regarded as a potent permeability enhancer in oral formulations; however, one concern related to the use of any permeation enhancer is its possible absorption of unwanted toxins during the period of epithelial permeability enhancement. In this work, the safety and efficacy of an SDS-containing bubble carrier system that is developed from an orally administered enteric-coated capsule are evaluated. The bubble carriers comprise diethylene triamine pentaacetic acid (DTPA) dianhydride, sodium bicarbonate (SBC), SDS, and insulin. Upon exposure to the intestinal fluid, DTPA dianhydride hydrolyzes to yield acids, and SBC rapidly reacts with these acids to generate CO 2 , producing bubble carriers, each containing a self-assembling water film. The hydrophilic insulin is entrapped in the self-assembled water film, which is stabilized by SDS. The SDS in the bubble carrier system can act as a dissolution enhancer in the dispersion of insulin molecules, as a surfactant that stabilizes the bubble carriers, as a protease inhibitor that protects the protein drug, and as a permeation enhancer that augments its oral bioavailability. Hence, a significant increase in the plasma insulin level and an excellent blood glucose-lowering response in diabetic rats are effectively achieved. Moreover, the enhancement of epithelial permeation by this SDS-containing formulation does not promote the absorption of intestinal endotoxins. The above facts indicate that the bubble carrier system that is stabilized by SDS can be used as a safe and potent carrier in the oral delivery of therapeutic proteins. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Biocompatible self-assembly of nano-materials for Bio-MEMS and insect reconnaissance.

    Energy Technology Data Exchange (ETDEWEB)

    Brozik, Susan Marie; Cesarano, Joseph, III; Brinker, C. Jeffrey; Dunphy, Darren Robert; Sinclair, Michael B.; Manginell, Monica; Ashley, Carlee E. (University of New Mexico, Albuquerque, NM); Timlin, Jerilyn Ann; Werner-Washburne, Margaret C. (University of New Mexico, Albuquerque, NM); Calvert, Paul Davidson (University of Massachusetts - Dartmouth, Dartmouth, MA); Hartenberger, Tamara N.; Flemming, Jeb Hunter; Baca, Helen Kennicott (University of New Mexico, Albuquerque, NM)


    This report summarizes the development of new biocompatible self-assembly procedures enabling the immobilization of genetically engineered cells in a compact, self-sustaining, remotely addressable sensor platform. We used evaporation induced self-assembly (EISA) to immobilize cells within periodic silica nanostructures, characterized by unimodal pore sizes and pore connectivity, that can be patterned using ink-jet printing or photo patterning. We constructed cell lines for the expression of fluorescent proteins and induced reporter protein expression in immobilized cells. We investigated the role of the abiotic/biotic interface during cell-mediated self-assembly of synthetic materials.

  20. Polymersomes with asymmetric membranes and self-assembled superstructures using pentablock quintopolymers resolved by electron tomography

    KAUST Repository

    Haataja, J. S.


    Polystyrene-block-poly(1,4-isoprene)-block-poly(dimethyl siloxane)-block-poly(tert-butyl methacrylate)-block-poly(2-vinyl pyridine), PS-b-PI-b-PDMS-b-PtBMA-b-P2VP, self-assembles in acetone into polymersomes with asymmetric (directional) PI-b-PDMS membranes. The polymersomes, in turn, self-assemble into superstructures. Analogically to supravesicular structures at a smaller length scale, we refer to them as suprapolymersome structures. Electron tomograms are shown to be invaluable in the structural assessment of such complex self-assemblies.

  1. Docking System Design and Self-Assembly Control of Distributed Swarm Flying Robots

    Directory of Open Access Journals (Sweden)

    Hongxing Wei


    Full Text Available This paper presents a novel docking system design and the distributed self-assembly control strategy for a Distributed Swarm Flying Robot (DSFR. The DSFR is a swarm robot comprising many identical robot modules that are able to move on the ground, dock with each other and fly coordinately once self-assembled into a robotic structure. A generalized adjacency matrix method is proposed to describe the configurations of robotic structures. Based on the docking system and the adjacency matrix, experiments are performed to demonstrate and verify the self-assembly control strategy.

  2. DNA–melamine hybrid molecules: from self-assembly to nanostructures

    Directory of Open Access Journals (Sweden)

    Rina Kumari


    Full Text Available Single-stranded DNA–melamine hybrid molecular building blocks were synthesized using a phosphoramidation cross-coupling reaction with a zero linker approach. The self-assembly of the DNA–organic hybrid molecules was achieved by DNA hybridization. Following self-assembly, two distinct types of nanostructures in the form of linear chains and network arrays were observed. The morphology of the self-assembled nanostructures was found to depend on the number of DNA strands that were attached to a single melamine molecule.

  3. Effects of rigid or adaptive confinement on colloidal self-assembly. Fixed vs. fluctuating number of confined particles

    Energy Technology Data Exchange (ETDEWEB)

    Pȩkalski, J.; Ciach, A. [Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warszawa (Poland); Almarza, N. G. [Instituto de Química Física Rocasolano, CSIC, Serrano 119, E-28006 Madrid (Spain)


    The effects of confinement on colloidal self-assembly in the case of fixed number of confined particles are studied in the one dimensional lattice model solved exactly in the grand canonical ensemble (GCE) in Pȩkalski et al. [J. Chem. Phys. 142, 014903 (2015)]. The model considers a pair interaction defined by a short-range attraction plus a longer-range repulsion. We consider thermodynamic states corresponding to self-assembly into clusters. Both fixed and adaptive boundaries are studied. For fixed boundaries, there are particular states in which, for equal average densities, the number of clusters in the GCE is larger than in the canonical ensemble. The dependence of pressure on density has a different form when the system size changes with fixed number of particles and when the number of particles changes with fixed size of the system. In the former case, the pressure has a nonmonotonic dependence on the system size. The anomalous increase of pressure for expanding system is accompanied by formation of a larger number of smaller clusters. In the case of elastic confining surfaces, we observe a bistability, i.e., two significantly different system sizes occur with almost the same probability. The mechanism of the bistability in the closed system is different to that of the case of permeable walls, where the two equilibrium system sizes correspond to a different number of particles.

  4. Self-assembling protein nanoparticles in the design of vaccines

    Directory of Open Access Journals (Sweden)

    Jacinto López-Sagaseta


    Full Text Available For over 100 years, vaccines have been one of the most effective medical interventions for reducing infectious disease, and are estimated to save millions of lives globally each year. Nevertheless, many diseases are not yet preventable by vaccination. This large unmet medical need demands further research and the development of novel vaccines with high efficacy and safety. Compared to the 19th and early 20th century vaccines that were made of killed, inactivated, or live-attenuated pathogens, modern vaccines containing isolated, highly purified antigenic protein subunits are safer but tend to induce lower levels of protective immunity. One strategy to overcome the latter is to design antigen nanoparticles: assemblies of polypeptides that present multiple copies of subunit antigens in well-ordered arrays with defined orientations that can potentially mimic the repetitiveness, geometry, size, and shape of the natural host-pathogen surface interactions. Such nanoparticles offer a collective strength of multiple binding sites (avidity and can provide improved antigen stability and immunogenicity. Several exciting advances have emerged lately, including preclinical evidence that this strategy may be applicable for the development of innovative new vaccines, for example, protecting against influenza, human immunodeficiency virus, and respiratory syncytial virus. Here, we provide a concise review of a critical selection of data that demonstrate the potential of this field. In addition, we highlight how the use of self-assembling protein nanoparticles can be effectively combined with the emerging discipline of structural vaccinology for maximum impact in the rational design of vaccine antigens.

  5. DNA-mediated self-assembly of artificial vesicles. (United States)

    Hadorn, Maik; Eggenberger Hotz, Peter


    Although multicompartment systems made of single unilamellar vesicles offer the potential to outperform single compartment systems widely used in analytic, synthetic, and medical applications, their use has remained marginal to date. On the one hand, this can be attributed to the binary character of the majority of the current tethering protocols that impedes the implementation of real multicomponent or multifunctional systems. On the other hand, the few tethering protocols theoretically providing multicompartment systems composed of several distinct vesicle populations suffer from the readjustment of the vesicle formation procedure as well as from the loss of specificity of the linking mechanism over time. In previous studies, we presented implementations of multicompartment systems and resolved the readjustment of the vesicle formation procedure as well as the loss of specificity by using linkers consisting of biotinylated DNA single strands that were anchored to phospholipid-grafted biotinylated PEG tethers via streptavidin as a connector. The systematic analysis presented herein provides evidences for the incorporation of phospholipid-grafted biotinylated PEG tethers to the vesicle membrane during vesicle formation, providing specific anchoring sites for the streptavidin loading of the vesicle membrane. Furthermore, DNA-mediated vesicle-vesicle self-assembly was found to be sequence-dependent and to depend on the presence of monovalent salts. This study provides a solid basis for the implementation of multi-vesicle assemblies that may affect at least three distinct domains. (i) Analysis. Starting with a minimal system, the complexity of a bottom-up system is increased gradually facilitating the understanding of the components and their interaction. (ii) Synthesis. Consecutive reactions may be implemented in networks of vesicles that outperform current single compartment bioreactors in versatility and productivity. (iii) Personalized medicine. Transport and

  6. Lubrication of polysilicon micromechanisms with self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, U.; Foster, J.D.; Habib, U.; Howe, R.T.; Maboudian, R. [Berkeley Sensor and Actuator Center, CA (United States); Senft, D.C.; Dugger, M.T. [Sandia National Labs., Albuquerque, NM (United States)


    Here, the authors report on the lubricating effects of self-assembled monolayers (SAMs) on MEMS by measuring static and dynamic friction with two polysilicon surface- micromachined devices. The first test structure is used to study friction between laterally sliding surfaces and with the second, friction between vertical sidewalls can be investigated. Both devices are SAM-coated following the sacrificial oxide etch and the microstructures emerge released and dry from the final water rinse. The coefficient of static friction, {mu}{sub s} was found to decrease from 2.1 {+-} 0.8 for the SiO{sub 2} coating to 0.11 {+-} 0.01 and 0.10 {+-} 0.01 for films derived from octadecyltrichloro-silane (OTS) and 1H,1H,2H,2H-perfluorodecyl-trichlorosilane (FDTS). Both OTS and FDTS SAM-coated structures exhibit dynamic coefficients of friction, {mu}{sub d} of 0.08 {+-} 0.01. These values were found to be independent of the apparent contact area, and remain unchanged after 1 million impacts at 5.6 {micro}N (17 kPa), indicating that these SAMs continue to act as boundary lubricants despite repeated impacts. Measurements during sliding friction from the sidewall friction testing structure give comparable initial {mu}{sub d} values of 0.02 at a contact pressure of 84 MPa. After 15 million wear cycles, {mu}{sub d} was found to rise to 0.27. Wear of the contacting surfaces was examined by SEM. Standard deviations in the {mu} data for SAM treatments indicate uniform coating coverage.

  7. Structural characterization of self-assembled multifunctional binary nanoparticle superlattices. (United States)

    Shevchenko, Elena V; Talapin, Dmitri V; Murray, Christopher B; O'Brien, Stephen


    Nanocrystals of different size and functionality (e.g., noble metals, semiconductors, oxides, magnetic alloys) can be induced to self-assemble into ordered binary superlattices (also known as opals or colloidal crystals), retaining the size tunable properties of their constituents. We have built a variety of binary superlattices from monodisperse PbS, PbSe, CoPt3, Fe2O3, Au, Ag, and Pd nanocrystals, mixing and matching these nanoscale building blocks to yield multifunctional nanocomposites (metamaterials). Superlattices with AB, AB2, AB3, AB4, AB5, AB6, and AB13 stoichiometry with cubic, hexagonal, tetragonal, and orthorhombic symmetries have been identified. Assemblies with the same stoichiometry can be produced in several polymorphous forms by tailoring the particle size and deposition conditions. We have identified arrays isostructural with NaCl, CuAu, AlB2, MgZn2, MgNi2, Cu3Au, Fe4C, CaCu5, CaB6, NaZn13, and cub-AB13 compounds emphasizing the parallels between nanoparticle assembly and atomic scale crystal growth and providing confidence that many more structures will follow. Recently, we have demonstrated that electrical charges on sterically stabilized nanoparticles in addition to such parameters as particle size ratio and their concentrations can provide the formation of a much broader pallet of binary nanoparticle superlattices as compared with the limited number of possible superlattices formed by hard noninteracting spheres. In this contribution, we demonstrate a large variety of different binary superlattices, provide their detailed structural characterization, and discuss the role of energetic and kinetic factors in the cocrystallization process. We found that Coulomb, van der Waals, charge-dipole, dipole-dipole, and other interactions can contribute equally to cocrystallization, allowing superlattice formation to be dependent on a number of tunable parameters. We present binary superlattices as a new class of materials with a potentially unlimited

  8. Surface Mediated Self-Assembly of Amyloid Peptides (United States)

    Fakhraai, Zahra


    Amyloid fibrils have been considered as causative agents in many neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, type II diabetes and amyloidosis. Amyloid fibrils form when proteins or peptides misfold into one dimensional crystals of stacked beta-sheets. In solution, amyloid fibrils form through a nucleation and growth mechanism. The rate limiting nucleation step requires a critical concentration much larger than those measured in physiological conditions. As such the exact origins of the seeds or oligomers that result in the formation of fully mature fibrils in the body remain topic intense studies. It has been suggested that surfaces and interfaces can enhance the fibrillization rate. However, studies of the mechanism and kinetics of the surface-mediated fibrillization are technologically challenging due to the small size of the oligomer and protofibril species. Using smart sample preparation technique to dry the samples after various incubation times we are able to study the kinetics of fibril formation both in solution and in the vicinity of various surfaces using high-resolution atomic force microscopy. These studies elucidate the role of surfaces in catalyzing amyloid peptide formation through a nucleation-free process. The nucleation free self-assembly is rapid and requires much smaller concentrations of peptides or proteins. We show that this process resembles diffusion limited aggregation and is governed by the peptide adhesion rate, two -dimensional diffusion of the peptides on the surface, and preferential interactions between the peptides. These studies suggest an alternative pathway for amyloid formation may exist, which could lead to new criteria for disease prevention and alternative therapies. Research was partially supported by a seed grant from the National Institute of Aging of the National Institutes of Health (NIH) under Award Number P30AG010124 (PI: John Trojanowski) and the University of Pennsylvania.

  9. Efficient exciton transport in layers of self-assembled porphyrin derivatives

    NARCIS (Netherlands)

    Huijser, A.; Suijkerbuijk, B.M.J.M.; Klein Gebbink, R.J.M.; Savenije, T.J.; Siebbeles, D.A.


    The photosynthetic apparatus of green sulfur bacteria, the chlorosome, is generally considered as a highly efficient natural light-harvesting system. The efficient exciton transport through chlorosomes toward the reaction centers originates from self-assembly of the bacteriochlorophyll molecules.

  10. Super-resolution imaging of self-assembly of amphiphilic photoswitchable macrocycles. (United States)

    Hua, Qiong-Xin; Xin, Bo; Xiong, Zu-Jing; Gong, Wen-Liang; Li, Chong; Huang, Zhen-Li; Zhu, Ming-Qiang


    Self-assembly of an amphiphilic photoswitchable fluorescent macrocycle methoxy-tetraethylene glycol-substituted hexaarylbiimidazole-borondipyrromethene can be observed directly under a super-resolution fluorescence microscope, with the nanoscale resolution beyond the optical diffraction limitation.

  11. Self-assembled peptide-based nanostructures: Smart nanomaterials toward targeted drug delivery. (United States)

    Habibi, Neda; Kamaly, Nazila; Memic, Adnan; Shafiee, Hadi


    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.

  12. Electro- and photochemical switching of dithienylethene self-assembled monolayers on gold electrodes

    DEFF Research Database (Denmark)

    Browne, W.R.; Kudernac, T.; Katsonis, N.


    The photochemical and electrochemical properties of self-assembled monolayers (SAM) of three structurally distinct hexahydro- and hexafluoro-dithienylcyclopentene-based photochromic switches on gold electrodes are reported. The photochemical and electrochemical switching between the open and clos...

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

    DEFF Research Database (Denmark)

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


    Glycol chitosan was linked to vitamin D2 hemisuccinate (ergocalciferol hemisuccinate) for controlled release through water-soluble carbodiimide activation. The resulting conjugate formed self-assembled nanoparticles in aqueous solution with particle size of 279 nm and ergocalciferol hemisuccinate...

  14. Formation of Biocompatible Nanoparticles by Self-Assembly of Enzymatic Hydrolysates of Chitosan and Carboxymethyl Cellulose

    National Research Council Canada - National Science Library

    ICHIKAWA, Sosaku; IWAMOTO, Satoshi; WATANABE, Jun


    ... %) by self-assembly of chitosan and carboxymethyl cellulose hydrolysates was developed. Chitosan and carboxymethyl cellulose were hydrolyzed beforehand with chitosanase and cellulase respectively to make fragments having lower molecular weights...

  15. Control of Self-Assembly of Lithographically Patternable Block Copolymer Films

    Energy Technology Data Exchange (ETDEWEB)

    Black, C.T.; Bosworth, J.K.; Paik, M.Y.; Ruiz, R.; Schwartz, E.L.; Huang, J.Q.; Ko, A.W.; Smilgies, D.-M.; Ober, C.K.


    Poly({alpha}-methylstyrene)-block-poly(4-hydroxystyrene) acts as both a lithographic deep UV photoresist and a self-assembling material, making it ideal for patterning simultaneously by both top-down and bottom-up fabrication methods. Solvent vapor annealing improves the quality of the self-assembled patterns in this material without compromising its ability to function as a photoresist. The choice of solvent used for annealing allows for control of the self-assembled pattern morphology. Annealing in a nonselective solvent (tetrahydrofuran) results in parallel orientation of cylindrical domains, while a selective solvent (acetone) leads to formation of a trapped spherical morphology. Finally, we have self-assembled both cylindrical and spherical phases within lithographically patterned features, demonstrating the ability to precisely control ordering. Observing the time evolution of switching from cylindrical to spherical morphology within these features provides clues to the mechanism of ordering by selective solvent.

  16. Control of Self-Assembly of Lithographically Patternable Block Copolymer Films

    Energy Technology Data Exchange (ETDEWEB)

    Bosworth, Joan K.; Paik, Marvin Y.; Ruiz, Ricardo; Schwartz, Evan L.; Huang, Jenny Q.; Ko, Albert W.; Smilgies, Detlef-M.; Black, Charles T.; Ober, Christopher K. (Cornell); (IBM)


    Poly({alpha}-methylstyrene)-block-poly(4-hydroxystyrene) acts as both a lithographic deep UV photoresist and a self-assembling material, making it ideal for patterning simultaneously by both top-down and bottom-up fabrication methods. Solvent vapor annealing improves the quality of the self-assembled patterns in this material without compromising its ability to function as a photoresist. The choice of solvent used for annealing allows for control of the self-assembled pattern morphology. Annealing in a nonselective solvent (tetrahydrofuran) results in parallel orientation of cylindrical domains, while a selective solvent (acetone) leads to formation of a trapped spherical morphology. Finally, we have self-assembled both cylindrical and spherical phases within lithographically patterned features, demonstrating the ability to precisely control ordering. Observing the time evolution of switching from cylindrical to spherical morphology within these features provides clues to the mechanism of ordering by selective solvent.

  17. Rapid self-assembly of brush block copolymers to photonic crystals

    National Research Council Canada - National Science Library

    Benjamin R. Sveinbjörnsson; Raymond A. Weitekamp; Garret M. Miyake; Yan Xia; Harry A. Atwater; Robert H. Grubbs


    .... In this report, we demonstrate the rapid self-assembly of brush block copolymers to nanostructures with photonic bandgaps spanning the entire visible spectrum, from ultraviolet (UV) to near infrared (NIR...

  18. DNAzyme-Based Logic Gate-Mediated DNA Self-Assembly. (United States)

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


    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.

  19. Effects of High Pressure on Internally Self-Assembled Lipid Nanoparticles

    DEFF Research Database (Denmark)

    Kulkarni, Chandrashekhar V; Yaghmur, Anan; Steinhart, Milos


    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...... samples, whereas the internal self-assemblies of the corresponding lipid nanoparticles displayed only pressure-modulated single phases. Interestingly, both the lattice parameters and the linear pressure expansion coefficients were larger for the self-assemblies enveloped inside the lipid nanoparticles...

  20. Self-assembly and flux closure studies of magnetic nanoparticle rings

    DEFF Research Database (Denmark)

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


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

  1. Tuning whispering gallery mode lasing from self-assembled polymer droplets

    National Research Council Canada - National Science Library

    Ta, Van Duong; Chen, Rui; Sun, Han Dong


    .... The droplets are self-assembly inside an elastic medium. By incorporating different dye molecules into the droplets, optically pumped lasing with selective wavelengths in a range of about 100 nm are achieved...

  2. Self assembly of rectangular shapes on concentration programming and probabilistic tile assembly models. (United States)

    Kundeti, Vamsi; Rajasekaran, Sanguthevar


    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 235-253, 2009

  3. Self-Assembly of Large-Scale Shape-Controlled DNA Nano-Structures (United States)


    Polyhedra self-assembled from DNA tripods and characterized with 3D DNA- PAINT DNA self-assembly has produced diverse synthetic three-dimensional...edge widths of 100 nanometers. The structures were visualized by means of transmission electron microscopy and three-dimensional DNA- PAINT super...mild conditions, this seed grows into a larger cast structure that fills and thus replicates the cavity. We synthesized a variety of nanoparticles

  4. Innovative self-assembled and microfabricated structures to be used in distinct biomedical applications


    Mendes, Ana Carina


    Tese de doutoramento em Engenharia Biomédica Advances in self-assembly offer new opportunities in molecular design of biomaterials. A major advantage of these systems is their ability to generate similar fibrillar structures to those found in the natural extracellular matrix (ECM) of tissues and to integrate directly into their structure biomolecular ligands for cell signalling. On the other hand, the integration of self-assembly into existing microtechnologies could offer new ...

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

    Directory of Open Access Journals (Sweden)

    Nobuo Kimizuka


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

  6. Polymerization-Induced Self-Assembly of Poly(ethylene glycol)-block-Poly(N-vinylcaprolactam)


    Häkkinen, Satu


    Preparation of polymer nanoparticles has become of great interest to polymer scientists due to their wide range of applications. Block copolymer nano-objects have been studied for decades, however new production methods are still needed to achieve better commercial viability and thus a wider use of the materials. Polymerization-induced self-assembly (PISA) is a new approach to preparing block copolymer nanoparticles, in which the polymerization of the second block and the self-assembly of the...

  7. A Self-Assembled Electro-Active M8L4 Cage Based on Tetrathiafulvalene Ligands

    Directory of Open Access Journals (Sweden)

    Sébastien Goeb


    Full Text Available Two self-assembled redox-active cages are presented. They are obtained by coordination-driven self-assembly of a tetra-pyridile tetrathiafulvalene ligand with cis-M(dppf(OTf2 (M = Pd or Pt; dppf = 1,1′-bis(diphenylphosphinoferrocene; OTf = trifluoromethane-sulfonate complexes. Both species are fully characterized and are constituted of 12 electro-active subunits that can be reversibly oxidized.

  8. Self-Assembly and Surface-Patterning of Polymer-Functionalized Nanoparticles (United States)

    Choueiri, Rachel

    This thesis explores the preparation of polymer-functionalized nanoparticles, the surface-segregation of their polymer ligands to generate patchy nanocolloids, and the use of patchy and non-patchy polymer-functionalized nanoparticles as building blocks for self-assembly. In Chapter 3, the self-assembly of nanospheres uniformly functionalized with polymer was explored. Both chain-like and globular structures were generated from the same spherical nanoparticle building blocks by tuning the interplay of nanoscale forces. The molecular weight of polymer ligands and the polarity and ionic strength of the self-assembly medium were changed to adjust the interparticle hydrophobic attraction and electrostatic repulsion in order to obtain the desired self-assembled structure. The experimental results were in agreement with theoretical predictions for the most thermodynamically favourable self-assemblies. Hierarchical structures made from assembled globules of nanospheres were also generated and the reversibility of the self-assemblies was demonstrated. In Chapter 4, the segregation of polymer ligands into pinned micelles on the surface of nanospheres was explored. Single and multi-patch nanospheres were generated by studying the interplay of nanosphere curvature and polymer molecular weight. The statistics of patchy nanosphere species was quantified and compared to theoretical predictions. Permanent crosslinking of polymer patches was achieved in addition to tomography of the generated colloids to further characterize the morphology. In Chapter 5, the surface segregation of polymer ligands on nanoparticles with different shapes and composition such as spherocylindrical nanorods, nanorods with a dumbbell shape, and nanocubes was demonstrated. The surface segregation of different polymers (including pH-responsive and conductive polymers) on nanospheres was also achieved demonstrating the versatility of the polymer segregation approach for nanopatterning. In addition, the self-assembly

  9. Metallacrowns as products of the aqueous medium self-assembly of histidinehydroxamic acid-containing polypeptides.


    Cal, M.; Kotynia, A.; Jaremko, L.; Jaremko, M.; Lisowski, M.; Cebo, M.; Brasun, J.; Stefanowicz, P.


    Self-assembly is a widely studied, spontaneous, and reversible phenomenon leading to the formation of the ordered structures by non-covalent specific interactions among starting molecules. In this work, a new template for the self-assembly of polypeptides based on peptides containing the C-terminal histidinehydroxamic acid moiety and Cu2+ ions is characterized. Two peptide (tripeptide and pentadecapeptide) hydroxamic acid systems were synthesized and their interactions with Cu2+ ions were inv...

  10. Latent pH-responsive ratiometric fluorescent cluster based on self-assembled photoactivated SNARF derivatives


    Nakata, Eiji; Yukimachi, Yoshihiro; Uto, Yoshihiro; Hori, Hitoshi; Morii, Takashi


    Abstract We have developed a self-assembled fluorescent cluster comprising a seminaphthorhodafluor (SNARF) derivative protected by a photoremovable o-nitrobenzyl group. Prior to UV irradiation, a colorless and nonfluorescent cluster was spontaneously assembled in aqueous solution. After UV irradiation, the self-assembled cluster remained intact and showed a large enhancement in pH-responsive fluorescence. The unique pH responsive fluorescent cluster could be used as a dual-emissive ratiometri...

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  12. Engineering Protein Self-Assembly: A New Approach for the Design of Octahedral Cages. (United States)

    Cougnon, Fabien B L


    A new symmetry-based approach allowed the self-assembly of an octahedral protein nanostructure. C3 trimeric and C4 tetrameric oligomerization domains can be combined in an engineered protein to direct assembly into a desired object. This work might provide the basis for a more general and flexible strategy to control protein self-assembly. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Driving forces for the self-assembly of graphene oxide on organic monolayers (United States)

    Kirschner, Johannes; Wang, Zhenxing; Eigler, Siegfried; Steinrück, Hans-Peter; Jäger, Christof M.; Clark, Timothy; Hirsch, Andreas; Halik, Marcus


    Graphene oxide (GO) flakes were self-assembled from solution on surfaces of self-assembled monolayers (SAMs), varying in the chemical structure of their head groups. The coverage density of GO relates to strength of attractive interaction, which is largest for Coulomb interaction provided by positively charged SAM head groups and negatively charged GO. A rough surface enhances the coverage density but with the same trend in driving force dependency. The self-assembly approach was used to fabricate field-effect transistors with reduced GO (rGO) as active layer. The SAMs as attractive layer for self-assembly remain almost unaffected by the reduction from GO to rGO and serve as ultra-thin gate dielectrics in devices, which operate at low voltages of maximum 3 V and exhibit a shift of the Dirac voltage related to the dipole moment of the SAMs.Graphene oxide (GO) flakes were self-assembled from solution on surfaces of self-assembled monolayers (SAMs), varying in the chemical structure of their head groups. The coverage density of GO relates to strength of attractive interaction, which is largest for Coulomb interaction provided by positively charged SAM head groups and negatively charged GO. A rough surface enhances the coverage density but with the same trend in driving force dependency. The self-assembly approach was used to fabricate field-effect transistors with reduced GO (rGO) as active layer. The SAMs as attractive layer for self-assembly remain almost unaffected by the reduction from GO to rGO and serve as ultra-thin gate dielectrics in devices, which operate at low voltages of maximum 3 V and exhibit a shift of the Dirac voltage related to the dipole moment of the SAMs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02527j

  14. Spontaneous self-assembly of SC3 hydrophobins into nanorods in aqueous solution. (United States)

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


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

  15. Investigating the effects of peptoid substitutions in self-assembly of Fmoc-diphenylalanine derivatives. (United States)

    Rajbhandary, Annada; Nilsson, Bradley L


    Low molecular weight agents that undergo self-assembly into fibril networks with hydrogel properties are promising biomaterials. Most low molecular weight hydrogelators are discovered empirically or serendipitously due to imperfect understanding of the mechanisms of self-assembly, the packing structure of self-assembled materials, and how the self-assembly process corresponds to emergent hydrogelation. Herein, the mechanisms of self-assembly and hydrogelation of N-fluorenylmethoxycarbonyl diphenylalanine (Fmoc-PhePhe), a well-studied low molecular weight hydrogelator, is probed by systematic comparison with derivatives in which Phe residues are replaced by corresponding N-benzyl glycine peptoid (Nphe) analogs. Peptoids are peptidomimetics that shift display of side chain functionality from the α-carbon to the terminal nitrogen. This alters the hydrogen bonding capacity, the side chain presentation geometry, amide cis/trans isomerization equilibrium, and β-sheet potential of the peptoid relative to the corresponding amino acid in the context of peptidic polymers. It was found that amino acid/peptoid hybrids Fmoc-Phe-Nphe and Fmoc-Nphe-Phe have altered fibril self-assembly propensity and reduced hydrogelation capacity relative to the parent dipeptide, and that fibril self-assembly of the dipeptoid, Fmoc-Nphe-Nphe, is completely curtailed. These findings provide insight into the potential of low molecular weight peptoids and peptide/peptoid hybrids as hydrogelation agents and illuminate the importance of hydrogen bonding and π-π interaction geometry in facilitating self-assembly of Fmoc-Phe-Phe. © 2016 Wiley Periodicals, Inc.

  16. Optical constants and self-assembly of phenylene ethynylene oligomer monolayers

    DEFF Research Database (Denmark)

    Marx, E.; Walzer, Karsten; Less, R.J.


    This paper studies the self-assembly on gold surfaces of 1,4-ethynylphenyl-4'-ethynylphenyl-2'-nitro-1-benzenedithiolate (EP2NO(2)), a substituted phenylene ethynylene trimer with applications in molecular electronics. We develop an ellipsometric technique to measure the optical constants of thes...... of these self-assembled monolayers, and we also use attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and scanning tunneling microscopy (STM) to confirm the structure of the films....

  17. Electrophoretic dynamics of self-assembling branched DNA structures (United States)

    Heuer, Daniel Milton

    This study advances our understanding of the electrophoretic dynamics of branched biopolymers and explores technologies designed to exploit their unique properties. New self-assembly techniques were developed to create branched DNA for visualization via fluorescence microscopy. Experiments in fixed gel networks reveal a distinct trapping behavior, in contrast with linear topologies. The finding that detection can be achieved by introducing a branch point contributes significantly to the field of separation science and can be exploited to develop new applications. Results obtained in polymer solutions point to identical mobilities for branched and linear topologies, despite large differences in their dynamics. This finding led to a new description of electrophoresis based on non-Newtonian viscoelastic effects in the electric double layer surrounding a charged object. This new theoretical framework presents a new outlook important not only to the electrophoretic physics of nucleic acids, but all charged objects including proteins, colloids, and nanoparticles. To study the behavior of smaller biopolymers, such as restriction fragments and recombination intermediates, a library of symmetrically branched DNA was synthesized followed by characterization in gels. The experimental results contribute a large body of information relating molecular architecture and the dynamics of rigid structures in an electric field. The findings allow us to create new separation technologies based on topology. These contributions can also be utilized in a number of different applications including the study of recombination intermediates and the separation of proteins according to structure. To demonstrate the importance of these findings, a sequence and mutation detection technique was envisioned and applied for genetic analysis. Restriction fragments from mutation "hotspots" in the p53 tumor suppressor gene, known to play a role in cancer development, were analyzed with this technique

  18. Double smectic self-assembly in block copolypeptide complexes

    KAUST Repository

    Haataja, Johannes S.


    We show double smectic-like self-assemblies in the solid state involving alternating layers of different polypeptide α-helices. We employed rod-coil poly(γ-benzyl l-glutamate)-block-poly(l-lysine) (PBLG-b-PLL) as the polymeric scaffold, where the PLL amino residues were ionically complexed to di-n-butyl phosphate (diC4P), di(2-ethylhexyl) phosphate (diC2/6P), di(2-octyldodecyl) phosphate (diC8/12P), or di-n-dodecyl phosphate (diC12P), forming PBLG-b-PLL(diC4P), PBLG-b-PLL(diC2/6P), PBLG-b-PLL(diC8/12P), and PBLG-b-PLL(diC12P) complexes, respectively. The complexes contain PBLG α-helices of fixed diameter and PLL-surfactant complexes adopting either α-helices of tunable diameters or β-sheets. For PBLG-b-PLL(diC4P), that is, using a surfactant with short n-butyl tails, both blocks were α-helical, of roughly equal diameter and thus with minor packing frustrations, leading to alternating PBLG and PLL(diC4P) smectic layers of approximately perpendicular alignment of both types of α-helices. Surfactants with longer and branched alkyl tails lead to an increased diameter of the PLL-surfactant α-helices. Smectic alternating PBLG and PLL(diC2/6P) layers involve larger packing frustration, which leads to poor overall order and suggests an arrangement of tilted PBLG α-helices. In PBLG-b-PLL(diC8/12P), the PLL(diC8/12P) α-helices are even larger and the overall structure is poor. Using a surfactant with two linear n-dodecyl tails leads to well-ordered β-sheet domains of PLL(diC12P), consisting of alternating PLL and alkyl chain layers. This dominates the whole assembly, and at the block copolypeptide length scale, the PBLG α-helices do not show internal order and have poor organization. Packing frustration becomes an important aspect to design block copolypeptide assemblies, even if frustration could be relieved by conformational imperfections. The results suggest pathways to control hierarchical liquid-crystalline assemblies by competing interactions and by

  19. Integrated Nanosystems Templated by Self-assembled Virus Capsids (United States)

    Stephanopoulos, Nicholas

    This dissertation presents the synthesis and modeling of multicomponent nanosystems templated by self-assembled virus capsids. The design principles, synthesis, analysis, and future directions for these capsid-based materials are presented. Chapter 1 gives an overview of the literature on the application of virus capsids in constructing nanomaterials. The uses of capsids in three main areas are considered: (1) as templates for inorganic materials or nanoparticles; (2) as vehicles for biological applications like medical imaging and treatment; and (3) as scaffolds for catalytic materials. In light of this introduction, an overview of the material in this dissertation is described. Chapters 2-4 all describe integrated nanosystems templated by bacteriophage MS2, a spherical icosahedral virus capsid. MS2 possesses an interior and exterior surface that can be modified orthogonally using bioconjugation chemistry to create multivalent, multicomponent constructs with precise localization of components attached to the capsid proteins. Chapter 2 describes the use of MS2 to synthesize a photocatalytic construct by modifying the internal surface with sensitizing chromophores and the external surface with a photocatalytic porphyrin. The chromophores absorbed energy that the porphyrin could not, and transferred it to the porphyrin via FRET through the protein shell. The porphyrin was then able to utilize the energy to carry out photocatalysis at new wavelengths. In Chapter 3, porphyrins were installed on the interior surface of MS2 and DNA aptamers specific for Jurkat leukemia T cells on the exterior surface. The dual-modified capsids were able to bind to Jurkat cells, and upon illumination the porphyrins generated singlet oxygen to kill them selectively over non-targeted cells. Chapter 4 explores integrating MS2 with DNA origami in order to arrange the capsids at larger length scales. Capsids modified with fluorescent dyes inside and single-stranded DNA outside were able to

  20. Self-assembly of microcapsules via colloidal bond hybridization and anisotropy (United States)

    Evers, Chris H. J.; Luiken, Jurriaan A.; Bolhuis, Peter G.; Kegel, Willem K.


    Particles with directional interactions are promising building blocks for new functional materials and may serve as models for biological structures. Mutually attractive nanoparticles that are deformable owing to flexible surface groups, for example, may spontaneously order themselves into strings, sheets and large vesicles. Furthermore, anisotropic colloids with attractive patches can self-assemble into open lattices and the colloidal equivalents of molecules and micelles. However, model systems that combine mutual attraction, anisotropy and deformability have not yet been realized. Here we synthesize colloidal particles that combine these three characteristics and obtain self-assembled microcapsules. We propose that mutual attraction and deformability induce directional interactions via colloidal bond hybridization. Our particles contain both mutually attractive and repulsive surface groups that are flexible. Analogously to the simplest chemical bond—in which two isotropic orbitals hybridize into the molecular orbital of H2—these flexible groups redistribute on binding. Via colloidal bond hybridization, isotropic spheres self-assemble into planar monolayers, whereas anisotropic snowman-shaped particles self-assemble into hollow monolayer microcapsules. A modest change in the building blocks thus results in much greater complexity of the self-assembled structures. In other words, these relatively simple building blocks self-assemble into markedly more complex structures than do similar particles that are isotropic or non-deformable.

  1. Amphiphiles Self-Assembly: Basic Concepts and Future Perspectives of Supramolecular Approaches

    Directory of Open Access Journals (Sweden)

    Domenico Lombardo


    Full Text Available Amphiphiles are synthetic or natural molecules with the ability to self-assemble into a wide variety of structures including micelles, vesicles, nanotubes, nanofibers, and lamellae. Self-assembly processes of amphiphiles have been widely used to mimic biological systems, such as assembly of lipids and proteins, while their integrated actions allow the performance of highly specific cellular functions which has paved a way for bottom-up bionanotechnology. While amphiphiles self-assembly has attracted considerable attention for decades due to their extensive applications in material science, drug and gene delivery, recent developments in nanoscience stimulated the combination of the simple approaches of amphiphile assembly with the advanced concept of supramolecular self-assembly for the development of more complex, hierarchical nanostructures. Introduction of stimulus responsive supramolecular amphiphile assembly-disassembly processes provides particularly novel approaches for impacting bionanotechnology applications. Leading examples of these novel self-assembly processes can be found, in fact, in biosystems where assemblies of different amphiphilic macrocomponents and their integrated actions allow the performance of highly specific biological functions. In this perspective, we summarize in this tutorial review the basic concept and recent research on self-assembly of traditional amphiphilic molecules (such as surfactants, amphiphile-like polymers, or lipids and more recent concepts of supramolecular amphiphiles assembly which have become increasingly important in emerging nanotechnology.

  2. Photon Upconversion and Molecular Solar Energy Storage by Maximizing the Potential of Molecular Self-Assembly. (United States)

    Kimizuka, Nobuo; Yanai, Nobuhiro; Morikawa, Masa-Aki


    The self-assembly of functional molecules into ordered molecular assemblies and the fulfillment of potentials unique to their nanotomesoscopic structures have been one of the central challenges in chemistry. This Feature Article provides an overview of recent progress in the field of molecular self-assembly with the focus on the triplet-triplet annihilation-based photon upconversion (TTA-UC) and supramolecular storage of photon energy. On the basis of the integration of molecular self-assembly and photon energy harvesting, triplet energy migration-based TTA-UC has been achieved in varied molecular systems. Interestingly, some molecular self-assemblies dispersed in solution or organogels revealed oxygen barrier properties, which allowed TTA-UC even under aerated conditions. The elements of molecular self-assembly were also introduced to the field of molecular solar thermal fuel, where reversible photoliquefaction of ionic crystals to ionic liquids was found to double the molecular storage capacity with the simultaneous pursuit of switching ionic conductivity. A future prospect in terms of innovating molecular self-assembly toward molecular systems chemistry is also discussed.

  3. Synthesis and Self-Assembly of Gold Nanoparticles by Chemically Modified Polyol Methods under Experimental Control

    Directory of Open Access Journals (Sweden)

    Nguyen Viet Long


    Full Text Available In our present research, bottom-up self-assembly of gold (Au nanoparticles on a flat copper (Cu substrate is performed by a facile method. The very interesting evidence of self-assembly of Au nanoparticles on the top of the thin assembled layer was observed by scanning electron microscopy (SEM. We had discovered one of the most general and simple methods for the self-assembly of metal nanoparticles. The general physical and chemical mechanisms of the evaporation process of the solvents can be used for self-assembly of the as-prepared nanoparticles. The important roles of molecules of the used solvents are very critical to self-assembly of the as-prepared Au nanoparticles in the case without using any polymers for those processes. It is clear that self-assembly of such one nanosystem of the uniform Au nanoparticles is fully examined. Finally, an exciting surface plasmon resonance (SPR phenomenon of the pure Au nanoparticles in the solvent was fully discovered in their exciting changes of the narrow and large SPR bands according to synthesis time. The SPR was considered as the collective oscillation of valence electrons of the surfaces of the pure Au nanoparticles in the solvent by incident ultraviolet-visible light. Then, the frequency of light photons matches the frequency of the oscillation of surface electrons of the Au nanoparticles that are excited.

  4. Self-assembly of microcapsules via colloidal bond hybridization and anisotropy. (United States)

    Evers, Chris H J; Luiken, Jurriaan A; Bolhuis, Peter G; Kegel, Willem K


    Particles with directional interactions are promising building blocks for new functional materials and may serve as models for biological structures. Mutually attractive nanoparticles that are deformable owing to flexible surface groups, for example, may spontaneously order themselves into strings, sheets and large vesicles. Furthermore, anisotropic colloids with attractive patches can self-assemble into open lattices and the colloidal equivalents of molecules and micelles. However, model systems that combine mutual attraction, anisotropy and deformability have not yet been realized. Here we synthesize colloidal particles that combine these three characteristics and obtain self-assembled microcapsules. We propose that mutual attraction and deformability induce directional interactions via colloidal bond hybridization. Our particles contain both mutually attractive and repulsive surface groups that are flexible. Analogously to the simplest chemical bond--in which two isotropic orbitals hybridize into the molecular orbital of H2--these flexible groups redistribute on binding. Via colloidal bond hybridization, isotropic spheres self-assemble into planar monolayers, whereas anisotropic snowman-shaped particles self-assemble into hollow monolayer microcapsules. A modest change in the building blocks thus results in much greater complexity of the self-assembled structures. In other words, these relatively simple building blocks self-assemble into markedly more complex structures than do similar particles that are isotropic or non-deformable.

  5. Micellar Self-Assembly of Recombinant Resilin-/Elastin-Like Block Copolypeptides. (United States)

    Weitzhandler, Isaac; Dzuricky, Michael; Hoffmann, Ingo; Garcia Quiroz, Felipe; Gradzielski, Michael; Chilkoti, Ashutosh


    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.

  6. Versatile Self-Assembly and Biosensing Applications of DNA and Carbon Quantum Dots Coordinated Cerium Ions. (United States)

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


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

  7. Formation of charge-nanopatterned templates with flexible geometry via layer by layer deposition of polyelectrolytes for directed self-assembly of gold nanoparticles (United States)

    Sayin, Mustafa; Dahint, Reiner


    Nanostructure formation via self-assembly processes offers a fast and cost-effective approach to generate surface patterns on large lateral scale. In particular, if the high precision of lithographic techniques is not required, a situation typical of many biotechnological and biomedical applications, it may be considered as the method of choice as it does not require any sophisticated instrumentation. However, in many cases the variety and complexity of the surface structures accessible with a single self-assembly based technique is limited. Here, we report on a new approach which combines two different self-assembly strategies, colloidal lithography and layer-by-layer deposition of polyelectrolytes, in order to significantly expand the spectrum of accessible patterns. In particular, flat and donut-like charge-patterned templates have been generated, which facilitate subsequent deposition of gold nanoparticles in dot, grid, ring, out-of-ring and circular patch structures. Potential applications are e.g. in the fields of biofunctional interfaces with well-defined lateral dimensions, optical devices with tuned properties, and controlled three-dimensional material growth.

  8. Multifunctional hybrid networks based on self assembling peptide sequences (United States)

    Sathaye, Sameer

    loose packing can be attributed to the designed wedge and trough shapes of the peptides disturbing formation of a uniform bilayer type structure proposed in the case of MAX1 with each hairpin having a flat hydrophobic surface. Although designed changes in hydrophobic shape of the peptide nanofibril core in the new peptides were found to significantly influence the self-assembled nanostructure and network rheological behavior, a lack of direct morphological and rheological evidence to prove shape specific hydrophobic interactions between wedge and trough shaped beta-hairpins was encountered. In the second approach, peptides with established differences in assembly kinetics and bulk mechanical properties of assembled peptide hydrogels were used to develop composite materials with diverse morphological and mechanical properties by blending with the biopolymer hyaluronic acid. The diverse properties of the composites have been correlated to the specific peptide hydrogels used to develop the composite and the different stages of peptide assembly at which blending with hyaluronic acid was carried out. Finally along with overall conclusions, the new area of co-assembly of peptides in solution has been explored and discussed as potential future work following the research discussed in this dissertation. Strategies such as construction of composite hydrogels from blends of MAX1/MAX8 peptide hydrogels and biologically important anionic species such as heparin biopolymer and DNA have been discussed. Another area of future work discussed is the design and study of peptides that can incorporate chemically crosslinkable functional groups in their hydrophobic amino acid side chains that can be covalently crosslinked after peptide assembly into fibrils. Such covalent crosslinking can potentially lead to stiffer individual peptide fibrils due to additional bond formation at the fibrillar core and therefore much stiffer hydrogels due to a synergistic effect. These enhanced stiffness

  9. Self-assembly of fibronectin mimetic peptide-amphiphile nanofibers (United States)

    Rexeisen, Emilie Lynn

    umbilical vein endothelial cells and alpha5beta1 integrins immobilized on an AFM tip preferred binding to a fibronectin mimetic peptide that contained both hydrophilic and hydrophobic residues in the linker and a medium length spacer. Most cells require a three-dimensional scaffold in order to thrive. To incorporate the fibronectin mimetic peptide into a three-dimensional structure, a single hydrocarbon tail was attached to form a peptideamphiphile. Single-tailed peptide-amphiphiles have been shown to form nanofibers in solution and gel after screening of the electrostatic charges in the headgroup. These gels show promise as scaffolds for tissue engineering. A fibronectin mimetic peptide-amphiphile containing a linker with alternating hydrophobic and hydrophilic residues was designed to form nanofibers in solution. The critical micelle concentration of the peptide-amphiphile was determined to be 38 muM, and all subsequent experiments were performed above this concentration. Circular dichroism (CD) spectroscopy indicated that the peptide headgroup of the peptide-amphiphile forms an alpha+beta secondary structure; whereas, the free peptide forms a random secondary structure. Cryogenic-transmission electron microscopy (cryo-TEM) and small angle neutron scattering showed that the peptide-amphiphile self-assembled into nanofibers. The cryo-TEM images showed single nanofibers with a diameter of 10 nm and lengths on the order of microns. Images of higher peptideamphiphile concentrations showed evidence of bundling between individual nanofibers, which could give rise to gelation behavior at higher concentrations. The peptide-amphiphile formed a gel at concentrations above 6 mM. A 10 mM sample was analyzed with oscillating plate rheometry and was found to have an elastic modulus within the range of living tissue, showing potential as a possible scaffold for tissue engineering.

  10. Templated self-assembly of SiGe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Dais, Christian


    This PhD thesis reports on the fabrication and characterization of exact aligned SiGe quantum dot structures. In general, SiGe quantum dots which nucleate via the Stranski-Krastanov growth mode exhibit broad size dispersion and nucleate randomly on the surface. However, to tap the full potential of SiGe quantum dots it is necessary to control the positioning and size of the dots on a nanometer length, e.g. for electronically addressing of individual dots. This can be realized by so-called templated self-assembly, which combines top-down lithography with bottom-up selfassembly. In this process the lithographically defined pits serve as pre-defined nucleation points for the epitaxially grown quantum dots. In this thesis, extreme ultraviolet interference lithography at a wavelength of e=13.4 nm is employed for prepatterning of the Si substrates. This technique allows the precise and fast fabrication of high-resolution templates with a high degree of reproducibility. The subsequent epitaxial deposition is either performed by molecular beam epitaxy or low-pressure chemical vapour deposition. It is shown that the dot nucleation on pre-patterned substrates depends strongly on the lithography parameters, e.g. size and periodicity of the pits, as well as on the epitaxy parameters, e.g. growth temperature or material coverage. The interrelations are carefully analyzed by means of scanning force microscopy, transmission electron microscopy and X-ray diffraction measurements. Provided that correct template and overgrowth parameters are chosen, perfectly aligned and uniform SiGe quantum dot arrays of different period, size as well as symmetry are created. In particular, the quantum dot arrays with the so far smallest period (35 nm) and smallest size dispersion are fabricated in this thesis. Furthermore, the strain fields of the underlying quantum dots allow the fabrication of vertically aligned quantum dot stacks. Combining lateral and vertical dot alignment results in three

  11. Sustained delivery of VEGF from designer self-assembling peptides improves cardiac function after myocardial infarction

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hai-dong [Department of Anatomy, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203 (China); Cui, Guo-hong; Yang, Jia-jun [Department of Neurology, Shanghai No. 6 People' s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200233 (China); Wang, Cun [Institutes of Biomedical Sciences, Fudan University, Shanghai 200032 (China); Zhu, Jing; Zhang, Li-sheng; Jiang, Jun [Department of Anatomy, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203 (China); Shao, Shui-jin, E-mail: [Department of Anatomy, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203 (China)


    Highlights: Black-Right-Pointing-Pointer The designer peptide LRKKLGKA could self-assemble into nanofibers. Black-Right-Pointing-Pointer Injection of LRKKLGKA peptides could promote the sustained delivery of VEGF. Black-Right-Pointing-Pointer Injection of VEGF with LRKKLGKA peptides lead to sufficient angiogenesis. Black-Right-Pointing-Pointer Injection of VEGF with LRKKLGKA peptides improves heart function. -- Abstract: Poor vascularization and insufficient oxygen supply are detrimental to the survival of residual cardiomyocytes or transplanted stem cells after myocardial infarction. To prolong and slow the release of angiogenic factors, which stimulate both angiogenesis and vasculogenesis, we constructed a novel self-assembling peptide by attaching the heparin-binding domain sequence LRKKLGKA to the self-assembling peptide RADA16. This designer self-assembling peptide self-assembled into nanofiber scaffolds under physiological conditions, as observed by atomic force microscopy. The injection of designer self-assembling peptides can efficiently provide the sustained delivery of VEGF for at least 1 month. At 4 weeks after transplantation, cardiac function was improved, and scar size and collagen deposition were markedly reduced in the group receiving VEGF with the LRKKLGKA scaffolds compared with groups receiving VEGF alone, LRKKLGKA scaffolds alone or VEGF with RADA16 scaffolds. The microvessel density in the VEGF with LRKKLGKA group was higher than that in the VEGF with RADA16 group. TUNEL and cleaved caspase-3 expression assays showed that the transplantation of VEGF with LRKKLGKA enhanced cell survival in the infarcted heart. These results present the tailor-made peptide scaffolds as a new generation of sustained-release biomimetic biomaterials and suggest that the use of angiogenic factors along with designer self-assembling peptides can lead to myocardial protection, sufficient angiogenesis, and improvement in cardiac function.

  12. Quantifying the Self-Assembly Behavior of Anisotropic Nanoparticles Using Liquid-Phase Transmission Electron Microscopy. (United States)

    Luo, Binbin; Smith, John W; Ou, Zihao; Chen, Qian


    For decades, one of the overarching objectives of self-assembly science has been to define the rules necessary to build functional, artificial materials with rich and adaptive phase behavior from the bottom-up. To this end, the computational and experimental efforts of chemists, physicists, materials scientists, and biologists alike have built a body of knowledge that spans both disciplines and length scales. Indeed, today control of self-assembly is extending even to supramolecular and molecular levels, where crystal engineering and design of porous materials are becoming exciting areas of exploration. Nevertheless, at least at the nanoscale, there are many stones yet to be turned. While recent breakthroughs in nanoparticle (NP) synthesis have amassed a vast library of nanoscale building blocks, NP-NP interactions in situ remain poorly quantified, in large part due to technical and theoretical impediments. While increasingly many applications for self-assembled architectures are being demonstrated, it remains difficult to predict-and therefore engineer-the pathways by which these structures form. Here, we describe how investigations using liquid-phase transmission electron microscopy (TEM) have begun to play a role in pursuing some of these long-standing questions of fundamental and far-reaching interest. Liquid-phase TEM is unique in its ability to resolve the motions and trajectories of single NPs in solution, making it a powerful tool for studying the dynamics of NP self-assembly. Since 2012, liquid-phase TEM has been used to investigate the self-assembly behavior of a variety of simple, metallic NPs. In this Account, however, we focus on our work with anisotropic NPs, which we show to have very different self-assembly behavior, and especially on how analysis methods we and others in the field are developing can be used to convert their motions and trajectories revealed by liquid-phase TEM into quantitative understanding of underlying interactions and dynamics

  13. Chemical and entropic control on the molecular self-assembly process (United States)

    Packwood, Daniel M.; Han, Patrick; Hitosugi, Taro


    Molecular self-assembly refers to the spontaneous assembly of molecules into larger structures. In order to exploit molecular self-assembly for the bottom-up synthesis of nanomaterials, the effects of chemical control (strength of the directionality in the intermolecular interaction) and entropic control (temperature) on the self-assembly process should be clarified. Here we present a theoretical methodology that unambiguously distinguishes the effects of chemical and entropic control on the self-assembly of molecules adsorbed to metal surfaces. While chemical control simply increases the formation probability of ordered structures, entropic control induces a variety of effects. These effects range from fine structure modulation of ordered structures, through to degrading large, amorphous structures into short, chain-shaped structures. Counterintuitively, the latter effect shows that entropic control can improve molecular ordering. By identifying appropriate levels of chemical and entropic control, our methodology can, therefore, identify strategies for optimizing the yield of desired nanostructures from the molecular self-assembly process. PMID:28195175

  14. Nanostructured functional hybrid materials via self-assembly of brush block copolymers (United States)

    Song, Dong-Po; Gai, Yue; Yavitt, Benjamin; Watkins, James

    The self-assembly of well-ordered nanoparticle (NP) / block copolymer (BCP) composites enables precise control over the spatial distribution of NP arrays, providing a simple route to the low-cost ``bottom-up'' fabrication of hybrid materials with enhanced mechanical, optical and electric properties. Here we summarize the fabrication of nanocomposites via the self-assembly of brush BCPs (BBCPs). In comparison to conventional materials based on linear BCPs, the BBCP hybrids exhibit many attractive features, including rapid supramolecular self-assembly (100 nm), and high loading of functional additives (>70 wt%). Both the self-assembled structures and the compositions of the nanocomposites can be widely tuned for applications such as photonic crystals or coatings, nonlinear optics, and metamaterials. In addition, BBCPs were employed as templates for the mesoporous hybrid materials that have large mesopores (up to 40 nm) and high loadings of functional NPs (up to 50 wt%). Simple solutionbased processing and rapid self-assembly of brush BCP nanocomposites are promising for roll-to-roll manufacturing of low-cost and flexible devices. This work was supported by NSF Center for Hierarchical Manufacturing at the University of Massachusetts, Amherst.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xinhua, E-mail:; Gao, Aiping; Zhao, Na; Yuan, Fangyuan; Liu, Chenxi; Li, Ruru


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

  16. Selective self-assembly of adenine-silver nanoparticles forms rings resembling the size of cells (United States)

    Choi, Sungmoon; Park, Soonyoung; Yang, Seon-Ah; Jeong, Yujin; Yu, Junhua


    Self-assembly has played critical roles in the construction of functional nanomaterials. However, the structure of the macroscale multicomponent materials built by the self-assembly of nanoscale building blocks is hard to predict due to multiple intermolecular interactions of great complexity. Evaporation of solvents is usually an important approach to induce kinetically stable assemblies of building blocks with a large-scale specific arrangement. During such a deweting process, we tried to monitor the possible interactions between silver nanoparticles and nucleobases at a larger scale by epifluorescence microscopy, thanks to the doping of silver nanoparticles with luminescent silver nanodots. ssDNA oligomer-stabilized silver nanoparticles and adenine self-assemble to form ring-like compartments similar to the size of modern cells. However, the silver ions only dismantle the self-assembly of adenine. The rings are thermodynamically stable as the drying process only enrich the nanoparticles-nucleobase mixture to a concentration that activates the self-assembly. The permeable membrane-like edge of the ring is composed of adenine filaments glued together by silver nanoparticles. Interestingly, chemicals are partially confined and accumulated inside the ring, suggesting that this might be used as a microreactor to speed up chemical reactions during a dewetting process. PMID:26643504

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

    Directory of Open Access Journals (Sweden)

    Yu Zhang


    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.

  18. Molecular dynamics simulations reveal disruptive self-assembly in dynamic peptide libraries. (United States)

    Sasselli, I R; Moreira, I P; Ulijn, R V; Tuttle, T


    There is significant interest in the use of unmodified self-assembling peptides as building blocks for functional, supramolecular biomaterials. Recently, dynamic peptide libraries (DPLs) have been proposed to select self-assembling materials from dynamically exchanging mixtures of dipeptide inputs in the presence of a nonspecific protease enzyme, where peptide sequences are selected and amplified based on their self-assembling tendencies. It was shown that the results of the DPL of mixed sequences (e.g. starting from a mixture of dileucine, L 2 , and diphenylalanine, F 2 ) did not give the same outcome as the separate L 2 and F 2 libraries (which give rise to the formation of F 6 and L 6 ), implying that interactions between these sequences could disrupt the self-assembly. In this study, coarse grained molecular dynamics (CG-MD) simulations are used to understand the DPL results for F 2 , L 2 and mixed libraries. CG-MD simulations demonstrate that interactions between precursors can cause the low formation yield of hexapeptides in the mixtures of dipeptides and show that this ability to disrupt is influenced by the concentration of the different species in the DPL. The disrupting self-assembly effect between the species in the DPL is an important effect to take into account in dynamic combinatorial chemistry as it affects the possible discovery of new materials. This work shows that combined computational and experimental screening can be used complementarily and in combination providing a powerful means to discover new supramolecular peptide nanostructures.

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

    Directory of Open Access Journals (Sweden)

    Da Hye Shin


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

  20. Anisotropic self-assembly of colloidal particles in polymer-colloid composites: A simulation study (United States)

    Goswami, Monojoy; Sumpter, Bobby


    The self-assembly of colloidal particles has potential applications in optical fibers, sensors and photovoltaic cells. In this work we have carried out stochastic molecular dynamics simulations of colloid-polymer composites in order to investigate the fundamental self-assembly processes of the particles, in an effort to design more optimal materials for the applications stated above. Results were obtained for spherical colloidal particles of different screening lengths dispersed in a polymer matrix at melt density. By tuning the screening length and interaction strengths between the colloid and polymer, self-assembly into structures that generate anisotropy in the composite material is demonstrated. This phenomenon in colloid-polymer mixtures is analogous to the previously observed self-assembly of grafted nanoparticles in polymer nanocomposites. Our results show a potentially easier way of producing anisotropic self-assembly in polymer-nanocomposites based on colloidal particles as fillers. We also discuss the dynamics of the polymer chains and colloidal particles for different screening lengths and polymer-filler interaction strengths.

  1. Controllable self-assembly of NaREF4 upconversion nanoparticles and their distinctive fluorescence properties (United States)

    Liu, Xiaoxia; Ni, Yaru; Zhu, Cheng; Fang, Liang; Kou, Jiahui; Lu, Chunhua; Xu, Zhongzi


    The paper presents the growth of hexagonal NaYF4:Yb3+, Tm3+ nanocrystals with tunable sizes induced by different contents of doped Yb3+ ions (10%-99.5%) using the thermal decomposition method. These nanoparticles, which have different sizes, are then self-assembled at the interface of cyclohexane and ethylene and transferred onto a normal glass slide. It is found that the size of nanoparticles directs their self-assembly. Due to the appropriate size of 40.5 nm, 15% Yb3+ ions doped nanoparticles are able to be self-assembled into an ordered inorganic monolayer membrane with a large area of about 10 × 10 μm2. More importantly, the obvious short-wave (300-500 nm) fluorescence improvement of the ordered 2D self-assembly structure is observed to be relative to disordered nanoparticles, which is because intrinsic absorption and scattering of upconversion nanoparticles leads to the self-loss of fluorescence, especially the short-wave fluorescence inside the disordered structure, and the relative emission of short-wave fluorescence is reduced. The construction of a 2D self-assembly structure can effectively avoid this and improve the radiated short-wave fluorescence, especially UV photons, and is able to direct the design of new types of solid-state optical materials in many fields.

  2. Biomimetic Branched Hollow Fibers Templated by Self-assembled Fibrous Polyvinylpyrrolidone (PVP) Structures in Aqueous Solution (United States)

    Qiu, Penghe; Mao, Chuanbin


    Branched hollow fibers are common in nature, but to form artificial fibers with a similar branched hollow structure is still a challenge. We discovered that polyvinylpyrrolidone (PVP) could self-assemble into branched hollow fibers in an aqueous solution after aging the PVP solution for about two weeks. Based on this finding, we demonstrated two approaches by which the self-assembly of PVP into branched hollow fibers could be exploited to template the formation of branched hollow inorganic fibers. First, inorganic material such as silica with high affinity against the PVP could be deposited on the surface of the branched hollow PVP fibers to form branched hollow silica fibers. To extend the application of PVP self-assembly in templating the formation of hollow branched fibers, we then adopted a second approach where the PVP molecules bound to inorganic nanoparticles (using gold nanoparticles as a model) co-self-assemble with the free PVP molecules in an aqueous solution, resulting in the formation of the branched hollow fibers with the nanoparticles embedded in the PVP matrix constituting the walls of the fibers. Heating the resultant fibers above the glass transition temperature of PVP led to the formation of branched hollow gold fibers. Our work suggests that the self-assembly of the PVP molecules in the solution can serve as a general method for directing the formation of branched hollow inorganic fibers. The branched hollow fibers may find potential applications in microfluidics, artificial blood vessel generation, and tissue engineering. PMID:20158250

  3. FOLDNA, a Web Server for Self-Assembled DNA Nanostructure Autoscaffolds and Autostaples

    Directory of Open Access Journals (Sweden)

    Chensheng Zhou


    Full Text Available DNA self-assembly is a nanotechnology that folds DNA into desired shapes. Self-assembled DNA nanostructures, also known as origami, are increasingly valuable in nanomaterial and biosensing applications. Two ways to use DNA nanostructures in medicine are to form nanoarrays, and to work as vehicles in drug delivery. The DNA nanostructures perform well as a biomaterial in these areas because they have spatially addressable and size controllable properties. However, manually designing complementary DNA sequences for self-assembly is a technically demanding and time consuming task, which makes it advantageous for computers to do this job instead. We have developed a web server, FOLDNA, which can automatically design 2D self-assembled DNA nanostructures according to custom pictures and scaffold sequences provided by the users. It is the first web server to provide an entirely automatic design of self-assembled DNA nanostructure, and it takes merely a second to generate comprehensive information for molecular experiments including: scaffold DNA pathways, staple DNA directions, and staple DNA sequences. This program could save as much as several hours in the designing step for each DNA nanostructure. We randomly selected some shapes and corresponding outputs from our server and validated its performance in molecular experiments.

  4. Self-Assembly through Noncovalent Preorganization of Reactants: Explaining the Formation of a Polyfluoroxometalate. (United States)

    Schreiber, Roy E; Avram, Liat; Neumann, Ronny


    High-order elementary reactions in homogeneous solutions involving more than two molecules are statistically improbable and very slow to proceed. They are not generally considered in classical transition-state or collision theories. Yet, rather selective, high-yield product formation is common in self-assembly processes that require many reaction steps. On the basis of recent observations of crystallization as well as reactions in dense phases, it is shown that self-assembly can occur by preorganization of reactants in a noncovalent supramolecular assembly, whereby directing forces can lead to an apparent one-step transformation of multiple reactants. A simple and general kinetic model for multiple reactant transformation in a dense phase that can account for many-bodied transformations was developed. Furthermore, the self-assembly of polyfluoroxometalate anion [H2 F6 NaW18 O56 ]7- from simple tungstate Na2 WO2 F4 was demonstrated by using 2D 19 F-19 F NOESY, 2D 19 F-19 F COSY NMR spectroscopy, a new 2D 19 F{183 W} NMR technique, as well as ESI-MS and diffusion NMR spectroscopy, and the crucial involvement of a supramolecular assembly was found. The deterministic kinetic reaction model explains the reaction in a dense phase and supports the suggested self-assembly mechanism. Reactions in dense phases may be of general importance in understanding other self-assembly reactions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Directory of Open Access Journals (Sweden)

    Nozomi Saito


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

  6. An approach to self-assembling swarm robots using multitree genetic programming. (United States)

    Lee, Jong-Hyun; Ahn, Chang Wook; An, Jinung


    In recent days, self-assembling swarm robots have been studied by a number of researchers due to their advantages such as high efficiency, stability, and scalability. However, there are still critical issues in applying them to practical problems in the real world. The main objective of this study is to develop a novel self-assembling swarm robot algorithm that overcomes the limitations of existing approaches. To this end, multitree genetic programming is newly designed to efficiently discover a set of patterns necessary to carry out the mission of the self-assembling swarm robots. The obtained patterns are then incorporated into their corresponding robot modules. The computational experiments prove the effectiveness of the proposed approach.

  7. Self-assembly of three-legged patchy particles into polyhedral cages (United States)

    den Otter, Wouter K.; Renes, Marten R.; Briels, W. J.


    The self-assembly of rigid three-legged building blocks into polyhedral cages is investigated by patchy particle simulations. A four-site anisotropic interaction potential is introduced to make pairs of overlapping legs bind in an anti-parallel fashion, thereby forming the edges of a polyhedron of pentagons and hexagons. A torsional potential, reflecting an asymmetry or polarity in the legs' binding potential, proves crucial for the successful formation of closed fullerene-like cages. Self-assembly proceeds by a nucleation-and-growth mechanism, with a high success rate of cage closure. The size distribution of the self-assembled buckyballs is largely determined by the pucker angle of the particle. Nature explores a similar building block, the clathrin triskelion, to regulate vesicle formation at the cell membrane during endocytosis.

  8. Electronic functionalization of the surface of organic semiconductors with self-assembled monolayers (United States)

    Calhoun, M. F.; Sanchez, J.; Olaya, D.; Gershenson, M. E.; Podzorov, V.


    Self-assembled monolayers (SAMs) are widely used in a variety of emerging applications for surface modification of metals and oxides. Here, we demonstrate a new type of molecular self-assembly: the growth of organosilane SAMs at the surface of organic semiconductors. Remarkably, SAM growth results in a pronounced increase of the surface conductivity of organic materials, which can be very large for SAMs with a strong electron-withdrawing ability. For example, the conductivity induced by perfluorinated alkyl silanes in organic molecular crystals approaches 10-5S per square, two orders of magnitude greater than the maximum conductivity typically achieved in organic field-effect transistors. The observed large electronic effect opens new opportunities for nanoscale surface functionalization of organic semiconductors with molecular self-assembly. In particular, SAM-induced conductivity shows sensitivity to different molecular species present in the environment, which makes this system very attractive for chemical sensing applications.

  9. Micrometer size rod formed by secondary self assembly of omeprazole with α- and β-cyclodextrins (United States)

    Rajendiran, N.; Venkatesh, G.


    Self assembly of α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD) micro rods induced by omeprazole (OMP) were observed by SEM and TEM. OMP/CD inclusion complexes have formed the secondary self assembly micro meter size rod like structure. This structure was driven by the intermolecular hydrogen bonding as well as van der Waals forces. Both forces induced the ordered assembly and arrangement of OMP/CD inclusion complexes, whereas CD molecules acted as molecular bricks. The OMP/CD inclusion complexes primary assembled form individual nanorods and then secondary self aggregate nanorods were form a micro meter rod structure. The results indicate that inter-nanotubular hydrogen bonding plays a crucial role in the formation of the self assembled micro rods. The inclusion complexes were also characterized using FT-IR, DSC, powder XRD, 1H NMR, absorption, fluorescence, life time measurements and molecular modeling methods.

  10. Controllable synthesis of self-assembly Co3O4 nanoflake microspheres for electrochemical performance (United States)

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


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

  11. Surfaces wettability and morphology modulation in a fluorene derivative self-assembly system (United States)

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


    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.

  12. Chiral recognition and selection during the self-assembly process of protein-mimic macroanions

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Panchao; Zhang, Zhi-Ming; Lv, Hongjin; Li, Tao; Haso, Fadi; Hu, Lang; Zhang, Baofang; Basca, John; Wei, Yongge; Gao, Yanqing; Hou, Yu; Li, Yang-Guang; Hill, Craig L.; Wang, En-Bo; Liu, Tianbo


    The research on chiral recognition and chiral selection is not only fundamental in resolving the puzzle of homochirality, but also instructive in chiral separation and stereoselective catalysis. Here we report the chiral recognition and chiral selection during the self-assembly process of two enantiomeric wheel-shaped macroanions, [Fe28(μ3-O)8(Tart)16(HCOO)24]20- (Tart=D- or L-tartaric acid tetra-anion). The enantiomers are observed to remain self-sorted and self-assemble into their individual assemblies in their racemic mixture solution. The addition of chiral co-anions can selectively suppress the self-assembly process of the enantiomeric macroanions, which is further used to separate the two enantiomers from their mixtures on the basis of the size difference between the monomers and the assemblies. We believe that delicate long-range electrostatic interactions could be responsible for such high-level chiral recognition and selection.

  13. Acid Denaturation Inducing Self-Assembly of Curcumin-Loaded Hemoglobin Nanoparticles

    Directory of Open Access Journals (Sweden)

    Kaikai Wang


    Full Text Available Hemoglobin is a promising drug carrier but lacks extensive investigation. The chemical conjugation of hemoglobin and drugs is costly and complex, so we have developed curcumin-loaded hemoglobin nanoparticles (CCM-Hb-NPs via self-assembly for the first time. Using the acid-denaturing method, we avoid introducing denaturants and organic solvents. The nanoparticles are stable with uniform size. We have conducted a series of experiments to examine the interaction of hemoglobin and CCM, including hydrophobic characterization, SDS-PAGE. These experiments substantiate that this self-assembly process is mainly driven by hydrophobic forces. Our nanoparticles achieve much higher cell uptake efficiency and cytotoxicity than free CCM solution in vitro. The uptake inhibition experiments also demonstrate that our nanoparticles were incorporated via the classic clathrin-mediated endocytosis pathway. These results indicate that hemoglobin nanoparticles formed by self-assembly are a promising drug delivery system for cancer therapy.

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

    KAUST Repository

    Yu, Haizhou


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

  15. XTile: An Error-Correction Package for DNA Self-Assembly

    CERN Document Server

    Chaurasia, Anshul; Jain, Prateek; Gupta, Manish K


    Self assembly is a process by which supramolecular species form spontaneously from their components. This process is ubiquitous throughout the life chemistry and is central to biological information processing. It has been predicted that in future self assembly will become an important engineering discipline by combining the fields of bio molecular computation, nano technology and medicine. However error control is a key challenge in realizing the potential of self assembly. Recently many authors have proposed several combinatorial error correction schemes to control errors which have a close analogy with the coding theory such as Winfree s proofreading scheme and its generalizations by Chen and Goel and compact scheme of Reif, Sahu and Yin. In this work, we present an error correction computational tool XTile that can be used to create input files to the Xgrow simulator of Winfree by providing the design logic of the tiles and it also allows the user to apply proofreading, snake and compact error correction ...

  16. Topological defects in liquid crystals as templates for molecular self-assembly (United States)

    Wang, Xiaoguang; Miller, Daniel S.; Bukusoglu, Emre; de Pablo, Juan J.; Abbott, Nicholas L.


    Topological defects in liquid crystals (LCs) have been widely used to organize colloidal dispersions and template polymerization, leading to a range of assemblies, elastomers and gels. However, little is understood about molecular-level assembly processes within defects. Here, we report that nanoscopic environments defined by LC topological defects can selectively trigger processes of molecular self-assembly. By using fluorescence microscopy, cryogenic transmission electron microscopy and super-resolution optical microscopy, we observed signatures of molecular self-assembly of amphiphilic molecules in topological defects, including cooperativity, reversibility and controlled growth. We also show that nanoscopic o-rings synthesized from Saturn-ring disclinations and other molecular assemblies templated by defects can be preserved by using photocrosslinkable amphiphiles. Our results reveal that, in analogy to other classes of macromolecular templates such as polymer-surfactant complexes, topological defects in LCs are a versatile class of three-dimensional, dynamic and reconfigurable templates that can direct processes of molecular self-assembly.

  17. Watching Nanoscale Self-Assembly Kinetics of Gold Prisms in Liquids (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.

  18. Self-assembly of mixed lipids into bicelles and vesicles: molecular dynamics simulations (United States)

    Sharma, Hari; Wang, Zilu; Dormidontova, Elena

    Formation of complex supramolecular nanostructures, such as micelles, bicelles, vesicles (liposomes) etc. via self-assembly of simple molecules has provided a new pathway for the design and development of effective drug carriers. Solid nanoparticles or functional biopolymers, such as RNA, DNA, peptides can be encapsulated into these carriers for controlled delivery or selective targeting. We performed coarse grained molecular dynamics simulation using the MARTINI force field to study the self-assembly of a binary surfactant mixture composed of long and short phospholipids, DPPC and DHPC, in the ratio 3:1. We found that at low temperature lipids self-assemble into a bicelle (nanodisc) with the longer lipid mainly forming the interior and short lipid the rim of the bicelle. At higher temperature the nanodisc transforms into a vesicle with homogeneously distributed lipids. The structural changes of these nanodiscs and vesicles imposed by gold nanoparticle encapsulation and pegylation will be addressed.

  19. Theory and application of shapelets to the analysis of surface self-assembly imaging. (United States)

    Suderman, Robert; Lizotte, Daniel J; Abukhdeir, Nasser Mohieddin


    A method for quantitative analysis of local pattern strength and defects in surface self-assembly imaging is presented and applied to images of stripe and hexagonal ordered domains. The presented method uses "shapelet" functions which were originally developed for quantitative analysis of images of galaxies (∝10(20)m). In this work, they are used instead to quantify the presence of translational order in surface self-assembled films (∝10(-9)m) through reformulation into "steerable" filters. The resulting method is computationally efficient (with respect to the number of filter evaluations), robust to variation in pattern feature shape, and, unlike previous approaches, is applicable to a wide variety of pattern types. An application of the method is presented which uses a nearest-neighbor analysis to distinguish between uniform (defect-free) and nonuniform (strained, defect-containing) regions within imaged self-assembled domains, both with striped and hexagonal patterns.

  20. Colloidal capsules: nano- and microcapsules with colloidal particle shells. (United States)

    Bollhorst, Tobias; Rezwan, Kurosch; Maas, Michael


    Utilizing colloidal particles for the assembly of the shell of nano- and microcapsules holds great promise for the tailor-made design of new functional materials. Increasing research efforts are devoted to the synthesis of such colloidal capsules, by which the integration of modular building blocks with distinct physical, chemical, or morphological characteristics in a capsule's shell can result in novel properties, not present in previous encapsulation structures. This review will provide a comprehensive overview of the synthesis strategies and the progress made so far of bringing nano- and microcapsules with shells of densely packed colloidal particles closer to application in fields such as chemical engineering, materials science, or pharmaceutical and life science. The synthesis routes are categorized into the four major themes for colloidal capsule formation, i.e. the Pickering-emulsion based formation of colloidal capsules, the colloidal particle deposition on (sacrificial) templates, the amphiphilicity driven self-assembly of nanoparticle vesicles from polymer-grafted colloids, and the closely related field of nanoparticle membrane-loading of liposomes and polymersomes. The varying fields of colloidal capsule research are then further categorized and discussed for micro- and nano-scaled structures. Finally, a special section is dedicated to colloidal capsules for biological applications, as a diverse range of reports from this field aim at pharmaceutical agent encapsulation, targeted drug-delivery, and theranostics.

  1. Self-assembly of polystyrene nanospheres and its applications as templates for plasmonic structures (United States)

    Chang, Shih-Hsin

    Monodispersed colloidal polystyrene spheres have been self-assembled into various structures as templates for the fabrication of different nanostructures. Two unique self-assembly processes have been developed and systematically investigated. A method to make the multi-layer and mono-layer close-packed structure by means of capillary-convective force has been developed. By directly visualizing the self-assembling process using optical microscopy, a mechanism based on the 2-D crystal formation and 3-D repulsive force model has been proposed to explain the process. A vertical deposition technique to produce nanosphere crystal structure with single orientation on hydrophilic glass substrate has also been developed. Using a lithographically patterned substrate with alternating areas of glass and Au, self-assembled crystal structures can be generated on the hydrophobic Au surface. It has been found that the contact angle of the colloid solution on the substrates controls this self-assembly process. Using self-assembled polystyrene nanosphere crystals as templates, Au nanovoid arrays, in which the voids about several hundreds of nanometer in diameter are embedded in a gold film with a thickness less than the void diameter, have been fabricated by templated electrodeposition. In order to use Au nanovoid arrays as surface enhanced Raman scattering (SERS) sensors on optical fiber tips for in situ and in vivo applications, a new structure has been designed. In such structure, each void has optical openings on both sides of the nanovoid array, one side is mounted to the fiber tip surface for introduction of incident light and collection of scattered light and the other side is for interrogation of analyte molecules in the voids. The effect of structural parameters, including void diameter, Au film thickness, and the bottom hole diameter of the nanovoid arrays on the electric field confinement are investigated using three-dimensional finite difference time domain (FDTD

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

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

    DEFF Research Database (Denmark)

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


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

  4. Highly efficient chirality transfer from diamines encapsulated within a self-assembled calixarene-salen host


    Kleij, Arjan W.; Bandeira, Nuno A. G.; Luis Martínez-Rodríguez; Carles Bo


    Highly efficient chirality transfer from diamines encapsulated within a self-assembled calixarene-salen host A calix[4]arene host equipped with two bis-[Zn(salphen)] complexes self-assembles into a capsular complex in the presence of a chiral diamine guest with an unexpected 2:1 ratio between the host and the guest. Effective chirality transfer from the diamine to the calix-salen hybrid host is observed by circular dichroism (CD) spectroscopy, and a high stability constant K2,1 of 1.59×101...

  5. Supramolecular gel phase crystallization: orthogonal self-assembly under non-equilibrium conditions. (United States)

    Kumar, D Krishna; Steed, Jonathan W


    This tutorial review charts the history of gel phase crystallization from its origins in Liesegang ring formation to current research in the generation of new pharmaceutical solid forms in low molecular weight organogels. The growth of molecular crystals under a supersaturation gradient within the same space and timescale as the formation of a gel phase material is placed into context as an example of orthogonal self-assembly. Such multi-component, weakly coupled orthogonal self-assembly processes occurring far from equilibrium represent a powerful conceptual paradigm for generating fascinating emergent behaviour in chemical systems.

  6. Fabrication of nanostructure via self-assembly of nanowires within the AAO template

    Directory of Open Access Journals (Sweden)

    Brust Mathias


    Full Text Available AbstractThe novel nanostructures are fabricated by the spatial chemical modification of nanowires within the anodic aluminum oxide (AAO template. To make the nanowires better dispersion in the aqueous solution, the copper is first deposited to fill the dendrite structure at the bottom of template. During the process of self-assembly, the dithiol compound was used as the connector between the nanowires and nanoparticles by a self-assembly method. The nanostructures of the nano cigars and structure which is containing particles junction are characterized by transmission electron microscopy (TEM. These kinds of novel nanostructure will be the building blocks for nanoelectronic and nanophotonic devices.

  7. Room temperature Coulomb blockade mediated field emission via self-assembled gold nanoparticles (United States)

    Wang, Fei; Fang, Jingyue; Chang, Shengli; Qin, Shiqiao; Zhang, Xueao; Xu, Hui


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

  8. Controlling self-assembly of diphenylalanine peptides at high pH using heterocyclic capping groups (United States)

    Martin, Adam D.; Wojciechowski, Jonathan P.; Robinson, Andrew B.; Heu, Celine; Garvey, Christopher J.; Ratcliffe, Julian; Waddington, Lynne J.; Gardiner, James; Thordarson, Pall


    Using small angle neutron scattering (SANS), it is shown that the existence of pre-assembled structures at high pH for a capped diphenylalanine hydrogel is controlled by the selection of N-terminal heterocyclic capping group, namely indole or carbazole. At high pH, changing from a somewhat hydrophilic indole capping group to a more hydrophobic carbazole capping group results in a shift from a high proportion of monomers to self-assembled fibers or wormlike micelles. The presence of these different self-assembled structures at high pH is confirmed through NMR and circular dichroism spectroscopy, scanning probe microscopy and cryogenic transmission electron microscopy.

  9. Layer-by-Layer Self-Assembled Ferrite Multilayer Nanofilms for Microwave Absorption


    Jiwoong Heo; Daheui Choi; Jinkee Hong


    We demonstrate a simple method for fabricating multilayer thin films containing ferrite (Co0.5Zn0.5Fe2O4) nanoparticles, using layer-by-layer (LbL) self-assembly. These films have microwave absorbing properties for possible radar absorbing and stealth applications. To demonstrate incorporation of inorganic ferrite nanoparticles into an electrostatic-interaction-based LbL self-assembly, we fabricated two types of films: (1) a blended three-component LbL film consisting of a sequential poly(acr...

  10. Self-assembly of rigid macromolecules to create ordered thin films

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez, E.P.; Samulski, E.T. [Univ. of North Carolina, Chapel Hill, NC (United States)


    Poly({gamma}-benzyl-L-glutamate) (PBLG) derivatized at its N-terminus with lipoic acid, a disulfide-containing moiety, self-assembles on gold from helicogenic solvents to give a thin film with the polypetide {alpha}-helices orientation distribution different from the planar orientation in the unlabeled, physisorbed PBLG films (control) and Langmuir-Blodgett monolayers. These films were studied by angle-dependent XPS, reflection-absorption FTIR spectroscopy, ellipsometry, and contact angle measurements. The IR dichroic properties of the amide vibrational frequencies, in particular, were used to infer the orientational distribution of the helices in the self-assembled film.

  11. Self-assembly of tris(ureidobenzyl)amines: flexible bricks for robust architectures. (United States)

    Alajarin, Mateo; Orenes, Raul-Angel; Steed, Jonathan W; Pastor, Aurelia


    Despite their high degree of flexibility, tribenzylamine molecules endowed with one ureido group in every arm are avid self-assemblers with a high capacity for self-recognition. Narcissistic self-sorting or chiral self-discrimination events take place when two modules associate giving capsular aggregates. The size of the cavity may be modulated by the relative position of the ureido group and the amino function works as a pH switch of the rupture-reassembly process. When chiral racemic triureas are present the self-assembly is highly diastereoselective.

  12. Self-assembled FePt nanodot arrays with mono-dispersion and -orientation

    Energy Technology Data Exchange (ETDEWEB)

    Gai, Prof. Zheng [Peking University; Howe, Jane Y [ORNL; Guo, Jiandong [University of Tennessee, Knoxville (UTK); Blom, Douglas Allen [ORNL; Plummer, E Ward [ORNL; Shen, Jian [ORNL


    For self-assembled nanodots, the ultimate dream is to simultaneously achieve tunable uniformity in size, spatial distribution, chemical composition, and crystallographic orientation. By utilizing the Volmer-Weber growth mode in thin film epitaxy, we have grown self-assembled two-dimensional arrays of FePt alloy nanodots that are uniform in size, chemical composition, and are all crystallgraphically aligned. These dot assemblies are ferromagnetic at room temperature and can be easily transferred onto other templates without destroying the size and orientation uniformity.

  13. Fiber Optic pH Sensor with Self-Assembled Polymer Multilayer Nanocoatings


    Hwa-Yaw Tam; Jacques Albert; Ming-Jie Yin; Li-Yang Shao


    A fiber-optic pH sensor based on a tilted fiber Bragg grating (TFBG) with electrostatic self-assembly multilayer sensing film is presented. The pH sensitive polymeric film, poly(diallyldimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA) was deposited on the circumference of the TFBG with the layer-by-layer (LbL) electrostatic self-assembly technique. The PDDA/PAA film exhibits a reduction in refractive index by swelling in different pH solutions. This effect results in wavelength s...

  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


    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 nanowire avoids all contact with any organic solvents otherwise traditionally used in clean room fabrication. This can be achieved due to the intriguing properties of the self-assembled peptide nanotubes utilized as a dry etching mask for the patterning of the PEDOT:TsO nanowire. The peptide nanotubes...

  15. Cation-Anion Arrangement Patterns in Self-Assembled Pd2L4 and Pd4L8 Coordination Cages. (United States)

    Clever, Guido H; Punt, Philip


    Compounds featuring one-dimensional regular arrangements of stacked metal complexes and alternating [cation-anion]∞ sequences have raised considerable interest owing to their peculiar electronic and optical properties as well as guest inclusion capabilities. While traditional ways to realize these structural motifs rely on crystalline compounds, exclusively existing in the solid state, recent progress in the area of metal-mediated supramolecular self-assembly allows for the rational synthesis of structurally well-defined short stretches of stacked metal complexes and cation-anion arrangements. Therefore, metal cations, counteranions, and suitably designed organic bridges are allowed to self-assemble in solution. While the bridges can be designed as cross-linkers to yield extended two- or three-dimensional networks such as layered materials, metal-organic frameworks (MOFs), or porous coordination polymers (PCPs), they can also be tailored to lead to discrete nanoscopic objects. Supramolecular helicates, grids, and knots belong to this class of compounds, and a particularly interesting subfamily are coordination cages and capsules, which possess nanosized cavities with the ability to encapsulate guest molecules. Here, we focus on coordination cages consisting of two or more square-planar Pd(II) or Pt(II) metal cations, bridged by banana-shaped bis-monodentate pyridyl ligands that encapsulate various guest molecules, usually anions, in their cavities. Monoanions as well as dianions with localized or delocalized charges can be bound with remarkable complementarity between cage and guest in terms of size and shape. We show how dimerization of the prototypical [Pd2L4] cages into their interpenetrated dimers [Pd4L8] leads to an increase in cavity number from one to three while the cavity volume decreases. Usually, all three pockets of these double cages are filled with monoanions such as BF4- or Cl-, thus leading to well-defined linear [Pd-anion]3Pd stacks, as observed

  16. Design of fluidic self-assembly bonds for precise component positioning (United States)

    Ramadoss, Vivek; Crane, Nathan B.


    Self Assembly is a promising alternative to conventional pick and place robotic assembly of micro components. Its benefits include parallel integration of parts with low equipment costs. Various approaches to self assembly have been demonstrated, yet demanding applications like assembly of micro-optical devices require increased positioning accuracy. This paper proposes a new method for design of self assembly bonds that addresses this need. Current methods have zero force at the desired assembly position and low stiffness. This allows small disturbance forces to create significant positioning errors. The proposed method uses a substrate assembly feature to provide a high accuracy alignment guide to the part. The capillary bond region of the part and substrate are then modified to create a non-zero positioning force to maintain the part in the desired assembly position. Capillary force models show that this force aligns the part to the substrate assembly feature and reduces sensitivity of part position to process variation. Thus, the new configuration can substantially improve positioning accuracy of capillary self-assembly. This will result in a dramatic decrease in positioning errors in the micro parts. Various binding site designs are analyzed and guidelines are proposed for the design of an effective assembly bond using this new approach.

  17. Linear hydrogen adsorbate structures on graphite induced by self-assembled molecular monolayers

    DEFF Research Database (Denmark)

    Nilsson, Louis; Sljivancanin, Zeljko; Balog, Richard


    Combined scanning tunnelling microscopy measurements and density functional theory calculations reveal a method to induce linear structures of hydrogen adsorbates on graphite by covering the surface with a self-assembled molecular monolayer of cyanuric acid and exposing it to atomic hydrogen...

  18. Linker-determined drug release mechanism of free camptothecin from self-assembling drug amphiphiles. (United States)

    Cheetham, Andrew G; Ou, Yu-Chuan; Zhang, Pengcheng; Cui, Honggang


    We report here that the release mechanism of free camptothecin from self-assembling drug amphiphiles can be regulated by use of different linker groups. Our results highlight the significance of the linker group of drug amphiphiles on the drug release efficiency and their consequent in vitro efficacy.

  19. The self-assembly of redox active peptides: Synthesis and electrochemical capacitive behavior. (United States)

    Piccoli, Julia P; Santos, Adriano; Santos-Filho, Norival A; Lorenzón, Esteban N; Cilli, Eduardo M; Bueno, Paulo R


    The present work reports on the synthesis of a redox-tagged peptide with self-assembling capability aiming applications in electrochemically active capacitive surfaces (associated with the presence of the redox centers) generally useful in electroanalytical applications. Peptide containing ferrocene (fc) molecular (redox) group (Ac-Cys-Ile-Ile-Lys(fc)-Ile-Ile-COOH) was thus synthesized by solid phase peptide synthesis (SPPS). To obtain the electrochemically active capacitive interface, the side chain of the cysteine was covalently bound to the gold electrode (sulfur group) and the side chain of Lys was used to attach the ferrocene in the peptide chain. After obtaining the purified redox-tagged peptide, the self-assembly and redox capability was characterized by cyclic voltammetry (CV) and electrochemical impedance-based capacitance spectroscopy techniques. The obtained results confirmed that the redox-tagged peptide was successfully attached by forming an electroactive self-assembled monolayer onto gold electrode. The design of redox active self-assembly ferrocene-tagged peptide is predictably useful in the development of biosensor devices precisely to detect, in a label-free platform, those biomarkers of clinical relevance. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 357-367, 2016. © 2016 Wiley Periodicals, Inc.

  20. The self-assembly mechanism of fibril-forming silk-based block copolymers

    NARCIS (Netherlands)

    Schor, M.; Bolhuis, P.G.


    Triblock copolymers consisting of a silk-based ((Gly-Ala)3Gly-Glu) repeat flanked by hydrophilic outer blocks self-assemble into micrometer long fibrils in response to a trigger. Since the exact mechanism of the fibril formation remains unclear, we employ a multiscale modelling approach in

  1. A simple coarse-grained model for self-assembling silk-like protein fibers

    NARCIS (Netherlands)

    Schor, M.; Ensing, B.; Bolhuis, P.G.


    Collagen-silk-collagen triblock polypeptides can self-assemble at low pH into nanometer thin fibers with a length in the order of micrometers. Previously we predicted, via all-atom simulations, the structure of the folded silk domain to be a beta-roll. In this work we develop a simple coarse-grained

  2. Self-Assembled Functional Organic Monolayers on Oxide-Free Copper

    NARCIS (Netherlands)

    Caipa Campos, M.A.; Trilling, A.K.; Yang, M.; Giesbers, M.; Beekwilder, J.; Paulusse, J.M.J.; Zuilhof, H.


    The preparation and characterization of self-assembled monolayers on copper with n-alkyl and functional thiols was investigated. Well-ordered monolayers were obtained, while the copper remained oxide-free. Direct attachment of N-succinimidyl mercaptoundecanoate (NHS-MUA) onto the copper surface

  3. Controlling the self-assembly of protein polymers via heterodimer-forming modules

    NARCIS (Netherlands)

    Domeradzka, Natalia Eliza


    Supramolecular assemblies formed by protein polymers are attractive candidates for future biomaterials. Ideally, one would like to be able to define the nanostructure, in which the protein polymers should self-assemble, and then design protein polymer sequences that assemble exactly into such

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

    DEFF Research Database (Denmark)

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


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

  5. Self-assembly and electrical properties of a novel heptameric thiophene-benzothiadiazole based architectures. (United States)

    Crivillers, Núria; Favaretto, Laura; Zanelli, Alberto; Manet, Ilse; Treier, Matthias; Morandi, Vittorio; Gazzano, Massimo; Samorì, Paolo; Melucci, Manuela


    A novel semiconducting benzothiadiazole (BTZ)-thiophene (T) co-oligomer having an unprecedented BTZ-T alternated motif has been synthesized and self-assembled into micrometer sized fibers by simple solution processing. The electrical properties of these low-dimensional architectures have been characterized by integrating them in an organic field-effect transistor.

  6. Exploring single chain amphiphile self-assembly and their possible roles in light transduction

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain


    source studied to date can supply one single type of amphiphile at concentrations conducive to self-assembly. Mixtures of single-chain amphiphiles were therefore proposed to better model primitive membranes and potentially enhance their structural integrity1-3. Recently, we have established that complex...

  7. Metal array fabrication based on ultrasound-induced self-assembly of metalated dipeptides. (United States)

    Isozaki, Katsuhiro; Haga, Yusuke; Ogata, Kazuki; Naota, Takeshi; Takaya, Hikaru


    Pd- and Pt-bound bis-metalated peptides were synthesised by the condensation of Pd- or Pt-aldimine-complex-bound glutamic acids to afford the four possible metal isomers of bis-Pd and bis-Pt-homometalated dipeptides and PdPt- and PtPd-heterometalated dipeptides without metal disproportionation. Ultrasound-induced self-assembly of these bis-metalated peptides proceeded effectively to afford supramolecular gels that displayed well-ordered metal arrays. The formation of parallel β-sheet type aggregates through interpeptide amide-amide hydrogen bonding was confirmed by IR, scanning electron microscopy (SEM), and synchrotron X-ray diffraction analyses (WAXS and SAXS). The mechanism of the ultrasound-induced self-assembly of the metalated dipeptides was elucidated via kinetic and association experiments by (1)H NMR, in which ultrasound-triggered dissociation of intramolecular hydrogen bonds between the chloride ligands of the Pd- and Pt-complexes and amides initially occurred. This was followed by the formation of intermolecular amide-amide hydrogen bonds, which afforded the corresponding oligomeric peptide self-assembly as the nucleus for supramolecular aggregation. The observed first-order relationship of the gelation rate versus the sonication frequency suggested that the microcavitation generated under sonication conditions acted as a crucial trigger and provided a reaction field for efficient self-assembly.

  8. Correlation of Effective Dispersive and Polar Surface Energies in Heterogeneous Self-Assembled Monolayer Coatings

    DEFF Research Database (Denmark)

    Zhuang, Yanxin; Hansen, Ole


    grown oil oxidized (100) silicon Surfaces in a vapor phase process using five different precursors. Experimentally, effective surface energy components of the fluorocarbon self-assembled monolayers were determined from measured contact angles using the Owens-Wendt-Rabel-Kaelble method. We show...

  9. Size control and compartmentalization in self-assembled nano-structures of a multisegment amphiphilew

    NARCIS (Netherlands)

    Boekhoven, J.; Van Rijn, P.; Brizard, A.M.; Stuart, M.C.A.; Van Esch, J.H.


    A ‘‘multisegment amphiphile’’ has been synthesized by covalently connecting two well known building blocks, a gelator and a micelle forming surfactant. Self-assembly results in the formation of compartmentalized nano-object displaying properties inherited from both parents.

  10. Out-of-equilibrium self-assembly approaches for new soft materials

    NARCIS (Netherlands)

    Hendriksen, W.E.


    Living creatures exists for an important part out of soft material, such as skin, organs and cells, that are out-of-equilibrium formed by the self-assembly of molecular building blocks. Natural materials are continuously active with dynamic processes occurring, such as growth, shrinkage and

  11. Self-assemblies of lecithin and a-tocopherol as gelators of lipid material

    NARCIS (Netherlands)

    Nikiforidis, C.V.; Scholten, E.


    Amongst the different mechanisms that have been proposed and used to structure organogels, self-assembly of the gelators into supramolecular structures linked through non-covalent bonds is the most interesting. The gelator activity of LMGOs is often found most effective when micellar or lamellar

  12. Functional materials based on self-assembled comb-shaped supramolecules

    NARCIS (Netherlands)

    ten Brinke, G; Ikkala, O; KorugicKarasz, LS; MacKnight, WJ; Martuscelli, E


    In this paper we will review the main features of our approach to create functional materials using self-assembly of hydrogenbonded comb-shaped supramolecules. Typically, the supramolecules consist of homopolymers or diblock copolymers, where short chain amphiphiles are hydrogenbonded to the

  13. Self-assembly of small-molecule fumaramides allows transmembrane chloride channel formation. (United States)

    Roy, Arundhati; Gautam, Amitosh; Malla, Javid Ahmad; Sarkar, Sohini; Mukherjee, Arnab; Talukdar, Pinaki


    This study reports the formation of self-assembled transmembrane anion channels by small-molecule fumaramides. Such artificial ion channel formation was confirmed by ion transport across liposomes and by planar bilayer conductance measurements. The geometry-optimized model of the channel and Cl - ion selectivity within the channel lumen was also illustrated.

  14. Rapid, Brushless Self-assembly of a PS-b-PDMS Block Copolymer for Nanolithography

    DEFF Research Database (Denmark)

    Rasappa, Sozaraj; Schulte, Lars; Borah, Dipu


    Block copolymers (BCP) are highly promising self-assembling precursors for scalable nanolithography. Very regular BCP nanopatterns can be used as on-chip etch masks. The first step in the processing of BCP thin films is usually the chemical modification of the substrate surface, typically by graf...

  15. UV/Vis and NIR Light-Responsive Spiropyran Self-Assembled Monolayers

    NARCIS (Netherlands)

    Ivashenko, Oleksii; Herpt, Jochem T. van; Feringa, Ben L.; Rudolf, Petra; Browne, Wesley R.


    Self-assembled monolayers of a 6-nitro BIPS spiropyran (SP) modified with a disulfide-terminated aliphatic chain were prepared on polycrystalline gold surfaces and characterized by UV/vis absorption, surface-enhanced Raman scattering (SEAS), and X-ray photoelectron spectroscopies (XPS). The SAMs

  16. Rapid Self-assembly of alpha-Synuclein Observed by In Situ Atomic Force Microscopy

    NARCIS (Netherlands)

    Hoyer, Wolfgang; Cherny, Dmitry; Subramaniam, Vinod; Jovin, Thomas M.


    Self-assembly of α-synuclein resulting in protein aggregates of diverse morphology has been implicated in the pathogenesis of Parkinson's disease and other neurodegenerative disorders known as synucleinopathies. Apart from its biomedical relevance, this aggregation process is representative of the

  17. Membranes Prepared by Self-assembly and Chelation Assisted Phase Inversion

    KAUST Repository

    Xie, Yihui


    We combine self-assembly in solution, complexation with metallic salts and phase separation induced by solvent-non-solvent exchange to prepare nanostructured membranes for separation in the nanofiltration range. The method was applied to synthesized poly(acrylic acid)-b-polysulfone-b-poly(acrylic acid) copolymers dissolved in a selective solvent mixture and immersed in aqueous Cu2+ or Ag+ solutions.

  18. Self-assembled monolayers with biospecific affinity for lactate dehydrogenase for the electroenzymatic oxidation of lactate

    NARCIS (Netherlands)

    Schlereth, Daniela D.; Kooyman, R.P.H.


    Surface modified gold electrodes with high biospecific affinity for NAD(H)-dependent lactate dehydrogenase have been prepared by covalent attachment of several traizine dyes to stepwise functionalized mixed alkanethiol self-assembled monolayers. The biospecific affinity of such ligand-anchored

  19. TOPICAL REVIEW: Self-assembly from milli- to nanoscales: methods and applications (United States)

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


    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.

  20. Calixarene-stabilised cobalt nanoparticle rings: Self-assembly and collective magnetic properties

    DEFF Research Database (Denmark)

    Wei, A; Tripp, SL; Liu, J


    Calixarenes can be used to promote the self-assembly of thermoremanent cobalt nanoparticles into bracelet-like rings below 100nm in diameter. These kinetically stable assemblies are regulated by the equilibrium between enthalpic gain (dipole-dipole and long-range van der Waals interactions...

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

    DEFF Research Database (Denmark)

    Cagliani, Alberto; Kosaka, Priscila; Tamayo, Javier


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

  2. A new building block for DNA network formation by self-assembly and polymerase chain reaction

    Directory of Open Access Journals (Sweden)

    Holger Bußkamp


    Full Text Available The predictability of DNA self-assembly is exploited in many nanotechnological approaches. Inspired by naturally existing self-assembled DNA architectures, branched DNA has been developed that allows self-assembly to predesigned architectures with dimensions on the nanometer scale. DNA is an attractive material for generation of nanostructures due to a plethora of enzymes which modify DNA with high accuracy, providing a toolbox for many different manipulations to construct nanometer scaled objects. We present a straightforward synthesis of a rigid DNA branching building block successfully used for the generation of DNA networks by self-assembly and network formation by enzymatic DNA synthesis. The Y-shaped 3-armed DNA construct, bearing 3 primer strands is accepted by Taq DNA polymerase. The enzyme uses each arm as primer strand and incorporates the branched construct into large assemblies during PCR. The networks were investigated by agarose gel electrophoresis, atomic force microscopy, dynamic light scattering, and electron paramagnetic resonance spectroscopy. The findings indicate that rather rigid DNA networks were formed. This presents a new bottom-up approach for DNA material formation and might find applications like in the generation of functional hydrogels.

  3. Novel collaboration and situational awareness environment for leaders and their support staff via self assembling software.

    Energy Technology Data Exchange (ETDEWEB)

    Bouchard, Ann Marie; Osbourn, Gordon Cecil (Org. 1001 : Complex Systems Science Department); Bartholomew, John Warren


    This is the final report on the Sandia Fellow LDRD, project 117865, 08-0281. This presents an investigation of self-assembling software intended to create shared workspace environment to allow online collaboration and situational awareness for use by high level managers and their teams.

  4. Gold electrode modified by self-assembled monolayers of thiols to ...

    Indian Academy of Sciences (India)

    The process of immobilization of biological molecules is one of the most important steps in the construction of a biosensor. In the case of DNA, the way it exposes its bases can result in electrochemical signals to acceptable levels. The use of self-assembled monolayer that allows a connection to the gold thiol group and ...

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

    NARCIS (Netherlands)

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


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

  6. Self-assembling properties of all γ-cyclic peptides containing sugar amino acid residues. (United States)

    Guerra, Arcadio; Brea, Roberto J; Amorín, Manuel; Castedo, Luis; Granja, Juan R


    In this study, a novel dimer-forming cyclic peptide composed exclusively by cyclic γ-amino acids with a saccharide-like outer surface is described. The antiparallel β-sheet type hydrogen bonding interactions responsible for the large association constant in non-polar solvents constitute a suitable model for a novel class of self-assembling peptide nanotubes.

  7. G protein-coupled receptors self-assemble in dynamics simulations of model bilayers

    NARCIS (Netherlands)

    Periole, Xavier; Huber, Thomas; Marrink, Siewert-Jan; Sakmar, Thomas P.


    Many integral membrane proteins assemble to form oligomeric structures in biological membranes. In particular, seven-transmembrane helical G protein-coupled receptors (GPCRs) appear to self-assemble constitutively in membranes, but the mechanism and physiological role of this assembly are unknown.

  8. Electrochemical and structural characterization of self-assembled thiol monolayers on gold

    NARCIS (Netherlands)

    Sondag-Huethorst, J.A.M.


    Self-assembled alkanethiol monolayers on gold are used as model systems in a fundamental study of the potential-dependent wetting and of the galvanic metal deposition. For using such monolayers as model systems, well-defined and ordered monolayers are required. In order to control the

  9. Supramolecular control of self-assembling terthiophene-peptide conjugates through the amino acid side chain

    Energy Technology Data Exchange (ETDEWEB)

    Lehrman, Jessica A.; Cui, Honggang; Tsai, Wei-Wen; Moyer, Tyson J.; Stupp, Samuel I. [NWU


    The self-assembly of oligothiophene–peptide conjugates can be directed through the systematic variation of the peptide sequence into different nanostructures, including flat spicules, nanotubes, spiral sheets, and giant, flat sheets. Furthermore, the assembly of these molecules is not controlled by steric interactions between the amino acid side chains.

  10. Focused ion beam processing and engineering of devices in self-assembled supramolecular structures. (United States)

    Huyang, George; Canning, John; Gibson, Brant C; Khoury, Tony; Sum, Tze Jing; Neto, Chiara; Crossley, Maxwell J


    Self-assembled supramolecular structures such as optical wires, films and 2D slabs offer a new generation of electronic and optical devices. In particular, self-assembled porphyrin devices, including those integrated onto silica and silicon platforms, open new opportunities in photonic applications spanning molecular biosensing, photovoltaics and telecommunications. All reports to date, however, largely highlight the potential but have not established a clear pathway to the actual implementation of more complex device prototypes. In this paper, we propose and demonstrate the use of a focused ion beam (FIB) to process and fabricate devices in porphyrin-based supramolecular structures. These self-assembled structures have an initial root mean squared (rms) values for surface roughness of atomic force microscopy. Under appropriate FIB processing and cutting conditions, the rms value for surface roughness falls to < 0.4 nm, comparable with some of the best optical flatnesses obtained within, for example, structured optical fibres and integrated optical waveguides. The milling rate of the porphyrin structures was estimated to be approximately 70% of that of silica. The versatility of a FIB as a tool for rapid processing and fabricating 1D and 2D photonic waveguide structures within supramolecular self-assembled platforms is demonstrated by fabricating a 2D coupler, setting the groundwork for true optical device engineering and integration using these new organic systems.

  11. Grooved nanowires from self-assembling hairpin molecules for solar cells. (United States)

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


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

  12. Double-resonance spectroscopy of InAs/GaAs self-assembled quantum dots

    NARCIS (Netherlands)

    Murdin, B. N.; Hollingworth, A. R.; Barker, J. A.; Clarke, D. G.; Findlay, P. C.; Pidgeon, C. R.; Wells, J. P. R.; Bradley, I. V.; Malik, S.; Murray, R.


    We present far-/near-infrared double resonance measurements of self-assembled InAs/GaAs quantum dots. The far-infrared resonance is unambiguously associated with a bound-bound intraband transition in the neutral dots. The results show that the interband photoluminescence (PL) lines originate from

  13. Aqueous Self-Assembly of Y-Shaped Amphiphilic Block Copolymers into Giant Vesicles. (United States)

    Li, Hanping; Jin, Yong; Fan, Baozhu; Lai, Shuangquan; Sun, Xiaopeng; Qi, Rui


    The preparation and aqueous self-assembly of newly Y-shaped amphiphilic block polyurethane (PUG) copolymers are reported here. These amphiphilic copolymers, designed to have two hydrophilic poly(ethylene oxide) (PEO) tails and one hydrophobic alkyl tail via a two-step coupling reaction, can self-assemble into giant unilamellar vesicles (GUVs) (diameter ≥ 1000 nm) with a direct dissolution method in aqueous solution, depending on their Y-shaped structures and initial concentrations. More interesting, the copolymers can self-assemble into various distinct nano-/microstructures, such as spherical micelles, small vesicles, and GUVs, with the increase of their concentrations. The traditional preparation methods of GUVs generally need conventional amphiphilic molecules and additional complicated conditions, such as alternating electrical field, buffer solution, or organic solvent. Therefore, the self-assembly of Y-shaped PUGs with a direct dissolution method in aqueous solution demonstrated in this study supplies a new clue to fabricate GUVs based on the geometric design of amphiphilic polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  15. [Biomimetics of crystal texture in dental enamel prism by self-assembly oligopeptide]. (United States)

    Wang, Lei; Bai, Wei; Feng, Hai-lan; Jia, Xin-ru


    To evaluate the possibility of self-assembly oligopeptide(T2) for dental enamel biomimetics, especially for the prism's crystal texture since it could prompt calcium phosphate precipitated in gel carrier. SEM (Scanning electron microscope) and TEM (Transmission electron microscope) were used to observe the morphologic presentation and ED(Electron diffraction) to crystal texture comparing with the human molar enamel powder. (a) Flake-like and needle-like octacalcium phosphate precipitated in the gel carrier with self-assemble oligopeptide(T2). They transformed into rod-like hydroxyapatite crystals gradually in the following 2-4 weeks. (b) The rod-like hydroxyapatite may arrange or grow into bundles which are similar to the human enamel prisms in both appearance and size. (c) The rod-like hydroxyapatite showed polycrystal while the enamel prisms showed monocrystal under examination of ED. The self-assemble oligopeptide(T2) could regulate the speed of nucleation and crystallization of hydroxyapatite in morphology and crystalline size. Thus, the self-assembly oligopeptide and the gel carrier mineralization system could be primarily applied in biomimetic use for the crystallization of hydroxyapatite in dental prism in vitro.

  16. 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: [School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu, 213164 (China); Jiang, Pengju, E-mail: [School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu, 213164 (China); State Key Laboratory of Pharmaceutical Biotechnology, Nanjing, Jiangsu (China)


    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”.

  17. [Effect of suet oil on formation of self-assembled micelles of flavonoids in Epimedium]. (United States)

    Li, Jie; Sun, E; Zhang, Zhen-hai; Jiang, Jun; Xu, Feng-juan; Jia, Xiao-bin


    In this paper, the action of suet oil in the preparation of self-assembled micelles of the active flavonoids in Epimedium in the simulated human environment was researched. Twelve suet oil samples were collected from different growing areas and different positions of sheep or goat to simulate the formation of micelles. Then the effects of the fatty acids in suet oil on the preparation of self-assembled micelles were studied furthermore. The results showed that the micelles had a dispersed state and spherical smooth surface. To compare the diameter, potential, encapsulation efficiency and drug loading of the 12 batches micelles, the micelles prepared by the suet oil from Qinghai were more stable and had a higher encapsulation efficiency. The fatty acids in suet oil could promote the formation of self-assembled micelles, but the whole suet oil had a better effect. Above all the study, we confirmed that the suet oil promoted the formation of self-assembled micelles of the flavonoids in Epimedium, it laid foundation for further research about increasing the efficacy of Epimedium and improved the absorption of the active flavonoids in Epimedium.

  18. Manganese Phosphate Self-assembled Nanoparticle Surface and Its application for Superoxide Anion Detection

    National Research Council Canada - National Science Library

    Shen, Xiaohui; Wang, Qi; Liu, Yuhong; Xue, Wenxiao; Ma, Lie; Feng, Shuaihui; Wan, Mimi; Wang, Fenghe; Mao, Chun


    .... Herein, a novel Mn-superoxide dismutase (MnSOD) mimics, silica-manganous phosphate (SiO2-Mn3(PO4)2) nanoparticles, were designed and synthesized by surface self-assembly processes that occur on the surface of silica-phytic acid...

  19. Supramolecular nanostructuring of silver surfaces via self-assembly of [60]fullerene and porphyrin modules

    NARCIS (Netherlands)

    Bonifazi, Davide; Kiebele, Andreas; Stöhr, Meike; Cheng, Fuyong; Jung, Thomas; Diederich, Francois; Spillmann, Hannes


    Recent achievements in our laboratory toward the "bottom-up" fabrication of addressable multicomponent molecular entities obtained by self-assembly of C-60 and porphyrins on Ag(100) and Ag(111) surfaces are described.. Scanning tunneling microscopy (STM) studies on ad-layers constituting monomeric

  20. Self-assembling behaviour of Pt nanoparticles onto surface of TiO2 ...

    Indian Academy of Sciences (India)

    In the present study, self-assembling behaviour of guest nanoparticles (platinum) onto the surface of host support (titanium dioxide) during photodeposition process as a function of solution pH has been explored in detail by means of transmission electron microscope (TEM). The photocatalytic activity of the resulting ...

  1. Self-assembled block copolymer membranes: From basic research to large-scale manufacturing

    KAUST Repository

    Nunes, Suzana Pereira


    Order and porosity of block copolymer membranes have been controlled by solution thermodynamics, self-assembly, and macrophase separation. We have demonstrated how the film manufacture with long-range order can be up-scaled with the use of conventional membrane production technology.

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

    NARCIS (Netherlands)

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


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

  3. Endgroups of Functionalized Siloxane Oligomers Direct Block Copolymeric or Liquid Crystalline Self-Assembly Behavior

    NARCIS (Netherlands)

    Zha, R. Helen; De Waal, Bas; Lutz, Martin|info:eu-repo/dai/nl/304828971; Teunissen, Abraham J.p.; Meijer, E. W.


    Monodisperse oligodimethylsiloxanes end-functionalized with the hydrogen-bonding ureidopyrimidinone (UPy) motif undergo phase separation between their aromatic end groups and dimethylsiloxane midblocks to form ordered nanostructures with domain spacings of <5 nm. The self-assembly behavior of these

  4. Controlling Peptide Self-Assembly through a Native Chemical Ligation/Desulfurization Strategy. (United States)

    Rasale, Dnyaneshwar B; Konda, Maruthi; Biswas, Sagar; Das, Apurba K


    Self-assembled peptides were synthesized by using a native chemical ligation (NCL)/desulfurization strategy that maintained the chemical diversity of the self-assembled peptides. Herein, we employed oxo-ester-mediated NCL reactions to incorporate cysteine, a cysteine-based dipeptide, and a sterically hindered unnatural amino acid (penicillamine) into peptides. Self-assembly of the peptides resulted in the formation of self-supporting gels. Microscopy analysis indicated the formation of helical nanofibers, which were responsible for the formation of gel matrices. The self-assembly of the ligated peptides was governed by covalent and non-covalent interactions, as confirmed by FTIR, CD, fluorescence spectroscopy, and MS (ESI) analyses. Peptide disassembly was induced by desulfurization reactions with tris(2-carboxyethyl)phosphine (TCEP) and glutathione at 80 °C. Desulfurization reactions of the ligated peptides converted the Cys and penicillamine functionalities into Ala and Val moieties, respectively. The self-supporting gels showed significant shear-thinning and thixotropic properties. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Design of calamitic self-assembling reactive mesogenic units: mesomorphic behaviour and rheological characterization

    Czech Academy of Sciences Publication Activity Database

    Bubnov, Alexej M.; Cigl, Martin; Machado, A.; Pociecha, D.; Hamplová, Věra; Cidade, M.T.


    Roč. 44, Aug (2017), s. 1-13 ISSN 0267-8292 R&D Projects: GA ČR GA16-12150S Institutional support: RVO:68378271 Keywords : functional reactive mesogens * liquid crystals * self-assembling behaviour * nematic * smectic * electrorheological fluids Subject RIV: JJ - Other Materials Impact factor: 2.661, year: 2016

  6. Modeling Textural Processes during Self-Assembly of Plant-Based Chiral-Nematic Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Yogesh K. Murugesan


    Full Text Available Biological liquid crystalline polymers are found in cellulosic, chitin, and DNA based natural materials. Chiral nematic liquid crystalline orientational order is observed frozen-in in the solid state in plant cell walls and is known as a liquid crystal analogue characterized by a helicoidal plywood architecture. The emergence of the plywood architecture by directed chiral nematic liquid crystalline self assembly has been postulated as the mechanism that leads to optimal cellulose fibril organization. In natural systems, tissue growth and development takes place in the presence of inclusions and secondary phases leaving behind characteristic defects and textures, which provide a unique testing ground for the validity of the liquid crystal self-assembly postulate. In this work, a mathematical model, based on the Landau-de Gennes theory of liquid crystals, is used to simulate defect textures arising in the domain of self assembly, due to presence of secondary phases representing plant cells, lumens and pit canals. It is shown that the obtained defect patterns observed in some plant cell walls are those expected from a truly liquid crystalline phase. The analysis reveals the nature and magnitude of the viscoelastic material parameters that lead to observed patterns in plant-based helicoids through directed self-assembly. In addition, the results provide new guidance to develop biomimetic plywoods for structural and functional applications.

  7. Nanosystem Self-Assembly Pathways Discovered via All-Atom Multiscale Analysis (United States)

    Pankavich, Stephen D.; Ortoleva, Peter J.


    We consider the self-assembly of composite structures from a group of nanocomponents, each consisting of particles within an N-atom system. Self-assembly pathways and rates for nanocomposites are derived via a multiscale analysis of the classical Liouville equation. From a reduced statistical framework, rigorous stochastic equations for population levels of beginning, intermediate, and final aggregates are also derived. It is shown that the definition of an assembly type is a self-consistency criterion that must strike a balance between precision and the need for population levels to be slowly varying relative to the timescale of atomic motion. The deductive multiscale approach is complemented by a qualitative notion of multicomponent association and the ensemble of exact atomic-level configurations consistent with them. In processes such as viral self-assembly from proteins and RNA or DNA, there are many possible intermediates so that it is usually difficult to predict the most efficient assembly pathway. However, in the current study rates of assembly of each possible intermediate can be predicted. This avoids the need, as in a phenomenological approach, for recalibration with each new application. The method accounts for the feedback across scales in space and time that is fundamental to nanosystem self-assembly. The theory has applications to bionanostructures, geomaterials, engineered composites, and nanocapsule therapeutic delivery systems. PMID:22372746

  8. Molecular design and synthesis of self-assembling camptothecin drug amphiphiles. (United States)

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


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

  9. Searching for avidity by chemical ligation of combinatorially self-assembled DNA-encoded ligand libraries. (United States)

    Matysiak, Stefan; Hellmuth, Klaus; El-Sagheer, Afaf H; Shivalingam, Arun; Ariyurek, Yavuz; de Jong, Marco; Hollestelle, Martine J; Out, Ruud; Brown, Tom


    DNA encoded ligands are self-assembled into bivalent complexes and chemically ligated to link their identities. To demonstrate their potential as a combinatorial screening platform for avidity interactions, the optimal bivalent aptamer design (examplar ligands) for human alpha-thrombin is determined in a single round of selection and the DNA scaffold replaced with minimal impact on the final design.

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

    DEFF Research Database (Denmark)

    Castillo, Jaime; Tanzi, Simone; Dimaki, Maria


    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......-nanoassemblies with concrete applications, such as field-effect transistors, microprobes, microarrays, and biosensing devices....

  11. Selective self-organization of guest molecules in self-assembled molecular boxes

    NARCIS (Netherlands)

    Kerckhoffs, J.M.C.A.; ten Cate, M.G.J.; Mateos timoneda, Miguel; van Leeuwen, F.W.B.; Ruel, Bianca H.M.; Spek, Anthony L.; Kooijman, Huub; Crego Calama, Mercedes; Reinhoudt, David


    This article describes the synthesis and binding properties of highly selective noncovalent molecular receptors 13·(DEB)6 and 33·(DEB)6 for different hydroxyl functionalized anthraquinones 2. These receptors are formed by the self-assembly of three calix[4]arene dimelamine derivative molecules (1 or

  12. Diastereoselective self-assembly of dinuclear heterochiral metallosupramolecular rhombs in a self-discriminating process. (United States)

    Weilandt, Torsten; Kiehne, Ulf; Schnakenburg, Gregor; Lützen, Arne


    A racemic bis(nitrile) ligand based on the Tröger's base scaffold self-assembles into an achiral dinuclear heterochiral rhomb in a diastereoselective self-discrimination process; this occurs upon coordination to (dppp)Pd(OTf)(2) as evidenced by nmr spectroscopy and X-ray crystal structure analysis.

  13. The nature of protein interactions governing globular protein-polymer block copolymer self-assembly. (United States)

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


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

  14. Properties of Self-Assembled Hybrid Organic Molecule/Quantum Dot Multilayered Structures

    NARCIS (Netherlands)

    Cohen, E.; Gruber, M.; Romero, E.; Yochelis, S.; van Grondelle, R.; Paltiel, Y.


    Hybrid nanostructures are attractive for future use in a variety of electronic components. Self-assembled hybrid organic/nanocrystals can couple quantum properties to semiconductor working devices and modify their functionality. For example, light absorption in some core quantum dot (QD)-based

  15. Molecular Dynamics Study of Alkanethiolate Self-Assembled Monolayer Coated Gold Nanoparticle (United States)


    of Organosulfur Compounds on Au( 111). Implications for Molecular Self-Assembly on Gold 21. Plimpton, S.J., "Fast Parallel Algorithms for Short-Range... Organosulfur Compounds SHAKE Algorithm for Molecular Dynamics." Journal of Adsorbed on Gold Single Crystals: Electron Diffraction Computational Physics, 52

  16. Tunable synthesis of self-assembled cyclic peptide nanotubes and nanoparticles. (United States)

    Sun, Leming; Fan, Zhen; Wang, Yongzhong; Huang, Yujian; Schmidt, Michael; Zhang, Mingjun


    While tremendous efforts have been made in investigating scalable approaches for fabricating nanoparticles, less progress has been made in scalable synthesis of cyclic peptide nanoparticles and nanotubes, despite their great potential for broader biomedical applications. In this paper, tunable synthesis of self-assembled cyclic peptide nanotubes and nanoparticles using three different methods, phase equilibrium, pH-driven, and pH-sensitive methods, were proposed and investigated. The goal is scalable nanomanufacturing of cyclic peptide nanoparticles and nanotubes with different sizes in large quality by controlling multiple process parameters. Cyclo-(L-Gln-D-Ala-L-Glu-D-Ala-)2 was applied to illustrate the proposed ideas. In the study, mass spectrometry and high performance liquid chromatography were employed to verify the chemical structures and purity of the cyclic peptides. Morphology and size of the synthesized nanomaterials were characterized using atomic force microscopy and dynamic light scattering. The dimensions of the self-assembled nanostructures were found to be strongly influenced by the cyclic peptide concentration, side chain modification, pH values, reaction time, stirring intensity, and sonication time. This paper proposed an overall strategy to integrate all the parameters to achieve optimal synthesis outputs. Mechanisms of the self-assembly of the cyclic peptide nanotubes and nanoparticles under variable conditions and tunable parameters were discussed. This study contributes to scalable nanomanufacturing of cyclic peptide based self-assembled nanoparticles and nanotubes for broader biomedical applications.

  17. Factors influencing the layer thickness of poly-L-glutamates grafted from self-assembled monolayers

    NARCIS (Netherlands)

    Menzel, H.; Heise, A.; Yim, H.; Foster, M.D.; Wieringa, R.H.; Schouten, A.J.; Frank, C.W.


    Factors influencing the thickness of polypeptide layers grafted from self-assembled monolayers were investigated by varying the initiator site density and the reactivity of the N-carboxyanhydride monomer. To vary the density of initiating sites and to match the steric requirements of the growing

  18. Sequential Block Copolymer Self-Assemblies Controlled by Metal-Ligand Stoichiometry. (United States)

    Yin, Liyuan; Wu, Hongwei; Zhu, Mingjie; Zou, Qi; Yan, Qiang; Zhu, Liangliang


    While numerous efforts have been devoted to developing easy-to-use probes based on block copolymers for detecting analytes due to their advantages in the fields of self-assembly and sensing, a progressive response on block copolymers in response to a continuing chemical event is not readily achievable. Herein, we report the self-assembly of a 4-piperazinyl-1,8-naphthalimide based functional block copolymer (PS-b-PN), whose self-assembly and photophysics can be controlled by the stoichiometry-dependent metal-ligand interaction upon the side chain. The work takes advantages of (1) stoichiometry-controlled coordination-structural transformation of the piperazinyl moiety on PS-b-PN toward Fe(3+) ions, thereby resulting in a shrinkage-expansion conversion of the self-assembled nanostructures in solution as well as in thin film, and (2) stoichiometry-controlled competition between photoinduced electron transfer and spin-orbital coupling process upon naphthalimide fluorophore leading to a boost-decline emission change of the system. Except Fe(3+) ions, such a stoichiometry-dependent returnable property cannot be observed in the presence of other transition ions. The strategy for realizing the dual-channel sequential response on the basis of the progressively alterable nanomorphologies and emissions might provide deeper insights for the further development of advanced polymeric sensors.

  19. Feasibility study of self-assembly mechanism for variable optical attenuator (United States)

    Lee, Chengkuo; Lai, Yen-Jyh; Wu, Chia-Yu; Yeh, J. Andrew; Huang, Ruey-Shing


    This paper describes the feasibility study result for a variable optical attenuator (VOA) realized by a new concept of self-assembled polysilicon structures and a continuously position-controllable curved beam actuator based on surface micromachining technology. The self-assembly mechanism includes a residual stress induced curved beam which lifts up the reflective mirror shutter first. This self-assembled reflective pop-up shutter is locked and fixed on a curved polysilicon beam actuator which is connected with a polysilicon frame clamped on the substrate. Secondly, a set of polysilicon scratch drive actuators drives the frame, curved beam actuator and shutter moving forward and sliding into the space between the two ends of the input and output fiber ports. The optical attenuation range of the proposed VOA is determined by the vertical position of the self-assembled reflective shutter which is controlled depending on the applied voltage value. This new VOA has demonstrated continuous attenuation capability and wide attenuation range. This device demonstrates 70 dB attenuation range and less than 1 dB insertion loss.

  20. Self-assembling peptide-based delivery of therapeutics for myocardial infarction. (United States)

    French, Kristin M; Somasuntharam, Inthirai; Davis, Michael E


    Cardiovascular disease, including myocardial infarction, is the number one cause of death. Current treatments are palliative and slow the progression toward heart failure, but to not regenerate healthy tissue. Self-assembling peptides are biomimietic, readily produced, non-immunogenic and non-cytotoxic. They do not assemble into hydrogels until triggered, allowing them to be injected into the myocardium and providing opportunities for minimally invasive therapies. The ability to tune the mechanical and bioactive properties of self-assembling peptides will continue to make them readily adaptable for mimicking natural microenvironments. To date, a variety of growth factors and signaling moieties have been incorporated into self-assembling peptide hydrogels, enhancing cell behavior and tissue function. Furthermore, the hydrogels serve as delivery vehicles for cells in vivo and platforms for improved cell culture. In addition to a brief review of self-assembling peptides, we will discuss a variety of their approaches for myocardial infarction therapy. Moreover, we will assess approaches taken in other tissue and discuss how these could benefit therapies for myocardial infarction. Copyright © 2015 Elsevier B.V. All rights reserved.