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Sample records for dimer-faced self-assembled prisms

  1. Watching Nanoscale Self-Assembly Kinetics of Gold Prisms in Liquids

    Science.gov (United States)

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

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

  2. PRISM

    Science.gov (United States)

    2017-12-21

    societal issues , given countervailing moral , legal, and ethical interpretations, as well as suspicions PRISM 7, NO. 2 FEATURES | 13 COGNITIVE-EMOTIONAL...to tell our story. Additionally, U.S. practi- tioners are bound by asymmetric legal, moral , and ethical constraints that often keep them from being...the founder of SpaceX and Tesla, withdrew from two business councils providing advice to the administration on economic issues . Further driving

  3. Self-assembled nanostructures

    CERN Document Server

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

    2003-01-01

    Nanostructures refer to materials that have relevant dimensions on the nanometer length scales and reside in the mesoscopic regime between isolated atoms and molecules in bulk matter. These materials have unique physical properties that are distinctly different from bulk materials. Self-Assembled Nanostructures provides systematic coverage of basic nanomaterials science including materials assembly and synthesis, characterization, and application. Suitable for both beginners and experts, it balances the chemistry aspects of nanomaterials with physical principles. It also highlights nanomaterial-based architectures including assembled or self-assembled systems. Filled with in-depth discussion of important applications of nano-architectures as well as potential applications ranging from physical to chemical and biological systems, Self-Assembled Nanostructures is the essential reference or text for scientists involved with nanostructures.

  4. Macroscopic magnetic Self assembly

    NARCIS (Netherlands)

    Löthman, Per Arvid

    2018-01-01

    Exploring the macroscopic scale's similarities to the microscale is part and parcel of this thesis as reflected in the research question: what can we learn about the microscopic scale by studying the macroscale? Investigations of the environment in which the self-assembly takes place, and the

  5. Modelling Polar Self Assembly

    Science.gov (United States)

    Olvera de La Cruz, Monica; Sayar, Mehmet; Solis, Francisco J.; Stupp, Samuel I.

    2001-03-01

    Recent experimental studies in our group have shown that self assembled thin films of noncentrosymmetric supramolecular objects composed of triblock rodcoil molecules exhibit finite polar order. These aggregates have both long range dipolar and short range Ising-like interactions. We study the ground state of a simple model with these competing interactions. We find that the competition between Ising-like and dipolar forces yield a periodic domain structure, which can be controlled by adjusting the force constants and film thickness. When the surface forces are included in the potential, the system exhibits a finite macroscopic polar order.

  6. 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 ...

  7. Onset of self-assembly

    International Nuclear Information System (INIS)

    Chitanvis, S.M.

    1998-01-01

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

  8. Self-assembling peptide semiconductors

    Science.gov (United States)

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

    2017-01-01

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

  9. Self-assembly of cyclodextrins

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  10. Biomedical Applications of Self-Assembling Peptides

    NARCIS (Netherlands)

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

    2016-01-01

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

  11. 3D Programmable Micro Self Assembly

    National Research Council Canada - National Science Library

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

    2005-01-01

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

  12. Chemical reactions directed Peptide self-assembly.

    Science.gov (United States)

    Rasale, Dnyaneshwar B; Das, Apurba K

    2015-05-13

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

  13. Self-Assembly of Infinite Structures

    Directory of Open Access Journals (Sweden)

    Scott M. Summers

    2009-06-01

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

  14. Bola-amphiphile self-assembly

    DEFF Research Database (Denmark)

    Svaneborg, Carsten

    2012-01-01

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

  15. Self-assembled nanomaterials for photoacoustic imaging

    Science.gov (United States)

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

    2016-01-01

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

  16. Self-assembled nanomaterials for photoacoustic imaging.

    Science.gov (United States)

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

    2016-02-07

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

  17. Molecular self-assembly advances and applications

    CERN Document Server

    Dequan, Alex Li

    2012-01-01

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

  18. A Theoretical and Experimental Study of DNA Self-assembly

    Science.gov (United States)

    Chandran, Harish

    providing detailed designs for local molecular computations that involve spatially contiguous molecules arranged on addressable substrates via enzyme-free DNA hybridization reaction cascades. We use the Visual DSD simulation software in conjunction with localized reaction rates obtained from biophysical modeling to create chemical reaction networks of localized hybridization circuits that are then model checked using the PRISM model checking software. We develop a DNA detection system employing the triggered self-assembly of a novel DNA dendritic nanostructure. Detection begins when a specific, single-stranded target DNA strand triggers a hybridization chain reaction between two distinct DNA hairpins. Each hairpin opens and hybridizes up to two copies of the other, and hence each layer of the growing dendritic nanostructure can in principle accommodate an exponentially increasing number of cognate molecules, generating a nanostructure with high molecular weight. We build linear activatable assemblies employing a novel protection/deprotection strategy to strictly enforce the direction of tiling assembly growth to ensure the robustness of the assembly process. Our system consists of two tiles that can form a linear co-polymer. These tiles, which are initially protected such that they do not react with each other, can be activated to form linear co-polymers via the use of a strand displacing enzyme.

  19. Self-Assembly of Colloidal Particles

    Indian Academy of Sciences (India)

    is self-assembly where one engineers interaction between nanoscopic building blocks so ..... big question in the field how this microscopic chirality of the virus gets translated ... shape emerges due to a competition between the surface tension.

  20. Polymorphism of lipid self-assembly systems

    International Nuclear Information System (INIS)

    Takahashi, Hiroshi

    2002-01-01

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

  1. Directed Self-Assembly of Nanodispersions

    Energy Technology Data Exchange (ETDEWEB)

    Furst, Eric M [University of Delaware

    2013-11-15

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

  2. Mechanical Self-Assembly Science and Applications

    CERN Document Server

    2013-01-01

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

  3. Self-assembled DNA Structures for Nanoconstruction

    Science.gov (United States)

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

    2004-09-01

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

  4. Self-assembling segmented coiled tubing

    Science.gov (United States)

    Raymond, David W.

    2016-09-27

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

  5. Large branched self-assembled DNA complexes

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  6. Self-assembled nanogaps for molecular electronics.

    Science.gov (United States)

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

    2009-06-17

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

  7. Self-assembled nanogaps for molecular electronics

    DEFF Research Database (Denmark)

    Tang, Qingxin; Tong, Yanhong; Jain, Titoo

    2009-01-01

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

  8. Self-assembly of patchy colloidal dumbbells

    NARCIS (Netherlands)

    Avvisati, Guido|info:eu-repo/dai/nl/407630198; Vissers, Teun|info:eu-repo/dai/nl/304829943; Dijkstra, Marjolein|info:eu-repo/dai/nl/123538807

    2015-01-01

    We employ Monte Carlo simulations to investigate the self-assembly of patchy colloidal dumbbells interacting via a modified Kern-Frenkel potential by probing the system concentration and dumbbell shape. We consider dumbbells consisting of one attractive sphere with diameter sigma(1) and one

  9. Inverse Problem in Self-assembly

    Science.gov (United States)

    Tkachenko, Alexei

    2012-02-01

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

  10. Self-assembled nanogaps for molecular electronics

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  11. Fluorescent Self-Assembled Polyphenylene Dendrimer Nanofibers

    NARCIS (Netherlands)

    Liu, Daojun; Feyter, Steven De; Cotlet, Mircea; Wiesler, Uwe-Martin; Weil, Tanja; Herrmann, Andreas; Müllen, Klaus; Schryver, Frans C. De

    2003-01-01

    A second-generation polyphenylene dendrimer 1 self-assembles into nanofibers on various substrates such as HOPG, silicon, glass, and mica from different solvents. The investigation with noncontact atomic force microscopy (NCAFM) and scanning electron microscopy (SEM) shows that the morphology of the

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

    NARCIS (Netherlands)

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

    2014-01-01

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

  13. Ternary self-assemblies in water

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  14. Self-assembling membranes and related methods thereof

    Science.gov (United States)

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

    2013-08-20

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

  15. Self-assembled Nanomaterials for Chemotherapeutic Applications

    Science.gov (United States)

    Shieh, Aileen

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

  16. Centrioles: Some Self-Assembly Required

    OpenAIRE

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

    2008-01-01

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

  17. Self-assembled biomimetic nanoreactors I: Polymeric template

    Science.gov (United States)

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

    2015-09-01

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

  18. Centrioles: some self-assembly required.

    Science.gov (United States)

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

    2008-12-01

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

  19. Quantifying quality in DNA self-assembly

    Science.gov (United States)

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

    2014-01-01

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

  20. Oxide nanostructures through self-assembly

    Science.gov (United States)

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

    2001-03-01

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

  1. Stereochemistry in subcomponent self-assembly.

    Science.gov (United States)

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

    2014-07-15

    CONSPECTUS: As Pasteur noted more than 150 years ago, asymmetry exists in matter at all organization levels. Biopolymers such as proteins or DNA adopt one-handed conformations, as a result of the chirality of their constituent building blocks. Even at the level of elementary particles, asymmetry exists due to parity violation in the weak nuclear force. While the origin of homochirality in living systems remains obscure, as does the possibility of its connection with broken symmetries at larger or smaller length scales, its centrality to biomolecular structure is clear: the single-handed forms of bio(macro)molecules interlock in ways that depend upon their handednesses. Dynamic artificial systems, such as helical polymers and other supramolecular structures, have provided a means to study the mechanisms of transmission and amplification of stereochemical information, which are key processes to understand in the context of the origins and functions of biological homochirality. Control over stereochemical information transfer in self-assembled systems will also be crucial for the development of new applications in chiral recognition and separation, asymmetric catalysis, and molecular devices. In this Account, we explore different aspects of stereochemistry encountered during the use of subcomponent self-assembly, whereby complex structures are prepared through the simultaneous formation of dynamic coordinative (N → metal) and covalent (N═C) bonds. This technique provides a useful method to study stereochemical information transfer processes within metal-organic assemblies, which may contain different combinations of fixed (carbon) and labile (metal) stereocenters. We start by discussing how simple subcomponents with fixed stereogenic centers can be incorporated in the organic ligands of mononuclear coordination complexes and communicate stereochemical information to the metal center, resulting in diastereomeric enrichment. Enantiopure subcomponents were then

  2. The self-assembly of monodisperse nanospheres within microtubes

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  3. Magnetic self-assembly of small parts

    Science.gov (United States)

    Shetye, Sheetal B.

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

  4. Multifunctional Materials Based on Self Assembly of Molecular Nanostructures

    National Research Council Canada - National Science Library

    Stupp, Samuel

    2001-01-01

    .... The objective was to integrate self assembly, encoded in the triblock structure, luminescent properties, and the properties characteristic of materials that have macroscopically polar structure...

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

    Science.gov (United States)

    Bouchard, Ann M.; Osbourn, Gordon C.

    2013-01-08

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

  6. Heterogeneous self-assembled media for biopolymerization

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain

    2011-01-01

    Heterogeneous media, such as micro-structured aqueous environments, could offer an alternative approach to the synthesis of biopolymers with novel functions. Structured media are here defined as specialized, self-assembled structures that are formed, e.g, by amphiphiles, such as liposomes, emulsion...... polymerization, the initial elongation rates clearly depended on the complementarity of the monomers with the templating nucleobases3. However, metal-ion catalyzed reactions deliver RNA analogs with heterogeneous linkages. Moreover, the usefulness of this medium in the form of quasi-compartmentalization extends...... beyond metal-ion catalysis reactions, as we have recently demonstrated the catalytic power of a dipeptide, SerHis, for the regioselective formation of phosphodiester bonds. These results in conjonction with the synthesis of nucleobases at -78˚C, the demonstration of ribozyme activity (RNA ligase ribozyme...

  7. Controlling water evaporation through self-assembly.

    Science.gov (United States)

    Roger, Kevin; Liebi, Marianne; Heimdal, Jimmy; Pham, Quoc Dat; Sparr, Emma

    2016-09-13

    Water evaporation concerns all land-living organisms, as ambient air is dryer than their corresponding equilibrium humidity. Contrarily to plants, mammals are covered with a skin that not only hinders evaporation but also maintains its rate at a nearly constant value, independently of air humidity. Here, we show that simple amphiphiles/water systems reproduce this behavior, which suggests a common underlying mechanism originating from responding self-assembly structures. The composition and structure gradients arising from the evaporation process were characterized using optical microscopy, infrared microscopy, and small-angle X-ray scattering. We observed a thin and dry outer phase that responds to changes in air humidity by increasing its thickness as the air becomes dryer, which decreases its permeability to water, thus counterbalancing the increase in the evaporation driving force. This thin and dry outer phase therefore shields the systems from humidity variations. Such a feedback loop achieves a homeostatic regulation of water evaporation.

  8. Beam damage of self-assembled monolayers

    International Nuclear Information System (INIS)

    Rieke, P.C.; Baer, D.R.; Fryxell, G.E.; Engelhard, M.H.; Porter, M.S.

    1993-01-01

    X-ray and electron beam damage studies were performed on Br-terminated and methyl-terminated alkylsilane self-assembled monolayers. X-ray beam initiated damage was primarily limited to removal of the labile Br group and did not significantly damage the hydrocarbon chain. Some of the x-ray beam damage could be attributed to low-energy electrons emitted by the non-monochromatic source, but further damage was attributed to secondary electrons produced in the sample by x-ray exposure. Electron beams caused significant damage to the hydrocarbon chains. Maximum damage occurred with a beam energy of 600 eV and a dosage of 6x10 -3 C/cm 2

  9. Multicomponent and Dissipative Self-Assembly Approaches : Towards functional materials

    NARCIS (Netherlands)

    Boekhoven, J.

    2012-01-01

    The use of self-assembly has proven to be a powerful approach to create smart and functional materials and has led to a vast variety of successful examples. However, the full potential of self-assembly has not been reached. Despite the number of successful artificial materials based on

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

    NARCIS (Netherlands)

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

    2013-01-01

    Discotic molecules, which self-assemble in water into columnar supramolecular polymers, emerged as an alternative platform for the organization of proteins. Here, a monovalent discotic decorated with one single biotin was synthesized to study the self-assembling multivalency of this system in regard

  11. Synthetic Self-Assembled Materials in Biological Environments

    NARCIS (Netherlands)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2009-04-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  14. Freezing-induced self-assembly of amphiphilic molecules

    Science.gov (United States)

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

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

  15. A Self-Assembled Trigonal Prismatic Molecular Vessel for Catalytic Dehydration Reactions in Water.

    Science.gov (United States)

    Das, Paramita; Kumar, Atul; Howlader, Prodip; Mukherjee, Partha Sarathi

    2017-09-12

    A water-soluble Pd 6 trigonal prism (A) was synthesized by two-component coordination-driven self-assembly of a Pd II 90° acceptor with a tetraimidazole donor. The walls of the prism are constructed by three conjugated aromatic building blocks, which means that the confined pocket of the prism is hydrophobic. In addition to the hydrophobic cavity, large product egress windows make A an ideal molecular vessel to catalyze otherwise challenging pseudo-multicomponent dehydration reactions in its confined nanospace in aqueous medium. This study is an attempt at selective generation of the intermediate tetraketones and xanthenes by fine-tuning the reaction conditions employing a supramolecular molecular vessel. Moreover, either poor or no yield of the dehydrated products in the absence of A under similar reaction conditions supports the ability of the confined space of the barrel to promote such reactions in water. Furthermore, we focused on the rigidification of the tetraphenylethylene-based tetraimidazole unit anchored within the Pd II coordination architecture; enabling counter-anion dependent aggregation induced emission in the presence of water. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

    Patitz, Matthew John

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

  17. Self-assembled nanostructures in oxide ceramics

    Science.gov (United States)

    Ansari, Haris Masood

    Self-assembled nanoislands in the gadolinia-doped ceria (GDC)/ yttria-stabilized zirconia (YSZ) system have recently been discovered. This dissertation is an attempt to study the mechanism by which these nanoislands form. Nanoislands in the GDC/YSZ system form via a strain based mechanism whereby the stress accumulated in the GDC-doped surface layer on the YSZ substrate is relieved by creation of self-assembled nanoislands by a mechanism similar to the ATG instability. Unlike what was previously believed, a modified surface layer is not required prior to annealing, that is, this modification can occur during annealing by surface diffusion of dopants from the GDC sources (distributed on the YSZ surface in either lithographically defined patch or powder form) with simultaneous breakup, which occurs at the hold temperature independent of the subsequent cooling. Additionally, we have developed a simple powder based process of producing nanoislands which bypasses lithography and thin film deposition setups. The versatility of the process is apparent in the fact that it allows us to study the effect of experimental parameters such as soak time, temperature, cooling rate and the effect of powder composition on nanoisland properties in a facile way. With the help of this process, we have shown that nanoislands are not peculiar to Gd containing oxide source materials on YSZ substrates and can also be produced with other source materials such as La2O3, Nd2O3, Sm 2O3, Eu2O3, Tb2O3 and even Y2O3, which is already present in the substrate and hence simplifies the system further. We have extended our work to include YSZ substrates of the (110) surface orientation and have found that instead of nanoisland arrays, we obtain an array of parallel nanobars which have their long axes oriented along the [1-10] direction on the YSZ-(110) surface. STEM EDS performed on both the bars and the nanoislands has revealed that they are solid YSZ-rich solid solutions with the dopant species and

  18. Self-assembled biomimetic superhydrophobic hierarchical arrays.

    Science.gov (United States)

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

    2013-09-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  20. Equation of State for Phospholipid Self-Assembly

    DEFF Research Database (Denmark)

    Marsh, Derek

    2016-01-01

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

  1. Onset wear in self-assembled monolayers

    International Nuclear Information System (INIS)

    D'Acunto, Mario

    2006-01-01

    Self-assembled monolayers (SAMs) are very useful for the systematic modification of the physical, chemical and structural properties of a surface by varying the chain length, tail group and composition. Many of these properties can be studied making use of atomic force microscopy (AFM), and the interaction between the AFM probe tip and the SAMs can also be considered an excellent reference to study the fundamental properties of dissipation phenomena and onset wear for viscoelastic materials on the nanoscale. We have performed a numerical study showing that the fundamental mechanism for the onset wear is a process of nucleation of domains starting from initial defects. An SAM surface repeatedly sheared by an AFM probe tip with enough applied loads shows the formation of progressive damages nucleating in domains. The AFM induced surface damages involve primarily the formation of radicals from the carbon chain backbones, but the deformations of the chains resulting in changes of period lattice also have to be taken into consideration. The nucleation of the wear domains generally starts at the initial surface defects where the energy cohesion between chains is lower. Moreover, the presence of surface defects is consistent with the changes in lateral force increasing the probability of the activation for the removal of carbon debris from the chain backbone. The quantification of the progressive worn area is performed making use of the Kolmogorov-Johnson-Mehl-Avrami (KJMA) theory for phase transition kinetic processes. The advantage of knowing the general conditions for onset wear on the SAM surfaces can help in studying the fundamental mechanisms for the tribological properties of viscoelastic materials, in solid lubrication applications and biopolymer mechanics

  2. Optical orientation in self assembled quantum dots

    International Nuclear Information System (INIS)

    Stevens, Gregory C.

    2002-01-01

    We examined Zeeman splitting in a series of ln x Ga (1-x) 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, for one sample, a (311) grown In 0.5 Ga 0.5 As/GaAs SAQD sample, we were able to ascertain the spin relaxation time, the maximum value of the nuclear field, and provide evidence of the existence of nuclear spin freezing in at least one of our samples. We have then used a novel technique investigated by D. J. Guerrier, to examine optically detected nuclear magnetic resonance in our samples. We believe this is the first such study on these structures. We could not ascertain the dipolar indium resonance signal, even though all other isotopes were seen. We have therefore suggested a number of possible mechanisms that may be responsible for the lack of an indium resonance signal. (author)

  3. Self-Assembled Nanostructured Health Monitoring Sensors, Phase I

    Data.gov (United States)

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

  4. Self-Assembling Wireless Autonomous Reconfigurable Modules (SWARM), Phase I

    Data.gov (United States)

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

  5. Self-Assembly of Rod-Coil Block Copolymers

    National Research Council Canada - National Science Library

    Jenekhe, S

    1999-01-01

    ... the self-assembly of new rod-coil diblock, rod- coil-rod triblock, and coil-rod-coil triblock copolymers from solution and the resulting discrete and periodic mesostmctares with sizes in the 100...

  6. Preparation and self-assembly of amphiphilic polylysine dendrons

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  7. Enabling complex nanoscale pattern customization using directed self-assembly.

    Science.gov (United States)

    Doerk, Gregory S; Cheng, Joy Y; Singh, Gurpreet; Rettner, Charles T; Pitera, Jed W; Balakrishnan, Srinivasan; Arellano, Noel; Sanders, Daniel P

    2014-12-16

    Block copolymer directed self-assembly is an attractive method to fabricate highly uniform nanoscale features for various technological applications, but the dense periodicity of block copolymer features limits the complexity of the resulting patterns and their potential utility. Therefore, customizability of nanoscale patterns has been a long-standing goal for using directed self-assembly in device fabrication. Here we show that a hybrid organic/inorganic chemical pattern serves as a guiding pattern for self-assembly as well as a self-aligned mask for pattern customization through cotransfer of aligned block copolymer features and an inorganic prepattern. As informed by a phenomenological model, deliberate process engineering is implemented to maintain global alignment of block copolymer features over arbitrarily shaped, 'masking' features incorporated into the chemical patterns. These hybrid chemical patterns with embedded customization information enable deterministic, complex two-dimensional nanoscale pattern customization through directed self-assembly.

  8. Understanding emergent functions in self-assembled fibrous networks

    Science.gov (United States)

    Sinko, Robert; Keten, Sinan

    2015-09-01

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

  9. Synthesis and self-assembly of complex hollow materials

    KAUST Repository

    Zeng, Hua Chun

    2011-01-01

    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

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

    DEFF Research Database (Denmark)

    Canning, John; Lindoy, Lachlan; Huyang, George

    2013-01-01

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

  11. Mesoscopic Self-Assembly: A Shift to Complexity

    Directory of Open Access Journals (Sweden)

    Massimo eMastrangeli

    2015-06-01

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

  12. Construction of Supramolecular Architectures via Self-assembly

    Institute of Scientific and Technical Information of China (English)

    Takeharu; Haino

    2007-01-01

    1 Results In this paper we report supramolecular polymeric nano networks formed by the molecular-recognition-directed self-assembly between a calix[5]arene and C60[1]. Covalently-linked double-calix[5]arenes take up C60 into their cavities[2]. This complementary interaction creates a strong non-covalent bonding; thus,the iterative self-assembly between dumbbell fullerene 1 and ditopic host 2 can produce the supramolecular polymer networks (See Fig.1).

  13. Design strategies for self-assembly of discrete targets

    International Nuclear Information System (INIS)

    Madge, Jim; Miller, Mark A.

    2015-01-01

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

  14. The Self-Assembly of Nanogold for Optical Metamaterials

    Science.gov (United States)

    Nidetz, Robert A.

    2011-12-01

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

  15. Self-assembled tethered bimolecular lipid membranes.

    Science.gov (United States)

    Sinner, Eva-Kathrin; Ritz, Sandra; Naumann, Renate; Schiller, Stefan; Knoll, Wolfgang

    2009-01-01

    This chapter describes some of the strategies developed in our group for designing, constructing and structurally and functionally characterizing tethered bimolecular lipid membranes (tBLM). We introduce this platform as a novel model membrane system that complements the existing ones, for example, Langmuir monolayers, vesicular liposomal dispersions and bimolecular ("black") lipid membranes. Moreover, it offers the additional advantage of allowing for studies of the influence of membrane structure and order on the function of integral proteins, for example, on how the composition and organization of lipids in a mixed membrane influence the ion translocation activity of integral channel proteins. The first strategy that we introduce concerns the preparation of tethered monolayers by the self-assembly of telechelics. Their molecular architecture with a headgroup, a spacer unit (the "tether") and the amphiphile that mimics the lipid molecule allows them to bind specifically to the solid support thus forming the proximal layer of the final architecture. After fusion of vesicles that could contain reconstituted proteins from a liposomal dispersion in contact to this monolayer the tethered bimolecular lipid membrane is obtained. This can then be characterized by a broad range of surface analytical techniques, including surface plasmon spectroscopies, the quartz crystal microbalance, fluorescence and IR spectroscopies, and electrochemical techniques, to mention a few. It is shown that this concept allows for the construction of tethered lipid bilayers with outstanding electrical properties including resistivities in excess of 10 MOmega cm2. A modified strategy uses the assembly of peptides as spacers that couple covalently via their engineered sulfhydryl or lipoic acid groups at the N-terminus to the employed gold substrate, while their C-terminus is being activated afterward for the coupling of, for example, dimyristoylphosphatidylethanol amine (DMPE) lipid molecules

  16. Three-Dimensional Self-Assembled Photonic Crystal Waveguide

    Science.gov (United States)

    Baek, Kang-Hyun

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

  17. Physical principles for DNA tile self-assembly.

    Science.gov (United States)

    Evans, Constantine G; Winfree, Erik

    2017-06-19

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

  18. Bioprinting synthetic self-assembling peptide hydrogels for biomedical applications

    International Nuclear Information System (INIS)

    Loo, Yihua; Hauser, Charlotte A E

    2016-01-01

    Three-dimensional (3D) bioprinting is a disruptive technology for creating organotypic constructs for high-throughput screening and regenerative medicine. One major challenge is the lack of suitable bioinks. Short synthetic self-assembling peptides are ideal candidates. Several classes of peptides self-assemble into nanofibrous hydrogels resembling the native extracellular matrix. This is a conducive microenvironment for maintaining cell survival and physiological function. Many peptides also demonstrate stimuli-responsive gelation and tuneable mechanical properties, which facilitates extrusion before dispensing and maintains the shape fidelity of the printed construct in aqueous media. The inherent biocompatibility and biodegradability bodes well for in vivo applications as implantable tissues and drug delivery matrices, while their short length and ease of functionalization facilitates synthesis and customization. By applying self-assembling peptide inks to bioprinting, the dynamic complexity of biological tissue can be recreated, thereby advancing current biomedical applications of peptide hydrogel scaffolds. (paper)

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

    Science.gov (United States)

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

    2017-12-14

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

  20. Actinide Sequestration Using Self-Assembled Monolayers on Mesoporous Supports

    International Nuclear Information System (INIS)

    Fryxell, Glen E.; Lin, Yuehe; Fiskum, Sandra K.; Birnbaum, Jerome C.; Wu, Hong; Kemner, K. M.; Kelly, Shelley

    2005-01-01

    Surfactant templated synthesis of mesoporous ceramics provides a versatile foundation upon which to create high efficiency environmental sorbents. These nanoporous ceramic oxides condense a huge amount of surface area into a very small volume. The ceramic oxide interface is receptive to surface functionalization through molecular self-assembly. The marriage of mesoporous ceramics with self-assembled monolayer chemistry creates a powerful new class of environmental sorbent materials called self-assembled monolayers on mesoporous supports (SAMMS). These SAMMS materials are highly efficient sorbents, whose interfacial chemistry can be fine-tuned to selectively sequester a specific target species, such as heavy metals, tetrahedral oxometallate anions and radionuclides. Details addressing the design, synthesis and characterization of SAMMS materials specifically designed to sequester actinides, of central importance to the environmental clean-up necessary after 40 years of weapons grade plutonium production, as well as evaluation of their binding affinities and kinetics are presented

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

    Science.gov (United States)

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

    2014-10-28

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

  2. Sambot II: A self-assembly modular swarm robot

    Science.gov (United States)

    Zhang, Yuchao; Wei, Hongxing; Yang, Bo; Jiang, Cancan

    2018-04-01

    The new generation of self-assembly modular swarm robot Sambot II, based on the original generation of self-assembly modular swarm robot Sambot, adopting laser and camera module for information collecting, is introduced in this manuscript. The visual control algorithm of Sambot II is detailed and feasibility of the algorithm is verified by the laser and camera experiments. At the end of this manuscript, autonomous docking experiments of two Sambot II robots are presented. The results of experiments are showed and analyzed to verify the feasibility of whole scheme of Sambot II.

  3. Self-assembled three-dimensional chiral colloidal architecture

    Science.gov (United States)

    Ben Zion, Matan Yah; He, Xiaojin; Maass, Corinna C.; Sha, Ruojie; Seeman, Nadrian C.; Chaikin, Paul M.

    2017-11-01

    Although stereochemistry has been a central focus of the molecular sciences since Pasteur, its province has previously been restricted to the nanometric scale. We have programmed the self-assembly of micron-sized colloidal clusters with structural information stemming from a nanometric arrangement. This was done by combining DNA nanotechnology with colloidal science. Using the functional flexibility of DNA origami in conjunction with the structural rigidity of colloidal particles, we demonstrate the parallel self-assembly of three-dimensional microconstructs, evincing highly specific geometry that includes control over position, dihedral angles, and cluster chirality.

  4. Ultrafine luminescent structures through nanoparticle self-assembly

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  5. Self-assembly of active amphiphilic Janus particles

    Science.gov (United States)

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

    2017-12-01

    In this article, we study the phenomenology of a two dimensional dilute suspension of active amphiphilic Janus particles. We analyze how the morphology of the aggregates emerging from their self-assembly depends on the strength and the direction of the active forces. We systematically explore and contrast the phenomenologies resulting from particles with a range of attractive patch coverages. Finally, we illustrate how the geometry of the colloids and the directionality of their interactions can be used to control the physical properties of the assembled active aggregates and suggest possible strategies to exploit self-propulsion as a tunable driving force for self-assembly.

  6. Electrostatic Force Microscopy of Self Assembled Peptide Structures

    DEFF Research Database (Denmark)

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

    2011-01-01

    In this report electrostatic force microscopy (EFM) is used to study different peptide self-assembled structures, such as tubes and particles. It is shown that not only geometrical information can be obtained using EFM, but also information about the composition of different structures. In partic......In this report electrostatic force microscopy (EFM) is used to study different peptide self-assembled structures, such as tubes and particles. It is shown that not only geometrical information can be obtained using EFM, but also information about the composition of different structures...

  7. Self-Assembled Hydrogel Nanoparticles for Drug Delivery Applications

    Directory of Open Access Journals (Sweden)

    Miguel Gama

    2010-02-01

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

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

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

    NARCIS (Netherlands)

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

    2005-01-01

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

  10. Applications of self-assembled monolayers in materials chemistry

    Indian Academy of Sciences (India)

    Unknown

    Physical and Materials Chemistry Division, National Chemical Laboratory,. Pune 411 008, India e-mail: viji@ems.ncl.res.in. Abstract. 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 ...

  11. Synthesis, characterization and self-assembly with gold nanoparticles

    Indian Academy of Sciences (India)

    Administrator

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

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

    NARCIS (Netherlands)

    Vutukuri, H.R.

    2012-01-01

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

  13. Self-assembled domain structures: From micro- to nanoscale

    Directory of Open Access Journals (Sweden)

    Vladimir Shur

    2015-06-01

    Full Text Available The recent achievements in studying the self-assembled evolution of micro- and nanoscale domain structures in uniaxial single crystalline ferroelectrics lithium niobate and lithium tantalate have been reviewed. The results obtained by visualization of static domain patterns and kinetics of the domain structure by different methods from common optical microscopy to more sophisticated scanning probe microscopy, scanning electron microscopy and confocal Raman microscopy, have been discussed. The kinetic approach based on various nucleation processes similar to the first-order phase transition was used for explanation of the domain structure evolution scenarios. The main mechanisms of self-assembling for nonequilibrium switching conditions caused by screening ineffectiveness including correlated nucleation, domain growth anisotropy, and domain–domain interaction have been considered. The formation of variety of self-assembled domain patterns such as fractal-type, finger and web structures, broad domain boundaries, and dendrites have been revealed at each of all five stages of domain structure evolution during polarization reversal. The possible applications of self-assembling for micro- and nanodomain engineering were reviewed briefly. The review covers mostly the results published by our research group.

  14. Characterization of self-assembled monolayers on a ruthenium surface

    NARCIS (Netherlands)

    Shaheen, Amrozia; Sturm, Jacobus Marinus; Ricciardi, R.; Huskens, Jurriaan; Lee, Christopher James; Bijkerk, Frederik

    2017-01-01

    We have modified and stabilized the ruthenium surface by depositing a self-assembled monolayer (SAM) of 1-hexadecanethiol on a polycrystalline ruthenium thin film. The growth mechanism, dynamics, and stability of these monolayers were studied. SAMs, deposited under ambient conditions, on

  15. Self-assembled fluorescent organic nanoparticles for live cell imaging

    NARCIS (Netherlands)

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

    2013-01-01

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

  16. Encapsulation of gold nanoparticles into self-assembling protein nanoparticles

    OpenAIRE

    Yang Yongkun; Burkhard Peter

    2012-01-01

    Abstract Background Gold nanoparticles are useful tools for biological applications due to their attractive physical and chemical properties. Their applications can be further expanded when they are functionalized with biological molecules. The biological molecules not only provide the interfaces for interactions between nanoparticles and biological environment, but also contribute their biological functions to the nanoparticles. Therefore, we used self-assembling protein nanoparticles (SAPNs...

  17. Self-assembly of concentric quantum double rings.

    Science.gov (United States)

    Mano, Takaaki; Kuroda, Takashi; Sanguinetti, Stefano; Ochiai, Tetsuyuki; Tateno, Takahiro; Kim, Jongsu; Noda, Takeshi; Kawabe, Mitsuo; Sakoda, Kazuaki; Kido, Giyuu; Koguchi, Nobuyuki

    2005-03-01

    We demonstrate the self-assembled formation of concentric quantum double rings with high uniformity and excellent rotational symmetry using the droplet epitaxy technique. Varying the growth process conditions can control each ring's size. Photoluminescence spectra emitted from an individual quantum ring complex show peculiar quantized levels that are specified by the carriers' orbital trajectories.

  18. Oscillatory persistent currents in self-assembled quantum rings

    NARCIS (Netherlands)

    Kleemans, N.A.J.M.; Bominaar-Silkens, I.M.A.; Fomin, V.; Gladilin, V.N.; Granados, D.; Taboada, A.G.; Garcia, J.M.; Offermans, P.; Zeitler, U.; Christianen, P.C.M.; Maan, J.C.; Devreese, J.T.; Koenraad, P.M.

    2007-01-01

    We report the direct measurement of the persistent current carried by a single electron by means of magnetization experiments on self-assembled InAs/GaAs quantum rings. We measured the first Aharonov-Bohm oscillation at a field of 14 T, in perfect agreement with our model based on the structural

  19. Dynamics of self-assembled cytosine nucleobases on graphene

    Science.gov (United States)

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

    2018-05-01

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

  20. Long lived coherence in self-assembled quantum dots

    DEFF Research Database (Denmark)

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

    2001-01-01

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

  1. Multiphonon capture processes in self-assembled quantum dots

    DEFF Research Database (Denmark)

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

    2001-01-01

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

  2. Coherence and dephasing in self-assembled quantum dots

    DEFF Research Database (Denmark)

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

    2003-01-01

    We measured dephasing times in InGaAl/As self-assembled quantum dots at low temperature using degenerate four-wave mixing. At 0K, the coherence time of the quantum dots is lifetime limited, whereas at finite temperatures pure dephasing by exciton-phonon interactions governs the quantum dot...

  3. Extending the self-assembly of coiled-coil hybrids

    NARCIS (Netherlands)

    Robson Marsden, Hana

    2009-01-01

    Of the various biomolecular building blocks in use in nature, coiled-coil forming peptides are amongst those with the most potential as building blocks for the synthetic self-assembly of nanostructures. Native coiled coils have the ability to function in, and influence, complex systems composed of

  4. Electrostatic Self-Assembly of Polysaccharides into Nanofibers

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  5. Self-assembly of hydrofluorinated Janus graphene monolayer

    DEFF Research Database (Denmark)

    Jin, Yakang; Xue, Qingzhong; Zhu, Lei

    2016-01-01

    With remarkably interesting surface activities, two-dimensional Janus materials arouse intensive interests recently in many fields. We demonstrate by molecular dynamic simulations that hydrofluorinated Janus graphene (J-GN) can self-assemble into Janus nanoscroll (J-NS) at room temperature. The van...

  6. Nanoporous Network Channels from Self-Assembled Triblock Copolymer Supramolecules

    NARCIS (Netherlands)

    du Sart, Gerrit Gobius; Vukovic, Ivana; Vukovic, Zorica; Polushkin, Evgeny; Hiekkataipale, Panu; Ruokolainen, Janne; Loos, Katja; ten Brinke, Gerrit

    2011-01-01

    Supramolecular complexes of a poly(tert-butoxystyrene)-block-polystyrene-block-poly(4-vinylpyridine) triblock copolymers and less than stoichiometric amounts of pentadecylphenol (PDP) are shown to self-assemble into a core-shell gyroid morphology with the core channels formed by the hydrogen-bonded

  7. Self-assembling bilayers of palladiumthiolates in organic media

    Indian Academy of Sciences (India)

    Unknown

    applications in catalytic systems, solubalizing agents and drug delivery matrices. Following the pioneering efforts of ... In this context, self-assembly of amphipiles in nonpolar organic media assumes significance 8 since .... structures in clear contrast to lamellar phases formed by the higher members. We sought to image the ...

  8. Self-assembling electroactive hydrogels for flexible display technology

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-12-15

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

  9. Self-assembled monolayers on metal oxides : applications in nanotechnology

    NARCIS (Netherlands)

    Yildirim, O.

    2010-01-01

    The thesis describes the use of phosph(on)ate-based self-assembled monolayers (SAMs) to modify and pattern metal oxides. Metal oxides have interesting electronic and magnetic properties such as insulating, semiconducting, metallic, ferromagnetic etc. and SAMs can tailor the surface properties. FePt

  10. Self-assembling electroactive hydrogels for flexible display technology

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  11. Self-assembling peptide hydrogels immobilized on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Franchi, Stefano; Battocchio, Chiara; Galluzzi, Martina; Navisse, Emanuele [Department of Sciences, University “Roma Tre”, Via della Vasca Navale 79, Roma, 00146 (Italy); Zamuner, Annj; Dettin, Monica [Department of Industrial Engineering, University of Padua, Via Marzolo, 9, Padua, 35131 (Italy); Iucci, Giovanna, E-mail: giovanna.iucci@uniroma3.it [Department of Sciences, University “Roma Tre”, Via della Vasca Navale 79, Roma, 00146 (Italy)

    2016-12-01

    The hydrogels of self-assembling ionic complementary peptides have collected in the scientific community increasing consensus as mimetics of the extracellular matrix that can offer 3D supports for cell growth or be vehicles for the delivery of stem cells or drugs. Such scaffolds have also been proposed as bone substitutes for small defects as they promote beneficial effects on human osteoblasts. In this context, our research deals with the introduction of a layer of self-assembling peptides on a silicon surface by covalent anchoring and subsequent physisorption. In this work, we present a spectroscopic investigation of the proposed bioactive scaffolds, carried out by surface-sensitive spectroscopic techniques such as XPS (X-ray photoelectron spectroscopy) and RAIRS (Reflection Absorption Infrared Spectroscopy) and by state-of-the-art synchrotron radiation methodologies such as angle dependent NEXAFS (Near Edge X-ray Absorption Fine Structure). XPS studies confirmed the change in the surface composition in agreement with the proposed enrichments, and led to assess the self-assembling peptide chemical stability. NEXAFS spectra, collected in angular dependent mode at the N K-edge, allowed to investigate the self-assembling behavior of the macromolecules, as well as to determine their molecular orientation on the substrate. Furthermore, Infrared Spectroscopy measurements demonstrated that the peptide maintains its secondary structure (β-sheet anti-parallel) after deposition on the silicon surface. The complementary information acquired by means of XPS, NEXAFS and RAIRS lead to hypothesize a “layer-by-layer” arrangement of the immobilized peptides, giving rise to an ordered 3D nanostructure. - Highlights: • A self-assembling peptide (SAP) was covalently immobilized of on a flat silicon surface. • A physisorbed SAP layer was grown on top of the covalently immobilized peptide layer. • Molecular order and orientation of the peptide overlayer on the flat silicon

  12. Self-assembling peptide hydrogels immobilized on silicon surfaces

    International Nuclear Information System (INIS)

    Franchi, Stefano; Battocchio, Chiara; Galluzzi, Martina; Navisse, Emanuele; Zamuner, Annj; Dettin, Monica; Iucci, Giovanna

    2016-01-01

    The hydrogels of self-assembling ionic complementary peptides have collected in the scientific community increasing consensus as mimetics of the extracellular matrix that can offer 3D supports for cell growth or be vehicles for the delivery of stem cells or drugs. Such scaffolds have also been proposed as bone substitutes for small defects as they promote beneficial effects on human osteoblasts. In this context, our research deals with the introduction of a layer of self-assembling peptides on a silicon surface by covalent anchoring and subsequent physisorption. In this work, we present a spectroscopic investigation of the proposed bioactive scaffolds, carried out by surface-sensitive spectroscopic techniques such as XPS (X-ray photoelectron spectroscopy) and RAIRS (Reflection Absorption Infrared Spectroscopy) and by state-of-the-art synchrotron radiation methodologies such as angle dependent NEXAFS (Near Edge X-ray Absorption Fine Structure). XPS studies confirmed the change in the surface composition in agreement with the proposed enrichments, and led to assess the self-assembling peptide chemical stability. NEXAFS spectra, collected in angular dependent mode at the N K-edge, allowed to investigate the self-assembling behavior of the macromolecules, as well as to determine their molecular orientation on the substrate. Furthermore, Infrared Spectroscopy measurements demonstrated that the peptide maintains its secondary structure (β-sheet anti-parallel) after deposition on the silicon surface. The complementary information acquired by means of XPS, NEXAFS and RAIRS lead to hypothesize a “layer-by-layer” arrangement of the immobilized peptides, giving rise to an ordered 3D nanostructure. - Highlights: • A self-assembling peptide (SAP) was covalently immobilized of on a flat silicon surface. • A physisorbed SAP layer was grown on top of the covalently immobilized peptide layer. • Molecular order and orientation of the peptide overlayer on the flat silicon

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

    Science.gov (United States)

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

    2014-01-01

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

  14. Predicting supramolecular self-assembly on reconstructed metal surfaces

    Science.gov (United States)

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

    2014-06-01

    The prediction of supramolecular self-assembly onto solid surfaces is still challenging in many situations of interest for nanoscience. In particular, no previous simulation approach has been capable to simulate large self-assembly patterns of organic molecules over reconstructed surfaces (which have periodicities over large distances) due to the large number of surface atoms and adsorbing molecules involved. Using a novel simulation technique, we report here large scale simulations of the self-assembly patterns of an organic molecule (DIP) over different reconstructions of the Au(111) surface. We show that on particular reconstructions, the molecule-molecule interactions are enhanced in a way that long-range order is promoted. Also, the presence of a distortion in a reconstructed surface pattern not only induces the presence of long-range order but also is able to drive the organization of DIP into two coexisting homochiral domains, in quantitative agreement with STM experiments. On the other hand, only short range order is obtained in other reconstructions of the Au(111) surface. The simulation strategy opens interesting perspectives to tune the supramolecular structure by simulation design and surface engineering if choosing the right molecular building blocks and stabilising the chosen reconstruction pattern.The prediction of supramolecular self-assembly onto solid surfaces is still challenging in many situations of interest for nanoscience. In particular, no previous simulation approach has been capable to simulate large self-assembly patterns of organic molecules over reconstructed surfaces (which have periodicities over large distances) due to the large number of surface atoms and adsorbing molecules involved. Using a novel simulation technique, we report here large scale simulations of the self-assembly patterns of an organic molecule (DIP) over different reconstructions of the Au(111) surface. We show that on particular reconstructions, the molecule

  15. Self-Assembly of Molecular Threads into Reversible Gels

    Science.gov (United States)

    Sayar, Mehmet; Stupp, Samuel I.

    2001-03-01

    Reversible gels formed by low concentrations of molecular gelators that self-assemble into fibers with molecular width and extremely long length have been studied via Monte Carlo simulations. The gelators of interest have two kinds of interactions, one governs self-assembly into fibers and the other provides inter-fiber connectivity to drive the formation of a network. The off-lattice Monte Carlo simulation presented here is based on a point particle representation of gelators. In this model each particle can form only two strong bonds, that enable linear fiber formation, but a variable number of weak bonds which provide inter-fiber connectivity. The gel formation has been studied as a function of concentration of monomers, the strength of interactions, number of bonding sites per particle for weak interactions, and the stiffness of the fibers. The simulation results are compared with two experimental systems synthesized in our group in order to understand gelation mechanisms.

  16. DNA Self-Assembly: From Chirality to Evolution

    Directory of Open Access Journals (Sweden)

    Youri Timsit

    2013-04-01

    Full Text Available Transient or long-term DNA self-assembly participates in essential genetic functions. The present review focuses on tight DNA-DNA interactions that have recently been found to play important roles in both controlling DNA higher-order structures and their topology. Due to their chirality, double helices are tightly packed into stable right-handed crossovers. Simple packing rules that are imposed by DNA geometry and sequence dictate the overall architecture of higher order DNA structures. Close DNA-DNA interactions also provide the missing link between local interactions and DNA topology, thus explaining how type II DNA topoisomerases may sense locally the global topology. Finally this paper proposes that through its influence on DNA self-assembled structures, DNA chirality played a critical role during the early steps of evolution.

  17. Thermomechanical Response of Self-Assembled Nanoparticle Membranes

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-07-21

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

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

    Science.gov (United States)

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

    2015-08-12

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

  19. The self-assembling process and applications in tissue engineering

    Science.gov (United States)

    Lee, Jennifer K.; Link, Jarrett M.; Hu, Jerry C. Y.; Athanasiou, Kyriacos A.

    2018-01-01

    Tissue engineering strives to create neotissues capable of restoring function. Scaffold-free technologies have emerged that can recapitulate native tissue function without the use of an exogenous scaffold. This chapter will survey, in particular, the self-assembling and self-organization processes as scaffold-free techniques. Characteristics and benefits of each process are described, and key examples of tissues created using these scaffold-free processes are examined to provide guidance for future tissue engineering developments. This chapter aims to explore the potential of self-assembly and self-organization scaffold-free approaches, detailing the recent progress in the in vitro tissue engineering of biomimetic tissues with these methods, toward generating functional tissue replacements. PMID:28348174

  20. Quantitative self-assembly prediction yields targeted nanomedicines

    Science.gov (United States)

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

    2018-02-01

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

  1. Molecular Gels Materials with Self-Assembled Fibrillar Networks

    CERN Document Server

    Weiss, Richard G

    2006-01-01

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

  2. Understanding the self-assembly of TCNQ on Cu(111)

    DEFF Research Database (Denmark)

    Stradi, Daniele; Borca, Bogdana; Barja, Sara

    2016-01-01

    The structure of self-assembled monolayers of 7,7',8,8'-tetracyano-p-quinodimethane (TCNQ) adsorbed on Cu(111) has been studied using a combination of scanning tunnelling microscopy (STM) experiments and density functional theory (DFT) calculations. We show that the polymorphism of the self......-assembled molecular layer can be controlled by tuning of the experimental conditions under which the deposition is carried out. When the Cu(111) substrate is held above room temperature (T-Cu(111) = 350 K) during deposition, a structure is formed in which the two molecules in the unit cell are oriented one...... perpendicular to the other. Conversely, when the substrate is held at room temperature during deposition and slightly annealed afterwards, a more complex structure with five molecules per unit cell is formed. DFT calculations complement the experimental results by revealing that the building blocks of the two...

  3. Self-assembling enzymes and the origins of the cytoskeleton

    Science.gov (United States)

    Barry, Rachael; Gitai, Zemer

    2011-01-01

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

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

    NARCIS (Netherlands)

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

    2016-01-01

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

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

    DEFF Research Database (Denmark)

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

    2002-01-01

    This letter reports the self-assembly and analysis of CdSe nanocrystal monolayers on both p- and a-doped GaAs substrates. The self-assembly was performed using a 1,6-hexanedithiol self-assembled monolayer (SAM) to link CdSe nanocrystals to GaAs substrates. Attenuated total reflection Fourier tran...

  6. Dispersion of nanoparticulate suspensions using self-assembled surfactant aggregates

    Science.gov (United States)

    Singh, Pankaj Kumar

    The dispersion of particles is critical for several industrial applications such as paints, inks, coatings, and cosmetics. Several emerging applications such as abrasives for precision polishing, and drug delivery systems are increasingly relying on nanoparticulates to achieve the desired performance. In the case of nanoparticles, the dispersion becomes more challenging because of the lack of fundamental understanding of dispersant adsorption and interparticle force prediction. Additionally, many of these processes use severe processing environments such as high normal forces (>100 mN/m), high shear forces (>10,000 s -1), and high ionic strengths (>0.1 M). Under such processing conditions, traditionally used dispersants based on electrostatics, and steric force repulsion mechanism may not be adequate. Hence, the development of optimally performing dispersants requires a fundamental understanding of the dispersion mechanism at the atomic/molecular scale. This study explores the use of self-assembled surfactant aggregates at the solid-liquid interface for dispersing nanoparticles in severe processing environments. Surfactant molecules can provide a feasible alternative to polymeric or inorganic dispersants for stabilizing ultrafine particles. The barrier to aggregation in the presence of surfactant molecules was measured using atomic force microscopy. The barrier heights correlated to suspension stability. To understand the mechanism for nanoparticulate suspension stability in the presence of surfactant films, the interface was characterized using zeta potential, contact angle, adsorption, and FT-IR (adsorbed surfactant film structure measurements). The effect of solution conditions such as pH and ionic strength on the suspension stability, and the self-assembled surfactant films was also investigated. It was determined that a transition from a random to an ordered orientation of the surfactant molecules at the interface was responsible for stability of

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

    DEFF Research Database (Denmark)

    Flyvbjerg, H.; Jobs, E.

    1997-01-01

    Inverse scattering theory describes the conditions necessary and sufficient to determine an unknown potential from known scattering data. No similar theory exists for when and how one may deduce the kinetics of an unknown chemical reaction from quantitative information about its final state and i...... 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....

  8. Fabrication of Nanostructures Using Self-Assembled Peptides as Templates

    DEFF Research Database (Denmark)

    Castillo, Jaime

    2015-01-01

    the advantages of diphenylalanine are explained step by step offering new alternatives to fabricate nanostructures in a simple and rapid way. The chapter is complemented with techniques to manipulate the self-assembled diphenylalanine nanostructures without changing its properties during the manipulation process.......This chapter evaluates the use of a short-aromatic dipeptide, diphenylalanine, as a template in the fabrication of new nanostructures (nanowires, coaxial nanocables, nanochannels) using materials such as silicon, conducting and non-conducting polymers. Diphenylalanine self...

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

    Science.gov (United States)

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

    2016-03-02

    A novel system of paramagnetic vesicles was designed using ion pairs of iron-containing surfactants. Unilamellar vesicles (diameter ≈ 200 nm) formed spontaneously and were characterized by cryogenic transmission electron microscopy, nanoparticle tracking analysis, and light and small-angle neutron scattering. Moreover, for the first time, it is shown that magnetization measurements can be used to investigate self-assembly of such functionalized systems, giving information on the vesicle compositions and distribution of surfactants between the bilayers and the aqueous bulk.

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

    OpenAIRE

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

    2016-01-01

    A novel system of paramagnetic vesicles was designed using ion pairs of iron-containing surfactants. Unilamellar vesicles (diameter ≈ 200 nm) formed spontaneously and were characterized by cryogenic transmission electron microscopy, nanoparticle tracking analysis, and light and small-angle neutron scattering. Moreover, for the first time, it is shown that magnetization measurements can be used to investigate self-assembly of such functionalized systems, giving information on the vesicle compo...

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

    Czech Academy of Sciences Publication Activity Database

    Stakkestad, O.; Lyngstadaas, S. P.; Thiede, B.; Vondrášek, Jiří; Skalhegg, B. S.; Reseland, J. E.

    2017-01-01

    Roč. 8, Jul 27 (2017), č. článku 531. ISSN 1664-042X Institutional support: RVO:61388963 Keywords : ameloblastin * phosphorylation * self-assembly * Ca2+-binding * enamel * intrinsically disordered proteins Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 4.134, year: 2016 http://journal.frontiersin.org/article/10.3389/fphys.2017.00531/full

  12. Self-assembled containers based on extended tetrathiafulvalene.

    Science.gov (United States)

    Bivaud, Sébastien; Goeb, Sébastien; Croué, Vincent; Dron, Paul I; Allain, Magali; Sallé, Marc

    2013-07-10

    Two original self-assembled containers constituted each by six electroactive subunits are described. They are synthesized from a concave tetratopic π-extended tetrathiafulvalene ligand bearing four pyridyl units and cis-M(dppf)(OTf)2 (M = Pd or Pt; dppf = 1,1'-bis(diphenylphosphino)ferrocene; OTf = trifluoromethane-sulfonate) complexes. Both fully characterized assemblies present an oblate spheroidal cavity that can incorporate one perylene molecule.

  13. Self-assembly and speed distributions of active granular particles

    Science.gov (United States)

    Sánchez, R.; Díaz-Leyva, P.

    2018-06-01

    The relationship between the dynamics of self-propelled systems and the self-assembly of structured clusters are studied via the experimental speed distributions of submonolayers of self-propelled granular particles. A distribution developed for non-self-propelled granular particles describes the speed distributions remarkably well, despite some of the assumptions behind its original derivation not being applicable. This is explained in terms of clustering and dissipation being the key phenomena governing this regime.

  14. Biocompatible and Biomimetic Self-Assembly of Functional Nanostructures

    Science.gov (United States)

    2010-02-28

    evaporation induced self-assembly of aqueous silica precursors with a biologically compatible surfactant, glycerol monooleate ( GMO ) via dip-coating...film is first deposited, it has a relatively low contact angle with water and remains in a semi-solid state. Upon exposure to UV/ozone, the GMO begins...Figure 8. A) Water contact angle of a GMO -templated silica film as a function of UV light and ozone exposure time, B) Localization of fluorescently

  15. Retroreflective Phase Retardation Prisms.

    Science.gov (United States)

    1981-06-01

    resonant cavity of a 1.064 Mm laser. This report shows that it is possible to coat the reflecting surfaces of a porro prism so that incident plane...with controlled phase retardation can be made by coating each reflecting surface of a porro prism with a single dielectric film. The amount of phase...of angle of incidence (n, < n2) S. Phase change on reflection as a function of angle of incidence (n" n ) [RL-0202-’R 6. Porro prism 7. Phase change

  16. Self-assembly of inorganic nanoparticles: Ab ovo

    Science.gov (United States)

    Kotov, Nicholas A.

    2017-09-01

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

  17. Supramolecular ribbons from amphiphilic trisamides self-assembly.

    Science.gov (United States)

    García, Fátima; Buendía, Julia; Sánchez, Luis

    2011-08-05

    Two amphiphilic C(3)-symmetric OPE-based trisamides have been synthesized and their self-assembling features investigated in solution and on surface. Variable-temperature UV-vis experiments demonstrate the cooperative supramolecular polymerization of these trisamides that self-assemble by the operation of triple C═O···H-N H-bonding arrays between the amide functional groups and π-π stacking between the aromatic units. The helical organization of the aggregates has been demonstrated by circular dichroism at a concentration as low as 1 × 10(-4) M in acetonitrile. In the reported trisamides, the large hydrophobic aromatic core acts as a solvophobic module impeding the interaction between the polar TEG chains and the amide H-bonds. This strategy makes unnecessary the separation of the amide functional groups to the polar tri(ethylene glycol) chains by paraffinic fragments. Achiral trisamide 1 self-assembles into flat ribbon-like structures that experience an amplification of chirality by the addition of a small amount of chiral 2 that generates twisted stripes.

  18. Molecular Motions in Functional Self-Assembled Nanostructures

    Directory of Open Access Journals (Sweden)

    Jean-Marc Saiter

    2013-01-01

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

  19. Self-assembled magnetic filter for highly efficient immunomagnetic separation.

    Science.gov (United States)

    Issadore, David; Shao, Huilin; Chung, Jaehoon; Newton, Andita; Pittet, Mikael; Weissleder, Ralph; Lee, Hakho

    2011-01-07

    We have developed a compact and inexpensive microfluidic chip, the self-assembled magnetic filter, to efficiently remove magnetically tagged cells from suspension. The self-assembled magnetic filter consists of a microfluidic channel built directly above a self-assembled NdFeB magnet. Micrometre-sized grains of NdFeB assemble to form alternating magnetic dipoles, creating a magnetic field with a very strong magnitude B (from the material) and field gradient ▽B (from the configuration) in the microfluidic channel. The magnetic force imparted on magnetic beads is measured to be comparable to state-of-the-art microfabricated magnets, allowing for efficient separations to be performed in a compact, simple device. The efficiency of the magnetic filter is characterized by sorting non-magnetic (polystyrene) beads from magnetic beads (iron oxide). The filter enriches the population of non-magnetic beads to magnetic beads by a factor of >10(5) with a recovery rate of 90% at 1 mL h(-1). The utility of the magnetic filter is demonstrated with a microfluidic device that sorts tumor cells from leukocytes using negative immunomagnetic selection, and concentrates the tumor cells on an integrated membrane filter for optical detection.

  20. Chitosan Based Self-Assembled Nanoparticles in Drug Delivery

    Directory of Open Access Journals (Sweden)

    Javier Pérez Quiñones

    2018-02-01

    Full Text Available Chitosan is a cationic polysaccharide that is usually obtained by alkaline deacetylation of chitin poly(N-acetylglucosamine. It is biocompatible, biodegradable, mucoadhesive, and non-toxic. These excellent biological properties make chitosan a good candidate for a platform in developing drug delivery systems having improved biodistribution, increased specificity and sensitivity, and reduced pharmacological toxicity. In particular, chitosan nanoparticles are found to be appropriate for non-invasive routes of drug administration: oral, nasal, pulmonary and ocular routes. These applications are facilitated by the absorption-enhancing effect of chitosan. Many procedures for obtaining chitosan nanoparticles have been proposed. Particularly, the introduction of hydrophobic moieties into chitosan molecules by grafting to generate a hydrophobic-hydrophilic balance promoting self-assembly is a current and appealing approach. The grafting agent can be a hydrophobic moiety forming micelles that can entrap lipophilic drugs or it can be the drug itself. Another suitable way to generate self-assembled chitosan nanoparticles is through the formation of polyelectrolyte complexes with polyanions. This paper reviews the main approaches for preparing chitosan nanoparticles by self-assembly through both procedures, and illustrates the state of the art of their application in drug delivery.

  1. DNA assisted self-assembly of PAMAM dendrimers.

    Science.gov (United States)

    Mandal, Taraknath; Kumar, Mattaparthi Venkata Satish; Maiti, Prabal K

    2014-10-09

    We report DNA assisted self-assembly of polyamidoamine (PAMAM) dendrimers using all atom Molecular Dynamics (MD) simulations and present a molecular level picture of a DNA-linked PAMAM dendrimer nanocluster, which was first experimentally reported by Choi et al. (Nano Lett., 2004, 4, 391-397). We have used single stranded DNA (ssDNA) to direct the self-assembly process. To explore the effect of pH on this mechanism, we have used both the protonated (low pH) and nonprotonated (high pH) dendrimers. In all cases studied here, we observe that the DNA strand on one dendrimer unit drives self-assembly as it binds to the complementary DNA strand present on the other dendrimer unit, leading to the formation of a DNA-linked dendrimer dimeric complex. However, this binding process strongly depends on the charge of the dendrimer and length of the ssDNA. We observe that the complex with a nonprotonated dendrimer can maintain a DNA length dependent inter-dendrimer distance. In contrast, for complexes with a protonated dendrimer, the inter-dendrimer distance is independent of the DNA length. We attribute this observation to the electrostatic complexation of a negatively charged DNA strand with the positively charged protonated dendrimer.

  2. Controlling Self-Assembly in Al(110) Homoepitaxy

    Science.gov (United States)

    Tiwary, Yogesh; Fichthorn, Kristen

    2010-03-01

    Homoepitaxial growth on Al(110) exhibits nanoscale self-assembly into huts with well-defined (100) and (111) facets [1]. Although some of the diffusion mechanisms underlying this kinetic self-assembly were identified and incorporated into a two-dimensional model [2], we used density-functional theory (DFT) to identify many other mechanisms that are needed to describe the three-dimensional assembly seen experimentally [3]. We developed a three-dimensional kinetic Monte Carlo (KMC) model of Al(110) homoepitaxy. The inputs to the model were obtained from DFT [3,4]. Our model is in agreement with experimentally observed trends for this system. We used KMC to predict self-assembly under various growth conditions. To achieve precise placement of Al nanohuts, we simulated thermal-field-directed assembly [5]. Our results indicate that this technique can be used to create uniform arrays of nanostructures. [1] F. Buatier de Mongeot, W. Zhu, A. Molle, R. Buzio, C. Boragno, U. Valbusa, E. Wang, and Z. Zhang, Phys. Rev. Lett. 91, 016102 (2003). [2] W. Zhu, F. Buatier de Mongeot, U. Valbusa, E. G. Wang, and Z. Y. Zhang, Phys. Rev. Lett. 92, 106102 (2004). [3] Y. Tiwary and K. A. Fichthorn, submitted to Phys. Rev. B. [4] Y. Tiwary and K. A. Fichthorn, Phys. Rev. B 78, 205418 (2008). [5] C. Zhang and R. Kalyanaraman, Appl. Phys. Lett. 83, 4827 (2003).

  3. Self-assembled nanomaterials based on beta (β"3) tetrapeptides

    International Nuclear Information System (INIS)

    Seoudi, Rania S; Hinds, Mark G; Wilson, David J D; Adda, Christopher G; Mechler, Adam; Del Borgo, Mark; Aguilar, Marie-Isabel; Perlmutter, Patrick

    2016-01-01

    β "3-amino acid based polypeptides offer a unique starting material for the design of self-assembled nanostructures such as fibres and hierarchical dendritic assemblies, due to their well-defined helical geometry in which the peptide side chains align at 120° due to the 3.0–3.1 residue pitch of the helix. In a previous work we have described the head-to-tail self-assembly of N-terminal acetylated β "3-peptides into infinite helical nanorods that was achieved by designing a bioinspired supramolecular self-assembly motif. Here we describe the effect of consecutively more polar side chains on the self-assembly characteristics of β "3-tetrapeptides Ac-β "3Ala-β "3Leu-β "3Ile-β "3Ala (Ac-β"3[ALIA]), Ac-β "3Ser-β "3Leu-β "3Ile-β "3Ala (Ac-β"3[SLIA]) and Ac-β "3Lys-β "3Leu-β "3Ile-β "3Glu (Ac-β"3[KLIE]). β "3-tetrapeptides complete 1 1/3 turns of the helix: thus in the oligomeric form the side chain positions shift 120° with each added monomer, forming a regular periodic pattern along the nanorod. Dynamic light scattering (DLS) measurements confirmed that these peptides self-assemble even in highly polar solvents such as water and DMSO, while diffusion-ordered NMR spectroscopy revealed the presence of a substantial monomeric population. Temperature dependence of the size distribution in DLS measurements suggests a dynamic equilibrium between monomers and oligomers. Solution casting produced distinct fibrillar deposits after evaporating the solvent. In the case of the apolar Ac-β "3[ALIA] the longitudinal helix morphology gives rise to geometrically defined (∼70°) junctions between fibres, forming a mesh that opens up possibilities for applications e.g. in tissue scaffolding. The deposits of polar Ac-β "3[SLIA] and Ac-β "3[KLIE] exhibit fibres in regular parallel alignment over surface areas in the order of 10 μm. (paper)

  4. Self-assembled Block Copolymer Membranes with Bioinspired Artificial Channels

    KAUST Repository

    Sutisna, Burhannudin

    2018-04-01

    Nature is an excellent design that inspires scientists to develop smart systems. In the realm of separation technology, biological membranes have been an ideal model for synthetic membranes due to their ultrahigh permeability, sharp selectivity, and stimuliresponse. In this research, fabrications of bioinspired membranes from block copolymers were studied. Membranes with isoporous morphology were mainly prepared using selfassembly and non-solvent induced phase separation (SNIPS). An effective method that can dramatically shorten the path for designing new isoporous membranes from block copolymers via SNIPS was first proposed by predetermining a trend line computed from the solvent properties, interactions and copolymer block sizes of previously-obtained successful systems. Application of the method to new copolymer systems and fundamental studies on the block copolymer self-assembly were performed. Furthermore, the manufacture of bioinspired membranes was explored using (1) poly(styrene-b-4-hydroxystyrene-b-styrene) (PS-b-PHS-b-PS), (2) poly(styrene-bbutadiene- b-styrene) (PS-b-PB-b-PS) and (3) poly(styrene-b-γ-benzyl-L-glutamate) (PSb- PBLG) copolymers via SNIPS. The structure formation was investigated using smallangle X-ray scattering (SAXS) and time-resolved grazing-Incidence SAXS. The PS-b- PHS-b-PS membranes showed preferential transport for proteins, presumably due to the hydrogen bond interactions within the channels, electrostatic attraction, and suitable pore dimension. Well-defined nanochannels with pore sizes of around 4 nm based on PS-b- PB-b-PS copolymers could serve as an excellent platform to fabricate bioinspired channels due to the modifiable butadiene blocks. Photolytic addition of thioglycolic acid was demonstrated without sacrificing the self-assembled morphology, which led to a five-fold increase in water permeance compared to that of the unmodified. Membranes with a unique feather-like structure and a lamellar morphology for dialysis and

  5. Self-assembly of amorphous biophotonic nanostructures by phase separation

    Energy Technology Data Exchange (ETDEWEB)

    Dufresne, Eric R.; Noh, Heeso; Saranathan, Vinodkumar; Mochrie, Simon G.J.; Cao, Hui; Prum, Richard O.; (Yale)

    2009-04-23

    Some of the most vivid colors in the animal kingdom are created not by pigments, but by wavelength-selective scattering of light from nanostructures. Here we investigate quasi-ordered nanostructures of avian feather barbs which produce vivid non-iridescent colors. These {beta}-keratin and air nanostructures are found in two basic morphologies: tortuous channels and amorphous packings of spheres. Each class of nanostructure is isotropic and has a pronounced characteristic length scale of variation in composition. These local structural correlations lead to strong backscattering over a narrow range of optical frequencies and little variation with angle of incidence. Such optical properties play important roles in social and sexual communication. To be effective, birds need to precisely control the development of these nanoscale structures, yet little is known about how they grow. We hypothesize that multiple lineages of birds have convergently evolved to exploit phase separation and kinetic arrest to self-assemble spongy color-producing nanostructures in feather barbs. Observed avian nanostructures are strikingly similar to those self-assembled during the phase separation of fluid mixtures; the channel and sphere morphologies are characteristic of phase separation by spinodal decomposition and nucleation and growth, respectively. These unstable structures are locked-in by the kinetic arrest of the {beta}-keratin matrix, likely through the entanglement or cross-linking of supermolecular {beta}-keratin fibers. Using the power of self-assembly, birds can robustly realize a diverse range of nanoscopic morphologies with relatively small physical and chemical changes during feather development.

  6. Particle self-assembly at ionic liquid-based interfaces.

    Science.gov (United States)

    Frost, Denzil S; Nofen, Elizabeth M; Dai, Lenore L

    2014-04-01

    This review presents an overview of the nature of ionic liquid (IL)-based interfaces and self-assembled particle morphologies of IL-in-water, oil- and water-in-IL, and novel IL-in-IL Pickering emulsions with emphasis on their unique phenomena, by means of experimental and computational studies. In IL-in-water Pickering emulsions, particles formed monolayers at ionic liquid-water interfaces and were close-packed on fully covered emulsion droplets or aggregated on partially covered droplets. Interestingly, other than equilibrating at the ionic liquid-water interfaces, microparticles with certain surface chemistries were extracted into the ionic liquid phase with a high efficiency. These experimental findings were supported by potential of mean force calculations, which showed large energy drops as hydrophobic particles crossed the interface into the IL phase. In the oil- and water-in-IL Pickering emulsions, microparticles with acidic surface chemistries formed monolayer bridges between the internal phase droplets rather than residing at the oil/water-ionic liquid interfaces, a significant deviation from traditional Pickering emulsion morphology. Molecular dynamics simulations revealed aspects of the mechanism behind this bridging phenomenon, including the role of the droplet phase, surface chemistry, and inter-particle film. Novel IL-in-IL Pickering emulsions exhibited an array of self-assembled morphologies including the previously observed particle absorption and bridging phenomena. The appearance of these morphologies depended on the particle surface chemistry as well as the ILs used. The incorporation of particle self-assembly with ionic liquid science allows for new applications at the intersection of these two fields, and have the potential to be numerous due to the tunability of the ionic liquids and particles incorporated, as well as the particle morphology by combining certain groups of particle surface chemistry, IL type (protic or aprotic), and whether oil

  7. Matrix development in self-assembly of articular cartilage.

    Directory of Open Access Journals (Sweden)

    Gidon Ofek

    2008-07-01

    Full Text Available Articular cartilage is a highly functional tissue which covers the ends of long bones and serves to ensure proper joint movement. A tissue engineering approach that recapitulates the developmental characteristics of articular cartilage can be used to examine the maturation and degeneration of cartilage and produce fully functional neotissue replacements for diseased tissue.This study examined the development of articular cartilage neotissue within a self-assembling process in two phases. In the first phase, articular cartilage constructs were examined at 1, 4, 7, 10, 14, 28, 42, and 56 days immunohistochemically, histologically, and through biochemical analysis for total collagen and glycosaminoglycan (GAG content. Based on statistical changes in GAG and collagen levels, four time points from the first phase (7, 14, 28, and 56 days were chosen to carry into the second phase, where the constructs were studied in terms of their mechanical characteristics, relative amounts of collagen types II and VI, and specific GAG types (chondroitin 4-sulfate, chondroitin 6-sulfate, dermatan sulfate, and hyaluronan. Collagen type VI was present in initial abundance and then localized to a pericellular distribution at 4 wks. N-cadherin activity also spiked at early stages of neotissue development, suggesting that self-assembly is mediated through a minimization of free energy. The percentage of collagen type II to total collagen significantly increased over time, while the proportion of collagen type VI to total collagen decreased between 1 and 2 wks. The chondroitin 6- to 4- sulfate ratio decreased steadily during construct maturation. In addition, the compressive properties reached a plateau and tensile characteristics peaked at 4 wks.The indices of cartilage formation examined in this study suggest that tissue maturation in self-assembled articular cartilage mirrors known developmental processes for native tissue. In terms of tissue engineering, it is

  8. Chemical solution route to self-assembled epitaxial oxide nanostructures.

    Science.gov (United States)

    Obradors, X; Puig, T; Gibert, M; Queraltó, A; Zabaleta, J; Mestres, N

    2014-04-07

    Self-assembly of oxides as a bottom-up approach to functional nanostructures goes beyond the conventional nanostructure formation based on lithographic techniques. Particularly, chemical solution deposition (CSD) is an ex situ growth approach very promising for high throughput nanofabrication at low cost. Whereas strain engineering as a strategy to define nanostructures with tight control of size, shape and orientation has been widely used in metals and semiconductors, it has been rarely explored in the emergent field of functional complex oxides. Here we will show that thermodynamic modeling can be very useful to understand the principles controlling the growth of oxide nanostructures by CSD, and some attractive kinetic features will also be presented. The methodology of strain engineering is applied in a high degree of detail to form different sorts of nanostructures (nanodots, nanowires) of the oxide CeO2 with fluorite structure which then is used as a model system to identify the principles controlling self-assembly and self-organization in CSD grown oxides. We also present, more briefly, the application of these ideas to other oxides such as manganites or BaZrO3. We will show that the nucleation and growth steps are essentially understood and manipulated while the kinetic phenomena underlying the evolution of the self-organized networks are still less widely explored, even if very appealing effects have been already observed. Overall, our investigation based on a CSD approach has opened a new strategy towards a general use of self-assembly and self-organization which can now be widely spread to many functional oxide materials.

  9. Self-assembly of silver nanoparticles and bacteriophage

    Directory of Open Access Journals (Sweden)

    Santi Scibilia

    2016-03-01

    Full Text Available Biohybrid nanostructured materials, composed of both inorganic nanoparticles and biomolecules, offer prospects for many new applications in extremely diverse fields such as chemistry, physics, engineering, medicine and nanobiotechnology. In the recent years, Phage display technique has been extensively used to generate phage clones displaying surface peptides with functionality towards organic materials. Screening and selection of phage displayed material binding peptides has attracted great interest because of their use for development of hybrid materials with multiple functionalities. Here, we present a self-assembly approach for the construction of hybrid nanostructured networks consisting of M13 P9b phage clone, specific for Pseudomonas aeruginosa, selected by Phage display technology, directly assembled with silver nanoparticles (AgNPs, previously prepared by pulsed laser ablation. These networks are characterized by UV–vis optical spectroscopy, scanning/transmission electron microscopies and Raman spectroscopy. We investigated the influence of different ions and medium pH on self-assembly by evaluating different phage suspension buffers. The assembly of these networks is controlled by electrostatic interactions between the phage pVIII major capsid proteins and the AgNPs. The formation of the AgNPs-phage networks was obtained only in two types of tested buffers at a pH value near the isoelectric point of each pVIII proteins displayed on the surface of the clone. This systematic study allowed to optimize the synthesis procedure to assembly AgNPs and bacteriophage. Such networks find application in the biomedical field of advanced biosensing and targeted gene and drug delivery. Keywords: Phage display, Silver nanoparticles, Self-assembly, Hybrid architecture, Raman spectroscopy

  10. Encapsulation of gold nanoparticles into self-assembling protein nanoparticles

    Directory of Open Access Journals (Sweden)

    Yang Yongkun

    2012-10-01

    Full Text Available Abstract Background Gold nanoparticles are useful tools for biological applications due to their attractive physical and chemical properties. Their applications can be further expanded when they are functionalized with biological molecules. The biological molecules not only provide the interfaces for interactions between nanoparticles and biological environment, but also contribute their biological functions to the nanoparticles. Therefore, we used self-assembling protein nanoparticles (SAPNs to encapsulate gold nanoparticles. The protein nanoparticles are formed upon self-assembly of a protein chain that is composed of a pentameric coiled-coil domain at the N-terminus and trimeric coiled-coil domain at the C-terminus. The self-assembling protein nanoparticles form a central cavity of about 10 nm in size, which is ideal for the encapsulation of gold nanoparticles with similar sizes. Results We have used SAPNs to encapsulate several commercially available gold nanoparticles. The hydrodynamic size and the surface coating of gold nanoparticles are two important factors influencing successful encapsulation by the SAPNs. Gold nanoparticles with a hydrodynamic size of less than 15 nm can successfully be encapsulated. Gold nanoparticles with citrate coating appear to have stronger interactions with the proteins, which can interfere with the formation of regular protein nanoparticles. Upon encapsulation gold nanoparticles with polymer coating interfere less strongly with the ability of the SAPNs to assemble into nanoparticles. Although the central cavity of the SAPNs carries an overall charge, the electrostatic interaction appears to be less critical for the efficient encapsulation of gold nanoparticles into the protein nanoparticles. Conclusions The SAPNs can be used to encapsulate gold nanoparticles. The SAPNs can be further functionalized by engineering functional peptides or proteins to either their N- or C-termini. Therefore encapsulation of gold

  11. Biomimetic self-assembly of a functional asymmetrical electronic device.

    Science.gov (United States)

    Boncheva, Mila; Gracias, David H; Jacobs, Heiko O; Whitesides, George M

    2002-04-16

    This paper introduces a biomimetic strategy for the fabrication of asymmetrical, three-dimensional electronic devices modeled on the folding of a chain of polypeptide structural motifs into a globular protein. Millimeter-size polyhedra-patterned with logic devices, wires, and solder dots-were connected in a linear string by using flexible wire. On self-assembly, the string folded spontaneously into two domains: one functioned as a ring oscillator, and the other one as a shift register. This example demonstrates that biomimetic principles of design and self-organization can be applied to generate multifunctional electronic systems of complex, three-dimensional architecture.

  12. Self-assembly of heterogeneous supramolecular structures with uniaxial anisotropy.

    Science.gov (United States)

    Ruiz-Osés, M; Gonzalez-Lakunza, N; Silanes, I; Gourdon, A; Arnau, A; Ortega, J E

    2006-12-28

    Uniaxial anisotropy in two-dimensional self-assembled supramolecular structures is achieved by the coadsorption of two different linear molecules with complementary amine and imide functionalization. The two-dimensional monolayer is defined by a one-dimensional stack of binary chains, which can be forced to line up along steps in vicinal surfaces. The competing driving forces in the self-organization process are discussed in light of the structures observed during single molecule adsorption and coadsorption on flat and vicinal surfaces and the corresponding theoretical calculations.

  13. Passivation effects in B doped self-assembled Si nanocrystals

    International Nuclear Information System (INIS)

    Puthen Veettil, B.; Wu, Lingfeng; Jia, Xuguang; Lin, Ziyun; Zhang, Tian; Yang, Terry; Johnson, Craig; Conibeer, Gavin; Perez-Würfl, Ivan; McCamey, Dane

    2014-01-01

    Doping of semiconductor nanocrystals has enabled their widespread technological application in optoelectronics and micro/nano-electronics. In this work, boron-doped self-assembled silicon nanocrystal samples have been grown and characterised using Electron Spin Resonance and photoluminescence spectroscopy. The passivation effects of boron on the interface dangling bonds have been investigated. Addition of boron dopants is found to compensate the active dangling bonds at the interface, and this is confirmed by an increase in photoluminescence intensity. Further addition of dopants is found to reduce the photoluminescence intensity by decreasing the minority carrier lifetime as a result of the increased number of non-radiative processes

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

    KAUST Repository

    Vignolini, Silvia

    2011-10-24

    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.

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

    KAUST Repository

    Vignolini, Silvia; Yufa, Nataliya A.; Cunha, Pedro S.; Guldin, Stefan; Rushkin, Ilia; Stefik, Morgan; Hur, Kahyun; Wiesner, Ulrich; Baumberg, Jeremy J.; Steiner, Ullrich

    2011-01-01

    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.

  16. Oscillatory persistent currents in self-assembled quantum rings.

    Science.gov (United States)

    Kleemans, N A J M; Bominaar-Silkens, I M A; Fomin, V M; Gladilin, V N; Granados, D; Taboada, A G; García, J M; Offermans, P; Zeitler, U; Christianen, P C M; Maan, J C; Devreese, J T; Koenraad, P M

    2007-10-05

    We report the direct measurement of the persistent current carried by a single electron by means of magnetization experiments on self-assembled InAs/GaAs quantum rings. We measured the first Aharonov-Bohm oscillation at a field of 14 T, in perfect agreement with our model based on the structural properties determined by cross-sectional scanning tunneling microscopy measurements. The observed oscillation magnitude of the magnetic moment per electron is remarkably large for the topology of our nanostructures, which are singly connected and exhibit a pronounced shape asymmetry.

  17. Microcolumns with self-assembled particle frits for proteomics

    DEFF Research Database (Denmark)

    Ishihama, Yasushi; Rappsilber, Juri; Andersen, Jens S

    2002-01-01

    LC-MS-MS experiments in proteomics are usually performed with packed microcolumns employing frits or outlets smaller than the particle diameter to retain the packing material. We have developed packed microcolumns using self-assembled particles (SAPs) as frits that are smaller than the size...... of the outlet. A five to one ratio of outlet size to particle diameter appears to be the upper maximum. In these situations the particles assembled into an arch over the outlet like the stones in a stone bridge. When 3 microm particles were packed into a tapered column with an 8 microm outlet, two particles...

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

    Directory of Open Access Journals (Sweden)

    Eugen Stulz

    2011-06-01

    Full Text Available We describe the synthesis of terpyridine modified DNA strands which selectively form DNA nanotubes through orthogonal hydrogen bonding and metal complexation interactions. The short DNA strands are designed to self-assemble into long duplexes through a sticky-end approach. Addition of weakly binding metals such as Zn(II and Ni(II induces the formation of tubular arrays consisting of DNA bundles which are 50-200 nm wide and 2-50 nm high. TEM shows additional long distance ordering of the terpy-DNA complexes into fibers.

  19. Self-assembly of silk fibroin under osmotic stress

    Science.gov (United States)

    Sohn, Sungkyun

    The supramolecular self-assembly behavior of silk fibroin was investigated using osmotic stress technique. In Chapter 2, a ternary phase diagram of water-silk-LiBr was constructed based on X-ray results on the osmotically stressed regenerated silk fibroin of Bombyx mori silkworm. Microscopic data indicated that silk I is a hydrated structure and a rough estimate of the number of water molecules lost by the structure upon converting from silk I to silk II has been made, and found to be about 2.2 per [GAGAGS] hexapeptide. In Chapter 3, wet-spinning of osmotically stressed, regenerated silk fibroin was performed, based on the prediction that the enhanced control over structure and phase behavior using osmotic stress method helps improve the physical properties of wet-spun regenerated silk fibroin fibers. The osmotic stress was applied in order to pre-structure the regenerated silk fibroin molecule from its original random coil state to more oriented state, manipulating the phase of the silk solution in the phase diagram before the start of spinning. Monofilament fiber with a diameter of 20 microm was produced. In Chapter 4, we investigated if there is a noticeable synergistic osmotic pressure increase between co-existing polymeric osmolyte and salt when extremely highly concentrated salt molecules are present both at sample subphase and stressing subphase, as is the case of silk fibroin self-assembly. The equilibration method that measures osmotic pressure relative to a reference with known osmotic pressure was introduced. Osmotic pressure of aqueous LiBr solution up to 2.75M was measured and it was found that the synergistic effect was insignificant up to this salt concentration. Solution parameters of stressing solutions and Arrhenius kinetics based on time-temperature relationship for the equilibration process were derived as well. In Chapter 5, self-assembly behavior of natural silk fibroin within the gland of Bombyx mori silkworm was investigated using osmotic

  20. Rapid self-assembly of block copolymers to photonic crystals

    Science.gov (United States)

    Xia, Yan; Sveinbjornsson, Benjamin R; Grubbs, Robert H; Weitekamp, Raymond; Miyake, Garret M; Atwater, Harry A; Piunova, Victoria; Daeffler, Christopher Scot; Hong, Sung Woo; Gu, Weiyin; Russell, Thomas P.

    2016-07-05

    The invention provides a class of copolymers having useful properties, including brush block copolymers, wedge-type block copolymers and hybrid wedge and polymer block copolymers. In an embodiment, for example, block copolymers of the invention incorporate chemically different blocks comprising polymer size chain groups and/or wedge groups that significantly inhibit chain entanglement, thereby enhancing molecular self-assembly processes for generating a range of supramolecular structures, such as periodic nanostructures and microstructures. The present invention also provides useful methods of making and using copolymers, including block copolymers.

  1. Light-assisted templated self assembly using photonic crystal slabs.

    Science.gov (United States)

    Mejia, Camilo A; Dutt, Avik; Povinelli, Michelle L

    2011-06-06

    We explore a technique which we term light-assisted templated self-assembly. We calculate the optical forces on colloidal particles over a photonic crystal slab. We show that exciting a guided resonance mode of the slab yields a resonantly-enhanced, attractive optical force. We calculate the lateral optical forces above the slab and predict that stably trapped periodic patterns of particles are dependent on wavelength and polarization. Tuning the wavelength or polarization of the light source may thus allow the formation and reconfiguration of patterns. We expect that this technique may be used to design all-optically reconfigurable photonic devices.

  2. Nanoporous network channels from self-assembled triblock copolymer supramolecules.

    Science.gov (United States)

    du Sart, Gerrit Gobius; Vukovic, Ivana; Vukovic, Zorica; Polushkin, Evgeny; Hiekkataipale, Panu; Ruokolainen, Janne; Loos, Katja; ten Brinke, Gerrit

    2011-02-16

    Supramolecular complexes of a poly(tert-butoxystyrene)-block-polystyrene-block-poly(4-vinylpyridine) triblock copolymers and less than stoichiometric amounts of pentadecylphenol (PDP) are shown to self-assemble into a core-shell gyroid morphology with the core channels formed by the hydrogen-bonded P4VP(PDP)complexes. After structure formation, PDP was removed using a simple washing procedure, resulting in well-ordered nanoporous films that were used as templates for nickel plating. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Self-Assembled Supramolecular Architectures Lyotropic Liquid Crystals

    CERN Document Server

    Garti, Nissim

    2012-01-01

    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

  4. Exploring the properties and possibilities of self-assembling

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Castillo, Jaime

    2013-01-01

    structures ranging from piezo electricity over semi conductance to fluorescence. If such peptide nanotubes could be controlled and incorporated in sensors such as a biological field effect transistor it would greatly reduce the fabrication costs while at the same time providing researchers with new...... and exciting possibilities. The major driving forces supporting the interest in the peptide nanotubes is the fast and simple assembly process combined with their remarkable stability towards alcohols, organic solvents, and biological analytes that was presented shortly after the self-assembling properties...... and illustrated their potential use as sensitive temperature sensor....

  5. Self-assembled manganese oxide structures through direct oxidation

    KAUST Repository

    Zhao, Chao; Wang, Qingxiao; Yang, Yang; Zhang, Bei; Zhang, Xixiang

    2012-01-01

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

  6. Self-assembled manganese oxide structures through direct oxidation

    KAUST Repository

    Zhao, Chao

    2012-12-01

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

  7. Surfactant self-assembly in alcohol-rich solutions

    International Nuclear Information System (INIS)

    Bouguerra, N.; Jebari, M.M.; Gomati, R.; Gharbi, A.

    2005-01-01

    Ionic conductivity and viscosity measurements are achieved along alcohol dilution lines of a single-isotropic phase domain, which extends from the alcohol corner to sponge phase domain to brine corner, of an alcohol-surfactant-brine phase diagram. The results are discussed in terms of amphiphilic self-assembly which leads to stable mixtures of the slightly miscible alcohol and brine used. We show the formation of reverse micelles, whose cores are either dry or charged of brine according to the samples composition, and whose sizes remain small near the sponge phase structure

  8. Biomimetic engineering: towards a self-assembled nanotechnology

    International Nuclear Information System (INIS)

    Braach-Maksvytis, V.

    2002-01-01

    Full text: The Nanoscience and Systems program was set up within CSIRO Telecommunications and Industrial Physics three years ago with an emphasis on biomimetic engineering, with the aim of developing new cross-disciplinary research in traditional physics areas. By combining expertise in experimental and theoretical physics with biology and chemistry, new approaches towards understanding and using nanoscale systems and devices are being explored. Research in the program ranges from using self-assembled lipid membranes for surface passivation of GaAs transistors to the electrical properties of nanoparticle films and devices. An overview of the research will be given, highlighting the diversity of nanotechnology applications

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

    Science.gov (United States)

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

    2018-04-01

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

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

    Science.gov (United States)

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

    2018-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-15

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

  12. Physical principles of filamentous protein self-assembly kinetics

    International Nuclear Information System (INIS)

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

    2017-01-01

    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. (topical review)

  13. Self-assembling layers created by membrane proteins on gold.

    Science.gov (United States)

    Shah, D S; Thomas, M B; Phillips, S; Cisneros, D A; Le Brun, A P; Holt, S A; Lakey, J H

    2007-06-01

    Membrane systems are based on several types of organization. First, amphiphilic lipids are able to create monolayer and bilayer structures which may be flat, vesicular or micellar. Into these structures membrane proteins can be inserted which use the membrane to provide signals for lateral and orientational organization. Furthermore, the proteins are the product of highly specific self-assembly otherwise known as folding, which mostly places individual atoms at precise places in three dimensions. These structures all have dimensions in the nanoscale, except for the size of membrane planes which may extend for millimetres in large liposomes or centimetres on planar surfaces such as monolayers at the air/water interface. Membrane systems can be assembled on to surfaces to create supported bilayers and these have uses in biosensors and in electrical measurements using modified ion channels. The supported systems also allow for measurements using spectroscopy, surface plasmon resonance and atomic force microscopy. By combining the roles of lipids and proteins, highly ordered and specific structures can be self-assembled in aqueous solution at the nanoscale.

  14. Self-assembled Nano-layering at the Adhesive interface.

    Science.gov (United States)

    Yoshida, Y; Yoshihara, K; Nagaoka, N; Hayakawa, S; Torii, Y; Ogawa, T; Osaka, A; Meerbeek, B Van

    2012-04-01

    According to the 'Adhesion-Decalcification' concept, specific functional monomers within dental adhesives can ionically interact with hydroxyapatite (HAp). Such ionic bonding has been demonstrated for 10-methacryloyloxydecyl dihydrogen phosphate (MDP) to manifest in the form of self-assembled 'nano-layering'. However, it remained to be explored if such nano-layering also occurs on tooth tissue when commercial MDP-containing adhesives (Clearfil SE Bond, Kuraray; Scotchbond Universal, 3M ESPE) were applied following common clinical application protocols. We therefore characterized adhesive-dentin interfaces chemically, using x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDS), and ultrastructurally, using (scanning) transmission electron microscopy (TEM/STEM). Both adhesives revealed nano-layering at the adhesive interface, not only within the hybrid layer but also, particularly for Clearfil SE Bond (Kuraray), extending into the adhesive layer. Since such self-assembled nano-layering of two 10-MDP molecules, joined by stable MDP-Ca salt formation, must make the adhesive interface more resistant to biodegradation, it may well explain the documented favorable clinical longevity of bonds produced by 10-MDP-based adhesives.

  15. New self-assembly strategies for next generation lithography

    Science.gov (United States)

    Schwartz, Evan L.; Bosworth, Joan K.; Paik, Marvin Y.; Ober, Christopher K.

    2010-04-01

    Future demands of the semiconductor industry call for robust patterning strategies for critical dimensions below twenty nanometers. The self assembly of block copolymers stands out as a promising, potentially lower cost alternative to other technologies such as e-beam or nanoimprint lithography. One approach is to use block copolymers that can be lithographically patterned by incorporating a negative-tone photoresist as the majority (matrix) phase of the block copolymer, paired with photoacid generator and a crosslinker moiety. In this system, poly(α-methylstyrene-block-hydroxystyrene)(PαMS-b-PHOST), the block copolymer is spin-coated as a thin film, processed to a desired microdomain orientation with long-range order, and then photopatterned. Therefore, selfassembly of the block copolymer only occurs in select areas due to the crosslinking of the matrix phase, and the minority phase polymer can be removed to produce a nanoporous template. Using bulk TEM analysis, we demonstrate how the critical dimension of this block copolymer is shown to scale with polymer molecular weight using a simple power law relation. Enthalpic interactions such as hydrogen bonding are used to blend inorganic additives in order to enhance the etch resistance of the PHOST block. We demonstrate how lithographically patternable block copolymers might fit in to future processing strategies to produce etch-resistant self-assembled features at length scales impossible with conventional lithography.

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

    Directory of Open Access Journals (Sweden)

    Chen Y

    2011-05-01

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

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  18. Stochastic lag time in nucleated linear self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, Nitin S. [Group Theory of Polymers and Soft Matter, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Schoot, Paul van der [Group Theory of Polymers and Soft Matter, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht (Netherlands)

    2016-06-21

    Protein aggregation is of great importance in biology, e.g., in amyloid fibrillation. The aggregation processes that occur at the cellular scale must be highly stochastic in nature because of the statistical number fluctuations that arise on account of the small system size at the cellular scale. We study the nucleated reversible self-assembly of monomeric building blocks into polymer-like aggregates using the method of kinetic Monte Carlo. Kinetic Monte Carlo, being inherently stochastic, allows us to study the impact of fluctuations on the polymerization reactions. One of the most important characteristic features in this kind of problem is the existence of a lag phase before self-assembly takes off, which is what we focus attention on. We study the associated lag time as a function of system size and kinetic pathway. We find that the leading order stochastic contribution to the lag time before polymerization commences is inversely proportional to the system volume for large-enough system size for all nine reaction pathways tested. Finite-size corrections to this do depend on the kinetic pathway.

  19. Probabilistic Performance Guarantees for Distributed Self-Assembly

    KAUST Repository

    Fox, Michael J.

    2015-04-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Kitae Ryu

    2015-01-01

    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.

  1. Self-assembly of colloids with magnetic caps

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-06-01

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

  2. Physical principles of filamentous protein self-assembly kinetics

    Science.gov (United States)

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

    2017-04-01

    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.

  3. Forces that Drive Nanoscale Self-assembly on Solid Surfaces

    International Nuclear Information System (INIS)

    Suo, Z.; Lu, W.

    2000-01-01

    Experimental evidence has accumulated in the recent decade that nanoscale patterns can self-assemble on solid surfaces. A two-component monolayer grown on a solid surface may separate into distinct phases. Sometimes the phases select sizes about 10 nm, and order into an array of stripes or disks. This paper reviews a model that accounts for these behaviors. Attention is focused on thermodynamic forces that drive the self-assembly. A double-welled, composition-dependent free energy drives phase separation. The phase boundary energy drives phase coarsening. The concentration-dependent surface stress drives phase refining. It is the competition between the coarsening and the refining that leads to size selection and spatial ordering. These thermodynamic forces are embodied in a nonlinear diffusion equation. Numerical simulations reveal rich dynamics of the pattern formation process. It is relatively fast for the phases to separate and select a uniform size, but exceedingly slow to order over a long distance, unless the symmetry is suitably broken

  4. Structural Diversity of Self-Assembled Iridescent Arthropod Biophotonic Nanostructures

    Science.gov (United States)

    Saranathan, Vinod Kumar; Prum, Richard O.

    2015-03-01

    Many organisms, especially arthropods, produce vivid interference colors using diverse mesoscopic (100-350 nm) integumentary biophotonic nanostructures that are increasingly being investigated for technological applications. Despite a century of interest, we lack precise structural knowledge of many biophotonic nanostructures and mechanisms controlling their development, when such knowledge can open novel biomimetic routes to facilely self-assemble tunable, multi-functional materials. Here, we use synchrotron small angle X-ray scattering and electron microscopy to characterize the photonic nanostructure of 140 iridescent integumentary scales and setae from 127 species of terrestrial arthropods in 85 genera from 5 orders. We report a rich nanostructural diversity, including triply-periodic bicontinuous networks, close-packed spheres, inverse columnar, perforated lamellar, and disordered sponge-like morphologies, commonly observed as stable phases of amphiphilic surfactants, block copolymer, and lyotropic lipid-water systems. Diverse arthropod lineages appear to have independently evolved to utilize the self-assembly of infolding bilayer membranes to develop biophotonic nanostructures that span the phase-space of amphiphilic morphologies, but at optical length scales.

  5. Managing lifelike behavior in a dynamic self-assembled system

    Science.gov (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.

  6. Synthesis and self-assembly of complex hollow materials

    KAUST Repository

    Zeng, Hua Chun

    2011-01-01

    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.

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

    Science.gov (United States)

    Yang, Jisheng; Li, Jinfeng

    2018-02-01

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

  8. Self-assembly of dodecaphenyl POSS thin films

    Science.gov (United States)

    Handke, Bartosz; Klita, Łukasz; Niemiec, Wiktor

    2017-12-01

    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.

  9. Proteins evolve on the edge of supramolecular self-assembly

    Science.gov (United States)

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

    2017-08-01

    The self-association of proteins into symmetric complexes is ubiquitous in all kingdoms of life. Symmetric complexes possess unique geometric and functional properties, but their internal symmetry can pose a risk. In sickle-cell disease, the symmetry of haemoglobin exacerbates the effect of a mutation, triggering assembly into harmful fibrils. Here we examine the universality of this mechanism and its relation to protein structure geometry. We introduced point mutations solely designed to increase surface hydrophobicity among 12 distinct symmetric complexes from Escherichia coli. Notably, all responded by forming supramolecular assemblies in vitro, as well as in vivo upon heterologous expression in Saccharomyces cerevisiae. Remarkably, in four cases, micrometre-long fibrils formed in vivo in response to a single point mutation. Biophysical measurements and electron microscopy revealed that mutants self-assembled in their folded states and so were not amyloid-like. Structural examination of 73 mutants identified supramolecular assembly hot spots predictable by geometry. A subsequent structural analysis of 7,471 symmetric complexes showed that geometric hot spots were buffered chemically by hydrophilic residues, suggesting a mechanism preventing mis-assembly of these regions. Thus, point mutations can frequently trigger folded proteins to self-assemble into higher-order structures. This potential is counterbalanced by negative selection and can be exploited to design nanomaterials in living cells.

  10. Self-assembled single-phase perovskite nanocomposite thin films.

    Science.gov (United States)

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

    2010-02-10

    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.

  11. Liposomes self-assembled from electrosprayed composite microparticles

    International Nuclear Information System (INIS)

    Yu Dengguang; Yang Junhe; Wang Xia; Tian Feng

    2012-01-01

    Composite microparticles, consisting of polyvinylpyrrolidone (PVP), naproxen (NAP) and lecithin (PC), have been successfully prepared using an electrospraying process and exploited as templates to manipulate molecular self-assembly for the synthesis of liposomes in situ. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) observations demonstrate that the microparticles have an average diameter of 960 ± 140 nm and a homogeneous structure. X-ray diffraction (XRD) patterns, differential scanning calorimetry (DSC) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) results verify that the building blocks NAP and PC are scattered in the polymer matrix in a molecular way owing to the very fast drying of the electrospraying process and the favorable secondary interactions among the components. FESEM, scanning probe microscope (SPM) and TEM observations demonstrate that the liposomes can be achieved through molecular self-assembly in situ when the microparticles contact water thanks to ‘like prefers like’ and by means of the confinement effect of the microparticles. The liposomes have an encapsulation rate of 91.3%, and 80.7% of the drug in the liposomes can be freed into the dissolution medium in a sustained way and by a diffusion mechanism over a period of 24 h. The developed strategy not only provides a new, facile, and effective method to assemble and organize molecules of multiple components into liposomes with electrosprayed microparticles as templates, but also opens a new avenue for nanofabrication in a step-by-step and controllable way. (paper)

  12. Mixed carboranethiol self-assembled monolayers on gold surfaces

    Science.gov (United States)

    Yavuz, Adem; Sohrabnia, Nima; Yilmaz, Ayşen; Danışman, M. Fatih

    2017-08-01

    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.

  13. A controllable spin prism

    International Nuclear Information System (INIS)

    Hakioglu, T

    2009-01-01

    Based on Khodas et al (2004 Phys. Rev. Lett. 92 086602), we propose a device acting like a controllable prism for an incident spin. The device is a large quantum well where Rashba and Dresselhaus spin-orbit interactions are present and controlled by the plunger gate potential, the electric field and the barrier height. A totally destructive interference can be manipulated externally between the Rashba and Dresselhaus couplings. The spin-dependent transmission/reflection amplitudes are calculated as the control parameters are changed. The device operates as a spin prism/converter/filter in different regimes and may stimulate research in promising directions in spintronics in analogy with linear optics.

  14. Morphology and Pattern Control of Diphenylalanine Self-Assembly via Evaporative Dewetting.

    Science.gov (United States)

    Chen, Jiarui; Qin, Shuyu; Wu, Xinglong; Chu, And Paul K

    2016-01-26

    Self-assembled peptide nanostructures have unique physical and biological properties and promising applications in electrical devices and functional molecular recognition. Although solution-based peptide molecules can self-assemble into different morphologies, it is challenging to control the self-assembly process. Herein, controllable self-assembly of diphenylalanine (FF) in an evaporative dewetting solution is reported. The fluid mechanical dimensionless numbers, namely Rayleigh, Marangoni, and capillary numbers, are introduced to control the interaction between the solution and FF molecules in the self-assembly process. The difference in the film thickness reflects the effects of Rayleigh and Marangoni convection, and the water vapor flow rate reveals the role of viscous fingering in the emergence of aligned FF flakes. By employing dewetting, various FF self-assembled patterns, like concentric and spokelike, and morphologies, like strips and hexagonal tubes/rods, can be produced, and there are no significant lattice structural changes in the FF nanostructures.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  16. Reflection by Porro Prisms

    Science.gov (United States)

    Greenslade, Thomas B.

    2010-04-01

    Students all know that reflection from a plane mirror produces an image that is reversed right to left and so cannot be read by anyone but Leonardo da Vinci, who kept his notes in mirror writing. A useful counter-example is the Porro prism, which produces an image that is not reversed.

  17. Self-assembling triblock proteins for biofunctional surface modification

    Science.gov (United States)

    Fischer, Stephen E.

    Despite the tremendous promise of cell/tissue engineering, significant challenges remain in engineering functional scaffolds to precisely regulate the complex processes of tissue growth and development. As the point of contact between the cells and the scaffold, the scaffold surface plays a major role in mediating cellular behaviors. In this dissertation, the development and utility of self-assembling, artificial protein hydrogels as biofunctional surface modifiers is described. The design of these recombinant proteins is based on a telechelic triblock motif, in which a disordered polyelectrolyte central domain containing embedded bioactive ligands is flanked by two leucine zipper domains. Under moderate conditions of temperature and pH, the leucine zipper end domains form amphiphilic alpha-helices that reversibly associate into homo-trimeric aggregates, driving hydrogel formation. Moreover, the amphiphilic nature of these helical domains enables surface adsorption to a variety of scaffold materials to form biofunctional protein coatings. The nature and stability of these coatings in various solution conditions, and their interaction with mammalian cells is the primary focus of this dissertation. In particular, triblock protein coatings functionalized with cell recognition sequences are shown to produce well-defined surfaces with precise control over ligand density. The impact of this is demonstrated in multiple cell types through ligand density-dependent cell-substrate interactions. To improve the stability of these physically self-assembled coatings, two covalent crosslinking strategies are described---one in which a zero-length chemical crosslinker (EDC) is utilized and a second in which disulfide bonds are engineered into the recombinant proteins. These targeted crosslinking approaches are shown to increase the stability of surface adsorbed protein layers with minimal effect on the presentation of many bioactive ligands. Finally, to demonstrate the versatility

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

    Science.gov (United States)

    Vemula, Praveen Kumar; John, George

    2008-06-01

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

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

    Directory of Open Access Journals (Sweden)

    Rose Franck

    2007-01-01

    Full Text Available AbstractMicrotubules are filamentous proteins that act as a substrate for the translocation of motor proteins. As such, they may be envisioned as a scaffold for the self-assembly of functional materials and devices. Physisorption, self-assembly and combing are here investigated as a potential prelude to microtubule-templated self-assembly. Dense films of self-assembled microtubules were successfully produced, as well as patterns of both dendritic and non-dendritic bundles of microtubules. They are presented in the present paper and the mechanism of their formation is discussed.

  20. The PRISM project

    Science.gov (United States)

    Guilyardi, E.

    2003-04-01

    The European Union's PRISM infrastructure project (PRogram for Integrated earth System Modelling) aims at designing a flexible environment to easily assemble and run Earth System Models (http://prism.enes.org). Europe's widely distributed modelling expertise is both a strength and a challenge. Recognizing this, the PRISM project aims at developing an efficient shared modelling software infrastructure for climate scientists, providing them with an opportunity for greater focus on scientific issues, including the necessary scientific diversity (models and approaches). The proposed PRISM system includes 1) the use - or definition - and promotion of scientific and technical standards to increase component modularity, 2) an end-to-end software environment (coupler, user interface, diagnostics) to launch, monitor and analyze complex Earth System Models built around the existing and future community models, 3) testing and quality standards to ensure HPC performance on a variety of platforms and 4) community wide inputs and requirements capture in all stages of system specifications and design through user/developers meetings, workshops and thematic schools. This science driven project, led by 22 institutes* and started December 1st 2001, benefits from a unique gathering of scientific and technical expertise. More than 30 models (both global and regional) have expressed interest to be part of the PRISM system and 6 types of components have been identified: atmosphere, atmosphere chemistry, land surface, ocean, sea ice and ocean biochemistry. Progress and overall architecture design will be presented. * MPI-Met (Coordinator), KNMI (co-coordinator), MPI-M&D, Met Office, University of Reading, IPSL, Meteo-France, CERFACS, DMI, SMHI, NERSC, ETH Zurich, INGV, MPI-BGC, PIK, ECMWF, UCL-ASTR, NEC, FECIT, SGI, SUN, CCRLE

  1. Spin-flip transitions in self-assembled quantum dots

    Science.gov (United States)

    Stavrou, V. N.

    2017-12-01

    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.

  2. Self assembled monolayers of octadecyltrichlorosilane for dielectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijay, E-mail: cirivijaypilani@gmail.com [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)

    2016-04-13

    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.

  3. Self-assembly of orthogonal three-axis sensors

    International Nuclear Information System (INIS)

    Cho, J. H.; Hu, S.; Gracias, D. H.

    2008-01-01

    Conventional planar microfabrication is widely utilized to construct sensors for the measurement of physical or chemical properties. However, in these devices, the information component measured is typically restricted to only one vectorial axis. Here, we describe a self-assembling strategy that can be utilized to construct three dimensional (3D) cubic devices that facilitate measurement along three axes. This 3D measurement is achieved by arranging sensing elements orthogonally; any sensing element that can be lithographically patterned can be utilized. The 3D arrangement of sensors allows for the measurement of angular and orientation parameters. As an example, we describe a three-axis cantilever based sensor and demonstrate measurement of an evaporated analyte using resonant frequency shifts of cantilevers in each of the x, y, and z axes

  4. Self-Assembled InAs Nanowires as Optical Reflectors

    Directory of Open Access Journals (Sweden)

    Francesco Floris

    2017-11-01

    Full Text Available Subwavelength nanostructured surfaces are realized with self-assembled vertically-aligned InAs nanowires, and their functionalities as optical reflectors are investigated. In our system, polarization-resolved specular reflectance displays strong modulations as a function of incident photon energy and angle. An effective-medium model allows one to rationalize the experimental findings in the long wavelength regime, whereas numerical simulations fully reproduce the experimental outcomes in the entire frequency range. The impact of the refractive index of the medium surrounding the nanostructure assembly on the reflectance was estimated. In view of the present results, sensing schemes compatible with microfluidic technologies and routes to innovative nanowire-based optical elements are discussed.

  5. Phase Diagrams of Electrostatically Self-Assembled Amphiplexes

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-31

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

  6. Thermosensitive Self-Assembling Block Copolymers as Drug Delivery Systems

    Directory of Open Access Journals (Sweden)

    Giovanni Filippo Palmieri

    2011-04-01

    Full Text Available Self-assembling block copolymers (poloxamers, PEG/PLA and PEG/PLGA diblock and triblock copolymers, PEG/polycaprolactone, polyether modified poly(Acrylic Acid with large solubility difference between hydrophilic and hydrophobic moieties have the property of forming temperature dependent micellar aggregates and, after a further temperature increase, of gellifying due to micelle aggregation or packing. This property enables drugs to be mixed in the sol state at room temperature then the solution can be injected into a target tissue, forming a gel depot in-situ at body temperature with the goal of providing drug release control. The presence of micellar structures that give rise to thermoreversible gels, characterized by low toxicity and mucomimetic properties, makes this delivery system capable of solubilizing water-insoluble or poorly soluble drugs and of protecting labile molecules such as proteins and peptide drugs.

  7. Self-Assembled PbSe Nanowire:Perovskite Hybrids

    KAUST Repository

    Yang, Zhenyu

    2015-12-02

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

  8. Electrochromic properties of self-assembled nanoparticle multilayer films

    International Nuclear Information System (INIS)

    Xue Bo; Li Hong; Zhang Lanlan; Peng Jun

    2010-01-01

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

  9. Charged triblock copolymer self-assembly into charged micelles

    Science.gov (United States)

    Chen, Yingchao; Zhang, Ke; Zhu, Jiahua; Wooley, Karen; Pochan, Darrin; Department of Material Science; Engineering University of Delaware Team; Department of Chemistry Texas A&M University Collaboration

    2011-03-01

    Micelles were formed through the self-assembly of amphiphlic block copolymer poly(acrylic acid)-block-poly(methyl acrylate)-block-polystyrene (PAA-PMA-PS). ~Importantly, the polymer is complexed with diamine molecules in pure THF solution prior to water titration solvent processing-a critical aspect in the control of final micelle geometry. The addition of diamine triggers acid-base complexation ~between the carboxylic acid PAA side chains and amines. ~Remarkably uniform spheres were found to form close-packed patterns when forced into dried films and thin, solvated films when an excess of amine was used in the polymer assembly process. Surface properties and structural features of these hexagonal-packed spherical micelles with charged corona have been explored by various characterization methods including Transmission Electron Microscopy (TEM), cryogenic TEM, z-potential analysis and Dynamic Light Scattering. The forming mechanism for this pattern and morphology changes against external stimulate such as salt will be discussed.

  10. Communication: Programmable self-assembly of thin-shell mesostructures

    Science.gov (United States)

    Halverson, Jonathan D.; Tkachenko, Alexei V.

    2017-10-01

    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.

  11. Engineering self-assembled bioreactors from protein microcompartments

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-10-12

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

  12. Dynamic simulations of many-body electrostatic self-assembly

    Science.gov (United States)

    Lindgren, Eric B.; Stamm, Benjamin; Maday, Yvon; Besley, Elena; Stace, A. J.

    2018-03-01

    Two experimental studies relating to electrostatic self-assembly have been the subject of dynamic computer simulations, where the consequences of changing the charge and the dielectric constant of the materials concerned have been explored. One series of calculations relates to experiments on the assembly of polymer particles that have been subjected to tribocharging and the simulations successfully reproduce many of the observed patterns of behaviour. A second study explores events observed following collisions between single particles and small clusters composed of charged particles derived from a metal oxide composite. As before, observations recorded during the course of the experiments are reproduced by the calculations. One study in particular reveals how particle polarizability can influence the assembly process. This article is part of the theme issue `Modern theoretical chemistry'.

  13. The Relationship between Self-Assembly and Conformal Mappings

    Science.gov (United States)

    Duque, Carlos; Santangelo, Christian

    The isotropic growth of a thin sheet has been used as a way to generate programmed shapes through controlled buckling. We discuss how conformal mappings, which are transformations that locally preserve angles, provide a way to quantify the area growth needed to produce a particular shape. A discrete version of the conformal map can be constructed from circle packings, which are maps between packings of circles whose contact network is preserved. This provides a link to the self-assembly of particles on curved surfaces. We performed simulations of attractive particles on a curved surface using molecular dynamics. The resulting particle configurations were used to generate the corresponding discrete conformal map, allowing us to quantify the degree of area distortion required to produce a particular shape by finding particle configurations that minimize the area distortion.

  14. Bioactive self-assembled peptide nanofibers for corneal stroma regeneration.

    Science.gov (United States)

    Uzunalli, G; Soran, Z; Erkal, T S; Dagdas, Y S; Dinc, E; Hondur, A M; Bilgihan, K; Aydin, B; Guler, M O; Tekinay, A B

    2014-03-01

    Defects in the corneal stroma caused by trauma or diseases such as macular corneal dystrophy and keratoconus can be detrimental for vision. Development of therapeutic methods to enhance corneal regeneration is essential for treatment of these defects. This paper describes a bioactive peptide nanofiber scaffold system for corneal tissue regeneration. These nanofibers are formed by self-assembling peptide amphiphile molecules containing laminin and fibronectin inspired sequences. Human corneal keratocyte cells cultured on laminin-mimetic peptide nanofibers retained their characteristic morphology, and their proliferation was enhanced compared with cells cultured on fibronectin-mimetic nanofibers. When these nanofibers were used for damaged rabbit corneas, laminin-mimetic peptide nanofibers increased keratocyte migration and supported stroma regeneration. These results suggest that laminin-mimetic peptide nanofibers provide a promising injectable, synthetic scaffold system for cornea stroma regeneration. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  15. Infrared spectroscopy of self-assembled monolayer films on silicon

    Science.gov (United States)

    Rowell, N. L.; Tay, Lilin; Boukherroub, R.; Lockwood, D. J.

    2007-07-01

    Infrared vibrational spectroscopy in an attenuated total reflection (ATR) geometry has been employed to investigate the presence of organic thin layers on Si-wafer surfaces. The phenomena have been simulated to show there can be a field enhancement with the presented single-reflection ATR (SR-ATR) approach which is substantially larger than for conventional ATR or specular reflection. In SR-ATR, a discontinuity of the field normal to the film contributes a field enhancement in the lower index thin film causing a two order of magnitude increase in sensitivity. SR-ATR was employed to characterize a single monolayer of undecylenic acid self-assembled on Si(1 1 1) and to investigate a two monolayer system obtained by adding a monolayer of bovine serum albumin protein.

  16. Self-assembled tunable photonic hyper-crystals.

    Science.gov (United States)

    Smolyaninova, Vera N; Yost, Bradley; Lahneman, David; Narimanov, Evgenii E; Smolyaninov, Igor I

    2014-07-16

    We demonstrate a novel artificial optical material, the "photonic hyper-crystal", which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing.

  17. Controlled doping by self-assembled dendrimer-like macromolecules

    Science.gov (United States)

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

    2017-02-01

    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.

  18. Graphene growth by conversion of aromatic self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Turchanin, Andrey [Institute of Physical Chemistry, Friedrich Schiller University Jena (Germany); Jena Center for Soft Matter (JCSM), Jena (Germany); Center for Energy and Environmental Chemistry Jena (CEEC), Jena (Germany); Abbe Center of Photonics (ACP), Jena (Germany)

    2017-11-15

    Despite present diversity of graphene production methods there is still a high demand for improvement of the existing production schemes or development of new. Here a method is reviewed to produce graphene employing aromatic self-assembled monolayers (SAMs) as molecular precursors. This method is based on electron irradiation induced crosslinking of aromatic SAMs resulting in their conversion into carbon nanomembranes (CNMs) with high thermal stability and subsequent pyrolysis of CNMs into graphene in vacuum or in the inert atmosphere. Depending on the production conditions, such as chemical structure of molecular precursors, irradiation and annealing parameters, various properties of the produced graphene sheets including shape, crystallinity, thickness, optical properties and electric transport can be adjusted. The assembly of CNM/graphene van der Waals heterostructures opens a flexible route to non-destructive chemical functionalization of graphene for a variety of applications in electronic and photonic devices. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Science.gov (United States)

    Huang, Wei-Han

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

  20. Characterization of manganese tetraarylthiosubstituted phthalocyanines self assembled monolayers

    International Nuclear Information System (INIS)

    Matemadombo, Fungisai; Durmus, Mahmut; Togo, Chamunorwa; Limson, Janice; Nyokong, Tebello

    2009-01-01

    Manganese tetraarylthiosubstituted phthalocyanines (complexes 1-5) have been deposited on Au electrode surfaces through the self assembled monolayer (SAM) technique. SAM characteristics reported in this work are: ion barrier factor (∼1); interfacial capacitance (303-539 μF cm -2 ) and surface coverage (1.06 x 10 -10 -2.80 x 10 -10 mol cm -2 ). Atomic force microscopy was employed in characterizing a SAM. SAMs of complexes 1-5 were employed to detect L-cysteine (with limit of detection ranging from 2.83 x 10 -7 to 3.14 x 10 -7 M at potentials of 0.68-0.75 V vs. Ag|AgCl) and nitrite (limit of detection ranging from 1.78 x 10 -7 to 3.02 x 10 -7 M at potentials of 0.69-0.76 V vs. Ag|AgCl).

  1. Bioengineering towards self-assembly of particulate vaccines.

    Science.gov (United States)

    Rehm, Bernd H A

    2017-12-01

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

  2. Mechanical properties of polyelectrolyte multilayer self-assembled films

    International Nuclear Information System (INIS)

    Dai Xinhua; Zhang Yongjun; Guan Ying; Yang Shuguang; Xu Jian

    2005-01-01

    The mechanical properties of electrostatic self-assembled multilayer films from polyacrylic acid (PAA) and C 60 -ethylenediamine adduct (C 60 -EDA) or poly(allylamine hydrochloride) (PAH) were evaluated by atomic force microscopy (AFM) wear experiments. Because of the higher molecular weight of PAH, the wear resistance of the (PAH/PAA) 10 film is higher than that of the (PAH/PAA) 2 (C 60 -EDA/PAA) 8 film; that is, the former is mechanically more stable than the latter. The mechanical stability of both films can be improved significantly by heat treatment, which changes the nature of the linkage from ionic to covalent. The AFM measurement also reveals that the (PAH/PAA) 2 (C 60 -EDA/PAA) 8 film is softer than the (PAH/PAA) 10 film. The friction properties of the heated films were measured. These films can be developed as potential lubrication coatings for microelectromechanical systems

  3. Functional Molecular Junctions Derived from Double Self-Assembled Monolayers.

    Science.gov (United States)

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

    2017-09-25

    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.

  4. Self-Assembled PbSe Nanowire:Perovskite Hybrids

    KAUST Repository

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

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-11-01

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

  6. Self-assembling hybrid diamond–biological quantum devices

    International Nuclear Information System (INIS)

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

    2014-01-01

    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. (papers)

  7. Self-assembling hybrid diamond-biological quantum devices

    Science.gov (United States)

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

    2014-09-01

    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.

  8. Guided self-assembly of nanostructured titanium oxide

    International Nuclear Information System (INIS)

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

    2012-01-01

    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 TiO x nanowires or smooth nanorods, and the molar ratio of TBT:EG determines which of these is obtained. Therefore, TiO x 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, TiO x 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 TiO x nanorods with rough surfaces are formed by the self-assembly of TiO x 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 TiO x nanorods shows stronger ER properties than that of the other nanostructured TiO x 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. (paper)

  9. 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: danisman@metu.edu.tr [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)

    2017-08-15

    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.

  10. Guided self-assembly of nanostructured titanium oxide

    Science.gov (United States)

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

    2012-02-01

    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.

  11. Self-Assembly and Crystallization of Conjugated Block Copolymers

    Science.gov (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

  12. Construction of energy transfer pathways self-assembled from DNA-templated stacks of anthracene.

    Science.gov (United States)

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

    2014-01-05

    We describe optical properties of anthracene stacks formed from single-component self-assembly of thymidylic acid-appended anthracene 2,6-bis[5-(3'-thymidylic acid)pentyloxy] anthracene (TACT) and the binary self-assembly of TACT and complementary 20-meric oligoadenylic acid (TACT/dA20) in an aqueous buffer. UV-Vis and emission spectra for the single-component self-assembly of TACT and the binary self-assembly of TACT/dA20 were very consistent with stacked acene moieties in both self-assemblies. Interestingly, time-resolved fluorescence spectra from anthracene stacks exhibited very different features of the single-component and binary self-assemblies. In the single-component self-assembly of TACT, a dynamic Stokes shift (DSS) and relatively short fluorescence lifetime (τ=0.35ns) observed at around 450nm suggested that the anthracene moieties were flexible. Moreover, a broad emission at 530nm suggested the formation of an excited dimer (excimer). In the binary self-assembly of TACT/dA20, we detected a broad, red-shifted emission component at 534nm with a lifetime (τ=0.4ns) shorter than that observed in the TACT single-component self-assembly. Combining these results with the emission spectrum of the binary self-assembly of TACT/5'-HEX dA20, we concluded that the energy transfer pathway was constructed by columnar anthracene stacks formed from the DNA-templated self-assembly of TACT. Copyright © 2013 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2016-09-14

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

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

    Science.gov (United States)

    Vincent, Bernadette Bensaude

    2016-09-01

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

  15. Vortex pinning in superconductors laterally modulated by nanoscale self-assembled arrays

    DEFF Research Database (Denmark)

    Vanacken, J.; Vinckx, W.; Moshchalkov, V.V.

    2008-01-01

    Being the exponent of the so-called "bottom-up" approach, self-assembled structures are now-a-days attracting a lot of attention in the fields of science and technology. In this work, we show that nanoscale self-assembled arrays used as templates can provide periodic modulation in superconducting...

  16. Bio-inspired supramolecular materials by orthogonal self-assembly of hydrogelators and phospholipids

    NARCIS (Netherlands)

    Boekhoven, J.; Brizard, AMA; Stuart, M. C A; Florusse, L.J.; Raffy, G.; Del Guerzo, A.; van Esch, J.H.

    2016-01-01

    The orthogonal self-assembly of multiple components is a powerful strategy towards the formation of complex biomimetic architectures, but so far the rules for designing such systems are unclear. Here we show how to identify orthogonal self-assembly at the supramolecular level and describe

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

    NARCIS (Netherlands)

    de Nijs, B.

    2014-01-01

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

  18. Self-Assembly of Colloidal Spheres into One, Two, and Three Dimensional Structures

    NARCIS (Netherlands)

    Guo, Y.

    2017-01-01

    The main goal of this thesis is to increase our understanding of colloidal self-assembly processes and develop new strategies to assemble colloidal building blocks into more sophisticated and well-defined super-structures. Self-assembly is a spontaneous process in which a disordered system of

  19. A self-assembled monolayer-assisted surface microfabrication and release technique

    NARCIS (Netherlands)

    Kim, B.J.; Liebau, M.; Huskens, Jurriaan; Reinhoudt, David; Brugger, J.P.

    2001-01-01

    This paper describes a method of thin film and MEMS processing which uses self-assembled monolayers as ultra-thin organic surface coating to enable a simple removal of microfabricated devices off the surface without wet chemical etching. A 1.5-nm thick self-assembled monolayer of

  20. Simulating three dimensional self-assembly of shape modified particles using magnetic dipolar forces

    NARCIS (Netherlands)

    Alink, Laurens; Marsman, G.H. (Mathijs); Woldering, L.A.; Abelmann, Leon

    2011-01-01

    The feasibility of 3D self-assembly of milli-magnetic particles that interact via magnetic dipolar forces is investigated. Typically magnetic particles, such as isotropic spheres, self-organize in stable 2D configurations. By modifying the shape of the particles, 3D self-assembly may be enabled. The

  1. Three-dimensional visualization and characterization of polymeric self-assemblies by Transmission Electron Microtomography

    NARCIS (Netherlands)

    H. Jinnai (Hiroshi); T. Higuchi (Takeshi); X. Zhuge (Jason); A. Kumamoto (Akihito); K.J. Batenburg (Joost); Y. Ikuhara (Yuichi)

    2017-01-01

    textabstractSelf-assembling structures and their dynamical processes in polymeric systems have been investigated using three-dimensional transmission electron microscopy (3D-TEM). Block copolymers (BCPs) self-assemble into nanoscale periodic structures called microphase-separated structures, a deep

  2. Synthesis of nanocrystals and nanocrystal self-assembly

    Science.gov (United States)

    Chen, Zhuoying

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

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

    Science.gov (United States)

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

    2013-12-01

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

  4. 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)

    2016-03-30

    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.

  5. Self-Assembly of Protein Nanostructures to Enhance Biosensor Sensitivity

    Science.gov (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).

  6. Self-assembling bubble carriers for oral protein delivery.

    Science.gov (United States)

    Chuang, Er-Yuan; Lin, Kun-Ju; Lin, Po-Yen; Chen, Hsin-Lung; Wey, Shiaw-Pyng; Mi, Fwu-Long; Hsiao, Hsu-Chan; Chen, Chiung-Tong; Sung, Hsing-Wen

    2015-09-01

    Successful oral delivery of therapeutic proteins such as insulin can greatly improve the quality of life of patients. This study develops a bubble carrier system by loading diethylene triamine pentaacetic acid (DTPA) dianhydride, a foaming agent (sodium bicarbonate; SBC), a surfactant (sodium dodecyl sulfate; SDS), and a protein drug (insulin) in an enteric-coated gelatin capsule. Following oral administration to diabetic rats, the intestinal fluid that has passed through the gelatin capsule saturates the mixture; concomitantly, DTPA dianhydride produces an acidic environment, while SBC decomposes to form CO2 bubbles at acidic pH. The gas bubbles grow among the surfactant molecules (SDS) owing to the expansion of the generated CO2. The walls of the CO2 bubbles consist of a self-assembled film of water that is in nanoscale and may serve as a colloidal carrier to transport insulin and DTPA. The grown gas bubbles continue to expand until they bump into the wall and burst, releasing their transported insulin, DTPA, and SDS into the mucosal layer. The released DTPA and SDS function as protease inhibitors to protect the insulin molecules as well as absorption enhancers to augment their epithelial permeability and eventual absorption into systemic circulation, exerting their hypoglycemic effects. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Percolation Diffusion into Self-Assembled Mesoporous Silica Microfibres

    Directory of Open Access Journals (Sweden)

    John Canning

    2014-03-01

    Full Text Available Percolation diffusion into long (11.5 cm self-assembled, ordered mesoporous microfibres is studied using optical transmission and laser ablation inductive coupled mass spectrometry (LA-ICP-MS. Optical transmission based diffusion studies reveal rapid penetration (<5 s, D > 80 μm2∙s−1 of Rhodamine B with very little percolation of larger molecules such as zinc tetraphenylporphyrin (ZnTPP observed under similar loading conditions. The failure of ZnTPP to enter the microfibre was confirmed, in higher resolution, using LA-ICP-MS. In the latter case, LA-ICP-MS was used to determine the diffusion of zinc acetate dihydrate, D~3 × 10−4 nm2∙s−1. The large differences between the molecules are accounted for by proposing ordered solvent and structure assisted accelerated diffusion of the Rhodamine B based on its hydrophilicity relative to the zinc compounds. The broader implications and applications for filtration, molecular sieves and a range of devices and uses are described.

  8. Nanoscale isoindigo-carriers: self-assembly and tunable properties

    Directory of Open Access Journals (Sweden)

    Tatiana N. Pashirova

    2017-02-01

    Full Text Available Over the last decade isoindigo derivatives have attracted much attention due to their high potential in pharmacy and in the chemistry of materials. In addition, isoindigo derivatives can be modified to form supramolecular structures with tunable morphologies for the use in drug delivery. Amphiphilic long-chain dialkylated isoindigos have the ability to form stable solid nanoparticles via a simple nanoprecipitation technique. Their self-assembly was investigated using tensiometry, dynamic light scattering, spectrophotometry, and fluorometry. The critical association concentrations and aggregate sizes were measured. The hydrophilic–lipophilic balance of alkylated isoindigo derivatives strongly influences aggregate morphology. In the case of short-chain dialkylated isoindigo derivatives, supramolecular polymers of 200 to 700 nm were formed. For long-chain dialkylated isoindigo derivatives, micellar aggregates of 100 to 200 nm were observed. Using micellar surfactant water-soluble forms of monosubstituted 1-hexadecylisoindigo as well as 1,1′-dimethylisoindigo were prepared for the first time. The formation of mixed micellar structures of different types in micellar anionic surfactant solutions (sodium dodecyl sulfate was determined. These findings are of practical importance and are of potential interest for the design of drug delivery systems and new nanomaterials.

  9. Supercapacitors based on self-assembled graphene organogel.

    Science.gov (United States)

    Sun, Yiqing; Wu, Qiong; Shi, Gaoquan

    2011-10-14

    Self-assembled graphene organogel (SGO) with 3-dimensional (3D) macrostructure was prepared by solvothermal reduction of a graphene oxide (GO) dispersion in propylene carbonate (PC). This SGO was used as an electrode material for fabricating supercapacitors with a PC electrolyte. The supercapacitor can be operated in a wide voltage range of 0-3 V and exhibits a high specific capacitance of 140 F g(-1) at a discharge current density of 1 A g(-1). Furthermore, it can still keep a specific capacitance of 90 F g(-1) at a high current density of 30 A g(-1). The maximum energy density of the SGO based supercapacitor was tested to be 43.5 Wh kg(-1), and this value is higher than those of the graphene based supercapacitors with aqueous or PC electrolytes reported previously. Furthermore, at a high discharge current density of 30 A g(-1), the energy and power densities of the supercapacitor were measured to be 15.4 Wh kg(-1) and 16,300 W kg(-1), respectively. These results indicate that the supercapacitor has a high specific capacitance and power density, and excellent rate capability.

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

    Science.gov (United States)

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

    2016-06-01

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

  11. Fatigue crack propagation in self-assembling nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Klingler, Andreas; Wetzel, Bernd [Institute for Composite Materials (IVW GmbH) Technical University of Kaiserslautern, 67633 Kaiserslautern (Germany)

    2016-05-18

    Self-assembling block-copolymers allow the easy manufacturing of nanocomposites due to the thermodynamically driven in situ formation of nanosized phases in thermosetting resins during the curing process. Complex mechanical dispersion processes can be avoided. The current study investigates the effect of a block-copolymer on the fatigue crack propagation resistance of a cycloaliphatic amine cured epoxy resin. It was found that a small amount of MAM triblock-copolymer significantly increases the resistance to fatigue crack propagation of epoxy. Crack growth rate and the Paris law exponent for fatigue-crack growth were considerably reduced from m=15.5 of the neat epoxy to m=8.1 of the nanocomposite. To identify the related reinforcing and fracture mechanisms structural analyses of the fractured surfaces were performed by scanning electron microscope. Characteristic features were identified to be deformation, debonding and fracture of the nano-phases as well as crack pinning. However, the highest resistance against fatigue crack propagation was achieved in a bi-continuous microstructure that consisted of an epoxy-rich phase with embedded submicron sized MAM inclusions, and which was surrounded by a block-copolymer-rich phase that showed rupture and plastic deformation.

  12. Templated Biomineralization on Self-Assembled Protein Fibers

    Energy Technology Data Exchange (ETDEWEB)

    Subburaman,K.; Pernodet, N.; Kwak, S.; DiMasi, E.; Ge, S.; Zaitsev, V.; Ba, X.; Yang, N.; Rafailovich, M.

    2006-01-01

    Biological mineralization of tissues in living organisms relies on proteins that preferentially nucleate minerals and control their growth. This process is often referred to as 'templating', but this term has become generic, denoting various proposed mineral-organic interactions including both chemical and structural affinities. Here, we present an approach using self-assembled networks of elastin and fibronectin fibers, similar to the extracellular matrix. When induced onto negatively charged sulfonated polystyrene surfaces, these proteins form fiber networks of {approx}10-{mu}m spacing, leaving open regions of disorganized protein between them. We introduce an atomic force microscopy-based technique to measure the elastic modulus of both structured and disorganized protein before and during calcium carbonate mineralization. Mineral-induced thickening and stiffening of the protein fibers during early stages of mineralization is clearly demonstrated, well before discrete mineral crystals are large enough to image by atomic force microscopy. Calcium carbonate stiffens the protein fibers selectively without affecting the regions between them, emphasizing interactions between the mineral and the organized protein fibers. Late-stage observations by optical microscopy and secondary ion mass spectroscopy reveal that Ca is concentrated along the protein fibers and that crystals form preferentially on the fiber crossings. We demonstrate that organized versus unstructured proteins can be assembled mere nanometers apart and probed in identical environments, where mineralization is proved to require the structural organization imposed by fibrillogenesis of the extracellular matrix.

  13. Modeling the self-assembly of ordered nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Monson, Peter [Univ. of Massachusetts, Amherst, MA (United States); Auerbach, Scott [Univ. of Massachusetts, Amherst, MA (United States)

    2017-11-13

    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.

  14. Proton electroinsertion in self-assembled materials for neutralization pseudocapacitors.

    Science.gov (United States)

    Facci, Tiago; Gomes, Wellington J A S; Bravin, Bruno; Araújo, Diógenes M; Huguenin, Fritz

    2014-01-14

    We propose novel pseudocapacitors that can store energy related to the partial entropy change associated with proton concentration variations following neutralization reactions. In this situation, it is possible to obtain electrochemical energy after the complete charge/discharge cycle conducted in electrolytic solutions with different proton concentrations. To this end, we prepared modified electrodes from phosphomolybdic acid (PMA), poly(3,4-ethylenedioxythiophene/poly(styrenesulfonate) (PEDOT-PSS), and polyallylamine (PAH) by the layer-by-layer (LbL) method and investigated their electrochemical behavior, aiming to use them in these neutralization pseudocapacitors. We analyzed the potentiodynamic profile of the current density at several scan rates, to evaluate the reversibility of the proton electroinsertion process, which is crucial to maximum energy storage efficiency. On the basis of the proposed reaction mechanism and by using frequency-domain measurements and models, we determined rate constants at different potentials. Our results demonstrated that the conducting polymer affects the self-assembled matrixes, ensuring that energy storage is high (22.5 kJ mol(-1)). The process involved neutralization of a hydrochloric acid solution from pH = 1 to pH = 6, which corresponds to 40% of the neutralization enthalpy.

  15. Energy Landscapes for the Self-Assembly of Supramolecular Polyhedra

    Science.gov (United States)

    Russell, Emily R.; Menon, Govind

    2016-06-01

    We develop a mathematical model for the energy landscape of polyhedral supramolecular cages recently synthesized by self-assembly (Sun et al. in Science 328:1144-1147, 2010). Our model includes two essential features of the experiment: (1) geometry of the organic ligands and metallic ions; and (2) combinatorics. The molecular geometry is used to introduce an energy that favors square-planar vertices (modeling {Pd}^{2+} ions) and bent edges with one of two preferred opening angles (modeling boomerang-shaped ligands of two types). The combinatorics of the model involve two-colorings of edges of polyhedra with four-valent vertices. The set of such two-colorings, quotiented by the octahedral symmetry group, has a natural graph structure and is called the combinatorial configuration space. The energy landscape of our model is the energy of each state in the combinatorial configuration space. The challenge in the computation of the energy landscape is a combinatorial explosion in the number of two-colorings of edges. We describe sampling methods based on the symmetries of the configurations and connectivity of the configuration graph. When the two preferred opening angles encompass the geometrically ideal angle, the energy landscape exhibits a very low-energy minimum for the most symmetric configuration at equal mixing of the two angles, even when the average opening angle does not match the ideal angle.

  16. Silica biomineralization via the self-assembly of helical biomolecules.

    Science.gov (United States)

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

    2015-01-21

    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.

  17. Fatigue crack propagation in self-assembling nanocomposites

    Science.gov (United States)

    Klingler, Andreas; Wetzel, Bernd

    2016-05-01

    Self-assembling block-copolymers allow the easy manufacturing of nanocomposites due to the thermodynamically driven in situ formation of nanosized phases in thermosetting resins during the curing process. Complex mechanical dispersion processes can be avoided. The current study investigates the effect of a block-copolymer on the fatigue crack propagation resistance of a cycloaliphatic amine cured epoxy resin. It was found that a small amount of MAM triblock-copolymer significantly increases the resistance to fatigue crack propagation of epoxy. Crack growth rate and the Paris law exponent for fatigue-crack growth were considerably reduced from m=15.5 of the neat epoxy to m=8.1 of the nanocomposite. To identify the related reinforcing and fracture mechanisms structural analyses of the fractured surfaces were performed by scanning electron microscope. Characteristic features were identified to be deformation, debonding and fracture of the nano-phases as well as crack pinning. However, the highest resistance against fatigue crack propagation was achieved in a bi-continuous microstructure that consisted of an epoxy-rich phase with embedded submicron sized MAM inclusions, and which was surrounded by a block-copolymer-rich phase that showed rupture and plastic deformation.

  18. Fatigue crack propagation in self-assembling nanocomposites

    International Nuclear Information System (INIS)

    Klingler, Andreas; Wetzel, Bernd

    2016-01-01

    Self-assembling block-copolymers allow the easy manufacturing of nanocomposites due to the thermodynamically driven in situ formation of nanosized phases in thermosetting resins during the curing process. Complex mechanical dispersion processes can be avoided. The current study investigates the effect of a block-copolymer on the fatigue crack propagation resistance of a cycloaliphatic amine cured epoxy resin. It was found that a small amount of MAM triblock-copolymer significantly increases the resistance to fatigue crack propagation of epoxy. Crack growth rate and the Paris law exponent for fatigue-crack growth were considerably reduced from m=15.5 of the neat epoxy to m=8.1 of the nanocomposite. To identify the related reinforcing and fracture mechanisms structural analyses of the fractured surfaces were performed by scanning electron microscope. Characteristic features were identified to be deformation, debonding and fracture of the nano-phases as well as crack pinning. However, the highest resistance against fatigue crack propagation was achieved in a bi-continuous microstructure that consisted of an epoxy-rich phase with embedded submicron sized MAM inclusions, and which was surrounded by a block-copolymer-rich phase that showed rupture and plastic deformation.

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

    KAUST Repository

    Al-Rehili, Safa’a

    2016-10-24

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

  20. Lipid dip-pen nanolithography on self-assembled monolayers

    International Nuclear Information System (INIS)

    Gavutis, Martynas; Navikas, Vytautas; Rakickas, Tomas; Vaitekonis, Šarūnas; Valiokas, Ramūnas

    2016-01-01

    Dip-pen nanolithography (DPN) with lipids as an ink enables functional micro/nanopatterning on different substrates at high process speeds. However, only a few studies have addressed the influence of the physicochemical properties of the surface on the structure and phase behavior of DPN-printed lipid assemblies. Therefore, by combining the scanning probe and optical imaging techniques in this work we have analyzed lipid microdomain formation on the self-assembled monolayers (SAMs) on gold as well-defined model surfaces that displayed hydrophilic (protein-repellent) or hydrophobic (protein-adhesive) characteristics. We have found that on the tri(ethylene glycol)-terminated SAM the lipid ink transfer was fast (∼10 –1 μm 3 s −1 ), quasi-linear and it yielded unstable, sparsely packed lipid microspots. Contrary to this, on the methyl-terminated SAM the lipid transfer was ∼20 times slower, nonlinear, and the obtained stable dots of ∼1 μm in diameter consisted of lipid multilayers. Our comparative analysis indicated that the measured lipid transfer was consistent with the previously reported so-called polymer transfer model (Felts et al 2012, Nanotechnology 23 215301). Further on, by employing the observed distinct contrast in the DPN ink behavior we constructed confined lipid microdomains on pre-patterned SAMs, in which the lipids assembled either into monolayer or multilamellar phases. Such microdomains can be further utilized for lipid membrane mimetics in microarray and lab-on-a-chip device formats. (paper)

  1. Magnetic Actuation of Self-assembled Bacteria Inspired Nanoswimmers

    Science.gov (United States)

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

    2017-11-01

    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.

  2. Random lasing actions in self-assembled perovskite nanoparticles

    Science.gov (United States)

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

    2016-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-17

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

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

    Science.gov (United States)

    Ma, Hongmin; Hao, Jingcheng

    2011-11-01

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

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

    Science.gov (United States)

    Thomas, Marcus; Schwartz, Russell

    2017-05-23

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

  6. Balancing the intermolecular forces in peptide amphiphiles for controlling self-assembly transitions.

    Science.gov (United States)

    Buettner, C J; Wallace, A J; Ok, S; Manos, A A; Nicholl, M J; Ghosh, A; Tweedle, M F; Goldberger, J E

    2017-06-21

    While the influence of alkyl chain length and headgroup size on self-assembly behaviour has been well-established for simple surfactants, the rational control over the pH- and concentration-dependent self-assembly behaviour in stimuli responsive peptides remains an elusive goal. Here, we show that different amphiphilic peptides can have similar self-assembly phase diagrams, providing the relative strengths of the attractive and repulsive forces are balanced. Using palmitoyl-YYAAEEEEK(DO3A:Gd)-NH 2 and palmitoyl-YAAEEEEK(DO3A:Gd)-NH 2 as controls, we show that reducing hydrophobic attractive forces through fewer methylene groups in the alkyl chain will lead to a similar self-assembly phase diagram as increasing the electrostatic repulsive forces via the addition of a glutamic acid residue. These changes allow creation of self-assembled MRI vehicles with slightly different micelle and nanofiber diameters but with minimal changes in the spin-lattice T 1 relaxivity. These findings reveal a powerful strategy to design self-assembled vehicles with different sizes but with similar self-assembly profiles.

  7. Self-assembly as a design tool for the integration of photonic structures into excitonic solar cells

    KAUST Repository

    Guldin, S.; Docampo, P.; Hü ttner, S.; Kohn, P.; Stefik, M.; Snaith, H. J.; Wiesner, U.; Steiner, U.

    2011-01-01

    ) into dye-sensitized solar cells (DSCs). In both cases, the self-assembly of soft matter plays a key role in the fabrication process of the TiO2 electrode. One approach relies on a combination of colloidal self-assembly and the self-assembly of block

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

    DEFF Research Database (Denmark)

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

    2011-01-01

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

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

    KAUST Repository

    Haataja, J. S.

    2018-01-09

    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.

  10. Classification of coordination polygons and polyhedra according to their mode of self-assembly.

    Science.gov (United States)

    Swiegers, G F; Malefetse, T J

    2001-09-03

    This work extends techniques for the controlled formation of synthetic molecular containers by metal-mediated self-assembly. A new classification system based on the self-assembly of such species is proposed. The system: 1) allows a systematic identification of suitable acceptor-donor combinations, 2) widens the variety of design possibilities available, 3) allows a ready comparison of the self-assembly of different compounds, 4) reveals useful commonalities between different compounds, 5) aids in the development of novel architectures, and 6) permits identification of systems capable of being switched back-and-forth between architectures.

  11. Self-assembly kinetics of microscale components: A parametric evaluation

    Science.gov (United States)

    Carballo, Jose M.

    The goal of the present work is to develop, and evaluate a parametric model of a basic microscale Self-Assembly (SA) interaction that provides scaling predictions of process rates as a function of key process variables. At the microscale, assembly by "grasp and release" is generally challenging. Recent research efforts have proposed adapting nanoscale self-assembly (SA) processes to the microscale. SA offers the potential for reduced equipment cost and increased throughput by harnessing attractive forces (most commonly, capillary) to spontaneously assemble components. However, there are challenges for implementing microscale SA as a commercial process. The existing lack of design tools prevents simple process optimization. Previous efforts have characterized a specific aspect of the SA process. However, the existing microscale SA models do not characterize the inter-component interactions. All existing models have simplified the outcome of SA interactions as an experimentally-derived value specific to a particular configuration, instead of evaluating it outcome as a function of component level parameters (such as speed, geometry, bonding energy and direction). The present study parameterizes the outcome of interactions, and evaluates the effect of key parameters. The present work closes the gap between existing microscale SA models to add a key piece towards a complete design tool for general microscale SA process modeling. First, this work proposes a simple model for defining the probability of assembly of basic SA interactions. A basic SA interaction is defined as the event where a single part arrives on an assembly site. The model describes the probability of assembly as a function of kinetic energy, binding energy, orientation and incidence angle for the component and the assembly site. Secondly, an experimental SA system was designed, and implemented to create individual SA interactions while controlling process parameters independently. SA experiments

  12. Self-assembled electrical materials from contorted aromatics

    Science.gov (United States)

    Xiao, Shengxiong

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

  13. Spin Properties of Transition-Metallorganic Self-Assembled Molecules

    International Nuclear Information System (INIS)

    Yu, Zhi Gang

    2010-01-01

    This report summarizes SRI's accomplishments on the project, 'Spin Properties of Transition-Metallorganic Self-Assembled Molecules' funded by the Office of Basic Energy Sciences, US Department of Energy. We have successfully carried out all tasks identified in our proposal and gained significant knowledge and understanding of spin-polarized electronic structure, spin relaxation, and spin-dependent transport in transition-metallorganic molecules and enhohedral fullerenes. These molecules contain integrated spin and charge components and will enable us to achieve sophisticated functions in spintronics and quantum computing at molecular level with simple circuitry and easy fabrication. We have developed microscopic theories that describe the underlying mechanisms of spin-dependent porcesses and constructed quantitative modeling tools that compute several important spin properties. These results represent the basic principles governing the spin-dependent behaviors in nanostructures containing such molecules. Based on these results we have shown that novel device functions, such as electrically controlled g-factor and noninvasive electrical detection of spin dynamics, can be achieved in these nanostructures. Some of our results have been published in peer-reviewed journals and presented at professional conferences. In addition, we have established a close collaboration with experimentalists at Oxford University, UK (Dr. J. Morton and Prof. G. Briggs), Princeton University (Dr. A. Tyryshkin and Prof. S. Lyon), University of Delaware (Prof. E. Nowak), and University of California (Profs. R. Kawakami and J. Shi), who have been studying related systems and supplying us with new experimental data. We have provided our understanding and physical insights to the experimentalists and helped analyze their experimental measurements. The collaboration with experimentalists has also broadened our research scope and helped us focus on the most relevant issues concerning these

  14. Spin Properties of Transition-Metallorganic Self-Assembled Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Zhi Gang Yu

    2010-06-30

    This report summarizes SRI's accomplishments on the project, 'Spin Properties of Transition-Metallorganic Self-Assembled Molecules' funded by the Office of Basic Energy Sciences, US Department of Energy. We have successfully carried out all tasks identified in our proposal and gained significant knowledge and understanding of spin-polarized electronic structure, spin relaxation, and spin-dependent transport in transition-metallorganic molecules and enhohedral fullerenes. These molecules contain integrated spin and charge components and will enable us to achieve sophisticated functions in spintronics and quantum computing at molecular level with simple circuitry and easy fabrication. We have developed microscopic theories that describe the underlying mechanisms of spin-dependent porcesses and constructed quantitative modeling tools that compute several important spin properties. These results represent the basic principles governing the spin-dependent behaviors in nanostructures containing such molecules. Based on these results we have shown that novel device functions, such as electrically controlled g-factor and noninvasive electrical detection of spin dynamics, can be achieved in these nanostructures. Some of our results have been published in peer-reviewed journals and presented at professional conferences. In addition, we have established a close collaboration with experimentalists at Oxford University, UK (Dr. J. Morton and Prof. G. Briggs), Princeton University (Dr. A. Tyryshkin and Prof. S. Lyon), University of Delaware (Prof. E. Nowak), and University of California (Profs. R. Kawakami and J. Shi), who have been studying related systems and supplying us with new experimental data. We have provided our understanding and physical insights to the experimentalists and helped analyze their experimental measurements. The collaboration with experimentalists has also broadened our research scope and helped us focus on the most relevant issues

  15. Measuring excess free energies of self-assembled membrane structures.

    Science.gov (United States)

    Norizoe, Yuki; Daoulas, Kostas Ch; Müller, Marcus

    2010-01-01

    Using computer simulation of a solvent-free, coarse-grained model for amphiphilic membranes, we study the excess free energy of hourglass-shaped connections (i.e., stalks) between two apposed bilayer membranes. In order to calculate the free energy by simulation in the canonical ensemble, we reversibly transfer two apposed bilayers into a configuration with a stalk in three steps. First, we gradually replace the intermolecular interactions by an external, ordering field. The latter is chosen such that the structure of the non-interacting system in this field closely resembles the structure of the original, interacting system in the absence of the external field. The absence of structural changes along this path suggests that it is reversible; a fact which is confirmed by expanded-ensemble simulations. Second, the external, ordering field is changed as to transform the non-interacting system from the apposed bilayer structure to two-bilayers connected by a stalk. The final external field is chosen such that the structure of the non-interacting system resembles the structure of the stalk in the interacting system without a field. On the third branch of the transformation path, we reversibly replace the external, ordering field by non-bonded interactions. Using expanded-ensemble techniques, the free energy change along this reversible path can be obtained with an accuracy of 10(-3)k(B)T per molecule in the n VT-ensemble. Calculating the chemical potential, we obtain the free energy of a stalk in the grandcanonical ensemble, and employing semi-grandcanonical techniques, we calculate the change of the excess free energy upon altering the molecular architecture. This computational strategy can be applied to compute the free energy of self-assembled phases in lipid and copolymer systems, and the excess free energy of defects or interfaces.

  16. Surface Mediated Self-Assembly of Amyloid Peptides

    Science.gov (United States)

    Fakhraai, Zahra

    2015-03-01

    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.

  17. Self-assembly of perylenediimide based semiconductor on polymer substrate

    Energy Technology Data Exchange (ETDEWEB)

    Wiatrowski, Michal, E-mail: Michal.Wiatrowski@p.lodz.p [Department of Molecular Physics, Technical University of Lodz, Zeromskiego 116, 90-924 Lodz (Poland); Dobruchowska, Ewa [Department of Molecular Physics, Technical University of Lodz, Zeromskiego 116, 90-924 Lodz (Poland); Maniukiewicz, Waldemar [Institute of General and Ecological Chemistry, Technical University of Lodz, Zeromskiego 116, 90-924 Lodz (Poland); Pietsch, Ulrich [FB7- Physik , Universitaet Siegen, 57068 Siegen (Germany); Kowalski, Jacek [Division of Non-Metallic Materials, Faculty of Mechanical Engineering, Technical University of Lodz, Stefanowskiego1/15, 90-924 Lodz (Poland); Szamel, Zbigniew; Ulanski, Jacek [Department of Molecular Physics, Technical University of Lodz, Zeromskiego 116, 90-924 Lodz (Poland)

    2010-02-01

    The continuous bi-layer composites consisting of top, ordered crystalline layer of perylenediimide derivative (2,9-di(pent-3-yl)-anthra[,1,9-def:6,5,10-d'e'f'] diisoquinoline-1,3,8,10-tetrone) - PTCDI-C5(3) and bottom poly(3-hexylthiophene-2,5-diyl) (P3HT) support were obtained from one solution, with a use of so called 'two-step reticulate doping' method. Optical, atomic force and scanning electron microscopy images show that the top crystalline layer is made of relatively large, anisotropic domains composed of long, parallel crystals. The crystalline character of the surface layer of PTCDI-C5(3) grown on the P3HT film was confirmed by wide angle X-ray scattering measurements. Furthermore, the grazing-incidence angle X-ray diffraction experiments revealed that the self-assembly of PTCDI-C5(3) molecules on P3HT is dominated by {pi}-{pi} interaction between the conjugated perylene cores, and the stacks are parallel to the long axis of the crystals and to the polymer surface. The surface conductivity, measured along the long axis of the crystals was estimated to be ca. 2.4 10{sup -8} {Omega}{sup -1} square{sup -}1 at 285 K. Temperature dependence of the conductivity in the range 140-285 K reveal semiconductor-like behaviour with activation energy ca. 150 meV.

  18. Evaporation, diffusion and self-assembly at drying interfaces.

    Science.gov (United States)

    Roger, K; Sparr, E; Wennerström, H

    2018-04-18

    Water evaporation from complex aqueous solutions leads to the build-up of structure and composition gradients at their interface with air. We recently introduced an experimental setup for quantitatively studying such gradients and discussed how structure formation can lead to a self-regulation mechanism for controlling water evaporation through self-assembly. Here, we provide a detailed theoretical analysis using an advection/diffusion transport equation that takes into account thermodynamically non-ideal conditions and we directly relate the theoretical description to quantitative experimental data. We derive that the concentration profile develops according to a general square root of time scaling law, which fully agrees with experimental observations. The evaporation rate notably decreases with time as t-1/2, which shows that diffusion in the liquid phase is the rate limiting step for this system, in contrast to pure water evaporation. For the particular binary system that was investigated experimentally, which is composed of water and a sugar-based surfactant (α-dodecylmaltoside), the interfacial layer consists in a sequence of liquid crystalline phases of different mesostructures. We extract values for mutual diffusion coefficients of lamellar, hexagonal and micellar cubic phases, which are consistent with previously reported values and simple models. We thus provide a method to estimate the transport properties of oriented mesophases. The macroscopic humidity-independence of the evaporation rate up to 85% relative humidities is shown to result from both an extremely low mutual diffusion coefficient and the large range of water activities corresponding to relative humidities below 85%, at which the lamellar phase exists. Such a humidity self-regulation mechanism is expected for a large variety of complex system.

  19. Calibration of the Wedge Prism

    Science.gov (United States)

    Charles B. Briscoe

    1957-01-01

    Since the introduction of plotless cruising in this country by Grosenbaugh and the later suggestion of using a wedge prism as an angle gauge by Bruce this method of determining basal area has been widely adopted in the South. One of the factors contributing to the occasionally unsatisfactory results obtained is failure to calibrate the prism used. As noted by Bruce the...

  20. Geometric formula for prism deflection

    Indian Academy of Sciences (India)

    , governs deflections produced by prisms of refractive index n. The refractive power, n − 1, of most materials is of the order of unity for visible light, which therefore gets deflected through several degrees by a prism. X-rays and neutrons however ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-08-12

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

  2. Self-assembled block copolymer membranes: From basic research to large-scale manufacturing

    KAUST Repository

    Nunes, Suzana Pereira; Behzad, Ali Reza; Peinemann, Klaus-Viktor

    2013-01-01

    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

  3. Self Assembly of Ionic Liquids at the Air/Water Interface

    Czech Academy of Sciences Publication Activity Database

    Minofar, Babak

    2015-01-01

    Roč. 3, aug (2015), s. 27-40 ISSN 2245-4551 Institutional support: RVO:67179843 Keywords : Ionic liquids * air/water interface * self assembly * ion-water interaction * ion-ion interaction Subject RIV: CE - Biochemistry

  4. Self-assembling peptide-based building blocks in medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Acar, Handan; Srivastava, Samanvaya; Chung, Eun Ji; Schnorenberg, Mathew R.; Barrett, John C.; LaBelle, James L.; Tirrell, Matthew

    2017-02-01

    Peptides and peptide-conjugates, comprising natural and synthetic building blocks, are an increasingly popular class of biomaterials. Self-assembled nanostructures based on peptides and peptide-conjugates offer advantages such as precise selectivity and multifunctionality that can address challenges and limitations in the clinic. In this review article, we discuss recent developments in the design and self-assembly of various nanomaterials based on peptides and peptide-conjugates for medical applications, and categorize them into two themes based on the driving forces of molecular self-assembly. First, we present the self-assembled nanostructures driven by the supramolecular interactions between the peptides, with or without the presence of conjugates. The studies where nanoassembly is driven by the interactions between the conjugates of peptide-conjugates are then presented. Particular emphasis is given to in vivo studies focusing on therapeutics, diagnostics, immune modulation and regenerative medicine. Finally, challenges and future perspectives are presented.

  5. Logical NAND and NOR Operations Using Algorithmic Self-assembly of DNA Molecules

    Science.gov (United States)

    Wang, Yanfeng; Cui, Guangzhao; Zhang, Xuncai; Zheng, Yan

    DNA self-assembly is the most advanced and versatile system that has been experimentally demonstrated for programmable construction of patterned systems on the molecular scale. It has been demonstrated that the simple binary arithmetic and logical operations can be computed by the process of self assembly of DNA tiles. Here we report a one-dimensional algorithmic self-assembly of DNA triple-crossover molecules that can be used to execute five steps of a logical NAND and NOR operations on a string of binary bits. To achieve this, abstract tiles were translated into DNA tiles based on triple-crossover motifs. Serving as input for the computation, long single stranded DNA molecules were used to nucleate growth of tiles into algorithmic crystals. Our method shows that engineered DNA self-assembly can be treated as a bottom-up design techniques, and can be capable of designing DNA computer organization and architecture.

  6. Self-Assembled Polystyrene Beads for Templated Covalent Functionalization of Graphitic Substrates Using Diazonium Chemistry.

    Science.gov (United States)

    Van Gorp, Hans; Walke, Peter; Bragança, Ana M; Greenwood, John; Ivasenko, Oleksandr; Hirsch, Brandon E; De Feyter, Steven

    2018-04-11

    A network of self-assembled polystyrene beads was employed as a lithographic mask during covalent functionalization reactions on graphitic surfaces to create nanocorrals for confined molecular self-assembly studies. The beads were initially assembled into hexagonal arrays at the air-liquid interface and then transferred to the substrate surface. Subsequent electrochemical grafting reactions involving aryl diazonium molecules created covalently bound molecular units that were localized in the void space between the nanospheres. Removal of the bead template exposed hexagonally arranged circular nanocorrals separated by regions of chemisorbed molecules. Small molecule self-assembly was then investigated inside the resultant nanocorrals using scanning tunneling microscopy to highlight localized confinement effects. Overall, this work illustrates the utility of self-assembly principles to transcend length scale gaps in the development of hierarchically patterned molecular materials.

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Science.gov (United States)

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

    2008-09-01

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

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

    KAUST Repository

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

    2012-01-01

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

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

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  11. Self-assembled peptide-based nanostructures: Smart nanomaterials toward targeted drug delivery.

    Science.gov (United States)

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

    2016-02-01

    Self-assembly of peptides can yield an array of well-defined nanostructures that are highly attractive nanomaterials for many biomedical applications such as drug delivery. Some of the advantages of self-assembled peptide nanostructures over other delivery platforms include their chemical diversity, biocompatibility, high loading capacity for both hydrophobic and hydrophilic drugs, and their ability to target molecular recognition sites. Furthermore, these self-assembled nanostructures could be designed with novel peptide motifs, making them stimuli-responsive and achieving triggered drug delivery at disease sites. The goal of this work is to present a comprehensive review of the most recent studies on self-assembled peptides with a focus on their "smart" activity for formation of targeted and responsive drug-delivery carriers.

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

    KAUST Repository

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

    2012-01-01

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

  13. Steering Self-Assembly of Amphiphilic Molecular Nanostructures via Halogen Exchange

    NARCIS (Netherlands)

    Kriete, Björn; Bondarenko, Anna S.; Jumde, Varsha R.; Franken, Linda E.; Minnaard, Adriaan J.; Jansen, Thomas L. C.; Knoester, Jasper; Pshenichnikov, Maxim S.

    2017-01-01

    In the field of self-assembly, the quest for gaining control over the supramolecular architecture without affecting the functionality of the individual molecular building blocks is intrinsically challenging. By using a combination of synthetic chemistry, cryogenic transmission electron microscopy,

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

    CSIR Research Space (South Africa)

    Nkosi, D

    2010-01-01

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

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

    Science.gov (United States)

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

    2016-01-13

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

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

    Science.gov (United States)

    Kundeti, Vamsi; Rajasekaran, Sanguthevar

    2012-06-01

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

  17. Amphiphilic building blocks for self-assembly: from amphiphiles to supra-amphiphiles.

    Science.gov (United States)

    Wang, Chao; Wang, Zhiqiang; Zhang, Xi

    2012-04-17

    The process of self-assembly spontaneously creates well-defined structures from various chemical building blocks. Self-assembly can include different levels of complexity: it can be as simple as the dimerization of two small building blocks driven by hydrogen bonding or as complicated as a cell membrane, a remarkable supramolecular architecture created by a bilayer of phospholipids embedded with functional proteins. The study of self-assembly in simple systems provides a fundamental understanding of the driving forces and cooperativity behind these processes. Once the rules are understood, these guidelines can facilitate the research of highly complex self-assembly processes. Among the various components for self-assembly, an amphiphilic molecule, which contains both hydrophilic and hydrophobic parts, forms one of the most powerful building blocks. When amphiphiles are dispersed in water, the hydrophilic component of the amphiphile preferentially interacts with the aqueous phase while the hydrophobic portion tends to reside in the air or in the nonpolar solvent. Therefore, the amphiphiles aggregate to form different molecular assemblies based on the repelling and coordinating forces between the hydrophilic and hydrophobic parts of the component molecules and the surrounding medium. In contrast to conventional amphiphiles, supra-amphiphiles are constructed on the basis of noncovalent interactions or dynamic covalent bonds. In supra-amphiphiles, the functional groups can be attached to the amphiphiles by noncovalent synthesis, greatly speeding their construction. The building blocks for supra-amphiphiles can be either small organic molecules or polymers. Advances in the development of supra-amphiphiles will not only enrich the family of conventional amphiphiles that are based on covalent bonds but will also provide a new kind of building block for the preparation of complex self-assemblies. When polymers are used to construct supra-amphiphiles, the resulting

  18. Optical constants and self-assembly of phenylene ethynylene oligomer monolayers

    DEFF Research Database (Denmark)

    Marx, E.; Walzer, Karsten; Less, R.J.

    2004-01-01

    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 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....

  19. Improved organic thin-film transistor performance using novel self-assembled monolayers

    Science.gov (United States)

    McDowell, M.; Hill, I. G.; McDermott, J. E.; Bernasek, S. L.; Schwartz, J.

    2006-02-01

    Pentacene-based organic thin-film transistors have been fabricated using a phosphonate-linked anthracene self-assembled monolayer as a buffer between the silicon dioxide gate dielectric and the active pentacene channel region. Vast improvements in the subthreshold slope and threshold voltage are observed compared to control devices fabricated without the buffer. Both observations are consistent with a greatly reduced density of charge trapping states at the semiconductor-dielectric interface effected by introduction of the self-assembled monolayer.

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

    Science.gov (United States)

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

    2016-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Nobuo Kimizuka

    2011-08-01

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

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

    Science.gov (United States)

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

    2004-08-23

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

  3. A Self-Assembling Protein Hydrogel Technology for Enzyme Incorporation onto Electrodes in Biofuel Cells

    Science.gov (United States)

    2015-10-26

    an ordered 3-dimentional space. In the first stage, we constructed protein building blocks able to self-assemble into 3D protein hydrogel upon...Chem 23, 1891-1901 (2012). 26. Jung, S. & Yi, H. Facile Strategy for Protein Conjugation with Chitosan -Poly(ethylene glycol) Hybrid Microparticle...multiple enzymes in an ordered 3-dimentional space. In the first stage, we constructed protein building blocks able to self-assemble into 3D protein

  4. Double smectic self-assembly in block copolypeptide complexes

    KAUST Repository

    Haataja, Johannes S.; Houbenov, Nikolay; Iatrou, Hermis; Hadjichristidis, Nikolaos; Karatzas, A.; Faul, Charl F. J.; Rannou, Patrice; Ikkala, Olli T.

    2012-01-01

    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

  5. Double smectic self-assembly in block copolypeptide complexes

    KAUST Repository

    Haataja, Johannes S.

    2012-11-12

    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

  6. SELF-ASSEMBLY CE OXIDE/ORGANOPOLYSILOXANE COMPOSITE COATINGS.

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA,T.; SABATINI,R.; GAWLIK,K.

    2005-01-01

    A self-assembly composite synthesis technology was used to put together a Ce(OH){sub 3}-dispersed poly-acetamide-acetoxyl methyl-propylsiloxane (PAAMPA) organometallic polymer. Three spontaneous reactions were involved; condensation, amidation, and acetoxylation, between the Ce acetate and aminopropylsilane triol (APST) at 150 C. An increase in temperature to 200 C led to the in-situ phase transformation of Ce(OH){sub 3} into Ce{sub 2}O{sub 3} in the PAAMPA matrix. A further increase to 250 C caused oxidative degradation of the PAAMPA, thereby generating copious fissures in the composite. We assessed the potential of Ce(OH){sub 3}/ and Ce{sub 2}O{sub 3}/ PAAMPA composite materials as corrosion-preventing coatings for carbon steel and aluminum. The Ce{sub 2}O{sub 3} composite coating displayed better performance in protecting both metals against NaCl-caused corrosion than did the Ce(OH){sub 3} composite. Using this coating formed at 200 C, we demonstrated that the following four factors played an essential role in further mitigating the corrosion of the metals: First was a minimum susceptibility of coating's surface to moisture; second was an enhanced densification of the coating layer; third was the retardation of the cathodic oxygen reduction reaction at the metal's corrosion sites due to the deposition of Ce{sub 2}O{sub 3} as a passive film over the metal's surface; and, fourth was its good adherence to metals. The last two factors contributed to minimizing the cathodic delamination of coating film from the metal's surface. We also noted that the affinity of the composite with the surface of aluminum was much stronger than that with steel. Correspondingly, the rate of corrosion of aluminum was reduced as much as two orders of magnitude by a nanoscale thick coating. In contrast, its ability to reduce the corrosion rate of steel was lower than one order of magnitude.

  7. Micellar Self-Assembly of Recombinant Resilin-/Elastin-Like Block Copolypeptides.

    Science.gov (United States)

    Weitzhandler, Isaac; Dzuricky, Michael; Hoffmann, Ingo; Garcia Quiroz, Felipe; Gradzielski, Michael; Chilkoti, Ashutosh

    2017-08-14

    Reported here is the synthesis of perfectly sequence defined, monodisperse diblock copolypeptides of hydrophilic elastin-like and hydrophobic resilin-like polypeptide blocks and characterization of their self-assembly as a function of structural parameters by light scattering, cryo-TEM, and small-angle neutron scattering. A subset of these diblock copolypeptides exhibit lower critical solution temperature and upper critical solution temperature phase behavior and self-assemble into spherical or cylindrical micelles. Their morphologies are dictated by their chain length, degree of hydrophilicity, and hydrophilic weight fraction of the ELP block. We find that (1) independent of the length of the corona-forming ELP block there is a minimum threshold in the length of the RLP block below which self-assembly does not occur, but that once that threshold is crossed, (2) the RLP block length is a unique molecular parameter to independently tune self-assembly and (3) increasing the hydrophobicity of the corona-forming ELP drives a transition from spherical to cylindrical morphology. Unlike the self-assembly of purely ELP-based block copolymers, the self-assembly of RLP-ELPs can be understood by simple principles of polymer physics relating hydrophilic weight fraction and polymer-polymer and polymer-solvent interactions to micellar morphology, which is important as it provides a route for the de novo design of desired nanoscale morphologies from first principles.

  8. Photon Upconversion and Molecular Solar Energy Storage by Maximizing the Potential of Molecular Self-Assembly.

    Science.gov (United States)

    Kimizuka, Nobuo; Yanai, Nobuhiro; Morikawa, Masa-Aki

    2016-11-29

    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.

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

    Institute of Scientific and Technical Information of China (English)

    Cun Zhang and Shaohua Chen

    2015-01-01

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

  10. Nanomaterial processing using self-assembly-bottom-up chemical and biological approaches

    International Nuclear Information System (INIS)

    Thiruvengadathan, Rajagopalan; Gangopadhyay, Keshab; Gangopadhyay, Shubhra; Korampally, Venumadhav; Ghosh, Arkasubhra; Chanda, Nripen

    2013-01-01

    Nanotechnology is touted as the next logical sequence in technological evolution. This has led to a substantial surge in research activities pertaining to the development and fundamental understanding of processes and assembly at the nanoscale. Both top-down and bottom-up fabrication approaches may be used to realize a range of well-defined nanostructured materials with desirable physical and chemical attributes. Among these, the bottom-up self-assembly process offers the most realistic solution toward the fabrication of next-generation functional materials and devices. Here, we present a comprehensive review on the physical basis behind self-assembly and the processes reported in recent years to direct the assembly of nanoscale functional blocks into hierarchically ordered structures. This paper emphasizes assembly in the synthetic domain as well in the biological domain, underscoring the importance of biomimetic approaches toward novel materials. In particular, two important classes of directed self-assembly, namely, (i) self-assembly among nanoparticle–polymer systems and (ii) external field-guided assembly are highlighted. The spontaneous self-assembling behavior observed in nature that leads to complex, multifunctional, hierarchical structures within biological systems is also discussed in this review. Recent research undertaken to synthesize hierarchically assembled functional materials have underscored the need as well as the benefits harvested in synergistically combining top-down fabrication methods with bottom-up self-assembly. (review article)

  11. Self-assembly via anisotropic interactions : Modeling association kinetics of patchy particle systems and self-assembly induced by critical Casimir forces

    NARCIS (Netherlands)

    Newton, A.C.

    2017-01-01

    Self-assembly, the non-dissipative spontaneous formation of structural order spans many length scales, from amphiphilic molecules forming micelles to stars forming galaxies. This thesis mainly deals with systems on the colloidal length scale where the size of a particle is between a nanometer and a

  12. Homochiral Evolution in Self-Assembled Chiral Polymers and Block Copolymers.

    Science.gov (United States)

    Wen, Tao; Wang, Hsiao-Fang; Li, Ming-Chia; Ho, Rong-Ming

    2017-04-18

    The significance of chirality transfer is not only involved in biological systems, such as the origin of homochiral structures in life but also in man-made chemicals and materials. How the chiral bias transfers from molecular level (molecular chirality) to helical chain (conformational chirality) and then to helical superstructure or phase (hierarchical chirality) from self-assembly is vital for the chemical and biological processes in nature, such as communication, replication, and enzyme catalysis. In this Account, we summarize the methodologies for the examination of homochiral evolution at different length scales based on our recent studies with respect to the self-assembly of chiral polymers and chiral block copolymers (BCPs*). A helical (H*) phase to distinguish its P622 symmetry from that of normal hexagonally packed cylinder phase was discovered in the self-assembly of BCPs* due to the chirality effect on BCP self-assembly. Enantiomeric polylactide-containing BCPs*, polystyrene-b-poly(l-lactide) (PS-PLLA) and polystyrene-b-poly(d-lactide) (PS-PDLA), were synthesized for the examination of homochiral evolution. The optical activity (molecular chirality) of constituted chiral repeating unit in the chiral polylactide is detected by electronic circular dichroism (ECD) whereas the conformational chirality of helical polylactide chain can be explicitly determined by vibrational circular dichroism (VCD). The H* phases of the self-assembled polylactide-containing BCPs* can be directly visualized by 3D transmission electron microscopy (3D TEM) technique at which the handedness (hierarchical chirality) of the helical nanostructure is thus determined. The results from the ECD, VCD, and 3D TEM for the investigated chirality at different length scales suggest the homochiral evolution in the self-assembly of the BCPs*. For chiral polylactides, twisted lamellae in crystalline banded spherulite can be formed by dense packing scheme and effective interactions upon helical

  13. Self-assembly of fibronectin mimetic peptide-amphiphile nanofibers

    Science.gov (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.

  14. Templated self-assembly of SiGe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Dais, Christian

    2009-08-19

    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

  15. Multifunctional hybrid networks based on self assembling peptide sequences

    Science.gov (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

  16. Simple Tidal Prism Models Revisited

    Science.gov (United States)

    Luketina, D.

    1998-01-01

    Simple tidal prism models for well-mixed estuaries have been in use for some time and are discussed in most text books on estuaries. The appeal of this model is its simplicity. However, there are several flaws in the logic behind the model. These flaws are pointed out and a more theoretically correct simple tidal prism model is derived. In doing so, it is made clear which effects can, in theory, be neglected and which can not.

  17. Symmetry and topology code of the cluster self-assembly of framework MT structures of alumophosphates AlPO4(H2O)2 (metavariscite and variscite) and Al2(PO4)2(H2O)3 (APC)

    Science.gov (United States)

    Ilyushin, G. D.; Blatov, V. A.

    2017-03-01

    The supramolecular chemistry of alumophosphates, which form framework 3D MT structures from polyhedral AlO4(H2O)2 clusters with octahedral O coordination (of M polyhedra) and PO4 and AlO4 with tetrahedral O coordination (of T polyhedra), is considered. A combinatorial-topological modeling of the formation of possible types of linear (six types) and ring (two types) tetrapolyhedral cluster precursors M2T2 from MT monomers is carried out. Different versions of chain formation from linked (MT)2 rings (six types) are considered. The model, which has a universal character, has been used to simulate the cluster selfassembly of the crystal structure of AlPO4(H2O)2 minerals (metavariscite, m-VAR, and variscite, VAR) and zeolite [Al2(PO4)2(H2O)2] · H2O (APC). A tetrapolyhedral linear precursor is established for m-VAR and a ring precursor (MT)2 is established for VAR and APC. The symmetry and topology code of the processes of crystal structure self-assembly from cluster precursors is completely reconstructed. The functional role of the O-H···O hydrogen bonds is considered for the first time. The cluster self-assembly model explains the specific features of the morphogenesis of single crystals: m-VAR prisms, flattened VAR octahedra, and needleshaped APC square-base prisms.

  18. The PRISM concept

    International Nuclear Information System (INIS)

    Circeo, L.J. Jr.; Camacho, S.L.; Tixier, J.S.

    1994-01-01

    Contaminated soils and buried wastes represent one of the most widespread and costly remediation problems in the United States and other developed countries around the world. This concept of in situ remediation using a plasma arc torch should be directly applicable to many of the contaminated soil remediation needs described the DOE, EPA, and DoD. Plasma Remediation of In Situ Materials (PRISM) could provide a highly efficient, cost-effective, reliable and controllable technique to selectively melt and vitrify any contaminated/buried volume of soils, materials, or objects at any depth underground. If necessary, it could pinpoint underground objects such as buried drums for selective remediation. Plasma arc technology was developed over 30 years ago by NASA for the US space program to simulate reentry temperatures on heat shields. Only recently has this technology begun to emerge as a commercial tool in several industries such as steelmaking, metallurgy, precious metal recovery, and waste disposal. Conceptually, a plasma torch could be used on the ground surface or lowered to the bottom of a small diameter, cased borehole. By raising and operating the torch at progressively higher levels a column of contaminated material would be vitrified and converted into an environmentally safe, glassy residue, highly resistant to leaching. With proper borehole spacing the vitrified columns could be coalesced together to form a contiguous, homogeneous mass of vitrified material which is environmentally safe and highly resistant to leaching

  19. Synthesis, Self-Assembly, and Drug-Release Properties of New Amphipathic Liquid Crystal Polycarbonates

    Directory of Open Access Journals (Sweden)

    Yujiao Xie

    2018-03-01

    Full Text Available New amphiphilic liquid crystal (LC polycarbonate block copolymers containing side-chain cholesteryl units were synthesized. Their structure, thermal stability, and LC phase behavior were characterized with Fourier transform infrared (FT-IR spectrum, 1H NMR, gel permeation chromatographic (GPC, thermogravimetric analysis (TGA, differential scanning calorimetry (DSC, polarizing optical microscope (POM, and XRD methods. The results demonstrated that the LC copolymers showed a double molecular arrangement of a smectic A phase at room temperature. With the elevating of LC unit content in such LC copolymers, the corresponding properties including decomposition temperature (Td, glass temperature (Tg, and isotropic temperature (Ti increased. The LC copolymers showed pH-responsive self-assembly behavior under the weakly acidic condition, and with more side-chain LC units, the self-assembly process was faster, and the formed particle size was smaller. It indicated that the self-assembly driving force was derived from the orientational ability of LC. The particle size and morphologies of self-assembled microspheres loaded with doxorubicin (DOX, together with drug release tracking, were evaluated by dynamic light scattering (DLS, SEM, and UV–vis spectroscopy. The results showed that DOX could be quickly released in a weakly acidic environment due to the pH response of the self-assembled microspheres. This would offer a new strategy for drug delivery in clinic applications.

  20. FOLDNA, a Web Server for Self-Assembled DNA Nanostructure Autoscaffolds and Autostaples

    Directory of Open Access Journals (Sweden)

    Chensheng Zhou

    2012-01-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Da Hye Shin

    2015-03-01

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

  2. Impact of cationic surfactant on the self-assembly of sodium caseinate.

    Science.gov (United States)

    Vinceković, Marko; Curlin, Marija; Jurašin, Darija

    2014-08-27

    The impact of a cationic surfactant, dodecylammonium chloride (DDACl), on the self-assembly of sodium caseinate (SC) has been investigated by light scattering, zeta potential, and rheological measurements as well as by microscopy (transmission electron and confocal laser scanning microscopy). In SC dilute solutions concentration-dependent self-assembly proceeds through the formation of spherical associates and their aggregation into elongated structures composed of connected spheres. DDACl interacts with SC via its hydrophilic and hydrophobic groups, inducing changes in SC self-assembled structures. These changes strongly depend on the surfactant aggregation states (monomeric or micellar) as well as concentration ratio of both components, leading to the formation of soluble and insoluble complexes of nano- to microdimensions. DDACl monomers interact with SC self-assembled entities in a different way compared to their micelles. Surfactant monomers form soluble complexes (similar to surfactant mixed micelles) at lower SC concentration but insoluble gelatinous complexes at higher SC concentration. At surfactant micellar concentration soluble complexes with casein chains wrapped around surfactant micelles are formed. This study suggests that the use of proper cationic surfactant concentration will allow modification and control of structural changes of SC self-assembled entities.

  3. Beta-Sheet-Forming, Self-Assembled Peptide Nanomaterials towards Optical, Energy, and Healthcare Applications.

    Science.gov (United States)

    Kim, Sungjin; Kim, Jae Hong; Lee, Joon Seok; Park, Chan Beum

    2015-08-12

    Peptide self-assembly is an attractive route for the synthesis of intricate organic nanostructures that possess remarkable structural variety and biocompatibility. Recent studies on peptide-based, self-assembled materials have expanded beyond the construction of high-order architectures; they are now reporting new functional materials that have application in the emerging fields such as artificial photosynthesis and rechargeable batteries. Nevertheless, there have been few reviews particularly concentrating on such versatile, emerging applications. Herein, recent advances in the synthesis of self-assembled peptide nanomaterials (e.g., cross β-sheet-based amyloid nanostructures, peptide amphiphiles) are selectively reviewed and their new applications in diverse, interdisciplinary fields are described, ranging from optics and energy storage/conversion to healthcare. The applications of peptide-based self-assembled materials in unconventional fields are also highlighted, such as photoluminescent peptide nanostructures, artificial photosynthetic peptide nanomaterials, and lithium-ion battery components. The relation of such functional materials to the rapidly progressing biomedical applications of peptide self-assembly, which include biosensors/chips and regenerative medicine, are discussed. The combination of strategies shown in these applications would further promote the discovery of novel, functional, small materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Self-assembled morphologies of an amphiphilic Y-shaped weak polyelectrolyte in a thin film.

    Science.gov (United States)

    Mu, Dan; Li, Jian-Quan; Feng, Sheng-Yu

    2017-11-29

    Different from the self-assembly of neutral polymers, polyelectrolytes self-assemble into smaller aggregates with a more loosely assembled structure, which results from the repulsive forces acting between similar electrical compositions with the introduction of ions. The Y-shaped weak polyelectrolytes self-assemble into a core-shell type cylindrical structure with a hexagonal arrangement in a thin film, whose thickness is smaller than the gyration radius of the polymer chain. The corresponding formation mechanism consists of enrichment of the same components, adjustment of the shape of the aggregate, and the subsequent separation into individual aggregates. With the increase in the thickness of the thin film until it exceeds the gyration radius of the polymer chain, combined with the greater freedom of movement along the direction of thin film thickness, the self-assembled structure changes into a micellar structure. Under confinement, the repulsive force to the polymeric components is weakened by the repulsive forces among polyelectrolyte components with like charges, and this helps in generating aggregates with more uniform size and density distribution. In particular, when the repulsive force between the walls and the core forming components is greater than that between the walls and the shell forming components, such asymmetric confinement produces a crossed-cylindrical structure with nearly perpendicular arrangement of two cylinder arrays. Similarly, a novel three-crossed cylinder morphology is self-assembled upon removal of confinement.

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

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    2011-08-01

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

  6. Self-assembly of proglycinin and hybrid proglycinin synthesized in vitro from cDNA

    Science.gov (United States)

    Dickinson, Craig D.; Floener, Liliane A.; Lilley, Glenn G.; Nielsen, Niels C.

    1987-01-01

    An in vitro system was developed that results in the self-assembly of subunit precursors into complexes that resemble those found naturally in the endoplasmic reticulum. Subunits of glycinin, the predominant seed protein of soybeans, were synthesized from modified cDNAs using a combination of the SP6 transcription and the rabbit reticulocyte translation systems. Subunits produced from plasmid constructions that encoded either Gy4 or Gy5 gene products, but modified such that their signal sequences were absent, self-assembled into trimers equivalent in size to those precursors found in the endoplasmic reticulum. In contrast, proteins synthesized in vitro from Gy4 constructs failed to self-assemble when the signal sequence was left intact (e.g., preproglycinin) or when the coding sequence was modified to remove 27 amino acids from an internal hydrophobic region, which is highly conserved among the glycinin subunits. Various hybrid subunits were also produced by trading portions of Gy4 and Gy5 cDNAs and all self-assembled in our system. The in vitro assembly system provides an opportunity to study the self-assembly of precursors and to probe for regions important for assembly. It will also be helpful in attempts to engineer beneficial nutritional changes into this important food protein. Images PMID:16593868

  7. [Self-assembly tissue engineering fibrocartilage model of goat temporomandibular joint disc].

    Science.gov (United States)

    Kang, Hong; Li, Zhen-Qiang; Bi, Yan-Da

    2011-06-01

    To construct self-assembly fibrocartilage model of goat temporomandibular joint disc and observe the biological characteristics of the self-assembled fibrocartilage constructs, further to provide a basis for tissue engineering of the temporomandibular joint disc and other fibrocartilage. Cells from temporomandibular joint discs of goats were harvested and cultured. 5.5 x 10(6) cells were seeded in each agarose well with diameter 5 mm x depth 10 mm, daily replace of medium, cultured for 2 weeks. One day after seeding, goat temporomandibular joint disc cells in agarose wells were gathered and began to self-assemble into a disc-shaped base, then gradually turned into a round shape. When cultured for 2 weeks, hematoxylin-eosin staining was conducted and observed that cells were round and wrapped around by the matrix. Positive Safranin-O/fast green staining for glycosaminoglycans was observed throughout the entire constructs, and picro-sirius red staining was examined and distribution of numerous type I collagen was found. Immunohistochemistry staining demonstrated brown yellow particles in cytoplasm and around extracellular matrix, which showed self-assembly construct can produce type I collagen as native temporomandibular joint disc tissue. Production of extracellular matrix in self-assembly construct as native temporomandibular joint disc tissue indicates that the use of agarose wells to construct engineered temporomandibular joint disc will be possible and practicable.

  8. Directed self-assembly of nanogold using a chemically modified nanopatterned surface

    Science.gov (United States)

    Nidetz, Robert; Kim, Jinsang

    2012-02-01

    Electron-beam lithography (EBL) was used to define an aminosilane nanopatterned surface in order to electrostatically self-assemble gold nanoparticles (Au NPs). The chemically modified nanopatterned surfaces were immersed into a Au NP solution to allow the Au NPs to self-assemble. Equilibrium self-assembly was achieved in only 20 min. The number of Au NPs that self-assembled on an aminosilane dot was controlled by manipulating the diameters of both the Au NPs and the dots. Adding salt to the Au NP solution enabled the Au NPs to self-assemble in greater numbers on the same sized dot. However, the preparation of the Au NP solution containing salt was sensitive to spikes in the salt concentration. These spikes led to aggregation of the Au NPs and non-specific deposition of Au NPs on the substrate. The Au NP patterned surfaces were immersed in a sodium hydroxide solution in order to lift-off the patterned Au NPs, but no lift-off was observed without adequate physical agitation. The van der Waals forces are too strong to allow for lift-off despite the absence of electrostatic forces.

  9. Directed self-assembly of nanogold using a chemically modified nanopatterned surface

    International Nuclear Information System (INIS)

    Nidetz, Robert; Kim, Jinsang

    2012-01-01

    Electron-beam lithography (EBL) was used to define an aminosilane nanopatterned surface in order to electrostatically self-assemble gold nanoparticles (Au NPs). The chemically modified nanopatterned surfaces were immersed into a Au NP solution to allow the Au NPs to self-assemble. Equilibrium self-assembly was achieved in only 20 min. The number of Au NPs that self-assembled on an aminosilane dot was controlled by manipulating the diameters of both the Au NPs and the dots. Adding salt to the Au NP solution enabled the Au NPs to self-assemble in greater numbers on the same sized dot. However, the preparation of the Au NP solution containing salt was sensitive to spikes in the salt concentration. These spikes led to aggregation of the Au NPs and non-specific deposition of Au NPs on the substrate. The Au NP patterned surfaces were immersed in a sodium hydroxide solution in order to lift-off the patterned Au NPs, but no lift-off was observed without adequate physical agitation. The van der Waals forces are too strong to allow for lift-off despite the absence of electrostatic forces. (paper)

  10. Driven self-assembly of hard nanoplates on soft elastic shells

    International Nuclear Information System (INIS)

    Zhang Yao-Yang; Hua Yun-Feng; Deng Zhen-Yu

    2015-01-01

    The driven self-assembly behaviors of hard nanoplates on soft elastic shells are investigated by using molecular dynamics (MD) simulation method, and the driven self-assembly structures of adsorbed hard nanoplates depend on the shape of hard nanoplates and the bending energy of soft elastic shells. Three main structures for adsorbed hard nanoplates, including the ordered aggregation structures of hard nanoplates for elastic shells with a moderate bending energy, the collapsed structures for elastic shells with a low bending energy, and the disordered aggregation structures for hard shells, are observed. The self-assembly process of adsorbed hard nanoplates is driven by the surface tension of the elastic shell, and the shape of driven self-assembly structures is determined on the basis of the minimization of the second moment of mass distribution. Meanwhile, the deformations of elastic shells can be controlled by the number of adsorbed rods as well as the length of adsorbed rods. This investigation can help us understand the complexity of the driven self-assembly of hard nanoplates on elastic shells. (paper)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-15

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

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

    Science.gov (United States)

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

    2018-04-18

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

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

    Directory of Open Access Journals (Sweden)

    Nozomi Saito

    2018-01-01

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

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

    Science.gov (United States)

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

    2018-05-29

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

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

    Science.gov (United States)

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

    2012-02-01

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

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

    KAUST Repository

    Yu, Haizhou

    2015-09-21

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

  17. A Springloaded Metal-Ligand Mesocate Allows Access to Trapped Intermediates of Self-Assembly.

    Science.gov (United States)

    Bogie, Paul M; Holloway, Lauren R; Lyon, Yana; Onishi, Nicole C; Beran, Gregory J O; Julian, Ryan R; Hooley, Richard J

    2018-04-02

    A strained, "springloaded" Fe 2 L 3 iminopyridine mesocate shows highly variable reactivity upon postassembly reaction with competitive diamines. The strained assembly is reactive toward transimination in minutes at ambient temperature and allows observation of kinetically trapped intermediates in the self-assembly pathway. When diamines are used that can only form less favored cage products upon full equilibration, trapped ML 3 fragments with pendant, "hanging" NH 2 groups are selectively formed instead. Slight variations in diamine structure have large effects on the product outcome: less rigid diamines convert the mesocate to more favored self-assembled cage complexes under mild conditions and allow observation of heterocomplex intermediates in the displacement pathway. The mesocate allows control of equilibrium processes and direction of product outcomes via small, iterative changes in added subcomponent structure and provides a method of accessing metal-ligand cage structures not normally observed in multicomponent Fe-iminopyridine self-assembly.

  18. Lipid-bilayer-assisted two-dimensional self-assembly of DNA origami nanostructures

    Science.gov (United States)

    Suzuki, Yuki; Endo, Masayuki; Sugiyama, Hiroshi

    2015-08-01

    Self-assembly is a ubiquitous approach to the design and fabrication of novel supermolecular architectures. Here we report a strategy termed `lipid-bilayer-assisted self-assembly' that is used to assemble DNA origami nanostructures into two-dimensional lattices. DNA origami structures are electrostatically adsorbed onto a mica-supported zwitterionic lipid bilayer in the presence of divalent cations. We demonstrate that the bilayer-adsorbed origami units are mobile on the surface and self-assembled into large micrometre-sized lattices in their lateral dimensions. Using high-speed atomic force microscopy imaging, a variety of dynamic processes involved in the formation of the lattice, such as fusion, reorganization and defect filling, are successfully visualized. The surface modifiability of the assembled lattice is also demonstrated by in situ decoration with streptavidin molecules. Our approach provides a new strategy for preparing versatile scaffolds for nanofabrication and paves the way for organizing functional nanodevices in a micrometer space.

  19. Supramolecule-to-supramolecule transformations of coordination-driven self-assembled polygons.

    Science.gov (United States)

    Zhao, Liang; Northrop, Brian H; Stang, Peter J

    2008-09-10

    Two types of supramolecular transformations, wherein a self-assembled Pt(II)-pyridyl metal-organic polygon is controllably converted into an alternative polygon, have been achieved through the reaction between cobalt carbonyl and the acetylene moiety of a dipyridyl donor ligand. A [6 + 6] hexagon is transformed into two [3 + 3] hexagons, and a triangle-square mixture is converted into [2 + 2] rhomboids. 1H and 31P NMR spectra are used to track the transformation process and evaluate the yield of new self-assembled polygons. Such transformed species are identified by electrospray ionization (ESI) mass spectrometry. This new kind of supramolecule-to-supramolecule transformations provides a viable means for constructing, and then converting, new self-assembled polygons.

  20. Electrical Programming of Soft Matter: Using Temporally Varying Electrical Inputs To Spatially Control Self Assembly.

    Science.gov (United States)

    Yan, Kun; Liu, Yi; Zhang, Jitao; Correa, Santiago O; Shang, Wu; Tsai, Cheng-Chieh; Bentley, William E; Shen, Jana; Scarcelli, Giuliano; Raub, Christopher B; Shi, Xiao-Wen; Payne, Gregory F

    2018-02-12

    The growing importance of hydrogels in translational medicine has stimulated the development of top-down fabrication methods, yet often these methods lack the capabilities to generate the complex matrix architectures observed in biology. Here we show that temporally varying electrical signals can cue a self-assembling polysaccharide to controllably form a hydrogel with complex internal patterns. Evidence from theory and experiment indicate that internal structure emerges through a subtle interplay between the electrical current that triggers self-assembly and the electrical potential (or electric field) that recruits and appears to orient the polysaccharide chains at the growing gel front. These studies demonstrate that short sequences (minutes) of low-power (∼1 V) electrical inputs can provide the program to guide self-assembly that yields hydrogels with stable, complex, and spatially varying structure and properties.

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

    Science.gov (United States)

    Fu, Xiuli; Chen, Lingxin; Li, Jinhua

    2012-08-21

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

  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

    2008-07-01

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

  3. Formation of self-assembled stripes on the anodic aluminum oxide

    International Nuclear Information System (INIS)

    Liu Hongwen; Guo Haiming; Wang Yeliang; Shen Chengmin; Yang Haitao; Wang Yutian; Wei Long

    2004-01-01

    Non-polished aluminum sheets were anodized and the coexistence of self-assembled stripes and porous arrays on the Al surface was observed. The nanostructures were investigated in details using an atomic force microscope. And the formation mechanism of the stripes was discussed and simulated using Brusselator model in this work. The authors demonstrated that the self-assembled patterns on the Al surface were governed by the competition of formation and dissolution of alumina film during the reaction process. Moreover, this type of ordered structure could only form in certain conditions

  4. Preparation and self-assembly of nanostructured BaCrO4 from CTAB reverse microemulsions

    International Nuclear Information System (INIS)

    Li Zhonghao; Zhang Jianling; Du Jimin; Han Buxing; Mu Tiancheng; Gao Yanan; Liu Zhimin

    2005-01-01

    Well-defined superstructures of rectangular-shaped BaCrO 4 and extensive network of BaCrO 4 nanoparticles constructed by self-assembly were prepared in cetyltrimethylammonium bromide (CTAB) reverse microemulsions. The effects of aging time and reactant concentrations on the morphology and the self-assemble pattern of the nanostructured BaCrO 4 were investigated. TEM combined with the electron diffraction was used to characterize the morphology and the crystal structure of the prepared nanostructured BaCrO 4 at different conditions

  5. Fiber Optic pH Sensor with Self-Assembled Polymer Multilayer Nanocoatings

    OpenAIRE

    Shao, Li-Yang; Yin, Ming-Jie; Tam, Hwa-Yaw; Albert, Jacques

    2013-01-01

    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...

  6. Diffuse x-ray scattering study of interfacial structure of self-assembled conjugated polymers

    International Nuclear Information System (INIS)

    Wang Jun; Park, Y.J.; Lee, K.-B.; Hong, H.; Davidov, D.

    2002-01-01

    The interfacial structures of self-assembled heterostructures through alternate deposition of conjugated and nonconjugated polymers were studied by x-ray reflectivity and nonspecular scattering. We found that the interfacial width including the effects of both interdiffusion and interfacial roughness (correlated) was mainly contributed by the latter one. The self-assembled deposition induced very small interdiffusion between layers. The lateral correlation length ξ parallel grew as a function of deposition time (or film thickness) described by a power law ξ parallel ∝t β/H and was also observed from the off-specular scattering

  7. Fabrication of textured SnO2 transparent conductive films using self-assembled Sn nanospheres

    Science.gov (United States)

    Fukumoto, Michitaka; Nakao, Shoichiro; Hirose, Yasushi; Hasegawa, Tetsuya

    2018-06-01

    We present a novel method to fabricate textured surfaces on transparent conductive SnO2 films by processing substrates through a bottom-up technique with potential for industrially scalable production. The substrate processing consists of three steps: deposition of precursor Sn films on glass substrates, formation of a self-assembled Sn nanosphere layer with reductive annealing, and conversion of Sn to SnO2 by oxidative annealing. Ta-doped SnO2 films conformally deposited on the self-assembled nanospherical SnO2 templates exhibited attractive optical and electrical properties, namely, enhanced haze values and low sheet resistances, for applications as transparent electrodes in photovoltaics.

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

    Science.gov (United States)

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

    2015-11-01

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

  9. Cross-sectional nanophotoluminescence studies of Stark effects in self-assembled quantum dots

    International Nuclear Information System (INIS)

    Htoon, H.; Keto, J. W.; Baklenov, O.; Holmes, A. L. Jr.; Shih, C. K.

    2000-01-01

    By using a cross-sectional geometry, we show the capability to perform single-dot spectroscopy in self-assembled quantum dots using far-field optics. By using this method, we study the quantum-confined Stark effect in self-assembled quantum dots. For single-stack quantum dots (QDs), we find that the spectra are redshifted with an increase in electric field. For vertically coupled double-stack quantum dots, while most of the QDs are redshifted, some QDs show blueshifted spectra, which can be interpreted as an evidence of coupled QD molecules. (c) 2000 American Institute of Physics

  10. Surface-Assisted Self-Assembly Strategies Leading to Supramolecular Hydrogels.

    Science.gov (United States)

    Vigier-Carrière, Cécile; Boulmedais, Fouzia; Schaaf, Pierre; Jierry, Loïc

    2018-02-05

    Localized molecular self-assembly processes leading to the growth of nanostructures exclusively from the surface of a material is one of the great challenges in surface chemistry. In the last decade, several works have been reported on the ability of modified or unmodified surfaces to manage the self-assembly of low-molecular-weight hydrogelators (LMWH) resulting in localized supramolecular hydrogel coatings mainly based on nanofiber architectures. This Minireview highlights all strategies that have emerged recently to initiate and localize LMWH supramolecular hydrogel formation, their related fundamental issues and applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    DEFF Research Database (Denmark)

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

    2004-01-01

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

  12. Light-assisted, templated self-assembly using a photonic-crystal slab.

    Science.gov (United States)

    Jaquay, Eric; Martínez, Luis Javier; Mejia, Camilo A; Povinelli, Michelle L

    2013-05-08

    We experimentally demonstrate the technique of light-assisted, templated self-assembly (LATS). We excite a guided-resonance mode of a photonic-crystal slab with 1.55 μm laser light to create an array of optical traps. We demonstrate assembly of a square lattice of 520 nm diameter polystyrene particles spaced by 860 nm. Our results demonstrate how LATS can be used to fabricate reconfigurable structures with symmetries different from traditional colloidal self-assembly, which is limited by free energetic constraints.

  13. Electrodynamic tailoring of self-assembled three-dimensional electrospun constructs

    Science.gov (United States)

    Reis, Tiago C.; Correia, Ilídio J.; Aguiar-Ricardo, Ana

    2013-07-01

    The rational design of three-dimensional electrospun constructs (3DECs) can lead to striking topographies and tailored shapes of electrospun materials. This new generation of materials is suppressing some of the current limitations of the usual 2D non-woven electrospun fiber mats, such as small pore sizes or only flat shaped constructs. Herein, we pursued an explanation for the self-assembly of 3DECs based on electrodynamic simulations and experimental validation. We concluded that the self-assembly process is driven by the establishment of attractive electrostatic forces between the positively charged aerial fibers and the already collected ones, which tend to acquire a negatively charged network oriented towards the nozzle. The in situ polarization degree is strengthened by higher amounts of clustered fibers, and therefore the initial high density fibrous regions are the preliminary motifs for the self-assembly mechanism. As such regions increase their in situ polarization electrostatic repulsive forces will appear, favoring a competitive growth of these self-assembled fibrous clusters. Highly polarized regions will evidence higher distances between consecutive micro-assembled fibers (MAFs). Different processing parameters - deposition time, electric field intensity, concentration of polymer solution, environmental temperature and relative humidity - were evaluated in an attempt to control material's design.The rational design of three-dimensional electrospun constructs (3DECs) can lead to striking topographies and tailored shapes of electrospun materials. This new generation of materials is suppressing some of the current limitations of the usual 2D non-woven electrospun fiber mats, such as small pore sizes or only flat shaped constructs. Herein, we pursued an explanation for the self-assembly of 3DECs based on electrodynamic simulations and experimental validation. We concluded that the self-assembly process is driven by the establishment of attractive

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

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  15. Exciplex formation and energy transfer in a self-assembled metal-organic hybrid system.

    Science.gov (United States)

    Haldar, Ritesh; Rao, K Venkata; George, Subi J; Maji, Tapas Kumar

    2012-05-07

    Exciting assemblies: A metal-organic self-assembly of pyrenebutyric acid (PBA), 1,10-phenanthroline (o-phen), and Mg(II) shows solid-state fluorescence originating from a 1:1 PBA-o-phen exciplex. This exciplex fluorescence is sensitized by another residual PBA chromophore through an excited-state energy-transfer process. The solvent polarity modulates the self-assembly and the corresponding exciplex as well as the energy transfer, resulting in tunable emission of the hybrid (see figure). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

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

    2014-03-01

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

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

    Directory of Open Access Journals (Sweden)

    Alexander Weddemann

    2010-11-01

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

  18. A simple method to prepare self-assembled organic-organic heterobilayers on metal substrates

    Directory of Open Access Journals (Sweden)

    L. D. Sun

    2011-06-01

    Full Text Available We demonstrate a self-assembly based simple method to prepare organic-organic heterobilayers on a metal substrate. By either sequential- or co-deposition of para-sexiphenyl (p-6P and pentacene molecules onto the Cu(110 surface in ultrahigh vacuum, p-6P/pentacene/Cu(110 heterobilayer is synthesized at room temperature. The layer sequence of the heterostructure is independent of the growth scenario indicating the p-6P/pentacene/Cu(110 is a self-assembled structure with lowest energy. Besides, the bilayer shows a very high orientational ordering and is thermally stable up to 430K.

  19. Fabrication of nanostructure via self-assembly of nanowires within the AAO template

    Directory of Open Access Journals (Sweden)

    Brust Mathias

    2006-01-01

    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.

  20. PRISMES. The INES microgrid platform

    Energy Technology Data Exchange (ETDEWEB)

    Barruel, F.; Vervaart, M.; Merten, J. [INES, 73 - Le Bourget-du-lac (FR). Lab. for Solar Systems (L2S)

    2010-07-01

    The massive penetration of fluctuating renewable energies will challenge the low voltage grids. Innovative solutions to address this issue need to be developed and tested. They may consist of intelligent energy management systems and the use of storage systems. For this purpose the PRISMES platform has been designed and implemented at the INES headquarter in Chambery. It is a universal test and development tool, such as stand alone hybrid systems and grid connected PV systems combined with a storage system and loads. This paper describes the PRISMES facility which will start operation in autumn 2008. (orig.)

  1. Correlation of Effective Dispersive and Polar Surface Energies in Heterogeneous Self-Assembled Monolayer Coatings

    DEFF Research Database (Denmark)

    Zhuang, Yanxin; Hansen, Ole

    2009-01-01

    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...

  2. Studies of G-quadruplexes formed within self-assembled DNA mini-circles.

    Science.gov (United States)

    Klejevskaja, Beata; Pyne, Alice L B; Reynolds, Matthew; Shivalingam, Arun; Thorogate, Richard; Hoogenboom, Bart W; Ying, Liming; Vilar, Ramon

    2016-10-13

    We have developed self-assembled DNA mini-circles that contain a G-quadruplex-forming sequence from the c-Myc oncogene promoter and demonstrate by FRET that the G-quadruplex unfolding kinetics are 10-fold slower than for the simpler 24-mer G-quadruplex that is commonly used for FRET experiments.

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

    Science.gov (United States)

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

    2017-07-01

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

  4. Lithographic stress control for the self-assembly of polymer MEMS structures

    International Nuclear Information System (INIS)

    Lee, S-W; Sameoto, D; Parameswaran, M; Mahanfar, A

    2008-01-01

    We present a novel self-assembly mechanism to produce an assortment of predetermined three-dimensional micromechanical structures in polymer MEMS technology using lithographically defined areas of stress and mechanical reinforcement within a single structural material. This self-assembly technology is based on the tensile stress that arises during the cross-linking of the negative tone, epoxy-based photoresist SU-8. Two different thicknesses of SU-8 are used in a single compliant structure. The first SU-8 layer forms the main structural element and the second SU-8 layer determines the aspects of self-assembly. The second SU-8 layer thickness acts to both to create a stress differential within the structure as well as define the direction in which the induced stress will cause the structure to deform. In this manner, both the magnitude and direction of self-assembled structures can be controlled using a single lithographic step. Although this technique uses a single structural material, the basic concept may be adapted for other processes, with different material choices, for a wide variety of applications

  5. Porphyrins with directly meso-attached disaccharide moieties: Synthesis, self-assembly and cellular study

    Czech Academy of Sciences Publication Activity Database

    Malachowska, M.; Sperduto, C.; Darmostuk, M.; Monti, D.; Venanzi, M.; Mancini, G.; D'Acunto, C.W.; Králová, Jarmila; Ruml, T.; Wimmer, Zdeněk; Drasar, P.

    2016-01-01

    Roč. 20, č. 7 (2016), s. 773-784 ISSN 1088-4246 Institutional support: RVO:61389030 ; RVO:68378050 Keywords : derivatives * aggregation * steroids * sucrose * porphyrinoids * carbohydrates * self-assembly * cellular localisation * liposomes Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.043, year: 2016

  6. Self-assembly of POSS-containing block copolymers: fixing the hierarchical structure in networks

    Czech Academy of Sciences Publication Activity Database

    Matějka, Libor; Janata, Miroslav; Pleštil, Josef; Zhigunov, Alexander; Šlouf, Miroslav

    2014-01-01

    Roč. 55, č. 1 (2014), s. 126-136 ISSN 0032-3861 R&D Projects: GA ČR GAP108/12/1459 Grant - others:AV ČR(CZ) M200500903 Institutional support: RVO:61389013 Keywords : block copolymers * self-assembly * POSS Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.562, year: 2014

  7. Self-assembly and stability of double rosette nanostructures with biological functionalities

    NARCIS (Netherlands)

    ten Cate, M.G.J.; Omerovic, Merdan; Oshovsky, G.; Crego Calama, Mercedes; Reinhoudt, David

    2005-01-01

    The syntheses of calix[4]arene dimelamines that are functionalized with alkyl, aminoalkyl, ureido, pyridyl, carbohydrate, amino acid and peptide functionalities, and their self-assembly with barbituric acid or cyanuric acid derivatives into well-defined hydrogen-bonded nanostructures are described.

  8. Sensitive detection of plastic explosives with self-assembled monolayer-coated microcantilevers

    Science.gov (United States)

    Pinnaduwage, L. A.; Boiadjiev, V.; Hawk, J. E.; Thundat, T.

    2003-08-01

    We report the detection of 10-30 parts-per-trillion levels of pentaerythritol tetranitrate and hexahydro-1,3,5-triazine within 20 s of exposure to a silicon microcantilever with its gold surface modified with a self-assembled monolayer of 4-mercaptobenzoic acid. These measurements correspond to a limit of detection of a few fg.

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

    NARCIS (Netherlands)

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

    2003-01-01

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

  10. High-Efficiency Colloidal Quantum Dot Photovoltaics via Robust Self-Assembled Monolayers

    KAUST Repository

    Kim, Gi-Hwan; Garcí a de Arquer, F. Pelayo; Yoon, Yung Jin; Lan, Xinzheng; Liu, Mengxia; Voznyy, Oleksandr; Yang, Zhenyu; Fan, Fengjia; Ip, Alexander H.; Kanjanaboos, Pongsakorn; Hoogland, Sjoerd; Kim, Jin Young; Sargent, Edward H.

    2015-01-01

    to voltage. With this goal in mind, self-assembled monolayers (SAMs) can be used to modify interface energy levels locally. However, to be effective SAMs must be made robust to treatment using the various solvents and ligands required for to fabricate high

  11. Large-scale molecular dynamics simulations of self-assembling systems.

    Science.gov (United States)

    Klein, Michael L; Shinoda, Wataru

    2008-08-08

    Relentless increases in the size and performance of multiprocessor computers, coupled with new algorithms and methods, have led to novel applications of simulations across chemistry. This Perspective focuses on the use of classical molecular dynamics and so-called coarse-grain models to explore phenomena involving self-assembly in complex fluids and biological systems.

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

    DEFF Research Database (Denmark)

    Castillo, Jaime; Tanzi, Simone; Dimaki, Maria

    2008-01-01

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

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

    DEFF Research Database (Denmark)

    Cagliani, Alberto; Kosaka, Priscila; Tamayo, Javier

    2012-01-01

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

  14. N-Type self-assembled monolayer field-effect transistors for flexible organic electronics

    NARCIS (Netherlands)

    Ringk, A.; Roelofs, Christian; Smits, E.C.P.; van der Marel, C.; Salzmann, I.; Neuhold, A.; Gelinck, G.H.; Resel, R.; de Leeuw, D.M.; Strohriegl, P.

    Within this work we present n-type self-assembled monolayer field-effect transistors (SAMFETs) based on a novel perylene bisimide. The molecule spontaneously forms a covalently fixed monolayer on top of an aluminium oxide dielectric via a phosphonic acid anchor group. Detailed studies revealed an

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

    KAUST Repository

    Haataja, J. S.; Houbenov, N.; Aseyev, V.; Fragouli, P.; Iatrou, H.; Sougrat, Rachid; Hadjichristidis, Nikolaos; Ikkala, O.

    2018-01-01

    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

  16. Dynamic stability of nano-fibers self-assembled from short amphiphilic A6D peptides.

    Science.gov (United States)

    Nikoofard, Narges; Maghsoodi, Fahimeh

    2018-04-07

    Self-assembly of A 6 D amphiphilic peptides in explicit water is studied by using coarse-grained molecular dynamics simulations. It is observed that the self-assembly of randomly distributed A 6 D peptides leads to the formation of a network of nano-fibers. Two other simulations with cylindrical nano-fibers as the initial configuration show the dynamic stability of the self-assembled nano-fibers. As a striking feature, notable fluctuations occur along the axes of the nano-fibers. Depending on the number of peptides per unit length of the nano-fiber, flat-shaped bulges or spiral shapes along the nano-fiber axis are observed at the fluctuations. Analysis of the particle distribution around the nano-fiber indicates that the hydrophobic core and the hydrophilic shell of the nano-structure are preserved in both simulations. The size of the deformations and their correlation times are different in the two simulations. This study gives new insights into the dynamics of the self-assembled nano-structures of short amphiphilic peptides.

  17. Force and time-dependent self-assembly, disruption and recovery of supramolecular peptide amphiphile nanofibers.

    Science.gov (United States)

    Dikecoglu, F Begum; Topal, Ahmet E; Ozkan, Alper D; Tekin, E Deniz; Tekinay, Ayse B; Guler, Mustafa O; Dana, Aykutlu

    2018-07-13

    Biological feedback mechanisms exert precise control over the initiation and termination of molecular self-assembly in response to environmental stimuli, while minimizing the formation and propagation of defects through self-repair processes. Peptide amphiphile (PA) molecules can self-assemble at physiological conditions to form supramolecular nanostructures that structurally and functionally resemble the nanofibrous proteins of the extracellular matrix, and their ability to reconfigure themselves in response to external stimuli is crucial for the design of intelligent biomaterials systems. Here, we investigated real-time self-assembly, deformation, and recovery of PA nanofibers in aqueous solution by using a force-stabilizing double-pass scanning atomic force microscopy imaging method to disrupt the self-assembled peptide nanofibers in a force-dependent manner. We demonstrate that nanofiber damage occurs at tip-sample interaction forces exceeding 1 nN, and the damaged fibers subsequently recover when the tip pressure is reduced. Nanofiber ends occasionally fail to reconnect following breakage and continue to grow as two individual nanofibers. Energy minimization calculations of nanofibers with increasing cross-sectional ellipticity (corresponding to varying levels of tip-induced fiber deformation) support our observations, with high-ellipticity nanofibers exhibiting lower stability compared to their non-deformed counterparts. Consequently, tip-mediated mechanical forces can provide an effective means of altering nanofiber integrity and visualizing the self-recovery of PA assemblies.

  18. 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.

    2013-01-01

    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

  19. Self-assembled M2L4 coordination cages : Synthesis and potential applications

    NARCIS (Netherlands)

    Schmidt, Andrea; Casini, Angela; Kuehn, Fritz E.

    2014-01-01

    Metal-mediated self-assemblies of the general formula MxLy (M = metal ion, L = ligand) have emerged as a promising research area of supramolecular chemistry because of their applicability in various fields such as molecular recognition, catalysis and drug delivery. The focus of this review is on

  20. Similarities in Self-Assembly of Proteins and Surfactants: an Attempt to Bridge the Gap

    NARCIS (Netherlands)

    Linden, van der E.; Venema, P.

    2007-01-01

    The area of surfactant self assembly has already received attention for more than half a century. Considerable progress has been made in regards to connecting the molecular properties to the assembly morphology and the phase behaviour, where a multitude of different (rather exotic) types of

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

    KAUST Repository

    Yu, Haizhou; Qiu, Xiaoyan; Moreno, Nicolas; Ma, Zengwei; Calo, Victor M.; Nunes, Suzana Pereira; Peinemann, Klaus-Viktor

    2015-01-01

    -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

  2. Opal-like Multicolor Appearance of Self-Assembled Photonic Array.

    Science.gov (United States)

    Arnon, Zohar A; Pinotsi, Dorothea; Schmidt, Matthias; Gilead, Sharon; Guterman, Tom; Sadhanala, Aditya; Ahmad, Shahab; Levin, Aviad; Walther, Paul; Kaminski, Clemens F; Fändrich, Marcus; Kaminski Schierle, Gabriele S; Adler-Abramovich, Lihi; Shimon, Linda J W; Gazit, Ehud

    2018-06-20

    Molecular self-assembly of short peptide building blocks leads to the formation of various material architectures that may possess unique physical properties. Recent studies had confirmed the key role of biaromaticity in peptide self-assembly, with the diphenylalanine (FF) structural family as an archetypal model. Another significant direction in the molecular engineering of peptide building blocks is the use of fluorenylmethoxycarbonyl (Fmoc) modification, which promotes the assembly process and may result in nanostructures with distinctive features and macroscopic hydrogel with supramolecular features and nanoscale order. Here, we explored the self-assembly of the protected, noncoded fluorenylmethoxycarbonyl-β,β-diphenyl-Ala-OH (Fmoc-Dip) amino acid. This process results in the formation of elongated needle-like crystals with notable aromatic continuity. By altering the assembly conditions, arrays of spherical particles were formed that exhibit strong light scattering. These arrays display vivid coloration, strongly resembling the appearance of opal gemstones. However, unlike the Rayleigh scattering effect produced by the arrangement of opal, the described optical phenomenon is attributed to Mie scattering. Moreover, by controlling the solution evaporation rate, i.e., the assembly kinetics, we were able to manipulate the resulting coloration. This work demonstrates a bottom-up approach, utilizing self-assembly of a protected amino acid minimal building block, to create arrays of organic, light-scattering colorful surfaces.

  3. Effect of linear alcohol molecular size on the self-assembly of fullerene whiskers

    International Nuclear Information System (INIS)

    Amer, Maher S.; Todd, T. Kyle; Busbee, John D.

    2011-01-01

    Highlights: → The longer the alcohol molecule, the shorter the length of the assembled whisker. → Interaction between alcohol and fullerene solvent is the key factor. → The stronger the alcohol/solvent interaction, the longer the whisker. - Abstract: The recent development of self-assembled fullerene whiskers and wires has created an enormous potential and resolved a serious challenge for utilizing such unique class of carbon material in advanced nano-scale, molecular-based electronic, optical, and thermal devices. In this paper we investigate, the self-assembly of C 60 molecules into one-dimensional whiskers using a series of linear alcohols H(CH 2 ) n OH, with n changing from 1 (methanol) to 3 (isopropyl alcohol), to elucidate the effect of alcohol molecular size on the size distribution of the self-assemble fullerene whiskers. Our results show that the length of the produced fullerene whiskers is affected by the molecular size of the alcohol used in the process. The crucial role played by solvent/alcohol interaction in the assembly process is discussed. In addition, Raman spectroscopy measurements support the notion that the self-assembled whiskers are primarily held by depletion forces and no evidence of fullerene polymerization was observed.

  4. Understanding the Elementary Steps in DNA Tile-Based Self-Assembly.

    Science.gov (United States)

    Jiang, Shuoxing; Hong, Fan; Hu, Huiyu; Yan, Hao; Liu, Yan

    2017-09-26

    Although many models have been developed to guide the design and implementation of DNA tile-based self-assembly systems with increasing complexity, the fundamental assumptions of the models have not been thoroughly tested. To expand the quantitative understanding of DNA tile-based self-assembly and to test the fundamental assumptions of self-assembly models, we investigated DNA tile attachment to preformed "multi-tile" arrays in real time and obtained the thermodynamic and kinetic parameters of single tile attachment in various sticky end association scenarios. With more sticky ends, tile attachment becomes more thermostable with an approximately linear decrease in the free energy change (more negative). The total binding free energy of sticky ends is partially compromised by a sequence-independent energy penalty when tile attachment forms a constrained configuration: "loop". The minimal loop is a 2 × 2 tetramer (Loop4). The energy penalty of loops of 4, 6, and 8 tiles was analyzed with the independent loop model assuming no interloop tension, which is generalizable to arbitrary tile configurations. More sticky ends also contribute to a faster on-rate under isothermal conditions when nucleation is the rate-limiting step. Incorrect sticky end contributes to neither the thermostability nor the kinetics. The thermodynamic and kinetic parameters of DNA tile attachment elucidated here will contribute to the future improvement and optimization of tile assembly modeling, precise control of experimental conditions, and structural design for error-free self-assembly.

  5. Nondeterministic self-assembly of two tile types on a lattice.

    Science.gov (United States)

    Tesoro, S; Ahnert, S E

    2016-04-01

    Self-assembly is ubiquitous in nature, particularly in biology, where it underlies the formation of protein quaternary structure and protein aggregation. Quaternary structure assembles deterministically and performs a wide range of important functions in the cell, whereas protein aggregation is the hallmark of a number of diseases and represents a nondeterministic self-assembly process. Here we build on previous work on a lattice model of deterministic self-assembly to investigate nondeterministic self-assembly of single lattice tiles and mixtures of two tiles at varying relative concentrations. Despite limiting the simplicity of the model to two interface types, which results in 13 topologically distinct single tiles and 106 topologically distinct sets of two tiles, we observe a wide variety of concentration-dependent behaviors. Several two-tile sets display critical behaviors in the form of a sharp transition from bound to unbound structures as the relative concentration of one tile to another increases. Other sets exhibit gradual monotonic changes in structural density, or nonmonotonic changes, while again others show no concentration dependence at all. We catalog this extensive range of behaviors and present a model that provides a reasonably good estimate of the critical concentrations for a subset of the critical transitions. In addition, we show that the structures resulting from these tile sets are fractal, with one of two different fractal dimensions.

  6. Deposition of metal Islands, metal clusters and metal containing single molecules on self-assembled monolayers

    NARCIS (Netherlands)

    Speets, Emiel Adrianus

    2005-01-01

    The central topic of this thesis is the deposition of metals on Self-Assembled Monolayers (SAMs). Metals are deposited in the form of submicron scale islands, nanometer scale clusters, and as supramolecular, organometallic coordination cages. Several SAMs on various substrates were prepared and

  7. DNA Self-Assembly and Computation Studied with a Coarse-grained Dynamic Bonded Model

    DEFF Research Database (Denmark)

    Svaneborg, Carsten; Fellermann, Harold; Rasmussen, Steen

    2012-01-01

    We utilize a coarse-grained directional dynamic bonding DNA model [C. Svaneborg, Comp. Phys. Comm. (In Press DOI:10.1016/j.cpc.2012.03.005)] to study DNA self-assembly and DNA computation. In our DNA model, a single nucleotide is represented by a single interaction site, and complementary sites can...

  8. Dynamics of decanethiol self-assembled monolayers on Au(111) studied by Scanning tunnelling microscopy

    NARCIS (Netherlands)

    Wu, Hairong; Sotthewes, Kai; Kumar, Avijit; Vancso, Gyula J.; Schön, Peter Manfred; Zandvliet, Henricus J.W.

    2013-01-01

    We investigated the dynamics of decanethiol self-assembled monolayers on Au(111) surfaces using time-resolved scanning tunneling microscopy at room temperature. The expected ordered phases (β, δ, χ*, and ) and a disordered phase (ε) were observed. Current–time traces with the feedback loop disabled

  9. Rapid Self-assembly of alpha-Synuclein Observed by In Situ Atomic Force Microscopy

    NARCIS (Netherlands)

    Hoyer, Wolfgang; Cherny, Dmitry; Subramaniam, Vinod; Jovin, Thomas M.

    2004-01-01

    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

  10. Determination of anisotropic dipole moments in self-assembled quantum dots using Rabi oscillations

    OpenAIRE

    Muller, A.; Wang, Q. Q.; Bianucci, P.; Xue, Q. K.; Shih, C. K.

    2004-01-01

    By investigating the polarization-dependent Rabi oscillations using photoluminescence spectroscopy, we determined the respective transition dipole moments of the two excited excitonic states |Ex> and |Ey> of a single self-assembled quantum dot that are nondegenerate due to shape anisotropy. We find that the ratio of the two dipole moments is close to the physical elongation ratio of the quantum dot.

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

    NARCIS (Netherlands)

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

    2006-01-01

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

  12. Transition voltages respond to synthetic reorientation of embedded dipoles in self-assembled monolayers

    NARCIS (Netherlands)

    Kovalchuk, Andrii; Abu-Husein, Tarek; Fracasso, Davide; Egger, David A.; Zojer, Egbert; Zharnikov, Michael; Terfort, Andreas; Chiechi, Ryan C.

    2016-01-01

    We studied the influence of embedded dipole moments in self-assembled monolayers (SAMs) formed on template stripped Au surfaces with liquid eutectic Ga-In alloy as a top electrode. We designed three molecules based on a p-terphenyl structure in which the central aromatic ring is either phenyl or a

  13. A new building block for DNA network formation by self-assembly and polymerase chain reaction.

    Science.gov (United States)

    Bußkamp, Holger; Keller, Sascha; Robotta, Marta; Drescher, Malte; Marx, Andreas

    2014-01-01

    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.

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...

  15. Out-of-equilibrium self-assembly approaches for new soft materials

    NARCIS (Netherlands)

    Hendriksen, W.E.

    2015-01-01

    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

  16. In situ microscopy of the self-assembly of branched nanocrystals in solution

    Science.gov (United States)

    Sutter, Eli; Sutter, Peter; Tkachenko, Alexei V.; Krahne, Roman; de Graaf, Joost; Arciniegas, Milena; Manna, Liberato

    2016-04-01

    Solution-phase self-assembly of nanocrystals into mesoscale structures is a promising strategy for constructing functional materials from nanoscale components. Liquid environments are key to self-assembly since they allow suspended nanocrystals to diffuse and interact freely, but they also complicate experiments. Real-time observations with single-particle resolution could have transformative impact on our understanding of nanocrystal self-assembly. Here we use real-time in situ imaging by liquid-cell electron microscopy to elucidate the nucleation and growth mechanism and properties of linear chains of octapod-shaped nanocrystals in their native solution environment. Statistical mechanics modelling based on these observations and using the measured chain-length distribution clarifies the relative importance of dipolar and entropic forces in the assembly process and gives direct access to the interparticle interaction. Our results suggest that monomer-resolved in situ imaging combined with modelling can provide unprecedented quantitative insight into the microscopic processes and interactions that govern nanocrystal self-assembly in solution.

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

    NARCIS (Netherlands)

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

    2014-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-03-15

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

  19. Self-assembly of polyhedral metal–organic framework particles into three-dimensional ordered superstructures

    NARCIS (Netherlands)

    Avci, Civan; Imaz, Inhar; Carné-Sánchez, Arnau; Pariente, Jose Angel; Tasios, Nikos; Pérez-Carvajal, Javier; Alonso, Maria Isabel; Blanco, Alvaro; Dijkstra, M.; López, Cefe; Maspoch, Daniel

    Self-assembly of particles into long-range, three-dimensional, ordered superstructures is crucial for the design of a variety of materials, including plasmonic sensing materials, energy or gas storage systems, catalysts and photonic crystals. Here, we have combined experimental and simulation data

  20. Selective intercalation of six ligands molecules in a self-assembled triple helix

    NARCIS (Netherlands)

    Mateos timoneda, Miguel; Kerckhoffs, J.M.C.A.; Reinhoudt, David; Crego Calama, Mercedes

    2007-01-01

    The addition of a ligand molecule to an artificial self-assembled triple helix leads to the selective intercalation of two hydrogen-bonded trimers in specific binding pockets. Furthermore, the triple helix suffers large conformational rearrangements in order to accommodate the ligand molecules in a

  1. Patterning functional materials using channel diffused plasma-etched self-assembled monolayer templates

    NARCIS (Netherlands)

    George, A.; Maijenburg, A.W.; Maas, M.G.; Blank, David H.A.; ten Elshof, Johan E.

    2011-01-01

    A simple and cost-effective methodology for large-area micrometer-scale patterning of a wide range of metallic and oxidic functional materials is presented. Self-assembled monolayers (SAM) of alkyl thiols on Au were micropatterned by channel-diffused oxygen plasma etching, a method in which selected

  2. Template-Directed Self-Assembly of Alkanethiol Monolayers: Selective Growth on Preexisting Monolayer Edges

    NARCIS (Netherlands)

    Sharpe, R.B.A.; Burdinski, Dirk; Huskens, Jurriaan; Zandvliet, Henricus J.W.; Reinhoudt, David; Poelsema, Bene

    2007-01-01

    Self-assembled monolayers were investigated for their suitability as two-dimensional scaffolds for the selective growth of alkanethiol edge structures. Heterostructures with chemical contrast could be grown, whose dimensions were governed by both the initial pattern sizes and the process time.

  3. Self-assembled diacetylene molecular wire polymerization on an insulating hexagonal boron nitride (0001) surface

    Czech Academy of Sciences Publication Activity Database

    Makarova, Marina; Okawa, Y.; Verveniotis, E.; Watanabe, K.; Taniguchi, T.; Joachim, Ch.; Aono, M.

    2016-01-01

    Roč. 27, č. 39 (2016), 1-8, č. článku 395303. ISSN 0957-4484 Institutional support: RVO:68378271 Keywords : molecular self-assembly * insulating substrate * molecular electronics * polydiacetylene Subject RIV: BJ - Thermodynamics Impact factor: 3.440, year: 2016

  4. Growth behaviour of twisted ribbons of barium carbonate/silica self-assembled ceramics

    International Nuclear Information System (INIS)

    Garcia-Ruiz, J.M.; Moreno, A.

    1997-01-01

    Twisted ribbons of self-assembled crystal aggregates of barium carbonate, in the presence of silicate ions at pH 9.5 grow at constant rate between 20 and 50 mu m/min. The morphological behaviour depends on temperature, while it was demonstrated to be independent of the viscosity of the growth environment. (Author) 7 refs

  5. A BPTTF-based self-assembled electron-donating triangle capable of C60 binding.

    Science.gov (United States)

    Goeb, Sébastien; Bivaud, Sébastien; Dron, Paul Ionut; Balandier, Jean-Yves; Chas, Marcos; Sallé, Marc

    2012-03-25

    A kinetically stable self-assembled redox-active triangle is isolated. The resulting electron-donating cavity, which incorporates three BPTTF units, exhibits a remarkable binding ability for electron-deficient C(60), supported by a favorable combination of structural and electronic features.

  6. Self assembled linear polymeric chains with tuneable semiflexibility using isotropic interactions

    Science.gov (United States)

    Abraham, Alex; Chatterji, Apratim

    2018-04-01

    We propose a two-body spherically symmetric (isotropic) potential such that particles interacting by the potential self-assemble into linear semiflexible polymeric chains without branching. By suitable control of the potential parameters, we can control the persistence length of the polymer and can even introduce a controlled number of branches. Thus we show how to achieve effective directional interactions starting from spherically symmetric potentials. The self-assembled polymers have an exponential distribution of chain lengths akin to what is observed for worm-like micellar systems. On increasing particle density, the polymeric chains self-organize to an ordered line-hexagonal phase where every chain is surrounded by six parallel chains, the transition is first order. On further increase in monomer density, the order is destroyed and we get a branched gel-like phase. This potential can be used to model semi-flexible equilibrium polymers with tunable semiflexibility and excluded volume. The use of the potential is computationally cheap and hence can be used to simulate and probe equilibrium polymer dynamics with long chains. The potential also gives a plausible method of tuning colloidal interactions in experiments such that one can obtain self-assembling polymeric chains made up of colloids and probe polymer dynamics using an optical microscope. Furthermore, we show how a modified potential leads to the observation of an intermediate nematic phase of self-assembled chains in between the low density disordered phase and the line-ordered hexagonal phase.

  7. Dynamic stability of nano-fibers self-assembled from short amphiphilic A6D peptides

    Science.gov (United States)

    Nikoofard, Narges; Maghsoodi, Fahimeh

    2018-04-01

    Self-assembly of A6D amphiphilic peptides in explicit water is studied by using coarse-grained molecular dynamics simulations. It is observed that the self-assembly of randomly distributed A6D peptides leads to the formation of a network of nano-fibers. Two other simulations with cylindrical nano-fibers as the initial configuration show the dynamic stability of the self-assembled nano-fibers. As a striking feature, notable fluctuations occur along the axes of the nano-fibers. Depending on the number of peptides per unit length of the nano-fiber, flat-shaped bulges or spiral shapes along the nano-fiber axis are observed at the fluctuations. Analysis of the particle distribution around the nano-fiber indicates that the hydrophobic core and the hydrophilic shell of the nano-structure are preserved in both simulations. The size of the deformations and their correlation times are different in the two simulations. This study gives new insights into the dynamics of the self-assembled nano-structures of short amphiphilic peptides.

  8. Optimization of the recombinant production and purification of a self-assembling peptide in Escherichia coli

    NARCIS (Netherlands)

    Rad-Malekshahi, Mazda; Flement, Matthias; Hennink, Wim E.; Mastrobattista, Enrico

    2014-01-01

    Background: Amphiphilic peptides are important building blocks to generate nanostructured biomaterials for drug delivery and tissue engineering applications. We have shown that the self-assembling peptide SA2 (Ac-AAVVLLLWEE) can be recombinantly produced in E. coli when fused to the small

  9. Rapid, Brushless Self-assembly of a PS-b-PDMS Block Copolymer for Nanolithography

    DEFF Research Database (Denmark)

    Rasappa, Sozaraj; Schulte, Lars; Borah, Dipu

    2014-01-01

    and antidot patterns after short solvo-thermal annealing. Unlike previous reports on this system, low temperature and short annealing time provide self-assembly in homogeneous thin films covering large substrate areas. This on-chip mask was then used for pattern transfer to the underlying silicon substrate...

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

    Directory of Open Access Journals (Sweden)

    Joaquín Calbo

    2018-01-01

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

  11. Self-Assembled Student Interactions in Undergraduate General Chemistry Clicker Classrooms

    Science.gov (United States)

    MacArthur, James R.; Jones, Loretta

    2013-01-01

    Student interviews, focus groups, and classroom observations were used in an exploratory study of the nature of student interactions in a large (300+ students) general chemistry course taught with clickers. These data suggest that students are self-assembling their learning environment: choosing ways in which to interact with one another during…

  12. Highly anisotropic optoelectronic properties of aligned films of self-assembled platinum molecular wires

    NARCIS (Netherlands)

    Debije, M.G.; Haas, de M.P.; Savenije, T.J.; Warman, J.M.; Fontana, M.; Stutzmann, N.; Caseri, W.R.; Smith, P.

    2003-01-01

    Self-assembled columns of alternating tetrachloro- and tetraalkylaminoplatinum moieties form stable, highly oriented, optically anisotropic films on a friction-deposited polytetrafluoroethylene surface (see Figure). Charge transport in the films is rapid (mobility =¿ca. 10–2 cm2¿V–1¿s–1) and highly

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

    Science.gov (United States)

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

    2017-02-10

    This research involves the rare utilisation of the kapok fibre (Ceiba pentandra) as a raw material for the fabrication of cellulose nanocrystal (CNC) and self-assembled CNC membranes. The isolation of CNC from Ceiba pentandra began with the extraction of cellulose via the chemical alkali extraction by using 5wt% NaOH, followed by the typical acidified bleaching method and, finally, the CNC production through acid hydrolysis with 60wt% H 2 SO 4 at the optimum time of 60min. The prepared CNC was then employed for the preparation of self-assembled membrane through the water suspension casting evaporation technique. The obtained CNC membrane was characterised in terms of its composition, crystallinity, thermal stability, as well as, structural and morphological features with the use of several techniques including FTIR, XRD, AFM, TEM, FESEM, and TGA. The FESEM and AFM analyses had illustrated the achievement of a self-assembled CNC membrane with a smooth surface and a well-distributed nano-porous structure, with the porosity of 52.82±7.79%. In addition, the findings proved that the self-assembled CNC membrane displayed good adsorption capability indicated by the recorded efficiency of 79% and 85% for 10mg/L and 5mg/L of methylene blue in an aqueous solution, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Formation of high-quality self-assembled monolayers of conjugated dithiols on gold : Base matters

    NARCIS (Netherlands)

    Valkenier, Hennie; Huisman, Everardus H.; Hal, Paul A. van; de Leeuw, Dagobert; Chiechi, Ryan C.; Hummelen, Jan C.

    2011-01-01

    This Article reports a systematic study on the formation of self-assembled monolayers (SAMs) of conjugated molecules for molecular electronic (ME) devices. We monitored the deprotection reaction of acetyl protected dithiols of oligophenylene ethynylenes (OPEs) in solution using two different bases

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

    Science.gov (United States)

    Xing, Pengyao; Zhao, Yanli

    2016-09-01

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

  16. Membranes Prepared by Self-assembly and Chelation Assisted Phase Inversion

    KAUST Repository

    Xie, Yihui

    2017-05-19

    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.

  17. Modeling Textural Processes during Self-Assembly of Plant-Based Chiral-Nematic Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Yogesh K. Murugesan

    2010-12-01

    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.

  18. Membranes Prepared by Self-assembly and Chelation Assisted Phase Inversion

    KAUST Repository

    Xie, Yihui; Sutisna, Burhannudin; Nunes, Suzana Pereira

    2017-01-01

    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.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    We present the first report on the effects of hydrostatic pressure on colloidally stabilized lipid nanoparticles enveloping inverse nonlamellar self-assemblies in their interiors. These internal self-assemblies were systematically tuned into bicontinuous cubic (Pn3m and Im3m), micellar cubic (Fd3...... the tolerance of lipid nanoparticles [cubosomes, hexosomes, micellar cubosomes, and emulsified microemulsions (EMEs)] for high pressures, confirming their robustness for various technological applications.......We present the first report on the effects of hydrostatic pressure on colloidally stabilized lipid nanoparticles enveloping inverse nonlamellar self-assemblies in their interiors. These internal self-assemblies were systematically tuned into bicontinuous cubic (Pn3m and Im3m), micellar cubic (Fd3m......), hexagonal (H2), and inverse micellar (L2) phases by regulating the lipid/oil ratio as the hydrostatic pressure was varied from atmospheric pressure to 1200 bar and back to atmospheric pressure. The effects of pressure on these lipid nanoparticles were compared with those on their equilibrium bulk...

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

    Science.gov (United States)

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

    2015-01-01

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

  1. Self-assembly of Archimedean tilings with enthalpically and entropically patchy polygons.

    Science.gov (United States)

    Millan, Jaime A; Ortiz, Daniel; van Anders, Greg; Glotzer, Sharon C

    2014-03-25

    Considerable progress in the synthesis of anisotropic patchy nanoplates (nanoplatelets) promises a rich variety of highly ordered two-dimensional superlattices. Recent experiments of superlattices assembled from nanoplates confirm the accessibility of exotic phases and motivate the need for a better understanding of the underlying self-assembly mechanisms. Here, we present experimentally accessible, rational design rules for the self-assembly of the Archimedean tilings from polygonal nanoplates. The Archimedean tilings represent a model set of target patterns that (i) contain both simple and complex patterns, (ii) are comprised of simple regular shapes, and (iii) contain patterns with potentially interesting materials properties. Via Monte Carlo simulations, we propose a set of design rules with general applicability to one- and two-component systems of polygons. These design rules, specified by increasing levels of patchiness, correspond to a reduced set of anisotropy dimensions for robust self-assembly of the Archimedean tilings. We show for which tilings entropic patches alone are sufficient for assembly and when short-range enthalpic interactions are required. For the latter, we show how patchy these interactions should be for optimal yield. This study provides a minimal set of guidelines for the design of anisostropic patchy particles that can self-assemble all 11 Archimedean tilings.

  2. Self-assembled diphenylalanine nanowires for cellular studies and sensor applications

    DEFF Research Database (Denmark)

    Sasso, Luigi; Vedarethinam, Indumathi; Emnéus, Jenny

    2012-01-01

    In this paper we present a series of experiments showing that vertical self-assembled diphenylalanine peptide nanowires (PNWs) are a suitable candidate material for cellular biosensing. We grew HeLa and PC12 cells onto PNW modified gold surfaces and observed no hindrance of cell growth caused by ...

  3. The self-assembly of redox active peptides: Synthesis and electrochemical capacitive behavior.

    Science.gov (United States)

    Piccoli, Julia P; Santos, Adriano; Santos-Filho, Norival A; Lorenzón, Esteban N; Cilli, Eduardo M; Bueno, Paulo R

    2016-05-01

    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.

  4. Gas sensing with self-assembled monolayer field-effect transistors

    NARCIS (Netherlands)

    Andringa, Anne-Marije; Spijkman, Mark-Jan; Smits, Edsger C. P.; Mathijssen, Simon G. J.; van Hal, Paul A.; Setayesh, Sepas; Willard, Nico P.; Borshchev, Oleg V.; Ponomarenko, Sergei A.; Blom, Paul W. M.; de Leeuw, Dago M.

    A new sensitive gas sensor based on a self-assembled monolayer field-effect transistor (SAMFET) was used to detect the biomarker nitric oxide. A SAMFET based sensor is highly sensitive because the analyte and the active channel are separated by only one monolayer. SAMFETs were functionalised for

  5. Programming Hierarchical Self-Assembly of Patchy Particles into Colloidal Crystals via Colloidal Molecules.

    Science.gov (United States)

    Morphew, Daniel; Shaw, James; Avins, Christopher; Chakrabarti, Dwaipayan

    2018-03-27

    Colloidal self-assembly is a promising bottom-up route to a wide variety of three-dimensional structures, from clusters to crystals. Programming hierarchical self-assembly of colloidal building blocks, which can give rise to structures ordered at multiple levels to rival biological complexity, poses a multiscale design problem. Here we explore a generic design principle that exploits a hierarchy of interaction strengths and employ this design principle in computer simulations to demonstrate the hierarchical self-assembly of triblock patchy colloidal particles into two distinct colloidal crystals. We obtain cubic diamond and body-centered cubic crystals via distinct clusters of uniform size and shape, namely, tetrahedra and octahedra, respectively. Such a conceptual design framework has the potential to reliably encode hierarchical self-assembly of colloidal particles into a high level of sophistication. Moreover, the design framework underpins a bottom-up route to cubic diamond colloidal crystals, which have remained elusive despite being much sought after for their attractive photonic applications.

  6. Metal selective co-ordinative self-assembly of π-donors

    Indian Academy of Sciences (India)

    Metal selective co-ordinative nanostructures were constructed by the supramolecular ... observed an anomalous binding of metal ion to the core sulphur groups causing redox changes in the TTF ... attention on metal-assisted co-ordinative self-assembly ..... M TTF-Py in 1:1 CHCl3: MeCN and (c) photographs showing visual.

  7. Single-Layer Pentacene Field-Effect Transistors Using Electrodes Modified With Self-assembled Monolayers

    NARCIS (Netherlands)

    Asadi, Kamal; Wu, Yu; Gholamrezaie, Fatemeh; Rudolf, Petra; Blom, Paul W. M.

    2009-01-01

    Pentacene field-effect transistor performance can be improved by modifying metal electrodes with self-assembled monolayers. The dominant role in performance is played by pentacene morphology rather than the work function of the modified electrodes. With optimized processing conditions,

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

    Science.gov (United States)

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

    2018-01-08

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-01

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

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

    KAUST Repository

    Junnila, Susanna; Houbenov, Nikolay; Karatzas, A.; Hadjichristidis, Nikolaos; Hirao, Akira; Iatrou, Hermis; Ikkala, Olli T.

    2012-01-01

    polypeptide-surfactant self-assemblies with β-sheet conformation in PS 2PLL(DS) and PS 2(PLL(DS)) 2 which dominate over the formation of block copolymer scale structures. Differences between the 3- and 4-arm systems illustrate how packing frustration between

  11. Unique Self-Assembly Patterns Based on the Thiacalix[4]arene-Silver Interactions

    Czech Academy of Sciences Publication Activity Database

    Sýkora, Jan; Himl, M.; Stibor, I.; Císařová, I.; Lhoták, P.

    2007-01-01

    Roč. 63, č. 10 (2007), s. 2244-2248 ISSN 0040-4020 Institutional research plan: CEZ:AV0Z40720504 Keywords : thiacalixarene * self-assembly * x-ray crystallography Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.869, year: 2007

  12. Film Self-Assembly of Oppositely Charged Macromolecules Triggered by Electrochemistry through a Morphogenic Approach.

    Science.gov (United States)

    Dochter, Alexandre; Garnier, Tony; Pardieu, Elodie; Chau, Nguyet Trang Thanh; Maerten, Clément; Senger, Bernard; Schaaf, Pierre; Jierry, Loïc; Boulmedais, Fouzia

    2015-09-22

    The development of new surface functionalization methods that are easy to use, versatile, and allow local deposition represents a real scientific challenge. Overcoming this challenge, we present here a one-pot process that consists in self-assembling, by electrochemistry on an electrode, films made of oppositely charged macromolecules. This method relies on a charge-shifting polyanion, dimethylmaleic-modified poly(allylamine) (PAHd), that undergoes hydrolysis at acidic pH, leading to an overall switching of its charge. When a mixture of the two polyanions, PAHd and poly(styrenesulfonate) (PSS), is placed in contact with an electrode, where the pH is decreased locally by electrochemistry, the transformation of PAHd into a polycation (PAH) leads to the continuous self-assembly of a nanometric PAH/PSS film by electrostatic interactions. The pH decrease is obtained by the electrochemical oxidation of hydroquinone, which produces protons locally over nanometric distances. Using a negatively charged enzyme, alkaline phosphatase (AP), instead of PSS, this one-pot process allows the creation of enzymatically active films. Under mild conditions, self-assembled PAH/AP films have an enzymatic activity which is adjustable simply by controlling the self-assembly time. The selective functionalization of microelectrode arrays by PAH/AP was achieved, opening the route toward miniaturized biosensors.

  13. Self-assembled block copolymer membranes: From basic research to large-scale manufacturing

    KAUST Repository

    Nunes, Suzana Pereira

    2013-09-24

    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.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  15. Facile preparation of luminescent and intelligent gold nanodots based on supramolecular self-assembly

    International Nuclear Information System (INIS)

    Shi Yunfeng; Li Sujuan; Zhou Yahui; Zhai Qingpan; Hu Mengyue; Cai Fensha; Du Jimin; Liang Jiamiao; Zhu Xinyuan

    2012-01-01

    A new strategy for preparing luminescent and intelligent gold nanodots based on supramolecular self-assembly is described in this paper. The supramolecular self-assembly was initiated through electrostatic interactions and ion pairing between palmitic acid and hyperbranched poly(ethylenimine). The resulting structures not only have the dynamic reversible properties of supramolecules but also possess torispherical and highly branched architectures. Thus they can be regarded as a new kind of ideal nanoreactor for preparing intelligent Au nanodots. By preparing Au nanodots within this kind of supramolecular self-assembly, the environmental sensitivity of intelligent polymers and the optical, electrical properties of Au nanodots can be combined, endowing the Au nanodots with intelligence. In this paper, a supramolecular self-assembly process based on dendritic poly(ethylenimine) and palmitic acid was designed and then applied to prepare fluorescent and size-controlled Au nanodots. The pH response of Au nanodots embodied by phase transfer from oil phase to water phase was also investigated. (paper)

  16. Self-assembling morphologies of symmetrical PS-b-PMMA in different sized confining grooves

    DEFF Research Database (Denmark)

    Chen, Wenhui; Luo, Jun; Shi, Peixiong

    2014-01-01

    Directed self-assembly (DSA), an emerging lithographic technique, has attracted increasing attention as a result of its advantages of low cost, high throughput and convenient processing. However, DSA still presents some challenges, such as the control of defects, the fabrication of complex patterns...

  17. Self-assembly strategies for the synthesis of functional nanostructured materials

    Science.gov (United States)

    Perego, M.; Seguini, G.

    2016-06-01

    Self-assembly is the autonomous organization of components into patterns or structures without human intervention. This is the approach followed by nature to generate living cells and represents one of the practical strategies to fabricate ensembles of nanostructures. In static self-assembly the formation of ordered structures could require energy but once formed the structures are stable. The introduction of additional regular features in the environment could be used to template the self-assembly guiding the organization of the components and determining the final structure they form. In this regard self-assembly of block copolymers represents a potent platform for fundamental studies at the nanoscale and for application-driven investigation as a tool to fabricate functional nanostructured materials. Block copolymers can hierarchically assemble into chemically distinct domains with size and periodicity on the order of 10nm or below, offering a potentially inexpensive route to generate large-area nanostructured materials. The final structure characteristics of these materials are dictated by the properties of the elementary block copolymers, like chain length, volume fraction or degree of block incompatibility. Modern synthetic chemistry offers the possibility to design these macromolecules with very specific length scales and geometries, directly embodying in the block copolymers the code that drives their self- assembling process. The understanding of the kinetics and thermodynamics of the block copolymer self-assembly process in the bulk phase as well as in thin films represents a fundamental prerequisite toward the exploitation of these materials. Incorporating block copolymer into device fabrication procedures or directly into devices, as active elements, will lead to the development of a new generation of devices fabricated using the fundamental law of nature to our advantage in order to minimize cost and power consumption in the fabrication process

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

    Science.gov (United States)

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

    2013-10-01

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

  19. Non-uniform self-assembly : On the anisotropic architecture of α-synuclein supra-fibrillar aggregates

    NARCIS (Netherlands)

    Semerdzhiev, Slav A.; Shvadchak, Volodymyr V.; Subramaniam, Vinod; Claessens, Mireille M.A.E.

    2017-01-01

    Although the function of biopolymer hydrogels in nature depends on structural anisotropy at mesoscopic length scales, the self-assembly of such anisotropic structures in vitro is challenging. Here we show that fibrils of the protein α-synuclein spontaneously self-assemble into structurally

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

    Science.gov (United States)

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

    2014-11-04

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

  1. Self-assembly of subwavelength nanostructures with symmetry breaking in solution

    Science.gov (United States)

    Tian, Xiang-Dong; Chen, Shu; Zhang, Yue-Jiao; Dong, Jin-Chao; Panneerselvam, Rajapandiyan; Zhang, Yun; Yang, Zhi-Lin; Li, Jian-Feng; Tian, Zhong-Qun

    2016-01-01

    Nanostructures with symmetry breaking can allow the coupling between dark and bright plasmon modes to induce strong Fano resonance. However, it is still a daunting challenge to prepare bottom-up self-assembled subwavelength asymmetric nanostructures with appropriate gaps between the nanostructures especially below 5 nm in solution. Here we present a viable self-assembly method to prepare symmetry-breaking nanostructures consisting of Ag nanocubes and Au nanospheres both with tunable size (90-250 nm for Au nanospheres; 100-160 nm for Ag nanocubes) and meanwhile control the nanogaps through ultrathin silica shells of 1-5 nm thickness. The Raman tag of 4-mercaptobenzoic acid (MBA) assists the self-assembly process and endows the subwavelength asymmetric nanostructures with surface-enhanced Raman scattering (SERS) activity. Moreover, thick silica shells (above 50 nm thickness) can be coated on the self-assembled nanostructures in situ to stabilize the whole nanostructures, paving the way toward bioapplications. Single particle scattering spectroscopy with a 360° polarization resolution is performed on individual Ag nanocube and Au nanosphere dimers, correlated with high-resolution TEM characterization. The asymmetric dimers exhibit strong configuration and polarization dependence Fano resonance properties. Overall, the solution-based self-assembly method reported here is opening up new opportunities to prepare diverse multicomponent nanomaterials with optimal performance.Nanostructures with symmetry breaking can allow the coupling between dark and bright plasmon modes to induce strong Fano resonance. However, it is still a daunting challenge to prepare bottom-up self-assembled subwavelength asymmetric nanostructures with appropriate gaps between the nanostructures especially below 5 nm in solution. Here we present a viable self-assembly method to prepare symmetry-breaking nanostructures consisting of Ag nanocubes and Au nanospheres both with tunable size (90-250 nm

  2. 21 CFR 886.1660 - Gonioscopic prism.

    Science.gov (United States)

    2010-04-01

    ... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior chamber. The device may have angled mirrors to facilitate visualization of anatomical features. (b...

  3. Structural Polymorphism in a Self-Assembled Tri-Aromatic Peptide System.

    Science.gov (United States)

    Brown, Noam; Lei, Jiangtao; Zhan, Chendi; Shimon, Linda J W; Adler-Abramovich, Lihi; Wei, Guanghong; Gazit, Ehud

    2018-04-24

    Self-assembly is a process of key importance in natural systems and in nanotechnology. Peptides are attractive building blocks due to their relative facile synthesis, biocompatibility, and other unique properties. Diphenylalanine (FF) and its derivatives are known to form nanostructures of various architectures and interesting and varied characteristics. The larger triphenylalanine peptide (FFF) was found to self-assemble as efficiently as FF, forming related but distinct architectures of plate-like and spherical nanostructures. Here, to understand the effect of triaromatic systems on the self-assembly process, we examined carboxybenzyl-protected diphenylalanine (z-FF) as a minimal model for such an arrangement. We explored different self-assembly conditions by changing solvent compositions and peptide concentrations, generating a phase diagram for the assemblies. We discovered that z-FF can form a variety of structures, including nanowires, fibers, nanospheres, and nanotoroids, the latter were previously observed only in considerably larger or co-assembly systems. Secondary structure analysis revealed that all assemblies possessed a β-sheet conformation. Additionally, in solvent combinations with high water ratios, z-FF formed rigid and self-healing hydrogels. X-ray crystallography revealed a "wishbone" structure, in which z-FF dimers are linked by hydrogen bonds mediated by methanol molecules, with a 2-fold screw symmetry along the c-axis. All-atom molecular dynamics (MD) simulations revealed conformations similar to the crystal structure. Coarse-grained MD simulated the assembly of the peptide into either fibers or spheres in different solvent systems, consistent with the experimental results. This work thus expands the building block library for the fabrication of nanostructures by peptide self-assembly.

  4. Swell Gels to Dumbbell Micelles: Construction of Materials and Nanostructure with Self-assembly

    Science.gov (United States)

    Pochan, Darrin

    2007-03-01

    Bionanotechnology, the emerging field of using biomolecular and biotechnological tools for nanostructure or nanotecnology development, provides exceptional opportunity in the design of new materials. Self-assembly of molecules is an attractive materials construction strategy due to its simplicity in application. By considering peptidic or charged synthetic polymer molecules in the bottom-up materials self-assembly design process, one can take advantage of inherently biomolecular attributes; intramolecular folding events, secondary structure, and electrostatic interactions; in addition to more traditional self-assembling molecular attributes such as amphiphilicty, to define hierarchical material structure and consequent properties. Several molecular systems will be discussed. Synthetic block copolymers with charged corona blocks can be assembled in dilute solution containing multivalent organic counterions to produce micelle structures such as toroids. These ring-like micelles are similar to the toroidal bundling of charged semiflexible biopolymers like DNA in the presence of multivalent counterions. Micelle structure can be tuned between toroids, cylinders, and disks simply by using different concentrations or molecular volumes of organic counterion. In addition, these charged blocks can consist of amino acids as monomers producing block copolypeptides. In addition to the above attributes, block copolypeptides provide the control of block secondary structure to further control self-assembly. Design strategies based on small (less than 24 amino acids) beta-hairpin peptides will be discussed. Self-assembly of the peptides is predicated on an intramolecular folding event caused by desired solution properties. Importantly, the intramolecular folding event impart a molecular-level mechanism for environmental responsiveness at the material level (e.g. infinite change in viscosity of a solution to a gel with changes in pH, ionic strength, temperature).

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

    KAUST Repository

    Junnila, Susanna

    2012-03-27

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

  6. Selection of conformational states in surface self-assembly for a molecule with eight possible pairs of surface enantiomers

    DEFF Research Database (Denmark)

    Nuermaimaiti, Ajiguli; Schultz-Falk, Vickie; Lind Cramer, Jacob

    2016-01-01

    Self-assembly of a molecule with many distinct conformational states, resulting in eight possible pairs of surface enantiomers, is investigated on a Au(111) surface under UHV conditions. The complex molecule is equipped with alkyl and carboxyl moieties to promote controlled self-assembly of lamel......Self-assembly of a molecule with many distinct conformational states, resulting in eight possible pairs of surface enantiomers, is investigated on a Au(111) surface under UHV conditions. The complex molecule is equipped with alkyl and carboxyl moieties to promote controlled self......-assembly of lamellae structures. From statistical analysis of Scanning Tunnelling Microscopy (STM) data we observe a clear selection of specific conformational states after self-assembly. Using Density Functional Theory (DFT) calculations we rationalise how this selection is correlated to the orientation of the alkyl...

  7. Self-assembly strategies for the synthesis of functional nanostructured materials

    International Nuclear Information System (INIS)

    Perego, M.; Seguini, G.

    2016-01-01

    Self-assembly is the autonomous organization of components into patterns or structures without human intervention. This is the approach followed by nature to generate living cells and represents one of the practical strategies to fabricate ensembles of nanostructures. In static self-assembly the formation of ordered structures could require energy but once formed the structures are stable. The introduction of additional regular features in the environment could be used to template the self-assembly guiding the organization of the components and determining the final structure they form. In this regard self-assembly of block copolymers represents a potent platform for fundamental studies at the nanoscale and for application-driven investigation as a tool to fabricate functional nanostructured materials. Block copolymers can hierarchically assemble into chemically distinct domains with size and periodicity on the order of 10 nm or below, offering a potentially inexpensive route to generate large-area nanostructured materials. The final structure characteristics of these materials are dictated by the properties of the elementary block copolymers, like chain length, volume fraction or degree of block incompatibility. Modern synthetic chemistry offers the possibility to design these macromolecules with very specific length scales and geometries, directly embodying in the block copolymers the code that drives their self- assembling process. The understanding of the kinetics and thermodynamics of the block copolymer selfassembly process in the bulk phase as well as in thin films represents a fundamental prerequisite toward the exploitation of these materials. Incorporating block copolymer into device fabrication procedures or directly into devices, as active elements, will lead to the development of a new generation of devices fabricated using the fundamental law of nature to our advantage in order to minimize cost and power consumption in the fabrication process

  8. Biomimetic Layer-by-Layer Self-Assembly of Nanofilms, Nanocoatings, and 3D Scaffolds for Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Shichao Zhang

    2018-06-01

    Full Text Available Achieving surface design and control of biomaterial scaffolds with nanometer- or micrometer-scaled functional films is critical to mimic the unique features of native extracellular matrices, which has significant technological implications for tissue engineering including cell-seeded scaffolds, microbioreactors, cell assembly, tissue regeneration, etc. Compared with other techniques available for surface design, layer-by-layer (LbL self-assembly technology has attracted extensive attention because of its integrated features of simplicity, versatility, and nanoscale control. Here we present a brief overview of current state-of-the-art research related to the LbL self-assembly technique and its assembled biomaterials as scaffolds for tissue engineering. An overview of the LbL self-assembly technique, with a focus on issues associated with distinct routes and driving forces of self-assembly, is described briefly. Then, we highlight the controllable fabrication, properties, and applications of LbL self-assembly biomaterials in the forms of multilayer nanofilms, scaffold nanocoatings, and three-dimensional scaffolds to systematically demonstrate advances in LbL self-assembly in the field of tissue engineering. LbL self-assembly not only provides advances for molecular deposition but also opens avenues for the design and development of innovative biomaterials for tissue engineering.

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

    Science.gov (United States)

    Sebastian, H Bri; Bryant, Steven L

    2017-06-15

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

  10. Effect of cationic/anionic organic surfactants on evaporation induced self assembled tin oxide nanostructured films

    International Nuclear Information System (INIS)

    Khun Khun, Kamalpreet; Mahajan, Aman; Bedi, R.K.

    2011-01-01

    Tin oxide nanostructures with well defined morphologies have been obtained through an evaporation induced self assembly process. The technique has been employed using an ultrasonic nebulizer for production of aersol and its subsequent deposition onto a heated glass substrate. The precursor used for aersol production was modified by introducing cationic and anionic surfactants namely cetyl trimethyl ammonium bromide and sodium dodecyl sulphate respectively. The effect of surfactants on the structural, electrical and optical properties of self assembled tin oxide nanostructures were investigated by using X-ray diffraction, field emission scanning electroscope microscopy, two probe technique and photoluminiscence studies. The results reveal that high concentration of surfactants in the precursor solution leads to reduction in crystallite size with significant changes in the morphology of tin oxide nanostructures. Photoluminiscence studies of the nanostructures show emissions in the visible region which exhibit marked changes in the intensities upon variation of surfactants in the precursor solutions.

  11. Effect of cationic/anionic organic surfactants on evaporation induced self assembled tin oxide nanostructured films

    Energy Technology Data Exchange (ETDEWEB)

    Khun Khun, Kamalpreet [Material Science Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Mahajan, Aman, E-mail: dramanmahajan@yahoo.co.in [Material Science Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Bedi, R.K. [Material Science Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

    2011-01-15

    Tin oxide nanostructures with well defined morphologies have been obtained through an evaporation induced self assembly process. The technique has been employed using an ultrasonic nebulizer for production of aersol and its subsequent deposition onto a heated glass substrate. The precursor used for aersol production was modified by introducing cationic and anionic surfactants namely cetyl trimethyl ammonium bromide and sodium dodecyl sulphate respectively. The effect of surfactants on the structural, electrical and optical properties of self assembled tin oxide nanostructures were investigated by using X-ray diffraction, field emission scanning electroscope microscopy, two probe technique and photoluminiscence studies. The results reveal that high concentration of surfactants in the precursor solution leads to reduction in crystallite size with significant changes in the morphology of tin oxide nanostructures. Photoluminiscence studies of the nanostructures show emissions in the visible region which exhibit marked changes in the intensities upon variation of surfactants in the precursor solutions.

  12. Novel alternating polymer adsorption/surface activation self-assembled film based on hydrogen bond

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yongjun; Yang Shuguang; Guan Ying; Miao Xiaopeng; Cao Weixiao; Xu Jian

    2003-08-01

    By combining hydrogen bonding layer-by-layer self-assembly and the stepwise chemisorption method, a new alternating polymer adsorption/surface activation self-assembly method was developed. First a layer of diphenylamine-4-diazonium-formaldehyde resin (diazo resin or DR) is deposited on a substrate. In the following surface activation step, the diazonium groups on the surface couple with resorcin in the outside solution. The deposition of another layer of DR is feasible due to the formation of hydrogen bond between the diazonium group of DR and the hydroxy group of the resorcin moieties. The resulting film is photosensitive. After UV irradiation, the film becomes very stable towards polar organic solvents.

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

    KAUST Repository

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

    2015-01-01

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  15. Block copolymer self-assembly-directed synthesis of mesoporous gyroidal superconductors.

    Science.gov (United States)

    Robbins, Spencer W; Beaucage, Peter A; Sai, Hiroaki; Tan, Kwan Wee; Werner, Jörg G; Sethna, James P; DiSalvo, Francis J; Gruner, Sol M; Van Dover, Robert B; Wiesner, Ulrich

    2016-01-01

    Superconductors with periodically ordered mesoporous structures are expected to have properties very different from those of their bulk counterparts. Systematic studies of such phenomena to date are sparse, however, because of a lack of versatile synthetic approaches to such materials. We demonstrate the formation of three-dimensionally continuous gyroidal mesoporous niobium nitride (NbN) superconductors from chiral ABC triblock terpolymer self-assembly-directed sol-gel-derived niobium oxide with subsequent thermal processing in air and ammonia gas. Superconducting materials exhibit a critical temperature (T c) of about 7 to 8 K, a flux exclusion of about 5% compared to a dense NbN solid, and an estimated critical current density (J c) of 440 A cm(-2) at 100 Oe and 2.5 K. We expect block copolymer self-assembly-directed mesoporous superconductors to provide interesting subjects for mesostructure-superconductivity correlation studies.

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

    Science.gov (United States)

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

    2016-08-01

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

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

    KAUST Repository

    Zhang, Ye

    2015-02-19

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

  18. Coevolutionary constraints in the sequence-space of macromolecular complexes reflect their self-assembly pathways.

    Science.gov (United States)

    Mallik, Saurav; Kundu, Sudip

    2017-07-01

    Is the order in which biomolecular subunits self-assemble into functional macromolecular complexes imprinted in their sequence-space? Here, we demonstrate that the temporal order of macromolecular complex self-assembly can be efficiently captured using the landscape of residue-level coevolutionary constraints. This predictive power of coevolutionary constraints is irrespective of the structural, functional, and phylogenetic classification of the complex and of the stoichiometry and quaternary arrangement of the constituent monomers. Combining this result with a number of structural attributes estimated from the crystal structure data, we find indications that stronger coevolutionary constraints at interfaces formed early in the assembly hierarchy probably promotes coordinated fixation of mutations that leads to high-affinity binding with higher surface area, increased surface complementarity and elevated number of molecular contacts, compared to those that form late in the assembly. Proteins 2017; 85:1183-1189. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  19. Highly ordered self-assembling polymer/clay nanocomposite barrier film.

    Science.gov (United States)

    Cook, Ray; Chen, Yihong; Beall, Gary W

    2015-05-27

    Efforts to mimic complex-structured biologically based materials such as abalone shell have occupied substantial research time and effort in science and engineering. The majority of the efforts involve tedious and expensive techniques and processes. Layer-by-layer (LBL) is one such technique that can produce materials with quite unique physical properties, approaching, and in some cases surpassing, those seen in nature. The LBL technique, however, is quite tedious and difficult to implement commercially. We report here the discovery of an organic/inorganic spontaneous self-assembling system that forms a highly structured nanocomposite. The driving force behind this self-assembly appears to be entropy. This discovery should open up completely new avenues to designing hierarchical composites and structures. The films have been studied by X-ray diffraction and the barrier properties for oxygen diffusion measured.

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

    Science.gov (United States)

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

    2009-12-01

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

  1. Change of cobalt magnetic anisotropy and spin polarization with alkanethiolates self-assembled monolayers

    International Nuclear Information System (INIS)

    Campiglio, Paolo; Breitwieser, Romain; Repain, Vincent; Guitteny, Solène; Chacon, Cyril; Bellec, Amandine; Lagoute, Jérôme; Girard, Yann; Rousset, Sylvie; Sassella, Adele; Imam, Mighfar; Narasimhan, Shobhana

    2015-01-01

    We demonstrate that the deposition of a self-assembled monolayer of alkanethiolates on a 1 nm thick cobalt ultrathin film grown on Au(111) induces a spin reorientation transition from in-plane to out-of-plane magnetization. Using ab initio calculations, we show that a methanethiolate layer changes slightly both the magnetocrystalline and shape anisotropy, both effects almost cancelling each other out for a 1 nm Co film. Finally, the change in hysteresis cycles upon alkanethiolate adsorption could be assigned to a molecular-induced roughening of the Co layer, as shown by STM. In addition, we calculate how a methanethiolate layer modifies the spin density of states of the Co layer and we show that the spin polarization at the Fermi level through the organic layer is reversed as compared to the uncovered Co. These results give new theoretical and experimental insights for the use of thiol-based self-assembled monolayers in spintronic devices. (paper)

  2. Time lapse microscopy of temperature control during self-assembly of 3D DNA crystals

    Science.gov (United States)

    Conn, Fiona W.; Jong, Michael Alexander; Tan, Andre; Tseng, Robert; Park, Eunice; Ohayon, Yoel P.; Sha, Ruojie; Mao, Chengde; Seeman, Nadrian C.

    2017-10-01

    DNA nanostructures are created by exploiting the high fidelity base-pairing interactions of double-stranded branched DNA molecules. These structures present a convenient medium for the self-assembly of macroscopic 3D crystals. In some self-assemblies in this system, crystals can be formed by lowering the temperature, and they can be dissolved by raising it. The ability to monitor the formation and melting of these crystals yields information that can be used to monitor crystal formation and growth. Here, we describe the development of an inexpensive tool that enables direct observation of the crystal growth process as a function of both time and temperature. Using the hanging-drop crystallization of the well-characterized 2-turn DNA tensegrity triangle motif for our model system, its response to temperature has been characterized visually.

  3. Self-Assembly of Narrowly Dispersed Brush Diblock Copolymers with Domain Spacing more than 100 nm

    Science.gov (United States)

    Gu, Weiyin; Sveinbjornsson, Benjamin; Hong, Sung Woo; Grubbs, Robert; Russell, Thomas

    2012-02-01

    Self-assembled structures of high molecular weight (MW), narrow molecular weight distribution brush block copolymers containing polylactic acid (PLA) and polystyrene (PS) side chains with similar MWs were studied in both the melt and thin films. The polynorbornene-backbone-based brush diblock copolymers containing approximately equal volume fractions of each block self-assembled into highly ordered lamellae with domain spacing over 100 nm, as revealed by SAXS, GISAXS and AFM. The domain size increased approximately linearly with backbone length, which indicated an extended conformation of the backbone in the ordered state. The length of side chains also played a significant role in terms of controlling the domain size. As the degree of polymerization (DP) increased, the symmetric brush diblock copolymers with longer side chains tended to form larger lamellar microdomains in comparison to those that have the same DP but shorter side chains.

  4. Biomineralization of a Self-assembled, Soft-Matrix Precursor: Enamel

    Science.gov (United States)

    Snead, Malcolm L.

    2015-04-01

    Enamel is the bioceramic covering of teeth, a composite tissue composed of hierarchical organized hydroxyapatite crystallites fabricated by cells under physiologic pH and temperature. Enamel material properties resist wear and fracture to serve a lifetime of chewing. Understanding the cellular and molecular mechanisms for enamel formation may allow a biology-inspired approach to material fabrication based on self-assembling proteins that control form and function. A genetic understanding of human diseases exposes insight from nature's errors by exposing critical fabrication events that can be validated experimentally and duplicated in mice using genetic engineering to phenocopy the human disease so that it can be explored in detail. This approach led to an assessment of amelogenin protein self-assembly that, when altered, disrupts fabrication of the soft enamel protein matrix. A misassembled protein matrix precursor results in loss of cell-to-matrix contacts essential to fabrication and mineralization.

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

    International Nuclear Information System (INIS)

    Cohen, Erez; Weissman, Haim; Rybtchinski, Boris; Shimoni, Eyal; Kaplan-Ashiri, Ifat; Werle, Kai; Wohlleben, Wendel

    2017-01-01

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

  6. Self-Assembly of Microscale Parts through Magnetic and Capillary Interactions

    Directory of Open Access Journals (Sweden)

    Madan Dubey

    2011-03-01

    Full Text Available Self-assembly is a promising technique to overcome fundamental limitations with integrating, packaging, and general handling of individual electronic-related components with characteristic lengths significantly smaller than 1 mm. Here we describe the use of magnetic and capillary forces to self-assemble 280 µm sized silicon building blocks into interconnected structures which approach a three-dimensional crystalline configuration. Integrated permanent magnet microstructures provided magnetic forces, while a low-melting-point solder alloy provided capillary forces. A finite element model of forces between the magnetic features demonstrated the utility of magnetic forces at this size scale. Despite a slight departure from designed dimensions in the actual fabricated parts, the combination of magnetic and capillary forces improved the assembly yield to 8%, over approximately 0.1% achieved previously with capillary forces alone.

  7. Kinetics of directed self-assembly of block copolymers on chemically patterned substrates

    International Nuclear Information System (INIS)

    Müller, Marcus; Li, Weihua; Rey, Juan Carlos Orozco; Welling, Ulrich

    2015-01-01

    Chemically patterned surfaces have been successfully employed to direct the kinetics of self-assembly of block copolymers into dense, periodic morphologies (”chemoepitaxy”). Significant efforts have been directed towards understanding the kinetics of structure formation and, particularly, the formation and annihilation of defects. In the present manuscript we use computer simulations of a soft, coarse-grained polymer model to study the kinetics of structure formation of lamellar-forming block copolymer thin films on a chemical pattern of lines and spaces. The case where the copolymer material replicates the surface pattern and the more subtle scenario of sparse guiding patterns are considered. Our simulation results highlight (1) the importance of the early stages of pattern-directed self-assembly that template the subsequent morphology and (2) the dependence of the free-energy landscape on the incompatibility between the two blocks of the copolymer. (paper)

  8. Photonic Resins: Designing Optical Appearance via Block Copolymer Self-Assembly.

    Science.gov (United States)

    Song, Dong-Po; Jacucci, Gianni; Dundar, Feyza; Naik, Aditi; Fei, Hua-Feng; Vignolini, Silvia; Watkins, James J

    2018-03-27

    Despite a huge variety of methodologies having been proposed to produce photonic structures by self-assembly, the lack of an effective fabrication approach has hindered their practical uses. These approaches are typically limited by the poor control in both optical and mechanical properties. Here we report photonic thermosetting polymeric resins obtained through brush block copolymer (BBCP) self-assembly. We demonstrate that the control of the interplay between order and disorder in the obtained photonic structure offers a powerful tool box for designing the optical appearance of the polymer resins in terms of reflected wavelength and scattering properties. The obtained materials exhibit excellent mechanical properties with hardness up to 172 MPa and Young's modulus over 2.9 GPa, indicating great potential for practical uses as photonic coatings on a variety of surfaces.

  9. Crystal-Structure-Guided Design of Self-Assembling RNA Nanotriangles.

    Science.gov (United States)

    Boerneke, Mark A; Dibrov, Sergey M; Hermann, Thomas

    2016-03-14

    RNA nanotechnology uses RNA structural motifs to build nanosized architectures that assemble through selective base-pair interactions. Herein, we report the crystal-structure-guided design of highly stable RNA nanotriangles that self-assemble cooperatively from short oligonucleotides. The crystal structure of an 81 nucleotide nanotriangle determined at 2.6 Å resolution reveals the so-far smallest circularly closed nanoobject made entirely of double-stranded RNA. The assembly of the nanotriangle architecture involved RNA corner motifs that were derived from ligand-responsive RNA switches, which offer the opportunity to control self-assembly and dissociation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Exploring single chain amphiphile self-assembly and their possible roles in light transduction

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain

    2011-01-01

    Self-assembled structures of single-chain amphiphiles have been used as hosts for biochemical, and chemical reactions. Their use as models for protocells (i.e., precursors to the first biological cells) has been extensively researched by various groups because the availability of single chain......: the medium composition in terms of ionic strengths and the medium physical parameters, such as temperature, significantly influence the formation of structures, as well as their subsequent stability. In addition, membranes composed of a single amphiphile type seem to be implausible as no potential amphiphile...... 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...

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

    DEFF Research Database (Denmark)

    Shillcock, J. C.

    2012-01-01

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

  12. Polymorphism in Self-Assembled Structures of 9-Anthracene Carboxylic Acid on Ag(111

    Directory of Open Access Journals (Sweden)

    Bo Xu

    2012-06-01

    Full Text Available Surface self-assembly process of 9-anthracene carboxylic acid (AnCA on Ag(111 was investigated using STM. Depending on the molecular surface density, four spontaneously formed and one annealed AnCA ordered phases were observed, namely a straight belt phase, a zigzag double-belt phase, two simpler dimer phases, and a kagome phase. The two high-density belt phases possess large unit cells on the scale length of 10 nm, which are seldom observed in molecular self-assembled structures. This structural diversity stems from a complicated competition of different interactions of AnCA molecules on metal surface, including intermolecular and molecular-substrate interactions, as well as the steric demand from high molecular surface density.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-02-13

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

  14. Interplay between spherical confinement and particle shape on the self-assembly of rounded cubes.

    Science.gov (United States)

    Wang, Da; Hermes, Michiel; Kotni, Ramakrishna; Wu, Yaoting; Tasios, Nikos; Liu, Yang; de Nijs, Bart; van der Wee, Ernest B; Murray, Christopher B; Dijkstra, Marjolein; van Blaaderen, Alfons

    2018-06-08

    Self-assembly of nanoparticles (NPs) inside drying emulsion droplets provides a general strategy for hierarchical structuring of matter at different length scales. The local orientation of neighboring crystalline NPs can be crucial to optimize for instance the optical and electronic properties of the self-assembled superstructures. By integrating experiments and computer simulations, we demonstrate that the orientational correlations of cubic NPs inside drying emulsion droplets are significantly determined by their flat faces. We analyze the rich interplay of positional and orientational order as the particle shape changes from a sharp cube to a rounded cube. Sharp cubes strongly align to form simple-cubic superstructures whereas rounded cubes assemble into icosahedral clusters with additionally strong local orientational correlations. This demonstrates that the interplay between packing, confinement and shape can be utilized to develop new materials with novel properties.

  15. Influence of topographically patterned angled guidelines on directed self-assembly of block copolymers

    Science.gov (United States)

    Rebello, Nathan; Sethuraman, Vaidyanathan; Blachut, Gregory; Ellison, Christopher J.; Willson, C. Grant; Ganesan, Venkat

    2017-11-01

    Single chain in mean-field Monte Carlo simulations were employed to study the self-assembly of block copolymers (BCP) in thin films that use trapezoidal guidelines to direct the orientation and alignment of lamellar patterns. The present study explored the influence of sidewall interactions and geometry of the trapezoidal guidelines on the self-assembly of perpendicularly oriented lamellar morphologies. When both the sidewall and the top surface exhibit preferential interactions to the same block of the BCP, trapezoidal guidelines with intermediate taper angles were found to result in less defective perpendicularly orientated morphologies. Similarly, when the sidewall and top surface are preferential to distinct blocks of the BCP, intermediate tapering angles were found to be optimal in promoting defect free structures. Such results are rationalized based on the energetics arising in the formation of perpendicularly oriented lamella on patterned substrates.

  16. Kinetic Effects in the Self-Assembly of Pure and Mixed Tetradecyland Octadecylamine Molecules on Mica

    Energy Technology Data Exchange (ETDEWEB)

    Benitez, J.J.; Salmeron, M.

    2005-09-21

    The self-assembly of tetradecylamine (C14) and of mixtures of tetradecyl and octadecylamine (C18) molecules from chloroform solutions on mica has been studied using atomic force microscopy(AFM). For pure components self-assembly proceeds more slowly for C14 than for C18. In both cases after equilibrium is reached islands of tilted molecules cover a similar fraction of the surface. Images of films formed by mixtures of molecules acquired before equilibrium is reached (short ripening time at room temperature) show only islands with the height corresponding to C18 with many pores. After a long ripening time, when equilibrium is reached, islands of segregated pure components are formed.

  17. Self-assembled bilayers based on organothiol and organotrimethoxysilane on zinc platform

    International Nuclear Information System (INIS)

    Berger, Francois; Delhalle, Joseph; Mekhalif, Zineb

    2010-01-01

    This study describes the formation of a bilayer system developed on electrodeposited zinc. In a first step, a monolayer of 11-mercapto-1-undecanol is grafted on zinc, optimization of the conditions of elaboration have been performed. In a second step, organotrimethoxysilane have been grafted on the zinc modified with the hydroxyl terminated self-assembled monolayer (SAM) to finalize the bilayer system. X-ray photoelectron spectroscopy (XPS), polarization modulation-infrared reflection absorption spectroscopy (PM-IRRAS) and contact angle measurements are used to characterize each step of modification. An electrochemical evaluation of the different created systems is carried out by linear sweep voltammetry (LSV), cyclic voltammetry (CV) and scanning vibrating electrode technique (SVET). The impact of the modification of zinc using SAM and self-assembled bilayer (SAB) on the electrochemical activity of the surface is highlighted.

  18. Nonequilibrium carrier dynamics in self-assembled InGaAs quantum dots

    International Nuclear Information System (INIS)

    Wesseli, M.; Ruppert, C.; Trumm, S.; Betz, M.; Krenner, H.J.; Finley, J.J.

    2006-01-01

    Carrier dynamics in InGaAs/GaAs quantum dots is analyzed with highly sensitive femtosecond transmission spectroscopy. In a first step, measurements on a large ensemble of nanoislands reveal the dynamical electronic filling of quantum dots from the surrounding wetting layer. Most interestingly, we find a spin-preserving phonon mediated scattering into fully localized states within a few picoseconds. Then, individual artificial atoms are isolated with metallic shadow masks. For the first time, a single self-assembled quantum dot is addressed in an ultrafast transmission experiment. We find bleaching signals in the order of 10 -5 that arise from individual interband transitions of one quantum dot. As a result, we have developed an ultrafast optical tool for both manipulation and read-out of a single self-assembled quantum dot. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Microsecond MD Simulations of Nano-patterned Polymer Brushes on Self-Assembled Monolayers

    Science.gov (United States)

    Buie, Creighton; Qiu, Liming; Cheng, Kwan; Park, Soyeun

    2010-03-01

    Nano-patterned polymer brushes end-grafted onto self-assembled monolayers have gained increasing research interests due to their unique thermodynamic properties and their chemical and biomedical applications in colloids, biosensing and tissue engineering. So far, the interactions between the polymer brushes with the surrounding environments such as the floor and solvent at the nanometer length scale and microsecond time scale are still difficult to obtained experimentally and computationally. Using a Coarse-Grained MD approach, polymer brushes of different monomeric lengths, grafting density and hydrophobicity of the monomers grafted on self-assembled monolayers and in explicit solvent were studied. Molecular level information, such as lateral diffusion, transverse height and volume contour of the brushes, were calculated from our microsecond-MD simulations. Our results demonstrated the significance of the hydration of the polymer in controlling the conformational arrangement of the polymer brushes.

  20. Characterization of iron surface modified by 2-mercaptobenzothiazole self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Feng Yuanyuan [Department of Chemistry, Shandong University, Jinan 250100 (China); Chen Shenhao [Department of Chemistry, Shandong University, Jinan 250100 (China) and State Key Laboratory for Corrosion and Protection, Shenyang 110016 (China)]. E-mail: shchen@sdu.edu.cn; Zhang Honglin [Department of Chemistry, Qufu Normal University, Qufu 273165 (China); Li Ping [Department of Chemistry, Shandong University, Jinan 250100 (China); Wu Ling [Department of Chemistry, Shandong University, Jinan 250100 (China); Guo Wenjuan [Department of Chemistry, Shandong University, Jinan 250100 (China)

    2006-12-30

    A self-assembled monolayer of 2-mercaptobenzothiazole (MBT) adsorbed on the iron surface was prepared. The films were characterized by electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared reflection spectroscopy (FT-IR) and scanning electron microscopy (SEM). Besides, the microcalorimetry method was utilized to study the self-assembled process on iron surface and the adsorption mechanism was discussed from the power-time curve. The results indicated that MBT was able to form a film spontaneously on iron surface and the presence of it could protect iron from corrosion effectively. However, the assembling time and the concentration influence the protection efficiency. Quantum chemical calculations, according to which adsorption mechanism was discussed, could explain the experimental results to some extent.

  1. Directing reaction pathways by catalyst active-site selection using self-assembled monolayers.

    Science.gov (United States)

    Pang, Simon H; Schoenbaum, Carolyn A; Schwartz, Daniel K; Medlin, J Will

    2013-01-01

    One key route for controlling reaction selectivity in heterogeneous catalysis is to prepare catalysts that exhibit only specific types of sites required for desired product formation. Here we show that alkanethiolate self-assembled monolayers with varying surface densities can be used to tune selectivity to desired hydrogenation and hydrodeoxygenation products during the reaction of furfural on supported palladium catalysts. Vibrational spectroscopic studies demonstrate that the selectivity improvement is achieved by controlling the availability of specific sites for the hydrogenation of furfural on supported palladium catalysts through the selection of an appropriate alkanethiolate. Increasing self-assembled monolayer density by controlling the steric bulk of the organic tail ligand restricts adsorption on terrace sites and dramatically increases selectivity to desired products furfuryl alcohol and methylfuran. This technique of active-site selection simultaneously serves both to enhance selectivity and provide insight into the reaction mechanism.

  2. Designing spatial correlation of quantum dots: towards self-assembled three-dimensional structures

    International Nuclear Information System (INIS)

    Bortoleto, J R R; Zelcovit, J G; Gutierrez, H R; Bettini, J; Cotta, M A

    2008-01-01

    Buried two-dimensional arrays of InP dots were used as a template for the lateral ordering of self-assembled quantum dots. The template strain field can laterally organize compressive (InAs) as well as tensile (GaP) self-assembled nanostructures in a highly ordered square lattice. High-resolution transmission electron microscopy measurements show that the InAs dots are vertically correlated to the InP template, while the GaP dots are vertically anti-correlated, nucleating in the position between two buried InP dots. Finite InP dot size effects are observed to originate InAs clustering but do not affect GaP dot nucleation. The possibility of bilayer formation with different vertical correlations suggests a new path for obtaining three-dimensional pseudocrystals

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

    Science.gov (United States)

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

    2007-03-01

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

  4. Controlling the stereochemistry and regularity of butanethiol self-assembled monolayers on Au(111)

    DEFF Research Database (Denmark)

    Yan, Jiawei; Ouyang, Runhai; Jensen, Palle Skovhus

    2014-01-01

    The rich stereochemistry of the self-assembled monolayers (SAMs) of four butanethiols on Au(111) is described, the SAMs containing up to 12 individual C, S, or Au chiral centers per surface unit cell. This is facilitated by synthesis of enantiomerically pure 2-butanethiol (the smallest unsubstitu......The rich stereochemistry of the self-assembled monolayers (SAMs) of four butanethiols on Au(111) is described, the SAMs containing up to 12 individual C, S, or Au chiral centers per surface unit cell. This is facilitated by synthesis of enantiomerically pure 2-butanethiol (the smallest...... when R is achiral, while adatom binding leads to rectangular plane groups that suppress long-range expression of chirality. Binding as RS• also inhibits the pitting intrinsically associated with adatom binding, desirably producing more regularly structured SAMs....

  5. New Strategies for Constructing Polymeric Micelles and Hollow Spheres Via Self-Assembly

    Institute of Scientific and Technical Information of China (English)

    Ming Jiang

    2005-01-01

    @@ 1Introduction In recent years, self-assembly of block copolymers leading to micelles in selective solvents, which dissolve only one of the blocks, has developed rapidly because the micelles are very strong candidates for potential applications in advanced technologies. The micelles usually have core-shell structure which are connected by covalent bonds. Based on our long-term research on interpolymer complexation due to hydrogen bonding, where we noticed that the complexation often led to the formation of irregular aggregates, we succeeded recently in developing a series of new approaches to polymeric micelles and hollow spheres via specific intermolecular interactions. As in these approaches, a variety of polymers with interacting groups i.e. homopolymers, random copolymers, graft copolymers as well as low mass compounds (LMC), can be used as building blocks, our research strategies have substantially extended the field of self-assembly.

  6. Micellar Self-Assembly of Block Copolymers for Fabrication of Nanostructured Membranes

    KAUST Repository

    Marques, Debora S.

    2013-11-01

    This research work examines the process of block copolymer membrane fabrication by self-assembly combined by non-solvent induced phase separation. Self-assembly takes place from the preparation of the primordial solution until the moment of immersion in a non-solvent bath. These mechanisms are driven thermodynamically but are limited by kinetic factors. It is shown in this work how the ordering of the assembly of micelles is improved by the solution parameters such as solvent quality and concentration of block copolymer. Order transitions are detected, yielding changes in the morphology. The evaporation of the solvents after casting is demonstrated to be essential to reach optimum membrane structure. The non-solvent bath stops the phase separation at an optimum evaporation time.

  7. Dual brush process for selective surface modification in graphoepitaxy directed self-assembly

    Science.gov (United States)

    Doise, Jan; Chan, Boon Teik; Hori, Masafumi; Gronheid, Roel

    2017-07-01

    Graphoepitaxy directed self-assembly is a potential low-cost solution for patterning via layers with pitches beyond the reach of a single optical lithographic exposure. In this process, selective control of the interfacial energy at the bottom and sidewall of the template is an important but challenging exercise. A dual brush process is implemented, in which two brushes with distinct end-groups are consecutively grafted to the prepattern to achieve fully independent modification of the bottom and sidewall surface of the template. A comprehensive study of hole pattern quality shows that using a dual brush process leads to a substantial improvement in terms of positional and dimensional variability across the process window. These findings will be useful to others who wish to manipulate polymer-surface interactions in directed self-assembly flows.

  8. Self-assembly scenarios of patchy colloidal particles in two dimensions

    International Nuclear Information System (INIS)

    Doppelbauer, Guenther; Bianchi, Emanuela; Kahl, Gerhard

    2010-01-01

    We have investigated the self-assembly scenario of patchy colloidal particles in a two-dimensional system. The energetically most favourable ordered particle arrangements have been identified via an optimization tool that is based on genetic algorithms. Assuming different simple models for patchy colloidal particles, which include binary mixtures as well as attraction and repulsion between the patches, we could identify a broad variety of highly non-trivial ordered structures. The strategies of the systems to self-assemble become evident from a systematic variation of the pressure: (i) saturation of patch bonds at low pressure and close packing at high pressure and (ii) for intermediate pressure values, the strategy is governed by a trade-off between these two energetic aspects. The present study is yet another demonstration of the efficiency and the high reliability of genetic algorithms as versatile optimization tools.

  9. Lead Selenide Nanostructures Self-Assembled across Multiple Length Scales and Dimensions

    Directory of Open Access Journals (Sweden)

    Evan K. Wujcik

    2016-01-01

    Full Text Available A self-assembly approach to lead selenide (PbSe structures that have organized across multiple length scales and multiple dimensions has been achieved. These structures consist of angstrom-scale 0D PbSe crystals, synthesized via a hot solution process, which have stacked into 1D nanorods via aligned dipoles. These 1D nanorods have arranged into nanoscale 2D sheets via directional short-ranged attraction. The nanoscale 2D sheets then further aligned into larger 2D microscale planes. In this study, the authors have characterized the PbSe structures via normal and cryo-TEM and EDX showing that this multiscale multidimensional self-assembled alignment is not due to drying effects. These PbSe structures hold promise for applications in advanced materials—particularly electronic technologies, where alignment can aid in device performance.

  10. Identifying the nature of surface chemical modification for directed self-assembly of block copolymers

    Directory of Open Access Journals (Sweden)

    Laura Evangelio

    2017-09-01

    Full Text Available In recent years, block copolymer lithography has emerged as a viable alternative technology for advanced lithography. In chemical-epitaxy-directed self-assembly, the interfacial energy between the substrate and each block copolymer domain plays a key role on the final ordering. Here, we focus on the experimental characterization of the chemical interactions that occur at the interface built between different chemical guiding patterns and the domains of the block copolymers. We have chosen hard X-ray high kinetic energy photoelectron spectroscopy as an exploration technique because it provides information on the electronic structure of buried interfaces. The outcome of the characterization sheds light onto key aspects of directed self-assembly: grafted brush layer, chemical pattern creation and brush/block co-polymer interface.

  11. Tunable and rapid self-assembly of block copolymers using mixed solvent vapors.

    Science.gov (United States)

    Park, Woon Ik; Tong, Sheng; Liu, Yuzi; Jung, Il Woong; Roelofs, Andreas; Hong, Seungbum

    2014-12-21

    Pattern generation of well-controlled block copolymers (BCPs) with a high Flory-Huggins interaction parameter (χ) is important for applications in sub-20 nm nanolithography. We used mixed solvents of dimethylformamide (DMF) and toluene to control the morphology as well as the time to achieve the targeted morphology via self-assembly of BCPs. By precisely controlling the volume ratio of DMF and toluene, well-ordered line, honeycomb, circular hole, and lamellar nanostructures were obtained from a cylinder-forming poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) BCP with high χ. Furthermore, a well-aligned 12 nm line pattern was successfully achieved in the guiding template within one minute using the mixed solvents. This practical method may also be applicable to self-assembly of other BCPs, providing more opportunities for the next-generation sub-10 nm lithography applications.

  12. Self-assembly of micro- and nano-scale particles using bio-inspired events

    International Nuclear Information System (INIS)

    McNally, H.; Pingle, M.; Lee, S.W.; Guo, D.; Bergstrom, D.E.; Bashir, R.

    2003-01-01

    High sensitivity chemical and biological detection techniques and the development of future electronic systems can greatly benefit from self-assembly processes and techniques. We have approached this challenge using biologically inspired events such as the hybridization of single (ss)- to double-stranded (ds) DNA and the strong affinity between the protein avidin and its associated Vitamin, biotin. Using these molecules, micro-scale polystyrene beads and nano-scale gold particles were assembled with high efficiency on gold patterns and the procedures used for these processes were optimized. The DNA and avidin-biotin complex was also used to demonstrate the attachment of micro-scale silicon islands to each other in a fluid. This work also provides insight into the techniques for the self-assembly of heterogeneous materials

  13. Nano-structured micropatterns by combination of block copolymer self-assembly and UV photolithography

    International Nuclear Information System (INIS)

    Gorzolnik, B; Mela, P; Moeller, M

    2006-01-01

    A procedure for the fabrication of nano-structured micropatterns by direct UV photo-patterning of a monolayer of a self-assembled block copolymer/transition metal hybrid structure is described. The method exploits the selective photochemical modification of a self-assembled monolayer of hexagonally ordered block copolymer micelles loaded with a metal precursor salt. Solvent development of the monolayer after irradiation results in the desired pattern of micelles on the surface. Subsequent plasma treatment of the pattern leaves ordered metal nanodots. The presented technique is a simple and low-cost combination of 'top-down' and 'bottom-up' approaches that allows decoration of large areas with periodic and aperiodic patterns of nano-objects, with good control over two different length scales: nano- and micrometres

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

    Science.gov (United States)

    Noguchi, Hiroshi

    2013-01-14

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

  15. Sulfate Anion Delays the Self-Assembly of Human Insulin by Modifying the Aggregation Pathway

    OpenAIRE

    Owczarz, Marta; Arosio, Paolo

    2014-01-01

    The understanding of the molecular mechanisms underlying protein self-assembly and of their dependence on solvent composition has implications in a large number of biological and biotechnological systems. In this work, we characterize the aggregation process of human insulin at acidic pH in the presence of sulfate ions using a combination of Thioflavin T fluorescence, dynamic light scattering, size exclusion chromatography, Fourier transform infrared spectroscopy, and transmission electron mi...

  16. SWARM-BOT: Pattern Formation in a Swarm of Self-Assembling Mobile Robots

    OpenAIRE

    El Kamel, A.; Mellouli, K.; Borne, P.; Sahin, E.; Labella, T.H.; Trianni, V.; Deneubourg, J.-L.; Rasse, P.; Floreano, D.; Gambardella, L.M.; Mondada, F.; Nolfi, S.; Dorigo, M.

    2002-01-01

    In this paper we introduce a new robotic system, called swarm-bot. The system consists of a swarm of mobile robots with the ability to connect to/disconnect from each other to self-assemble into different kinds of structures. First, we describe our vision and the goals of the project. Then we present preliminary results on the formation of patterns obtained from a grid-world simulation of the system.

  17. Passivation of Black Phosphorus via Self-Assembled Organic Monolayers by van der Waals Epitaxy.

    Science.gov (United States)

    Zhao, Yinghe; Zhou, Qionghua; Li, Qiang; Yao, Xiaojing; Wang, Jinlan

    2017-02-01

    An effective passivation approach to protect black phosphorus (BP) from degradation based on multi-scale simulations is proposed. The self-assembly of perylene-3,4,9,10-tetracarboxylic dianhydride monolayers via van der Waals epitaxy on BP does not break the original electronic properties of BP. The passivation layer thickness is only 2 nm. This study opens up a new pathway toward fine passivation of BP. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Supporting Self-Assembly : the IKEA Effect on Mobile Health Persuasive Technology

    OpenAIRE

    Wang, Yunlong; Pfeil, Ulrike; Reiterer, Harald

    2016-01-01

    In this paper, we propose the idea of examining the effect of self-assembly on the success of mobile health persuasive technology. The IKEA effect shows that individuals evaluate products assembled by themselves more positively than pre-assembled products. The IKEA effect has been proven in several domains, e.g., in human robot interaction, where participants who assembled the robot evaluated the robot and the interaction with the robot more favorably than participants who did not assemble th...

  19. Modeling of block copolymer dry etching for directed self-assembly lithography

    Science.gov (United States)

    Belete, Zelalem; Baer, Eberhard; Erdmann, Andreas

    2018-03-01

    Directed self-assembly (DSA) of block copolymers (BCP) is a promising alternative technology to overcome the limits of patterning for the semiconductor industry. DSA exploits the self-assembling property of BCPs for nano-scale manufacturing and to repair defects in patterns created during photolithography. After self-assembly of BCPs, to transfer the created pattern to the underlying substrate, selective etching of PMMA (poly (methyl methacrylate)) to PS (polystyrene) is required. However, the etch process to transfer the self-assemble "fingerprint" DSA patterns to the underlying layer is still a challenge. Using combined experimental and modelling studies increases understanding of plasma interaction with BCP materials during the etch process and supports the development of selective process that form well-defined patterns. In this paper, a simple model based on a generic surface model has been developed and an investigation to understand the etch behavior of PS-b-PMMA for Ar, and Ar/O2 plasma chemistries has been conducted. The implemented model is calibrated for etch rates and etch profiles with literature data to extract parameters and conduct simulations. In order to understand the effect of the plasma on the block copolymers, first the etch model was calibrated for polystyrene (PS) and poly (methyl methacrylate) (PMMA) homopolymers. After calibration of the model with the homopolymers etch rate, a full Monte-Carlo simulation was conducted and simulation results are compared with the critical-dimension (CD) and selectivity of etch profile measurement. In addition, etch simulations for lamellae pattern have been demonstrated, using the implemented model.

  20. Low-voltage self-assembled monolayer field-effect transistors on flexible substrates.

    Science.gov (United States)

    Schmaltz, Thomas; Amin, Atefeh Y; Khassanov, Artoem; Meyer-Friedrichsen, Timo; Steinrück, Hans-Georg; Magerl, Andreas; Segura, Juan José; Voitchovsky, Kislon; Stellacci, Francesco; Halik, Marcus

    2013-08-27

    Self-assembled monolayer field-effect transistors (SAMFETs) of BTBT functionalized phosphonic acids are fabricated. The molecular design enables device operation with charge carrier mobilities up to 10(-2) cm(2) V(-1) s(-1) and for the first time SAMFETs which operate on rough, flexible PEN substrates even under mechanical substrate bending. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.