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Sample records for nanosphere self-assembly initiated

  1. Magnetic Films on Self-assembled Nanospheres

    Institute of Scientific and Technical Information of China (English)

    T.Ulbrich; I.Guhr; T.Schrefl; O.Hellwig; S.van; Dijken; M.Albrecht

    2007-01-01

    1 Results Nanoparticle media using arrays of monodisperse nanoparticles with high magneticanisotropy are assumed to be the ideal future magnetic recording media. However,key requirements like control of the magnetic anisotropy orientation along with magnetic domain isolation have not been achieved so far. Here, we report on a combination of a two-dimensional topographic pattern formed of self-assembled nanoparticles with sizes as small as 20 nm and magnetic multilayer film deposition[1]. The so formed n...

  2. Self-assembly of Carboxyl Functionalized Polystyrene Nanospheres into Close-packed Monolayers via Chemical Adsorption

    Institute of Scientific and Technical Information of China (English)

    LI,Zhi-Wei(李志伟); ZHOU,Jing-Fang(周静芳); ZHANG,Zhi-Jun(张治军); DANG,Hong-Xin(党鸿辛)

    2004-01-01

    The polyacrylic acid functionalized polystyrene nanospheres were synthesized and self-assembled into irregular,densely packed monolayers in non-aqueous media. The polymer nanoparticles were chemically adhered to substrates. The morphologies of the resulting films were investigated. The impact of the volume fraction of alcohol in the mixed solvents on the particle adsorption and fabrication of nanosphere assembled films was examined.

  3. Amphiphilic Graft Copolymer Nanospheres: From Colloidal Self-Assembly to CO2 Capture Membranes.

    Science.gov (United States)

    Jeon, Harim; Kim, Dong Jun; Park, Min Su; Ryu, Du Yeol; Kim, Jong Hak

    2016-04-13

    Colloidal nanosphere self-assembly effectively generates ordered nanostructures, prompting tremendous interest in many applications such as photonic crystals and templates for inverse opal fabrication. Here we report the self-assembly of low-cost, graft copolymer nanospheres for CO2 capture membranes. Specifically, poly(dimethylsiloxane)-graft-poly(4-vinylpyridine) (PDMS-g-P4VP) is synthesized via one-pot, free radical dispersion polymerization to give discrete monodisperse nanospheres. These nanospheres comprise a surface-anchored highly permeable PDMS layer and internal CO2-philic P4VP spherical core. Their diameter is controllable below the submicrometer range by varying grafting ratios. The colloidal dispersion forms a long-range, close-packed hexagonal array on a substrate by inclined deposition and convective assembly. The array shows dispersion medium-dependent packing characteristics. A thermodynamic correlation is determined using different solvents to obtain stable PDMS-g-P4VP dispersions and interpreted in terms of Flory-Huggins interaction parameter. As a proof-of-concept, the implementation of these nanospheres into membranes simultaneously enhances the CO2 permeability and CO2/N2 selectivity of PDMS-based transport matrixes. Upon physical aging of the solution, the CO2/N2 selectivity is improved up to 26, one of the highest values for highly permeable PDMS-based polymeric membranes.

  4. Electric Field Enhancement in a Self-Assembled 2D Array of Silver Nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, Patrick Z.; Khon, Elena; Gong, Yu; Joly, Alan G.; Abellan, Patricia; Evans, James E.; Browning, Nigel D.; Hu, Dehong; Zamkov, Mikhail; Hess, Wayne P.

    2014-12-07

    We investigate the plasmonic properties of a self-assembled 2D array of Ag nanospheres (average particle diameter/inter-particle separation distance of ~9/~4 nm). The structures of the individual particles and their assemblies are characterized using high-resolution transmission electron microscopy (HR-TEM). The plasmonic response of the nanoparticle network is probed using two-photon photoemission electron microscopy (TP-PEEM). HR-TEM and TP-PEEM statistics reveal the structure and plasmonic response of the network to be homogeneous on average. This translates into a relatively uniform surface-enhanced Raman scattering (SERS) response from biphenyl,4-4’-dithiol (BPDT) molecules adsorbed onto different sites of the network. Bright and background free SERS spectra are recorded, assigned on the basis of density 2 functional theory calculations in which BPDT is chemisorbed onto the vertex of a finitie tetrahedral Ag cluster consisting of 20 Ag atoms. A remarkable agreement between experiment and theory allows us to rigorously account for the observable vibrational states of BPDT in the ~200-2200 cm-1 region of the spectrum. Finite difference time domain simulations further reveal that physical enhancement factors on the order of 106 are attainable at the nanogaps formed between the silver nanospheres in the 2D array. Combined with modest chemical enhancement factors, this study paves the way for reproducible single molecule signals from an easily self-assembled SERS substrate.

  5. Electric field enhancement in a self-assembled 2D array of silver nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, Patrick Z., E-mail: patrick.elkhoury@pnnl.gov, E-mail: wayne.hess@pnnl.gov; Gong, Yu; Joly, Alan G.; Abellan, Patricia; Browning, Nigel D.; Hess, Wayne P., E-mail: patrick.elkhoury@pnnl.gov, E-mail: wayne.hess@pnnl.gov [Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Khon, Elena; Hu, Dehong; Zamkov, Mikhail [Department of Physics and the Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403 (United States); Evans, James E. [Environ. Molecular Sci. Lab., Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

    2014-12-07

    We investigate the plasmonic properties of a self-assembled 2D array of Ag nanospheres (average particle diameter/inter-particle separation distance of 9/3.7 nm). The structures of the individual particles and their assemblies are characterized using high-resolution transmission electron microscopy (HR-TEM). The plasmonic response of the nanoparticle network is probed using two-photon photoemission electron microscopy (TP-PEEM). HR-TEM and TP-PEEM statistics reveal the structure and plasmonic response of the network to be homogeneous on average. This translates into a relatively uniform surface-enhanced Raman scattering (SERS) response from biphenyl,4-4{sup ′}-dithiol (BPDT) molecules adsorbed onto different sites of the network. Reproducible, bright, and low-background SERS spectra are recorded and assigned on the basis of density functional theory calculations in which BPDT is chemisorbed onto the vertex of a finite tetrahedral Ag cluster consisting of 20 Ag atoms. A notable agreement between experiment and theory allows us to rigorously account for the observable vibrational states of BPDT in the ∼200–2200 cm{sup −1} region of the spectrum. Finite difference time domain simulations further reveal that physical enhancement factors on the order of 10{sup 6} are attainable at the nanogaps formed between the silver nanospheres in the 2D array. Combined with modest chemical enhancement factors, this study paves the way for reproducible single molecule signals from an easily self-assembled SERS substrate.

  6. Self-assembly and nanosphere lithography for large-area plasmonic patterns on graphene.

    Science.gov (United States)

    Lotito, Valeria; Zambelli, Tomaso

    2015-06-01

    Plasmonic structures on graphene can tailor its optical properties, which is essential for sensing and optoelectronic applications, e.g. for the enhancement of photoresponsivity of graphene photodetectors. Control over their structural and, hence, spectral properties can be attained by using electron beam lithography, which is not a viable solution for the definition of patterns over large areas. For the fabrication of large-area plasmonic nanostructures, we propose to use self-assembled monolayers of nanospheres as a mask for metal evaporation and etching processes. An optimized approach based on self-assembly at air/water interface with a properly designed apparatus allows the attainment of monolayers of hexagonally closely packed patterns with high long-range order and large area coverage; special strategies are devised in order to protect graphene against damage resulting from surface treatment and further processing steps such as reactive ion etching, which could potentially impair graphene properties. Therefore we demonstrate that nanosphere lithography is a cost-effective solution to create plasmonic patterns on graphene. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Gold(I) catalysis at extreme concentrations inside self-assembled nanospheres.

    Science.gov (United States)

    Gramage-Doria, Rafael; Hessels, Joeri; Leenders, Stefan H A M; Tröppner, Oliver; Dürr, Maximilian; Ivanović-Burmazović, Ivana; Reek, Joost N H

    2014-12-01

    Homogeneous transition-metal catalysis is a crucial technology for the sustainable preparation of valuable chemicals. The catalyst concentration is usually kept as low as possible, typically at mM or μM levels, and the effect of high catalyst concentration is hardly exploited because of solubility issues and the inherent unfavorable catalyst/substrate ratio. Herein, a self-assembly strategy is reported which leads to local catalyst concentrations ranging from 0.05 M to 1.1 M, inside well-defined nanospheres, whilst the overall catalyst concentration in solution remains at the conventional mM levels. We disclose that only at this high concentration, the gold(I) chloride is reactive and shows high selectivity in intramolecular CO and CC bond-forming cyclization reactions.

  8. Self-assembly directed synthesis of poly(ortho-toluidine)-metal(gold and palladium) composite nanospheres.

    Science.gov (United States)

    Reddy, Kakarla Raghava; Lee, Kwang-Pill; Gopalan, Anantha Iyenger

    2007-09-01

    Poly(ortho-toluidine) (POT)-gold (Au) and palladium (Pd) composite nanospheres were successfully synthesized by the reaction of o-toluidine with the corresponding metal (Au or Pd) colloidal solution through self-assembly process in the presence of dodecylbenzenesulfonic acid (DBSA), which acts as both a dopant and surfactant, and ammonium peroxydisulfate as an oxidizing agent. The composites (POT-DBSA/Au or Pd) were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, UV-Visible (UV-Vis) spectroscopy, and electrical conductivity measurements. TEM images of the nanocomposites reveal that metal (Au or Pd) nanoparticles were well dispersed on POT spheres. TGA and XRD results show that the composites exhibit high thermal stability and are more crystalline compared with pristine POT. It was found that the electrical conductivity of the POT-DBSA/Au or Pd composites is 2 orders of magnitude higher than that of pristine polymer. Also, the POT-DBSA/Pd composite exhibits magnetic property. The formation mechanism of the POT-DBSA/Au or Pd composite nanosphere is discussed.

  9. GREEN AND CONTROLLED SYNTHESIS OF GOLD AND PLATINUM NANOMATERIALS USING VITAMIN B2: DENSITY-ASSISTED SELF-ASSEMBLY OF NANOSPHERES, WIRES AND RODS

    Science.gov (United States)

    For the first time, we report density-assisted self-assembly and efficient synthesis of gold (Au) and platinum (Pt) nanospheres, nanowires and nanorods using vitamin B2 (riboflavin) without employing any special capping or dispersing agent at room temperature; this env...

  10. Hydrophobic and high transparent honeycomb diamond-like carbon thin film fabricated by facile self-assembled nanosphere lithography

    Science.gov (United States)

    Peng, Kai-Yu; Wei, Da-Hua; Lin, Chii-Ruey; Yu, Yueh-Chung; Yao, Yeong-Der; Lin, Hong-Ming

    2014-01-01

    In this paper, we take advantage of a facile fabrication technique called self-assembled nanosphere lithography (SANSL) combining with proper two-step reactive ion etching (RIE) method and radio frequency (RF) sputtering deposition process for manufacturing honeycomb diamond-like carbon (DLC) thin film structures with hydrophobic and high transparent properties. It is found that the DLC thin films deposited on clean glass substrates at the RF power of 100 W with the surface roughness (Ra) of 2.08 nm and the ID/IG ratio of 1.96 are realized. With a fill-factor of 0.691, the honeycomb DLC patterned thin film shows the best transmittance performance of 87% in the wavelength of visible light, and the optimized contact angle measurement is ˜108°. Compared with the pure DLC thin film and original glass substrate, the hydrophobic property of the patterned DLC films is significantly improved by 80 and 160%, respectively.

  11. Linear and nonlinear optical characterization of self-assembled, large-area gold nanosphere metasurfaces with sub-nanometer gaps.

    Science.gov (United States)

    Fontana, Jake; Maldonado, Melissa; Charipar, Nicholas; Trammell, Scott A; Nita, Rafaela; Naciri, Jawad; Pique, Alberto; Ratna, Banahalli; Gomes, Anderson S L

    2016-11-28

    We created centimeter-scale area metasurfaces consisting of a quasi-hexagonally close packed monolayer of gold nanospheres capped with alkanethiol ligands on glass substrates using a directed self-assembly approach. We experimentally characterized the morphology and the linear and nonlinear optical properties of metasurfaces. We show these metasurfaces, with interparticle gaps of 0.6 nm, are modeled well using a classical (without charge transfer) description. We find a large dispersion of linear refractive index, ranging from values less than vacuum, 0.87 at 600 nm, to Germanium-like values of 4.1 at 880 nm, determined using spectroscopic ellipsometry. Nonlinear optical characterization was carried out using femtosecond Z-scan and we observe saturation behavior of the nonlinear absorption (NLA) and nonlinear refraction (NLR). We find a negative NLR from these metasurfaces two orders of magnitude larger (nsub>2,satsub> = -7.94x10-9 cm2/W at Isub>sat,n2sub> = 0.43 GW/cm2) than previous reports on gold nanostructures at similar femtosecond time scales. We also find the magnitude of the NLA comparable to the largest values reported (βsub>2,satsub> = -0.90x105 cm/GW at Isub>sat,β2sub> = 0.34 GW/cm2). Precise knowledge of the index of refraction is of crucial importance for emerging dispersion engineering technologies. Furthermore, utilizing this directed self-assembly approach enables the nanometer scale resolution required to develop the unique optical response and simultaneously provides high-throughput for potential device realization.

  12. Preparation, Properties, and Self-Assembly Behavior of PTFE-Based Core-Shell Nanospheres

    Directory of Open Access Journals (Sweden)

    Katia Sparnacci

    2012-01-01

    Full Text Available Nanosized PTFE-based core-shell particles can be prepared by emulsifier-free seed emulsion polymerization technique starting from spherical or rod-like PTFE seeds of different size. The shell can be constituted by the relatively high Tg polystyrene and polymethylmethacrylate as well as by low Tg polyacrylic copolymers. Peculiar thermal behavior of the PTFE component is observed due to the high degree of PTFE compartmentalization. A very precise control over the particle size can be exerted by properly adjusting the ratio between the monomers and the PTFE seed. In addition, the particle size distribution self-sharpens as the ratio monomer/PTFE increases. Samples with uniformity ratios suited to build 2D and 3D colloidal crystals are easily prepared. In particular, 2D colloidal crystal of spheres leads to very small 2D nanostructuration, useful for the preparation of masks with a combination of nanosphere lithography and reactive ion etching. 3D colloidal crystals were also obtained featuring excellent opal quality, which is a direct consequence of the monodispersity of colloids used for their growth.

  13. Ordered silicon nanowire arrays prepared by an improved nanospheres self-assembly in combination with Ag-assisted wet chemical etching

    Science.gov (United States)

    Jia, Guobin; Westphalen, Jasper; Drexler, Jan; Plentz, Jonathan; Dellith, Jan; Dellith, Andrea; Andrä, Gudrun; Falk, Fritz

    2016-04-01

    An improved Langmuir-Blodgett self-assembly process combined with Ag-assisted wet chemical etching for the preparation of ordered silicon nanowire arrays is presented in this paper. The new process is independent of the surface conditions (hydrophilic or hydrophobic) of the substrate, allowing for depositing a monolayer of closely packed polystyrene nanospheres onto any flat surface. A full control of the morphology of the silicon nanowire is achieved. Furthermore, it is observed that the formation of porous-Si at the tips of the nanowires is closely related to the release of Ag nanoparticles from the Ag mask during the etching, which subsequently redeposit on the surface initially free of Ag, and these Ag nanoparticles catalyze the etching of the tips and lead to the porous-Si formation. This finding will help to improve the resulting nano- and microstructures to get them free of pores, and renders it a promising technology for low-cost high throughput fabrication of specific optical devices, photonic crystals, sensors, MEMS, and NEMS by substituting the costly BOSCH process. It is shown that ordered nanowire arrays free of porous structures can be produced if all sources of Ag nanoparticles are excluded, and structures with aspect ratio more than 100 can be produced.

  14. Light extraction improvement of InGaN light-emitting diodes with large-area highly ordered ITO nanobowls photonic crystal via self-assembled nanosphere lithography

    Directory of Open Access Journals (Sweden)

    Kui Wu

    2013-09-01

    Full Text Available The InGaN multiple quantum well light-emitting diodes (LEDs with different sizes of indium-tin-oxide (ITO nanobowl photonic crystal (PhC structure has been fabricated using self-assembled monolayer nanosphere lithography. The light output power (LOP of PhC LEDs (at 350 mA has been enhanced by 63.5% and the emission divergence exhibits a 28.8° reduction compared to conventional LEDs without PhC structure. Current-Voltage curves have shown that these PhC structures on ITO layer will not degrade the LED electrical properties. The finite-difference time-domain simulation (FDTD has also been performed for light extraction and emission characteristics, which is consistent with the experimental results.

  15. Bi-Component Nanostructured Arrays of Co Dots Embedded in Ni80Fe20 Antidot Matrix: Synthesis by Self-Assembling of Polystyrene Nanospheres and Magnetic Properties.

    Science.gov (United States)

    Coïsson, Marco; Celegato, Federica; Barrera, Gabriele; Conta, Gianluca; Magni, Alessandro; Tiberto, Paola

    2017-08-23

    A bi-component nanostructured system composed by a Co dot array embedded in a Ni80Fe20 antidot matrix has been prepared by means of the self-assembling polystyrene nanospheres lithography technique. Reference samples constituted by the sole Co dots or Ni80Fe20 antidots have also been prepared, in order to compare their properties with those of the bi-component material. The coupling between the two ferromagnetic elements has been studied by means of magnetic and magneto-transport measurements. The Ni80Fe20 matrix turned out to affect the vortex nucleation field of the Co dots, which in turn modifies the magneto-resistance behaviour of the system and its spinwave properties.

  16. Soft-Templated Self-Assembly of Mesoporous Anatase TiO2/Carbon Composite Nanospheres for High-Performance Lithium Ion Batteries.

    Science.gov (United States)

    Wu, Ruofei; Shen, Shuiyun; Xia, Guofeng; Zhu, Fengjuan; Lastoskie, Christian; Zhang, Junliang

    2016-08-10

    Mesoporous anatase TiO2/carbon composite nanospheres (designated as meso-ATCCNs) were successfully synthesized via a facile soft-templated self-assembly followed by thermal treatment. Structural and morphological analyses reveal that the as-synthesized meso-ATCCNs are composed of primary TiO2 nanoparticles (∼5 nm), combined with in situ deposited carbon either on the surface or between the primary TiO2 nanoparticles. When cycled in an extended voltage window from 0.01 to 3.0 V, meso-ATCCNs exhibit excellent rate capabilities (413.7, 289.7, and 206.8 mAh g(-1) at 200, 1000, and 3000 mA g(-1), respectively) as well as stable cyclability (90% capacity retention over 500 cycles at 1000 mA g(-1)). Compared with both mesoporous TiO2 nanospheres and bulk TiO2, the superior electrochemical performance of the meso-ATCCNs electrode could be ascribed to a synergetic effect induced by hierarchical structure that includes uniform TiO2 nanoparticles, the presence of hydrothermal carbon derived from phenolic resols, a high surface area, and open mesoporosity.

  17. Fabrication of composite thin films with microstructures of honeycomb, foam, and nanosphere arrays through adsorption and self-assembly of block copolymers at the liquid/liquid interface.

    Science.gov (United States)

    Liu, Yanan; Chen, Lifang; Geng, Yuanyuan; Lee, Yong-Ill; Li, Ying; Hao, Jingcheng; Liu, Hong-Guo

    2013-10-01

    The adsorption and self-organization behaviors of two kinds of block copolymers, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and poly(4-vinylpyridine)-block-polystyrene-block-poly(4-vinylpyridine) (P4VP-b-PS-b-P4VP), at planar liquid/liquid interfaces were investigated. A gel film decorating with honeycomb-like microstructures forms at the liquid/liquid interface between PS-b-P4VP chloroform solution and chloroauric acid aqueous solution. However, foam films were developed when the chloroauric acid aqueous solution was replaced by a chloroplatinic acid solution or a silver nitrate solution. Furthermore, a free-standing film containing the ordered arrays of nanospheres appeared at the liquid/liquid interface between P4VP-b-PS-b-P4VP chloroform solution and chloroauric acid aqueous solution. The formation of these microstructures was attributed to the adsorption of polymer molecules, combining with inorganic ions and the self-assembly of the composite species at the interface. The doped metal ions and complex ions were transformed to metal nanoparticles after further treatment. This is a facile and convenient method to prepare polymer/inorganic nanoparticle composites. These results also indicate the great influences of the polymer structures and the inorganic species in the aqueous phases on the self-assembly behaviors of the polymers at the interfaces, the final morphology, and structure of the composites. In addition, the formed thin composite films doped with well-dispersed, homogeneous small noble metal nanoparticles exhibit great and durable catalytic activities for the reduction of 4-nitrophenol (4-NP) by potassium borohydride.

  18. Self-assembly of an amphiphilic macromolecule under spherical confinement: An efficient route to generate hollow nanospheres

    Science.gov (United States)

    Glagoleva, A. A.; Vasilevskaya, V. V.; Yoshikawa, K.; Khokhlov, A. R.

    2013-12-01

    In general, bio-macromolecules are composed of hydrophilic and hydrophobic moieties and are confined within small cavities, such as cell membranes and intracellular organelles. Here, we studied the self-organization of macromolecules having groups with different affinities to solvents under spherical nano-scale confinement by means of computer modeling. It is shown that depending on the interaction parameters of monomer units composed of side- and main-chain monomer groups along a single linear macromolecule and on cavity size, such amphiphilic polymers undergo the conformational transitions between hollow nanospheres, rod-like and folded cylindrical structures, and a necklace conformation with and without a particular ordering of beads. The diagram of the conformations in the variables the incompatibility parameter of monomer units and the cavity radius is constructed.

  19. One-Pot Synthesis of Cu2O/Cu Self-Assembled Hollow Nanospheres with Enhanced Photocatalytic Performance

    Directory of Open Access Journals (Sweden)

    Bo Zhou

    2014-01-01

    Full Text Available Cu2O/Cu hollow spheres are prepared using one-pot template-free solvent-thermal synthesis route with (CH3COO2Cu·H2O as a precursor. With the reaction time increasing gradually from 2 h to 20 h, the morphology of the Cu2O/Cu evolves from nanoparticle to hollow nanosphere. The hollow structure is obtained when the cooling rate falls down to 0.7°C/min. And the content of Cu in the hollow spheres also can be easily controlled by adjusting the solvent-thermal synthesis time. Using photocatalytic degradation of phenol as the probe molecules under visible-light illumination, we have investigated the influence of hollow structure on the photocatalytic activity of Cu2O/Cu. The prepared hollow sphere Cu2O/Cu particles exhibited a higher photodegradation capability than nanoparticles and solid spheres. When the content of Cu lies in the range of 11–86 wt%, the samples exhibit higher photocatalytic performance, indicating that the Cu2O/Cu particles with hollow structure are promising candidates for the processing of pollutants.

  20. Nanoscience and technology: An interdisciplinary initiative, self-assembling nanoscale quantum devices

    Energy Technology Data Exchange (ETDEWEB)

    Doolen, G.; Smith, D.; Mineev, M. [and others

    1996-10-01

    This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Our objective is to develop the devices, interconnection technologies, and self-assembling systems required for quantum-based information processing that permit ultra-dense integrated circuits and that allow continuation of the on-going silicon VLSI miniaturization process. That process is facing increasing difficulties related to switch performance, heat dissipation, interconnect failure, quantum effect complications, and rapidly escalating manufacturing costs. Our approach is intended to address these concerns and consists of the development of highly parallel stochastic computers utilizing quantum components and self-assembly methods; the development of self-assembling monolayers for use as resists and memory devices; and research on approaches to molecular self-assembly of the precursors to molecular transistors. The work will provide confirmation of principles, is intended to provide near-term results of potential relevance to the commercial sector, and has a range of applications that include high performance computing, biotechnology, and nanoscale chemistry.

  1. Anti-fouling surfaces by combined molecular self-assembly and surface-initiated ATRP for micropatterning active proteins.

    Science.gov (United States)

    Xiu, K M; Cai, Q; Li, J S; Yang, X P; Yang, W T; Xu, F J

    2012-02-01

    A simple method by combined molecular self assembly and surface-initiated atom transfer radical polymerization (SI-ATRP) was proposed to prepare a biologically inert surface for micropatterning active proteins. The MPEG microdomains having a short terminal poly(ethylene glycol) (PEG) unit were prepared by self assembly of 2-(methyoxy(polyethylenoxy) propyl)trimethoxy silane (MPEG-silane). The remaining local regions or poly(poly(ethylene glycol)methyl ether methacrylate-co-glycidyl methacrylate) (P(PEGMEMA-co-GMA)) microdomains were produced via SI-ATRP of PEGMEMA and GMA comonomers. The epoxy groups of the P(PEGMEMA-co-GMA) microdomains were used directly for covalent coupling of an active protein (human immunoglobulin or IgG) via the ring-opening reaction to produce the IgG-coupled microdomains. The IgG-coupled microdomains interact only and specifically with target anti-IgG, while the other antifouling microregions from self-assembled monolayers with short terminal PEG units effectively prevent specific and non-specific protein fouling. When extended to other active biomolecules, microarrays for specific and non-specific analyte interactions with a high signal-to-noise ratio could be readily tailored.

  2. Selective inhibition of MG-63 osteosarcoma cell proliferation induced by curcumin-loaded self-assembled arginine-rich-RGD nanospheres

    Directory of Open Access Journals (Sweden)

    Chang R

    2015-05-01

    Full Text Available Run Chang,1 Linlin Sun,1 Thomas J Webster1,2 1Department of Chemical Engineering, Northeastern University, Boston, MA, USA; 2Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia Abstract: Osteosarcoma is the most frequent primary malignant form of bone cancer, comprising 30% of all bone cancer cases. The objective of this in vitro study was to develop a treatment against osteosarcoma with higher selectivity toward osteosarcoma cells and lower cytotoxicity toward normal healthy osteoblast cells. Curcumin (or diferuloylmethane has been found to have antioxidant and anticancer effects by multiple cellular pathways. However, it has lower water solubility and a higher degradation rate in alkaline conditions. In this study, the amphiphilic peptide C18GR7RGDS was used as a curcumin carrier in aqueous solution. This peptide contains a hydrophobic aliphatic tail group leading to their self-assembly by hydrophobic interactions, as well as a hydrophilic head group composed of an arginine-rich and an arginine-glycine-aspartic acid structure. Through characterization by transmission electron microscopy, self-assembled structures of spherical amphiphilic nanoparticles (APNPs with diameters of 10–20 nm in water and phosphate-buffered saline were observed, but this structure dissociated when the pH value was reduced to 4. Using a method of codissolution with acetic acid and dialysis tubing, the solubility of curcumin was enhanced and a homogeneous solution was formed in the presence of APNPs. Successful encapsulation of curcumin in APNPs was then confirmed by Fourier transform infrared and X-ray diffraction analyses. The cytotoxicity and cellular uptake of the APNP/curcumin complexes on both osteosarcoma and normal osteoblast cell lines were also evaluated by methyl-thiazolyl-tetrazolium assays and confocal fluorescence microscopy. The results showed that the curcumin-loaded APNPs had significant selective

  3. Facile fabrication of dual emissive nanospheres via the self-assembling of CdSe@CdS and zinc phthalocyanine and their application for silver ion detection

    Science.gov (United States)

    Liu, Shuning; Liu, Chenchen; Luan, Xinying; Yao, Rui; Feng, Yakai

    2017-09-01

    The far-red/near infrared photoluminescence of zinc phthalocyanines would be strongly quenched once they are aggregated, which will obviously hinder their wide applications in environmental, energy related and biomedical fields. Herein, the ultra-small sized semiconductor quantum dots with core-shell structures (CdSe@CdS) have been firstly synthesized and then assembled with a dendritic zinc phthalocyanine (ZnPc) in the H2O/DMF mixed solvent to obtain monodispersed nanospheres. Finally, it was found that the resultant ethanolic colloids can be employed as a sensitive and specific fluorescent nanoprobe for silver ions discrimination with a limit of detection (LOD) approaching to 10-8 mol/L.

  4. Initiation of blood coagulation - Evaluating the relevance of specific surface functionalities using self assembled monolayers

    OpenAIRE

    Fischer, Marion

    2010-01-01

    The surface of biomaterials can induce contacting blood to coagulate, similar to the response initiated by injured blood vessels to control blood loss. This poses a challenge to the use of biomaterials as the resulting coagulation can impair the performance of hemocompatible devices such as catheters, vascular stents and various extracorporeal tubings [1], what can moreover cause severe host reactions like embolism and infarction. Biomaterial induced coagulation processes limit the therape...

  5. Atomic-level elucidation of the initial stages of self-assembled monolayer metallization and nanoparticle formation.

    Science.gov (United States)

    Keith, John A; Jacob, Timo

    2010-11-02

    The development of high-performance molecular electronics and nanotech applications requires deep understanding of atomic level structural, electronic, and magnetic properties of electrode/molecular interfaces. Recent electrochemical experiments on self-assembled monolayers (SAMs) have identified highly practical means to generate nanoparticles and metal monolayers suspended above substrate surfaces through SAM metallizations. A rational basis why this process is even possible is not yet well-understood. To clarify the initial stages of interface formation during SAM metallization, we used first-principles spin-polarized density functional theory (DFT) calculations to study Pd diffusion on top of 4-mercaptopyridine (4MP) SAMs on Au(111). After distinguishing potential-energy surfaces (PESs) for different spin configurations for transition metal atoms on the SAM, we find adatom diffusion is not possible over the clean 4MP-SAM surface. Pre-adsorption of transition-metal atoms, however, facilitates atomic diffusion that appears to explain multiple reports on experimentally observed island and monolayer formation on top of SAMs. Furthermore, these diffusions most likely occur by moving across low-lying and intersecting PESs of different spin states, opening the possibility of magnetic control over these systems. Vertical diffusion processes were also investigated, and the electrolyte was found to play a key role in preventing metal permeation through the SAM to the substrate.

  6. Self-assembled SnO2 micro- and nanosphere-based gas sensor thick films from an alkoxide-derived high purity aqueous colloid precursor

    Science.gov (United States)

    Kelp, G.; Tätte, T.; Pikker, S.; Mändar, H.; Rozhin, A. G.; Rauwel, P.; Vanetsev, A. S.; Gerst, A.; Merisalu, M.; Mäeorg, U.; Natali, M.; Persson, I.; Kessler, V. G.

    2016-03-01

    Tin oxide is considered to be one of the most promising semiconductor oxide materials for use as a gas sensor. However, a simple route for the controllable build-up of nanostructured, sufficiently pure and hierarchical SnO2 structures for gas sensor applications is still a challenge. In the current work, an aqueous SnO2 nanoparticulate precursor sol, which is free of organic contaminants and sorbed ions and is fully stable over time, was prepared in a highly reproducible manner from an alkoxide Sn(OR)4 just by mixing it with a large excess of pure neutral water. The precursor is formed as a separate liquid phase. The structure and purity of the precursor is revealed using XRD, SAXS, EXAFS, HRTEM imaging, FTIR, and XRF analysis. An unconventional approach for the estimation of the particle size based on the quantification of the Sn-Sn contacts in the structure was developed using EXAFS spectroscopy and verified using HRTEM. To construct sensors with a hierarchical 3D structure, we employed an unusual emulsification technique not involving any additives or surfactants, using simply the extraction of the liquid phase, water, with the help of dry butanol under ambient conditions. The originally generated crystalline but yet highly reactive nanoparticles form relatively uniform spheres through self-assembly and solidify instantly. The spheres floating in butanol were left to deposit on the surface of quartz plates bearing sputtered gold electrodes, producing ready-for-use gas sensors in the form of ca. 50 μm thick sphere-based-films. The films were dried for 24 h and calcined at 300 °C in air before use. The gas sensitivity of the structures was tested in the temperature range of 150-400 °C. The materials showed a very quickly emerging and reversible (20-30 times) increase in electrical conductivity as a response to exposure to air containing 100 ppm of H2 or CO and short (10 s) recovery times when the gas flow was stopped.Tin oxide is considered to be one of the

  7. SYNTHESIS OF pH-RESPONSIVE AMPHIPHILIC DIBLOCK COPOLYMERS CONTAINING POLYISOBUTYLENE via OXYANION-INITIATED POLYMERIZATION AND THEIR MULTIPLE SELF-ASSEMBLY MORPHOLOGIES

    Institute of Scientific and Technical Information of China (English)

    Huai-chao Wang; Ming-zu Zhang; Pei-hong Ni; Jin-lin He; Ying Hao; Yi-xian Wu

    2013-01-01

    Two pH-responsive amphiphilic diblock copolymers,namely polyisobutylene-block-poly[2-(N,N-dimethylamino)ethyl methacrylate] (PIB-b-PDMAEMA) and polyisobutylene-block-poly(metharylic acid) (PIB-b-PMAA),were synthesized via oxyanion-initiated polymerization,and their multiple self-assembly behaviors have been studied.An exo-o1efin-terminated highly reactive polyisobutylene (HRPIB) was first changed to hydroxyl-terminated PIB (PIB-OH) via hydroboration-oxidation of C=C double bond in the chain end,and then reacted with KH to yield a potassium alcoholate of PIB (PIB-O-K+).PIB-O-K+ was immediately used as a macroinitiator to polymerize DMAEMA monomer,resulting in a cationic diblock copolymer PIB-b-PDMAEMA.With the similar synthesis procedure,the anionic diblock copolymer PIB-b-PMAA could be prepared via a combination of oxyanion-initiated polymerization of tert-butyl methacrylate (tBMA) and subsequent hydrolysis of tert-butyl ester groups in PtBMA block.The functional PIB and block copolymers have been fully characterized by 1H-NMR,FT-IR spectroscopy,and gel permeation chromatography (GPC).These samples allowed us to systematically investigate the effects of block composition on the pH responsivity and various self-assembled morphologies of the copolymers in THF/water mixed solvent.Transmission electron microscopy (TEM) images revealed that these diblock copolymers containing small amount of original PIB without exo-olefin-terminated group are able to self-assemble into micelles,vesicles with different particle sizes and cylindrical aggregates,depending on various factors including block copolymer composition,solvent polarity and pH value.

  8. 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.

  9. Self assembling proteins

    Science.gov (United States)

    Yeates, Todd O.; Padilla, Jennifer; Colovos, Chris

    2004-06-29

    Novel fusion proteins capable of self-assembling into regular structures, as well as nucleic acids encoding the same, are provided. The subject fusion proteins comprise at least two oligomerization domains rigidly linked together, e.g. through an alpha helical linking group. Also provided are regular structures comprising a plurality of self-assembled fusion proteins of the subject invention, and methods for producing the same. The subject fusion proteins find use in the preparation of a variety of nanostructures, where such structures include: cages, shells, double-layer rings, two-dimensional layers, three-dimensional crystals, filaments, and tubes.

  10. Photovoltaic self-assembly.

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-10-01

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

  11. Clinical performance of self-assembling peptide P11 -4 in the treatment of initial proximal carious lesions: A practice-based case series.

    Science.gov (United States)

    Schlee, Markus; Schad, Till; Koch, Jan H; Cattin, Philippe C; Rathe, Florian

    2017-09-03

    The aim of the present study was to investigate the clinical performance of self-assembling peptide P11 -4 on non-cavitated initial proximal carious lesions 12 months after treatment. Twenty-six patients, aged between 18 and 65 years, with 35 carious lesions were included in this practice-based, uncontrolled, prospective case series. The opacity and size of the proximal lesions were evaluated visually at baseline and at day 360 using standardized single-tooth or bite-wing and digital-subtraction radiography. Pairwise evaluation of images was carried out in a randomized and blinded manner with respect to the time point. Twelve months after treatment of the proximal carious lesions, the visual evaluation showed a predominant shift toward regression of the initial lesions. Radiographic assessment yielded regression of the caries in 17 of 28 cases; four of 28 were regarded as unchanged, and seven of 28 lesions showed progression of the carious lesion. Combined assessment of clinical radiographs and digital subtraction radiographs confirmed the radiographic assessment, with 20 of 28 lesions showing total or partial regression, four unchanged, and four progressing. Radiographic and digital subtraction analyses suggest that initial proximal carious lesions can regress after treatment with P11 -4, but additional factors might influence the overall treatment outcome. © 2017 John Wiley & Sons Australia, Ltd.

  12. Self-assembled monolayer initiated electropolymerization: a route to thin-film materials with enhanced photovoltaic performance.

    Science.gov (United States)

    Hwang, Euiyong; de Silva, K M Nalin; Seevers, Chad B; Li, Jie-Ren; Garno, Jayne C; Nesterov, Evgueni E

    2008-09-02

    Continuing progress in the field of organic polymer photovoltaic (PV) devices requires the development of new materials with better charge-transport efficiency. To improve this parameter, we have investigated surface-attached bilayer polymer PV thin films prepared starting from a covalently attached monolayer of an electroactive initiator using sequential electropolymerization of dithiophene and its derivatives. These systems were found to show significantly increased photocurrent generation quantum yields as compared to systems made through conventional approaches. In addition, the described PV thin films possess remarkable mechanical, air, and photostability. These properties likely arise from the more uniform and better ordered bulk layer morphologies as well as tighter covalently bonded contacts at the interfacial junctions, contributing to improved charge transport. While more studies on the fundamental reasons behind the discovered phenomenon are currently underway, this information can be readily applied to build more efficient organic polymer photovoltaics.

  13. Porous nano-structured Co3O4 anode materials generated from coordination-driven self-assembled aggregates for advanced lithium ion batteries.

    Science.gov (United States)

    Ge, Danhua; Geng, Hongbo; Wang, Jiaqing; Zheng, Junwei; Pan, Yue; Cao, Xueqin; Gu, Hongwei

    2014-08-21

    A simple and scalable coordination-derived method for the synthesis of porous Co3O4 hollow nanospheres is described here. The initially formed coordination-driven self-assembled aggregates (CDSAAs) could act as the precursor followed by calcination treatment. Then the porous hollow Co3O4 nanospheres are obtained, in which the primary Co3O4 nanoparticles are inter-dispersed. When the nanospheres are used as anode materials for lithium storage, they show excellent coulombic efficiency, high lithium storage capacity and superior cycling performance. In view of the facile synthesis and excellent electrochemical performance obtained, this protocol to fabricate special porous hollow frameworks could be further extended to other metal oxides and is expected to improve the practicality of superior cycle life anode materials with large volume excursions for the development of the next generation of LIBs.

  14. Self-assembling segmented coiled tubing

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, David W.

    2016-09-27

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

  15. Coded nanoscale self-assembly

    Indian Academy of Sciences (India)

    Prathyush Samineni; Debabrata Goswami

    2008-12-01

    We demonstrate coded self-assembly in nanostructures using the code seeded at the component level through computer simulations. Defects or cavities occur in all natural assembly processes including crystallization and our simulations capture this essential aspect under surface minimization constraints for self-assembly. Our bottom-up approach to nanostructures would provide a new dimension towards nanofabrication and better understanding of defects and crystallization process.

  16. 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...... the nanoparticles can be stabilized and tuned to have specific properties....

  17. Self-Assembly of Large Amyloid Fibers

    Science.gov (United States)

    Ridgley, Devin M.

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

  18. Final Report for Grant # DE-FG02-02ER46000 Simulations of Self-Assembly of Tethered Nanoparticle Shape Amphiphiles

    Energy Technology Data Exchange (ETDEWEB)

    Glotzer, Sharon C. [The University of Michigan

    2014-08-25

    Self-assembly of nanoparticle building blocks including nanospheres, nanorods, nanocubes, nano plates, nanoprisms, etc., may provide a promising means for manipulating these building blocks into functional and useful materials. One increasingly popular method for self-assembly involves functionalizing nanoparticles and nanostructured molecules with “tethers” of organic polymers or biomolecules with specific or nonspecific interactions to facilitate their assembly. However, there is little theory and little understanding of the general principles underlying self-assembly in these complex materials. Using computer simulation to elucidate the principles of self-assembly and develop a predictive theoretical framework was the central goal of this project.

  19. Self-assembly of self-assembled molecular triangles

    Indian Academy of Sciences (India)

    Mili C Naranthatta; V Ramkumar; Dillip Kumar Chand

    2014-09-01

    A rare variety of self-assembledmolecular triangle [Pd3(bpy)3(imidazolate)3](NO3)3, 1 is prepared by the combination of Pd(bpy)(NO3)2 with imidazole, at 1:1 ratio, in acetonitrile-water. Deprotonation of imidazole happened during the course of the complexation reaction where upon the metallomacrocycle is formed. The bowl-shaped trinuclear architecture of 1 is crafted with three peripheral bpy units capable of - stacking interactions. 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 manner utilizing intermolecular - interactions where upon two out of three bpy units of each molecule participated in the chain formation.

  20. Moiré Nanosphere Lithography.

    Science.gov (United States)

    Chen, Kai; Rajeeva, Bharath Bangalore; Wu, Zilong; Rukavina, Michael; Dao, Thang Duy; Ishii, Satoshi; Aono, Masakazu; Nagao, Tadaaki; Zheng, Yuebing

    2015-06-23

    We have developed moiré nanosphere lithography (M-NSL), which incorporates in-plane rotation between neighboring monolayers, to extend the patterning capability of conventional nanosphere lithography (NSL). NSL, which uses self-assembled layers of monodisperse micro/nanospheres as masks, is a low-cost, scalable nanofabrication technique and has been widely employed to fabricate various nanoparticle arrays. Combination with dry etching and/or angled deposition has greatly enriched the family of nanoparticles NSL can yield. In this work, we introduce a variant of this technique, which uses sequential stacking of polystyrene nanosphere monolayers to form a bilayer crystal instead of conventional spontaneous self-assembly. Sequential stacking leads to the formation of moiré patterns other than the usually observed thermodynamically stable configurations. Subsequent O2 plasma etching results in a variety of complex nanostructures. Using the etched moiré patterns as masks, we have fabricated complementary gold nanostructures and studied their optical properties. We believe this facile technique provides a strategy to fabricate complex nanostructures or metasurfaces.

  1. Self-assembled plasmonic metamaterials

    Science.gov (United States)

    Mühlig, Stefan; Cunningham, Alastair; Dintinger, José; Scharf, Toralf; Bürgi, Thomas; Lederer, Falk; Rockstuhl, Carsten

    2013-07-01

    Nowadays for the sake of convenience most plasmonic nanostructures are fabricated by top-down nanofabrication technologies. This offers great degrees of freedom to tailor the geometry with unprecedented precision. However, it often causes disadvantages as well. The structures available are usually planar and periodically arranged. Therefore, bulk plasmonic structures are difficult to fabricate and the periodic arrangement causes undesired effects, e.g., strong spatial dispersion is observed in metamaterials. These limitations can be mitigated by relying on bottom-up nanofabrication technologies. There, self-assembly methods and techniques from the field of colloidal nanochemistry are used to build complex functional unit cells in solution from an ensemble of simple building blocks, i.e., in most cases plasmonic nanoparticles. Achievable structures are characterized by a high degree of nominal order only on a short-range scale. The precise spatial arrangement across larger dimensions is not possible in most cases; leading essentially to amorphous structures. Such self-assembled nanostructures require novel analytical means to describe their properties, innovative designs of functional elements that possess a desired near- and far-field response, and entail genuine nanofabrication and characterization techniques. Eventually, novel applications have to be perceived that are adapted to the specifics of the self-assembled nanostructures. This review shall document recent progress in this field of research. Emphasis is put on bottom-up amorphous metamaterials. We document the state-of-the-art but also critically assess the problems that have to be overcome.

  2. 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

  3. Acoustic vibration modes and electron-lattice coupling in self-assembled silver nanocolumns.

    Science.gov (United States)

    Burgin, J; Langot, P; Arbouet, A; Margueritat, J; Gonzalo, J; Afonso, C N; Vallée, F; Mlayah, A; Rossell, M D; Van Tendeloo, G

    2008-05-01

    Using ultrafast spectroscopy, we investigated electron-lattice coupling and acoustic vibrations in self-assembled silver nanocolumns embedded in an amorphous Al2O3 matrix. The measured electron-lattice energy exchange time is smaller in the nanocolumns than in bulk silver, with a value very close to that of isolated nanospheres with comparable surface to volume ratio. Two vibration modes were detected and ascribed to the breathing and extensional mode of the nanocolumns, in agreement with numerical simulations.

  4. Molecular self-assembly at solid surfaces.

    Science.gov (United States)

    Otero, Roberto; Gallego, José María; de Parga, Amadeo L Vázquez; Martín, Nazario; Miranda, Rodolfo

    2011-11-23

    Self-assembly, the process by which objects initially distributed at random arrange into well-defined patterns exclusively due to their local mutual interactions without external intervention, is generally accepted to be the most promising method for large-scale fabrication of functional nanostructures. In particular, the ordering of molecular building-blocks deposited at solid surfaces is relevant for the performance of many organic electronic and optoelectronic devices, such as organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs) or photovoltaic solar cells. However, the fundamental knowledge on the nature and strength of the intermolecular and molecule-substrate interactions that govern the ordering of molecular adsorbates is, in many cases, rather scarce. In most cases, the structure and morphology of the organic-metal interface is not known and it is just assumed to be the same as in the bulk, thereby implicitly neglecting the role of the surface on the assembly. However, this approximation is usually not correct, and the evidence gathered over the last decades points towards an active role of the surface in the assembly, leading to self-assembled structures that only in a few occasions can be understood by considering just intermolecular interactions in solid or gas phases. In this work we review several examples from our recent research demonstrating the apparently endless variety of ways in which the surface might affect the assembly of organic adsorbates.

  5. Self-assembled nanostructured metamaterials

    Science.gov (United States)

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

    2017-07-01

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

  6. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-10-01

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

  8. Stereochemistry in subcomponent self-assembly.

    Science.gov (United States)

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

    2014-07-15

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

  9. Functionalization of Recombinant Amelogenin Nanospheres Allows Their Binding to Cellulose Materials.

    Science.gov (United States)

    Butler, Samuel J; Bülow, Leif; Bonde, Johan

    2016-10-01

    Protein engineering to functionalize the self-assembling enamel matrix protein amelogenin with a cellulose binding domain (CBD) is used. The purpose is to examine the binding of the engineered protein, rh174CBD, to cellulose materials, and the possibility to immobilize self-assembled amelogenin nanospheres on cellulose. rh174CBD assembled to nanospheres ≈35 nm in hydrodynamic diameter, very similar in size to wild type amelogenin (rh174). Uniform particles are formed at pH 10 for both rh174 and rh174CBD, but only rh174CBD nanospheres showes significant binding to cellulose (Avicel). Cellulose binding of rh174CBD is promoted when the protein is self-assembled to nanospheres, compared to being in a monomeric form, suggesting a synergistic effect of the multiple CBDs on the nanospheres. The amount of bound rh174CBD nanospheres reached ≈15 mg/g Avicel, which corresponds to 4.2 to 6.3 × 10(-7) mole/m(2) . By mixing rh174 and rh174CBD, and then inducing self-assembly, composite nanospheres with a high degree of cellulose binding can be formed, despite a lower proportion of rh174CBD. This demonstrates that amelogenin variants like rh174 can be incorporated into the nanospheres, and still retain most of the binding to cellulose. Engineered amelogenin nanoparticles can thus be utilized to construct a range of new cellulose based hybrid materials, e.g. for wound treatment.

  10. Shape Restoration by Active Self-Assembly

    Directory of Open Access Journals (Sweden)

    D. Arbuckle

    2005-01-01

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

  11. Research on Self-Assembling Quantum Dots.

    Science.gov (United States)

    1995-10-30

    0K. in a second phase of this contract we turned our efforts to the fabrication and studies of self assembled quantum dots . We first demonstrated a...method for producing InAs-GasAs self assembled quantum dots (SAD) using MBE. (AN)

  12. 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.

  13. 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

  14. Developmental self-assembly of a DNA tetrahedron.

    Science.gov (United States)

    Sadowski, John P; Calvert, Colby R; Zhang, David Yu; Pierce, Niles A; Yin, Peng

    2014-04-22

    Kinetically controlled isothermal growth is fundamental to biological development, yet it remains challenging to rationally design molecular systems that self-assemble isothermally into complex geometries via prescribed assembly and disassembly pathways. By exploiting the programmable chemistry of base pairing, sophisticated spatial and temporal control have been demonstrated in DNA self-assembly, but largely as separate pursuits. By integrating temporal with spatial control, here we demonstrate the "developmental" self-assembly of a DNA tetrahedron, where a prescriptive molecular program orchestrates the kinetic pathways by which DNA molecules isothermally self-assemble into a well-defined three-dimensional wireframe geometry. In this reaction, nine DNA reactants initially coexist metastably, but upon catalysis by a DNA initiator molecule, navigate 24 individually characterizable intermediate states via prescribed assembly pathways, organized both in series and in parallel, to arrive at the tetrahedral final product. In contrast to previous work on dynamic DNA nanotechnology, this developmental program coordinates growth of ringed substructures into a three-dimensional wireframe superstructure, taking a step toward the goal of kinetically controlled isothermal growth of complex three-dimensional geometries.

  15. Recent development of peptide self-assembly

    Institute of Scientific and Technical Information of China (English)

    Xiubo Zhao; Fang Pan; Jian R. Lu

    2008-01-01

    Amino acids are the building blocks to build peptides and proteins. Recent development in peptide synthesis has however enabled us to mimic this natural process by preparing various long and short peptides possessing different conformations and biological functions. The self-assembly of short designed peptides into molecular nanostructures is becoming a growing interest in nanobiotechnology. Self-assembled peptides exhibit several attractive features for applications in tissue regeneration, drug delivery, biological surface engineering as well as in food science, cosmetic industry and antibiotics. The aim of this review is to introduce the readers to a number of representative studies on peptide self-assembly.

  16. Shape-induced separation of nanospheres and aligned nanorods

    NARCIS (Netherlands)

    Ahmad, I.; Zandvliet, H.J.W.; Kooij, E.S.

    2014-01-01

    We studied the phase separation and spatial arrangement of gold nanorods and nanospheres after evaporative self-assembly from aqueous suspension. Depending on the position relative to the contact line of the drying droplet, spheres and rods separate into various liquid-crystalline phases. Nanorods e

  17. 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

  18. Designing large scale chiral metamaterials by nanosphere shadowing lithography

    Science.gov (United States)

    He, Yizhuo; Zhao, Yiping

    2016-09-01

    A scalable nanofabrication technique for chiral metamaterials is presented, which combines the dynamic shadowing growth and self-assembled nanosphere monolayers, and is also known as nanosphere shadowing lithography. We have developed two strategies based on nanosphere shadowing lithography to prepare chiral nanostructures. The first strategy is to create a quasi-three-dimensional single-layer fan-shaped chiral nanostructure on nanospheres with one plasmonic material. The second strategy is to create three-dimensional multi-layers helical nanostructures with one plasmonic material and one dielectric material. Both strategies can produce large-area chiral nanostructures with strong chiral optical response, which makes nanosphere shadowing lithography suitable for producing chiral metamaterial based devices such as an ultrathin narrow-band circular polarizer.

  19. 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 ...

  20. Tailoring self-assembled monolayers at the electrochemical interface

    Indian Academy of Sciences (India)

    S Varatharajan; Sheela Berchmans; V Yegnaraman

    2009-09-01

    The main focus of this review is to illustrate the amenability of self-assembled monolayers (SAMs) for functionalisation with different receptors, catalytic materials, biomolecules, enzymes, antigen-antibody, etc for various applications. The review discusses initially about the preparation and characterization of SAMs and tailoring of SAMs by incorporation of suitable recognition elements. A description of how the molecular recognition is achieved through forces like electrostatic, covalent and host-guest interactions is included in the review.

  1. Self-assembling holographic biosensors and biocomputers.

    Energy Technology Data Exchange (ETDEWEB)

    Light, Yooli Kim; Bachand, George David (Sandia National Laboratories, Albuquerque, NM); Schoeniger, Joseph S.; Trent, Amanda M. (Sandia National Laboratories, Albuquerque, NM)

    2006-05-01

    We present concepts for self-assembly of diffractive optics with potential uses in biosensors and biocomputers. The simplest such optics, diffraction gratings, can potentially be made from chemically-stabilized microtubules migrating on nanopatterned tracks of the motor protein kinesin. We discuss the fabrication challenges involved in patterning sub-micron-scale structures with proteins that must be maintained in aqueous buffers to preserve their activity. A novel strategy is presented that employs dry contact printing onto glass-supported amino-silane monolayers of heterobifunctional crosslinkers, followed by solid-state reactions of these cross-linkers, to graft patterns of reactive groups onto the surface. Successive solution-phase addition of cysteine-mutant proteins and amine-reactive polyethylene glycol allows assembly of features onto the printed patterns. We present data from initial experiments showing successful micro- and nanopatterning of lines of single-cysteine mutants of kinesin interleaved with lines of polyethylene, indicating that this strategy can be employed to arrays of features with resolutions suitable for gratings.

  2. Strip-Pattern-Spheres Self-Assembled from Polypeptide-Based Polymer Mixtures: Structure and Defect Features

    Science.gov (United States)

    Zhu, Xingyu; Guan, Zhou; Lin, Jiaping; Cai, Chunhua

    2016-07-01

    We found that poly(γ-benzyl-L-glutamate)-block-poly(ethylene glycol) (PBLG-b-PEG) rod-coil block copolymers and polystyrene (PS) homopolymers can cooperatively self-assemble into nano-spheres with striped patterns on their surfaces (strip-pattern-spheres) in aqueous solution. With assistance of dissipative particle dynamics simulation, it is discovered that the PS homopolymers form a spherical template core and the PBLG-b-PEG block copolymers assemble into striped patterns on the spherical surface. The hydrophobic PBLG rods are packed orderly in the strips, while the hydrophilic PEG blocks stabilize the strip-pattern-spheres in solution. Defects such as dislocations and disclinations can be observed in the striped patterns. Self-assembling temperature and sphere radius are found to affect defect densities in the striped patterns. A possible mechanism is proposed to illustrate how PBLG-b-PEG and PS cooperatively self-assemble into hierarchical spheres with striped patterns on surfaces.

  3. Self-assembly and semiconductivity of an oligothiophene supergelator

    Directory of Open Access Journals (Sweden)

    Pampa Pratihar

    2010-11-01

    Full Text Available A bis(trialkoxybenzamide-functionalized quaterthiophene derivative was synthesized and its self-assembly properties in solution were studied. In non-polar solvents such as cyclohexane, this quaterthiophene π-system formed fibril aggregates with an H-type molecular arrangement due to synergistic effect of hydrogen bonding and π-stacking. The self-assembled fibres were found to gelate numerous organic solvents of diverse polarity. The charge transport ability of such elongated fibres of quaterthiophene π-system was explored by the pulse radiolysis time resolved microwave conductivity (PR-TRMC technique and moderate mobility values were obtained. Furthermore, initial AFM and UV-vis spectroscopic studies of a mixture of our electron-rich quaterthiophene derivative with the electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM revealed a nanoscale segregated assembly of the individual building blocks in the blend.

  4. Self-Assembled Fluorodendrimers Combine the Features of Lipid and Polymeric Vectors in Gene Delivery.

    Science.gov (United States)

    Wang, Hui; Wang, Yitong; Wang, Yu; Hu, Jingjing; Li, Tianfu; Liu, Hongmei; Zhang, Qiang; Cheng, Yiyun

    2015-09-28

    An ideal vector in gene therapy should exhibit high serum stability, excellent biocompatibility, a desired transfection efficacy and permeability into targeted tissues. Here, we describe a class of low-molecular-weight fluorodendrimers for efficient gene delivery. These materials self-assemble into uniform nanospheres and allow for efficient transfection at low charge ratios and very low DNA doses with minimal cytotoxicity. Our results demonstrate that these vectors combine the features of synthetic gene vectors such as liposomes and cationic polymers and present promising potential for clinical gene therapy.

  5. Self-assembled hemicapsules with inherent functionalities: modeling of a supramolecular electrostatic self-assembly

    NARCIS (Netherlands)

    Oshovsky, G.; Reinhoudt, David; Verboom, Willem

    2006-01-01

    An approach to functional self-assembled hemicapsules is described consisting of the use of multivalent (valency ≥ 4) and divalent components, the functional groups of which have a relatively weak binding affinity. Electrostatic self-assembly of tetrakis(pyridiniummethyl)cavitand hemispheres (H) and

  6. Programming biomolecular self-assembly pathways.

    Science.gov (United States)

    Yin, Peng; Choi, Harry M T; Calvert, Colby R; Pierce, Niles A

    2008-01-17

    In nature, self-assembling and disassembling complexes of proteins and nucleic acids bound to a variety of ligands perform intricate and diverse dynamic functions. In contrast, attempts to rationally encode structure and function into synthetic amino acid and nucleic acid sequences have largely focused on engineering molecules that self-assemble into prescribed target structures, rather than on engineering transient system dynamics. To design systems that perform dynamic functions without human intervention, it is necessary to encode within the biopolymer sequences the reaction pathways by which self-assembly occurs. Nucleic acids show promise as a design medium for engineering dynamic functions, including catalytic hybridization, triggered self-assembly and molecular computation. Here, we program diverse molecular self-assembly and disassembly pathways using a 'reaction graph' abstraction to specify complementarity relationships between modular domains in a versatile DNA hairpin motif. Molecular programs are executed for a variety of dynamic functions: catalytic formation of branched junctions, autocatalytic duplex formation by a cross-catalytic circuit, nucleated dendritic growth of a binary molecular 'tree', and autonomous locomotion of a bipedal walker.

  7. S-layer protein self-assembly.

    Science.gov (United States)

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

    2013-01-25

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

  8. Patterned self-assembled film guided electrodeposition

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Feng; LI; Bin; XU; Tao; CHEN; Miao; HAO; Jingcheng; LI

    2004-01-01

    The paper describes the fabrication of polypyrrole (PPy) microstructures through patterned self-assembled film guided electrodeposition. Thus the patterned self-assembled monolayer is prepared by microcontact printing (μCP) and used as the template in the electrodeposition of PPy. It has been found that the self-assembled monolayer plays completely different roles on different substrates in directing the deposition of the PPy. Namely, the electrodeposition mainly occurs on the exposed area of the gold substrates patterned with dodecanethiol (DDT) and octadecanelthiol (ODT) and on the indium tin oxide (ITO) substrate patterned with octadecyltrichlorosilane (OTS), while PPy nucleates on the OTS covered area and no deposition is found on the exposed area of a semiconductor substrate (silicon). This is attributed to the cooperative effect between the substrate conductivity and the compatibility of the PPy oligomer with the covered or exposed area of the substrate surface.

  9. Self-assembled gelators for organic electronics.

    Science.gov (United States)

    Babu, Sukumaran Santhosh; Prasanthkumar, Seelam; Ajayaghosh, Ayyappanpillai

    2012-02-20

    Nature excels at engineering materials by using the principles of chemical synthesis and molecular self-assembly with the help of noncovalent forces. Learning from these phenomena, scientists have been able to create a variety of self-assembled artificial materials of different size, shapes, and properties for wide ranging applications. An area of great interest in this regard is solvent-assisted gel formation with functional organic molecules, thus leading to one-dimensional fibers. Such fibers have improved electronic properties and are potential soft materials for organic electronic devices, particularly in bulk heterojunction solar cells. Described herein is how molecular self-assembly, which was originally proposed as a simple laboratory curiosity, has helped the evolution of a variety of soft functional materials useful for advanced electronic devices such as organic field-effect transistors and organic solar cells. Highlights on some of the recent developments are discussed.

  10. Self-assembled histidine acid phosphatase nanocapsules in ionic liquid [BMIM][BF4] as functional templates for hollow metal nanoparticles.

    Science.gov (United States)

    Soni, Sarvesh K; Selvakannan, P R; Bhargava, Suresh K; Bansal, Vipul

    2012-07-17

    We report the biomacromolecular self-assembly of histidine acid phosphatase (HAP), an enzyme of significant biomedical and industrial importance, in the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF(4)]). The spontaneous self-assembly of HAP enzyme in [BMIM][BF(4)] results in the formation of HAP nanocapsules. The HAP enzyme molecules were found to retain their enzymatic activity after the self-assembly process, which enabled us to utilize self-assembled HAP capsules as self-catalyzing templates for the synthesis of a range of hollow metal nanoparticles (Au, Ag, Pd, and Ni) without employing any additional reducing agent. The hollow metal nanospheres with HAP encapsulated within their cavity were found to retain enzymatic activity for at least up to four cycles, as demonstrated in the case of Au-coated HAP capsules as the model system.

  11. Self-assembly of small peptidomimetic cyclophanes.

    Science.gov (United States)

    Becerril, Jorge; Burguete, M Isabel; Escuder, Beatriu; Galindo, Francisco; Gavara, Raquel; Miravet, Juan F; Luis, Santiago V; Peris, Gabriel

    2004-08-20

    The self-assembly of a series of small peptidomimetic cyclophanes in organic solvents was studied. X-ray diffraction, NMR spectroscopy, and molecular modelling were used to understand the structural features of these self-assembling compounds both at the molecular and supramolecular level. The factors that could influence the formation of gels rather than crystals were studied and a model for the arrangement of molecules in the gel was proposed. Furthermore, scanning electron microscopy revealed that in some cases these compounds undergo a transcription of chirality when going from organogelator to helicoidal gel fibres.

  12. Remote control of self-assembled microswimmers

    CERN Document Server

    Grosjean, Galien; Darras, Alexis; Hubert, Maxime; Lumay, Geoffroy; Vandewalle, Nicolas

    2015-01-01

    Physics governing the locomotion of microorganisms and other microsystems is dominated by viscous damping. An effective swimming strategy involves the non-reciprocal and periodic deformations of the considered body. Here, we show that a magnetocapillary-driven self-assembly, composed of three soft ferromagnetic beads, is able to swim along a liquid-air interface when powered by an external magnetic field. More importantly, we demonstrate that trajectories can be fully controlled, opening ways to explore low Reynolds number swimming. This magnetocapillary system spontaneously forms by self-assembly, allowing miniaturization and other possible applications such as cargo transport or solvent flows.

  13. Integrating nanosphere lithography in device fabrication

    Science.gov (United States)

    Laurvick, Tod V.; Coutu, Ronald A.; Lake, Robert A.

    2016-03-01

    This paper discusses the integration of nanosphere lithography (NSL) with other fabrication techniques, allowing for nano-scaled features to be realized within larger microelectromechanical system (MEMS) based devices. Nanosphere self-patterning methods have been researched for over three decades, but typically not for use as a lithography process. Only recently has progress been made towards integrating many of the best practices from these publications and determining a process that yields large areas of coverage, with repeatability and enabled a process for precise placement of nanospheres relative to other features. Discussed are two of the more common self-patterning methods used in NSL (i.e. spin-coating and dip coating) as well as a more recently conceived variation of dip coating. Recent work has suggested the repeatability of any method depends on a number of variables, so to better understand how these variables affect the process a series of test vessels were developed and fabricated. Commercially available 3-D printing technology was used to incrementally alter the test vessels allowing for each variable to be investigated individually. With these deposition vessels, NSL can now be used in conjunction with other fabrication steps to integrate features otherwise unattainable through current methods, within the overall fabrication process of larger MEMS devices. Patterned regions in 1800 series photoresist with a thickness of ~700nm are used to capture regions of self-assembled nanospheres. These regions are roughly 2-5 microns in width, and are able to control the placement of 500nm polystyrene spheres by controlling where monolayer self-assembly occurs. The resulting combination of photoresist and nanospheres can then be used with traditional deposition or etch methods to utilize these fine scale features in the overall design.

  14. Functional materials of self-assembled compounds

    NARCIS (Netherlands)

    Hameren, R. van

    2010-01-01

    The research described in the thesis entitled “Functional materials of self-assembled compounds” has been carried out at the interface of physics and chemistry, with the aim to explore new scientific opportunities and develop new applications. The research mainly focuses on porphyrins,

  15. 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...

  16. 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...

  17. Functional materials of self-assembled compounds

    NARCIS (Netherlands)

    Hameren, R. van

    2010-01-01

    The research described in the thesis entitled “Functional materials of self-assembled compounds” has been carried out at the interface of physics and chemistry, with the aim to explore new scientific opportunities and develop new applications. The research mainly focuses on porphyrins, chromophoric

  18. DNA addition using linear self-assembly

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jian; QIAN LuLu; LIU Qiang; ZHANG ZhiZhou; HE Lin

    2007-01-01

    This paper presents a DNA algorithm which adds two nonnegative binary integers using self-assembly in constant steps. The approach has the benefit of greater experimental simplicity when compared with previous DNA addition algorithms. For the addition of two binary n-bit integers, O(n) is different from DNA strands and only O(1) biochemical experimental procedures are required.

  19. 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

  20. [INVITED] Self-assembled optical metamaterials

    Science.gov (United States)

    Baron, Alexandre; Aradian, Ashod; Ponsinet, Virginie; Barois, Philippe

    2016-08-01

    Self-assembled metamaterials constitute a promising platform to achieving bulk and homogenous optical materials that exhibit unusual effective medium properties. For many years now, the research community has contemplated lithographically fabricated metasurfaces, with extraordinary optical features. However, achieving large volumes at low cost is still a challenge by top-down fabrication. Bottom-up fabrication, that relies both on nanochemistry and self-assembly, is capable of building such materials while greatly reducing the energy footprint in the formulation of the metamaterial. Self-assembled metamaterials have shown that they are capable of reaching unprecedented values of bulkiness and homogeneity figures of merit. This feat is achieved by synthesizing plasmonic nanoresonators (meta-atoms in the sense of artificial polarizable units) and assembling them into a fully three-dimensional matrix through a variety of methods. Furthermore it has been shown that a wide range of material parameters can be tailored by controlling the geometry and composition of the meta-atoms as well as the volume fraction of the nano-objects in the metamaterial. Here we conduct a non-comprehensive review of some of the recent trends in self-assembled optical metamaterials and illustrate these trends with our recent work.

  1. Stabilization of Self-Assembled Alumina Mesophases

    NARCIS (Netherlands)

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

    2013-01-01

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

  2. Nanopropulsion by biocatalytic self-assembly.

    Science.gov (United States)

    Leckie, Joy; Hope, Alexander; Hughes, Meghan; Debnath, Sisir; Fleming, Scott; Wark, Alastair W; Ulijn, Rein V; Haw, Mark D

    2014-09-23

    A number of organisms and organelles are capable of self-propulsion at the micro- and nanoscales. Production of simple man-made mimics of biological transportation systems may prove relevant to achieving movement in artificial cells and nano/micronscale robotics that may be of biological and nanotechnological importance. We demonstrate the propulsion of particles based on catalytically controlled molecular self-assembly and fiber formation at the particle surface. Specifically, phosphatase enzymes (acting as the engine) are conjugated to a quantum dot (the vehicle), and are subsequently exposed to micellar aggregates (fuel) that upon biocatalytic dephosphorylation undergo fibrillar self-assembly, which in turn causes propulsion. The motion of individual enzyme/quantum dot conjugates is followed directly using fluorescence microscopy. While overall movement remains random, the enzyme-conjugates exhibit significantly faster transport in the presence of the fiber forming system, compared to controls without fuel, a non-self-assembling substrate, or a substrate which assembles into spherical, rather than fibrous structures upon enzymatic dephosphorylation. When increasing the concentration of the fiber-forming fuel, the speed of the conjugates increases compared to non-self-assembling substrate, although directionality remains random.

  3. Stabilization of Self-Assembled Alumina Mesophases

    NARCIS (Netherlands)

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

    2013-01-01

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

  4. Self-assembly micro optical filter

    Science.gov (United States)

    Zhang, Ping (Cerina); Le, Kevin; Malalur-Nagaraja-Rao, Smitha; Hsu, Lun-Chen; Chiao, J.-C.

    2006-01-01

    Optical communication and sensor industry face critical challenges in manufacturing for system integration. Due to the assembly complexity and integration platform variety, micro optical components require costly alignment and assembly procedures, in which many required manual efforts. Consequently, self-assembly device architectures have become a great interest and could provide major advantages over the conventional optical devices. In this paper, we discussed a self-assembly integration platform for micro optical components. To demonstrate the adaptability and flexibility of the proposed optical device architectures, we chose a commercially available MEMS fabrication foundry service - MUMPs (Multi-User MEMS Process). In this work, polysilicon layers of MUMPS are used as the 3-D structural material for construction of micro component framework and actuators. However, because the polysilicon has high absorption in the visible and near infrared wavelength ranges, it is not suitable for optical interaction. To demonstrate the required optical performance, hybrid integration of materials was proposed and implemented. Organic compound materials were applied on the silicon-based framework to form the required optical interfaces. Organic compounds provide good optical transparency, flexibility to form filters or lens and inexpensive manufacturing procedures. In this paper, we have demonstrated a micro optical filter integrated with self-assembly structures. We will discuss the self-assembly mechanism, optical filter designs, fabrication issues and results.

  5. A NOVEL METHOD TO PREPARE CROSSLINKED POLYETHYLENEIMINE HOLLOW NANOSPHERES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel method to prepare crosslinked polyethyleneimine (CPEI) hollow nanospheres was reported.Uniform silica nanospheres were used as templates,3-aminopropyl trimethoxysilane (APS) was immobilized on the surface of silica nanospheres as couple agent.Aziridine was initiated ring-opening polymerization with the amino groups in APS to form polyethyleneimine (PEI) shell layer.1,4-Butanediol diacrylate was utilized to crosslink PEI polymeric shell.The silica nanospheres in core were etched by hydrofluoric acid to obtain hollow CPEI nanospheres.The hollow nanospheres were characterized by X-ray photoelectron spectroscopy (XPS),transmission electron microscopy (TEM),and thermogravimetric analysis (TGA).

  6. Self-assembled nanolaminate coatings (SV)

    Energy Technology Data Exchange (ETDEWEB)

    Fan, H.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Aeronautics (LM Aero) are collaborating to develop affordable, self-assembled, nanocomposite coatings and associated fabrication processes that will be tailored to Lockheed Martin product requirements. The purpose of this project is to develop a family of self-assembled coatings with properties tailored to specific performance requirements, such as antireflective (AR) optics, using Sandia-developed self-assembled techniques. The project met its objectives by development of a simple and economic self-assembly processes to fabricate multifunctional coatings. Specifically, materials, functionalization methods, and associated coating processes for single layer and multiple layers coatings have been developed to accomplish high reflective coatings, hydrophobic coatings, and anti-reflective coatings. Associated modeling and simulations have been developed to guide the coating designs for optimum optical performance. The accomplishments result in significant advantages of reduced costs, increased manufacturing freedom/producibility, improved logistics, and the incorporation of new technology solutions not possible with conventional technologies. These self-assembled coatings with tailored properties will significantly address LMC's needs and give LMC a significant competitive lead in new engineered materials. This work complements SNL's LDRD and BES programs aimed at developing multifunctional nanomaterials for microelectronics and optics as well as structure/property investigations of self-assembled nanomaterials. In addition, this project will provide SNL with new opportunities to develop and apply self-assembled nanocomposite optical coatings for use in the wavelength ranges of 3-5 and 8-12 micrometers, ranges of vital importance to military-based sensors and weapons. The SANC technologies will be applied to multiple programs within the LM Company including the F-35, F-22, ADP (Future Strike Bomber

  7. Preparation of ZnO Nanospheres and Their Applications in Dye-Sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong-Zhe; WU Li-Hui; LIU Yan-Ping; XIE Er-Qing; YAN De; CHEN Jiang-Tao

    2009-01-01

    ZnO nanospheres are synthesized by a two-step self-assembly method.X-ray diffraction pattern and Raman scattering spectra measurements show that all the samples present a typical wurtzite structure.A regular sphere shape is inspected by field emission scanning electron microscope and transmission electron microscope for the samples.It is shown that the as-synthesized ZnO nanosphere is composed of numbers of primary particles with size of around 10 nm.A possible growth mechanism for the two-step self-assembly ZnO nanosphere is proposed.After applying the ZnO nanospheres to dye-sensitized solar cells (DSSCs),a 117% increase of the overall light to electricity conversion efficiency η is observed compared with that of the ZnO nanoparticles based DSSCs.Associated with the UV-vis results,light scattering is assigned to the great improvement of η.

  8. Synthesis and Characterization of Fatty Acid/Amino Acid Self-Assemblies

    Directory of Open Access Journals (Sweden)

    Joanna Gajowy

    2014-10-01

    Full Text Available In this paper, we discuss the synthesis and self-assembling behavior of new copolymers derived from fatty acid/amino acid components, namely dimers of linoleic acid (DLA and tyrosine derived diphenols containing alkyl ester pendent chains, designated as “R” (DTR. Specific pendent chains were ethyl (E and hexyl (H. These poly(aliphatic/aromatic-ester-amides were further reacted with poly(ethylene glycol (PEG and poly(ethylene glycol methyl ether of different molecular masses, thus resulting in ABA type (hydrophilic-hydrophobic-hydrophilic triblock copolymers. We used Fourier transform infrared (FTIR and nuclear magnetic resonance (NMR spectroscopies to evaluate the chemical structure of the final materials. The molecular masses were estimated by gel permeation chromatography (GPC measurements. The self-organization of these new polymeric systems into micellar/nanospheric structures in aqueous environment was evaluated using ultraviolet/visible (UV-VIS spectroscopy, dynamic light scattering (DLS and transmission electron microscopy (TEM. The polymers were found to spontaneously self-assemble into nanoparticles with sizes in the range 196–239 nm and critical micelle concentration (CMC of 0.125–0.250 mg/mL. The results are quite promising and these materials are capable of self-organizing into well-defined micelles/nanospheres encapsulating bioactive molecules, e.g., vitamins or antibacterial peptides for antibacterial coatings on medical devices.

  9. Chemical Functionalization, Self-Assembly, and Applications of Nanomaterials and Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Tifeng [Yanshan University; Yan, Xingbin [Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences; Balan, Lavinia [French National Centre for Scientific Research (CNRS), Institute of Materials Science of Mulhouse (IS2M), France; Stepanov, Andrey [Russian Academy of Sciences (RAS), Kazan Physical-Technical Institute, Russia; Chen, Xinqing [Hong Kong University of Science and Technology, Hong Kong; Hu, Michael Z. [ORNL

    2014-01-01

    This special issue addresses the research studies on chemical functionalization, self-assembly, and applications of nanomaterials and nanocomposites. It contains twentyfour articles including two reviews and twenty-two research articles. It is used to create new functional nanomaterials and nanocomposites with a variety of sizes and morphologies such as Zn/Al layered double hydroxide, tin oxide nanowires, FeOOH-modified anion resin, Au nanoclusters silica composite nanospheres, Ti-doped ZnO sol-composite films, TiO2/ZnO composite, graphene oxide nanocomposites, LiFePO4/C nanocomposites, and chitosan nanoparticles. These nanomaterials and nanocomposites have widespread applications in tissue engineering, antitumor, sensors, photoluminescence, electrochemical, and catalytic properties. In addition, this themed issue includes some research articles about self-assembly systems covering organogels and Langmuir films. Furthermore, B. Blasiak et al. performed a literature survey on the recent advances in production, functionalization, toxicity reduction, and application of nanoparticles in cancer diagnosis, treatment, and treatment monitoring. P. Colson et al. performed a literature survey on the recent advances in nanosphere lithography due to its compatibility with wafer-scale processes as well as its potential to manufacture a wide variety of homogeneous one-, two-, or three-dimensional nanostructures.

  10. Ultrasmall peptides self-assemble into diverse nanostructures: morphological evaluation and potential implications.

    Science.gov (United States)

    Lakshmanan, Anupama; Hauser, Charlotte A E

    2011-01-01

    In this study, we perform a morphological evaluation of the diverse nanostructures formed by varying concentration and amino acid sequence of a unique class of ultrasmall self-assembling peptides. We modified these peptides by replacing the aliphatic amino acid at the C-aliphatic terminus with different aromatic amino acids. We tracked the effect of introducing aromatic residues on self-assembly and morphology of resulting nanostructures. Whereas aliphatic peptides formed long, helical fibers that entangle into meshes and entrap >99.9% water, the modified peptides contrastingly formed short, straight fibers with a flat morphology. No helical fibers were observed for the modified peptides. For the aliphatic peptides at low concentrations, different supramolecular assemblies such as hollow nanospheres and membrane blebs were found. Since the ultrasmall peptides are made of simple, aliphatic amino acids, considered to have existed in the primordial soup, study of these supramolecular assemblies could be relevant to understanding chemical evolution leading to the origin of life on Earth. In particular, we propose a variety of potential applications in bioengineering and nanotechnology for the diverse self-assembled nanostructures.

  11. Ultrasmall Peptides Self-Assemble into Diverse Nanostructures: Morphological Evaluation and Potential Implications

    Directory of Open Access Journals (Sweden)

    Charlotte A.E. Hauser

    2011-09-01

    Full Text Available In this study, we perform a morphological evaluation of the diverse nanostructures formed by varying concentration and amino acid sequence of a unique class of ultrasmall self-assembling peptides. We modified these peptides by replacing the aliphatic amino acid at the C-aliphatic terminus with different aromatic amino acids. We tracked the effect of introducing aromatic residues on self-assembly and morphology of resulting nanostructures. Whereas aliphatic peptides formed long, helical fibers that entangle into meshes and entrap >99.9% water, the modified peptides contrastingly formed short, straight fibers with a flat morphology. No helical fibers were observed for the modified peptides. For the aliphatic peptides at low concentrations, different supramolecular assemblies such as hollow nanospheres and membrane blebs were found. Since the ultrasmall peptides are made of simple, aliphatic amino acids, considered to have existed in the primordial soup, study of these supramolecular assemblies could be relevant to understanding chemical evolution leading to the origin of life on Earth. In particular, we propose a variety of potential applications in bioengineering and nanotechnology for the diverse self-assembled nanostructures.

  12. 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.

  13. 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.

  14. Heterogeneous self-assembled media for biopolymerization

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain

    2011-01-01

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

  15. Towards negative index self-assembled metamaterials

    CERN Document Server

    Fruhnert, Martin; Lederer, Falk; Rockstuhl, Carsten

    2016-01-01

    We investigate the magnetic response of meta-atoms that can be fabricated by a bottom-up technique. Usually such meta-atoms consist of a dielectric core surrounded by a large number of solid metallic nanoparticles. In contrast to those meta-atoms considered thus far, we study here for the first time hollow metallic nanoparticles (shells). In doing so we solve one of the most pertinent problems of current self-assembled metamaterials, namely implementing meta-atoms with sufficiently large resonance strength and small absorption. Both conditions have to be met for deep sub-wavelength meta-atoms to obtain effectively homogeneous metamaterials which may be meaningfully described by negative material parameters. Eventually we show that by using these findings self-assembled negative index materials come in reach.

  16. 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...

  17. Self-assembled nanoparticles made of fucan

    OpenAIRE

    Dantas-Santos, N.; Almeida-Lima, J.; Vidal, A. A. J.; Pereira, Paula Alexandra Cunha; Pedrosa, Sílvia Santos; Gama, F. M.; Rocha,H.A.O.

    2011-01-01

    Amphiphilic polymers can self-assemble in water due to hydrophilic and hydrophobic interactions, forming nanoparticles (NPs) with unique physicochemical characteristics and thermodynamic stability. A non toxic sulfated Fucan, extracted from Spatoglossum schroederi was chemically modified by the grafting of Hexadecylamine (C16) to the polymer hydrophilic backbone. The resulting modified material (Fucan-C16) formed nanosized particles which were characterized by 1H NMR to asse...

  18. Templated Self Assemble of Nano-Structures

    Energy Technology Data Exchange (ETDEWEB)

    Suo, Zhigang [Harvard University

    2013-04-29

    This project will identify and model mechanisms that template the self-assembly of nanostructures. We focus on a class of systems involving a two-phase monolayer of molecules adsorbed on a solid surface. At a suitably elevated temperature, the molecules diffuse on the surface to reduce the combined free energy of mixing, phase boundary, elastic field, and electrostatic field. With no template, the phases may form a pattern of stripes or disks. The feature size is on the order of 1-100 nm, selected to compromise the phase boundary energy and the long-range elastic or electrostatic interaction. Both experimental observations and our theoretical simulations have shown that the pattern resembles a periodic lattice, but has abundant imperfections. To form a perfect periodic pattern, or a designed aperiodic pattern, one must introduce a template to guide the assembly. For example, a coarse-scale pattern, lithographically defined on the substrate, will guide the assembly of the nanoscale pattern. As another example, if the molecules on the substrate surface carry strong electric dipoles, a charged object, placed in the space above the monolayer, will guide the assembly of the molecular dipoles. In particular, the charged object can be a mask with a designed nanoscale topographic pattern. A serial process (e.g., e-beam lithography) is necessary to make the mask, but the pattern transfer to the molecules on the substrate is a parallel process. The technique is potentially a high throughput, low cost process to pattern a monolayer. The monolayer pattern itself may serve as a template to fabricate a functional structure. This project will model fundamental aspects of these processes, including thermodynamics and kinetics of self-assembly, templated self-assembly, and self-assembly on unconventional substrates. It is envisioned that the theory will not only explain the available experimental observations, but also motivate new experiments.

  19. Engineered Self-Assembly of Plasmonic Nanomaterials

    Science.gov (United States)

    Tao, Andrea

    2013-03-01

    A critical need in nanotechnology is the development of new tools and methods to organize, connect, and integrate solid-state nanocomponents. Self-assembly - where components spontaneously organize themselves - can be carried out on a massively parallel scale to construct large-scale architectures using solid-state nanocrystal building blocks. I will present our recent work on the synthesis and self-assembly of nanocrystals for plasmonics, where light is propagated, manipulated, and confined by solid-state components that are smaller than the wavelength of light itself. We show the organization of polymer-grafted metal nanocrystals into hierarchical nanojunction arrays that possess intense ``hot spots'' due to electromagnetic field localization. We also show that doped semiconductor nanocrystals can serve as a new class of plasmonic building blocks, where shape and carrier density can be actively tuned to engineer plasmon resonances. These examples demonstrate that nanocrystals possess unique electromagnetic properties that rival top-down structures, and the potential of self-assembly for fabricating designer plasmonic materials.

  20. Polymer Self-assembly on Carbon Nanotubes

    Science.gov (United States)

    Giulianini, Michele; Motta, Nunzio

    This chapter analyses the poly(3-hexylthiophene) self-assembly on carbon nanotubes and the interaction between the two materials forming a new hybrid nanostructure. The chapter starts with a review of the several studies investigating polymers and biomolecules self-assembled on nanotubes. Then conducting polymers and polythiophenes are briefly introduced. Accordingly, carbon nanotube structure and properties are reported in Sect. 3. The experimental section starts with the bulk characterisation of polymer thin films with the inclusion of uniformly distributed carbon nanotubes. By using volume film analysis techniques (AFM, TEM, UV-Vis and Raman), we show how the polymer's higher degree of order is a direct consequence of interaction with carbon nanotubes. Nevertheless, it is through the use of nanoscale analysis and molecular dynamic simulations that the self-assembly of the polymer on the nanotube surface can be clearly evidenced and characterised. In Sect. 6, the effect of the carbon templating structure on the P3HT organisation on the surface is investigated, showing the chirality-driven polymer assembly on the carbon nanotube surface. The interaction between P3HT and CNTs brings also to charge transfer, with the modification of physical properties for both species. In particular, the alteration of the polymer electronic properties and the modification of the nanotube mechanical structure are a direct consequence of the P3HT π-π stacking on the nanotube surface. Finally, some considerations based on molecular dynamics studies are reported in order to confirm and support the experimental results discussed.

  1. Self-assembly of Artificial Actin Filaments

    Science.gov (United States)

    Grosenick, Christopher; Cheng, Shengfeng

    Actin Filaments are long, double-helical biopolymers that make up the cytoskeleton along with microtubules and intermediate filaments. In order to further understand the self-assembly process of these biopolymers, a model to recreate actin filament geometry was developed. A monomer in the shape of a bent rod with vertical and lateral binding sites was designed to assemble into single or double helices. With Molecular Dynamics simulations, a variety of phases were observed to form by varying the strength of the binding sites. Ignoring lateral binding sites, we have found a narrow range of binding strengths that lead to long single helices via various growth pathways. When lateral binding strength is introduced, double helices begin to form. These double helices self-assemble into substantially more stable structures than their single helix counterparts. We have found double helices to form long filaments at about half the vertical binding strength of single helices. Surprisingly, we have found that triple helices occasionally form, indicating the importance of structural regulation in the self-assembly of biopolymers.

  2. Self-assembly of knots and links

    Science.gov (United States)

    Orlandini, Enzo; Polles, Guido; Marenduzzo, Davide; Micheletti, Cristian

    2017-03-01

    Guiding the self-assembly of identical building blocks towards complex three-dimensional structures with a set of desired properties is a major goal in material science, chemistry and physics. A particularly challenging problem, especially explored in synthetic chemistry, is that of self-assembling closed structures with a target topology starting by simple geometrical templates. Here we overview and revisit recent advancements, based on stochastic simulations, where the geometry of rigid helical templates with functionalised sticky ends has been designed for self-assembling efficiently and reproducibly into a wide range of three-dimensional closed structures. Notably, these include non trivial topologies of links and knots, including the 819 knot that we had predicted to be highly encodable and that has only recently been obtained experimentally. By appropriately tuning the parameters that define the template shape, we show that, for fixed concentration of templates, the assembly process can be directed towards the formation of specific knotted and linked structures such as the trefoils, pentafoil knots, Hopf and Solomon links. More exotic and unexpected knots and links are also found. Our results should be relevant to the design of new protocols that can both increase and broaden the population of synthetise molecular knots and catenanes.

  3. Differential self-assembly behaviors of cyclic and linear peptides.

    Science.gov (United States)

    Choi, Sung-ju; Jeong, Woo-jin; Kang, Seong-Kyun; Lee, Myongsoo; Kim, Eunhye; Ryu, Du Yeol; Lim, Yong-beom

    2012-07-01

    Here we ask the fundamental questions about the effect of peptide topology on self-assembly. The study revealed that the self-assembling behaviors of cyclic and linear peptides are significantly different in several respects, in addition to sharing several similarities. Their clear differences included the morphological dissimilarities of the self-assembled nanostructures and their thermal stability. The similarities include their analogous critical aggregation concentration values and cytotoxicity profiles, which are in fact closely related. We believe that understanding topology-dependent self-assembly behavior of peptides is important for developing tailor-made self-assembled peptide nanostructures.

  4. 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.

  5. Amphiphilic Janus gold nanoparticles prepared by interface-directed self-assembly: synthesis and self-assembly.

    Science.gov (United States)

    Liu, Guannan; Tian, Jia; Zhang, Xu; Zhao, Hanying

    2014-09-01

    Materials with Janus structures are attractive for wide applications in materials science. Although extensive efforts in the synthesis of Janus particles have been reported, the synthesis of sub-10 nm Janus nanoparticles is still challenging. Herein, the synthesis of Janus gold nanoparticles (AuNPs) based on interface-directed self-assembly is reported. Polystyrene (PS) colloidal particles with AuNPs on the surface were prepared by interface-directed self-assembly, and the colloidal particles were used as templates for the synthesis of Janus AuNPs. To prepare colloidal particles, thiol-terminated polystyrene (PS-SH) was dissolved in toluene and citrate-stabilized AuNPs were dispersed in aqueous solution. Upon mixing the two solutions, PS-SH chains were grafted to the surface of AuNPs and amphiphilic AuNPs were formed at the liquid-liquid interface. PS colloidal particles decorated with AuNPs on the surfaces were prepared by adding the emulsion to excess methanol. On the surface, AuNPs were partially embedded in the colloidal particles. The outer regions of the AuNPs were exposed to the solution and were functionalized through the grafting of atom-transfer radical polymerization (ATRP) initiator. Poly[2-(dimethamino)ethyl methacrylate] (PDMAEMA) on AuNPs were prepared by surface-initiated ATRP. After centrifugation and dissolving the colloidal particles in tetrahydrofuran (THF), Janus AuNPs with PS and PDMAEMA on two hemispheres were obtained. In acidic pH, Janus AuNPs are amphiphilic and are able to emulsify oil droplets in water; in basic pH, the Janus AuNPs are hydrophobic. In mixtures of THF/methanol at a volume ratio of 1:5, the Janus AuNPs self-assemble into bilayer structures with collapsed PS in the interiors and solvated PDMAEMA at the exteriors of the structures.

  6. Large organized surface domains self-assembled from nonpolar amphiphiles.

    Science.gov (United States)

    Krafft, Marie Pierre

    2012-04-17

    unambiguously demonstrated the presence of surface micelles in monolayers of diblocks prior to LB transfer for atomic force microscopy imaging. We characterized an almost perfect two-dimensional crystal, with 12 assignable diffraction peaks, which established that self-assembly and regular nanopatterning were not caused by transfer or induced by the solid support. These experiments also provide the first direct identification of surface micelles on water, and the first identification of such large-size domains using GISAXS. Revisiting Langmuir film compression behavior after we realized that it actually was a compression of nanometric objects led to further unanticipated observations. These films could be compressed far beyond the documented film "collapse", eventually leading to the buildup of two superimposed, less-organized bilayers of diblocks on top of the initially formed monolayer of hemimicelles. Remarkably, the latter withstood the final, irreversible collapse of the composite films. "Gemini" tetrablocks, di(FnHm), with two Fn-chains and two Hm-chains, provided two superposed layers of discrete micelles, apparently the first example of thin films made of stacked discrete self-assembled nanoobjects. Decoration of solid surfaces with domains of predetermined size of these small "nonpolar" molecules is straightforward. Initial examples of applications include deposition of metal dots and catalytic oxidation of CO, and nanopatterning of SiO(2) films.

  7. Molecular Self-Assembly of Short Aromatic Peptides: From Biology to Nanotechnology and Material Science

    Science.gov (United States)

    Gazit, Ehud

    2013-03-01

    The formation of ordered amyloid fibrils is the hallmark of several diseases of unrelated origin. In spite of grave clinical consequence, the mechanism of amyloid formation is not fully understood. We have suggested, based on experimental and bioinformatic analysis, that aromatic interactions may provide energetic contribution as well as order and directionality in the molecular-recognition and self-association processes that lead to the formation of these assemblies. This is in line with the well-known central role of aromatic-stacking interactions in self-assembly processes. Our works on the mechanism of aromatic peptide self-assembly, lead to the discovery that the diphenylalanine recognition motif self-assembles into peptide nanotubes with a remarkable persistence length. Other aromatic homodipeptides could self-assemble in nano-spheres, nano-plates, nano-fibrils and hydrogels with nano-scale order. We demonstrated that the peptide nanostructures have unique chemical, physical and mechanical properties including ultra-rigidity as aramides, semi-conductive, piezoelectric and non-linear optic properties. We also demonstrated the ability to use these peptide nanostructures as casting mold for the fabrication of metallic nano-wires and coaxial nano-cables. The application of the nanostructures was demonstrated in various fields including electrochemical biosensors, tissue engineering, and molecular imaging. Finally, we had developed ways for depositing of the peptide nanostructures and their organization. We had use inkjet technology as well as vapour deposition methods to coat surface and from the peptide ``nano-forests''. We recently demonstrated that even a single phenylalanine amino-acid can form well-ordered fibrilar assemblies.

  8. Improving Light Extraction of Organic Light-Emitting Devices by Attaching Nanostructures with Self-Assembled Photonic Crystal Patterns

    Directory of Open Access Journals (Sweden)

    Kai-Yu Peng

    2014-01-01

    Full Text Available A single-monolayered hexagonal self-assembled photonic crystal (PC pattern fabricated onto polyethylene terephthalate (PET films by using simple nanosphere lithography (NSL method has been demonstrated in this research work. The patterned nanostructures acted as a scattering medium to extract the trapped photons from substrate mode of optical-electronic device for improving the overall external quantum efficiency of the organic light-emitting diodes (OLEDs. With an optimum latex concentration, the distribution of self-assembled polystyrene (PS nanosphere patterns on PET films can be easily controlled by adjusting the rotation speed of spin-coater. After attaching the PS nanosphere array brightness enhancement film (BEF sheet as a photonic crystal pattern onto the device, the luminous intensity of OLEDs in the normal viewing direction is 161% higher than the one without any BEF attachment. The electroluminescent (EL spectrum of OLEDs with PS patterned BEF attachment also showed minor color offset and superior color stabilization characteristics, and thus it possessed the potential applications in all kinds of display technology and solid-state optical-electronic devices.

  9. Potential control of DNA self-assembly on gold electrode

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The self-assembly monolayer (SAM) was prepared with 2-aminoethanethiol (AET) on the gold electrode.A new approach based on potential was first used to control DNA self-assembly covalently onto the SAM with the activation of 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysulfosuccinimide (NHS). The influence of potential on DNA self-assembly was investigated by means of cyclic voltammetry (CV), AC impedance, Auger electron spectrometry (AES) and atomic force microscopy (AFM). The result proves that controlled potential can affect the course of DNA self-assembly. More negative potential can restrain the DNA self-assembly, while more positive potential can accelerate the DNA self-assembly, which is of great significance for the control of DNA self-assembly and will find wide application in the field of DNA-based devices.

  10. Self-assembly of intramolecular charge-transfer compounds into functional molecular systems.

    Science.gov (United States)

    Li, Yongjun; Liu, Taifeng; Liu, Huibiao; Tian, Mao-Zhong; Li, Yuliang

    2014-04-15

    Highly polarized compounds exhibiting intramolecular charge transfer (ICT) are used widely as nonlinear optical (NLO) materials and red emitters and in organic light emitting diodes. Low-molecular-weight donor/acceptor (D/A)-substituted ICT compounds are ideal candidates for use as the building blocks of hierarchically structured, multifunctional self-assembled supramolecular systems. This Account describes our recent studies into the development of functional molecular systems with well-defined self-assembled structures based on charge-transfer (CT) interactions. From solution (sensors) to the solid state (assembled structures), we have fully utilized intrinsic and stimulus-induced CT interactions to construct these functional molecular systems. We have designed some organic molecules capable of ICT, with diversity and tailorability, that can be used to develop novel self-assembled materials. These ICT organic molecules are based on a variety of simple structures such as perylene bisimide, benzothiadiazole, tetracyanobutadiene, fluorenone, isoxazolone, BODIPY, and their derivatives. The degree of ICT is influenced by the nature of both the bridge and the substituents. We have developed new methods to synthesize ICT compounds through the introduction of heterocycles or heteroatoms to the π-conjugated systems or through extending the conjugation of diverse aromatic systems via another aromatic ring. Combining these ICT compounds featuring different D/A units and different degrees of conjugation with phase transfer methodologies and solvent-vapor techniques, we have self-assembled various organic nanostructures, including hollow nanospheres, wires, tubes, and ribbonlike architectures, with controllable morphologies and sizes. For example, we obtained a noncentrosymmetric microfiber structure that possessed a permanent dipole along its fibers' long axis and a transition dipole perpendicular to it; the independent NLO responses of this material can be separated and

  11. Dynamic modeling and scaling of nanostructure formation in the lithographically induced self-assembly and self-construction

    Science.gov (United States)

    Wu, Lin; Chou, Stephen Y.

    2003-05-01

    We numerically studied the dynamical formation process and the scaling of the nanostructures in the lithographically induced self-assembly and self-construction of thin polymer films. Our studies show that the period of the self-assembled pillars depends on the ratio between the surface tension force and the electrostatic force. The viscosity of the polymer has no effect on the final pillar shape. When the feature width of the mold is comparable to or smaller than the most unstable disturbance wavelength of the system, the initially self-assembled pillars will merge to form a self-constructed mesa.

  12. Self-assembly of colloidal surfactants

    Science.gov (United States)

    Kegel, Willem

    2012-02-01

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

  13. Mineral Surface Chemistry and Nanoparticle-aggregation Control Membrane Self-Assembly

    Science.gov (United States)

    Sahai, Nita; Kaddour, Hussein; Dalai, Punam; Wang, Ziqiu; Bass, Garrett; Gao, Min

    2017-01-01

    The self-assembly of lipid bilayer membranes to enclose functional biomolecules, thus defining a “protocell,” was a seminal moment in the emergence of life on Earth and likely occurred at the micro-environment of the mineral-water interface. Mineral-lipid interactions are also relevant in biomedical, industrial and technological processes. Yet, no structure-activity relationships (SARs) have been identified to predict lipid self-assembly at mineral surfaces. Here we examined the influence of minerals on the self-assembly and survival of vesicles composed of single chain amphiphiles as model protocell membranes. The apparent critical vesicle concentration (CVC) increased in the presence of positively-charged nanoparticulate minerals at high loadings (mg/mL) suggesting unfavorable membrane self-assembly in such situations. Above the CVC, initial vesicle formation rates were faster in the presence of minerals. Rates were correlated with the mineral’s isoelectric point (IEP) and reactive surface area. The IEP depends on the crystal structure, chemical composition and surface hydration. Thus, membrane self-assembly showed rational dependence on fundamental mineral properties. Once formed, membrane permeability (integrity) was unaffected by minerals. Suggesting that, protocells could have survived on rock surfaces. These SARs may help predict the formation and survival of protocell membranes on early Earth and other rocky planets, and amphiphile-mineral interactions in diverse other phenomena. PMID:28266537

  14. Hollow Nanospheres Array Fabrication via Nano-Conglutination Technology.

    Science.gov (United States)

    Zhang, Man; Deng, Qiling; Xia, Liangping; Shi, Lifang; Cao, Axiu; Pang, Hui; Hu, Song

    2015-09-01

    Hollow nanospheres array is a special nanostructure with great applications in photonics, electronics and biochemistry. The nanofabrication technique with high resolution is crucial to nanosciences and nano-technology. This paper presents a novel nonconventional nano-conglutination technology combining polystyrenes spheres (PSs) self-assembly, conglutination and a lift-off process to fabricate the hollow nanospheres array with nanoholes. A self-assembly monolayer of PSs was stuck off from the quartz wafer by the thiol-ene adhesive material, and then the PSs was removed via a lift-off process and the hollow nanospheres embedded into the thiol-ene substrate was obtained. Thiolene polymer is a UV-curable material via "click chemistry" reaction at ambient conditions without the oxygen inhibition, which has excellent chemical and physical properties to be attractive as the adhesive material in nano-conglutination technology. Using the technique, a hollow nanospheres array with the nanoholes at the diameter of 200 nm embedded into the rigid thiol-ene substrate was fabricated, which has great potential to serve as a reaction container, catalyst and surface enhanced Raman scattering substrate.

  15. Triggered self-assembly of magnetic nanoparticles

    Science.gov (United States)

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

    2016-03-01

    Colloidal magnetic nanoparticles are candidates for application in biology, medicine and nanomanufac-turing. Understanding how these particles interact collectively in fluids, especially how they assemble and aggregate under external magnetic fields, is critical for high quality, safe, and reliable deployment of these particles. Here, by applying magnetic forces that vary strongly over the same length scale as the colloidal stabilizing force and then varying this colloidal repulsion, we can trigger self-assembly of these nanoparticles into parallel line patterns on the surface of a disk drive medium. Localized within nanometers of the medium surface, this effect is strongly dependent on the ionic properties of the colloidal fluid but at a level too small to cause bulk colloidal aggregation. We use real-time optical diffraction to monitor the dynamics of self-assembly, detecting local colloidal changes with greatly enhanced sensitivity compared with conventional light scattering. Simulations predict the triggering but not the dynamics, especially at short measurement times. Beyond using spatially-varying magnetic forces to balance interactions and drive assembly in magnetic nanoparticles, future measurements leveraging the sensitivity of this approach could identify novel colloidal effects that impact real-world applications of these nanoparticles.

  16. Directed Self-Assembly: Expectations and Achievements

    Directory of Open Access Journals (Sweden)

    Kumar Prashant

    2010-01-01

    Full Text Available Abstract Nanotechnology has been a revolutionary thrust in recent years of development of science and technology for its broad appeal for employing a novel idea for relevant technological applications in particular and for mass-scale production and marketing as common man commodity in general. An interesting aspect of this emergent technology is that it involves scientific research community and relevant industries alike. Top–down and bottom–up approaches are two broad division of production of nanoscale materials in general. However, both the approaches have their own limits as far as large-scale production and cost involved are concerned. Therefore, novel new techniques are desired to be developed to optimize production and cost. Directed self-assembly seems to be a promising technique in this regard; which can work as a bridge between the top–down and bottom–up approaches. This article reviews how directed self-assembly as a technique has grown up and outlines its future prospects.

  17. Coarse-grained simulation reveals key features of HIV-1 capsid self-assembly

    Science.gov (United States)

    Grime, John M. A.; Dama, James F.; Ganser-Pornillos, Barbie K.; Woodward, Cora L.; Jensen, Grant J.; Yeager, Mark; Voth, Gregory A.

    2016-05-01

    The maturation of HIV-1 viral particles is essential for viral infectivity. During maturation, many copies of the capsid protein (CA) self-assemble into a capsid shell to enclose the viral RNA. The mechanistic details of the initiation and early stages of capsid assembly remain to be delineated. We present coarse-grained simulations of capsid assembly under various conditions, considering not only capsid lattice self-assembly but also the potential disassembly of capsid upon delivery to the cytoplasm of a target cell. The effects of CA concentration, molecular crowding, and the conformational variability of CA are described, with results indicating that capsid nucleation and growth is a multi-stage process requiring well-defined metastable intermediates. Generation of the mature capsid lattice is sensitive to local conditions, with relatively subtle changes in CA concentration and molecular crowding influencing self-assembly and the ensemble of structural morphologies.

  18. Tunable Self-Assembly of Diblock Copolymers into Colloidal Particles with Triply Periodic Minimal Surfaces.

    Science.gov (United States)

    Lin, Zhixing; Liu, Shaohua; Mao, Wenting; Tian, Hao; Wang, Nan; Zhang, Ninghe; Tian, Feng; Han, Lu; Feng, Xinliang; Mai, Yiyong

    2017-06-12

    We herein report the tunable self-assembly of simple block copolymers, namely polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymers, into porous cubosomes with inverse Im3‾m or Pn3‾m mesophases of controlled unit cell parameters as well as hexasomes with an inverse hexagonal (p6mm) structure, which have been rarely observed in polymer self-assembly. A new morphological phase diagram was constructed for the solution self-assembly of PS-b-PEO based on the volume fraction of the PS block against the initial copolymer concentration. The formation mechanisms of the cubosomes and hexasomes have also been revealed. This study not only affords a simple system for the controllable preparation and fundamental studies of ordered bicontinuous structures, but also opens up a new avenue towards porous architectures with highly ordered pores. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Designed post-self-assembly structural and functional modifications of a truncated tetrahedron.

    Science.gov (United States)

    Zheng, Yao-Rong; Lan, Wen-Jie; Wang, Ming; Cook, Timothy R; Stang, Peter J

    2011-10-26

    Post-self-assembly modifications of a discrete metal-organic supramolecular structure have been developed. Such modifications allow the properties of the self-assembled supramolecular species to be changed in a simple and efficient manner (>90% yield). Initiated by the application of chemical stimuli, the post-self-assembly modifications described herein result in three distinct changes to the supramolecular system: an individual building-block component change, an overall structural modification, and a functional evolution of a [6+4] metal-organic supramolecular structure. The three modifications have been carefully examined by a range of characterization methods, including NMR and UV-vis spectroscopy, electrospray ionization mass spectrometry, pulsed field gradient spin echo NMR measurements, electrochemical analysis, and computational simulations.

  20. Efficient Confinement of Ultraviolet Light into the Self-Assembled, Dielectric Colloidal Monolayer on a Flat Aluminum Film

    CERN Document Server

    Lee, Seungwoo

    2014-01-01

    Here we propose the efficient confinement of ultraviolet (UV) light into the plasmonic-photonic crystal hybrid, which can be practically developed by the self-assembly of dielectric colloidal nanosphere monolayer onto a flat aluminum (Al) film. Using a numerical approach, we analyzed modal characteristics of each different resonant mode at the UV wavelengths including surface plasmon polariton (SPP) mode and waveguided (WG) mode and tuned these resonant modes from deep to far UV simply by adjusting the size of dielectric colloidal nanosphere. The calculated quality-factor (Q-factor) of such plasmonic-photonic crystal hybrid is at least one order of magnitude higher than that of the existing Al nanostructures (Al nanoparticles, nanodisks, nanovoids, or nanogratings) standing on the dielectric substrate. Also, we systematically studied how the amount of native oxide, which can be generated during the general process for the deposition of Al, can influence on both the SPP and WG modes of such plasmonic-photonic ...

  1. The determinism and boundedness of self-assembling structures

    CERN Document Server

    Tesoro, S

    2016-01-01

    Self-assembly processes are widespread in nature, and lie at the heart of many biological and physical phenomena. The characteristics of self-assembly building blocks determine the structures that they form. Among the most important of these properties are whether the self-assembly is deterministic or nondeterministic, and whether it is bound or unbound. The former tells us whether the same set of building blocks always generates the same structure, and the latter whether it grows indefinitely. These properties are highly relevant in the context of protein structures, as the difference between deterministic protein self-assembly and nondeterministic protein aggregation is central to a number of diseases. Here we introduce a graph-based approach that can determine, with a few restrictions, whether a set of self-assembly building blocks is deterministic or nondeterministic, and whether it is bound or unbound. We apply this methodology to a previously studied lattice self-assembly model and discuss generalisatio...

  2. Molecular Component Structures Mediated Formation of Self-assemblies

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Molecular recognition directed self-assemblies from complementary molecular components, melamine and barbituric acid derivatives were studied by means of NMR, fluorescence, and TEM. It was found that both the process of the self-assembly and the morphologies of the result ed self-assemblies could be mediated by modifying the structures of the molecular components used. The effect of the structures of the molecular components on the formation of the self-as semblies was discussed in terms of intermolecular interactions.

  3. Terminal groups control self-assembly of amphiphilic block copolymers in solution

    Science.gov (United States)

    Grzelakowski, M.; Kita-Tokarczyk, K.

    2016-03-01

    The terminal groups of amphiphilic block copolymers are shown to control macromolecular self-assembly in aqueous solutions, in the micellar/lamellar region of the phase diagram. At the same concentration and using the same self-assembly conditions, dramatic differences are observed in polymer hydration and the resulting nano-/microstructure for two series of polymers with identical block chemistry and hydrophilic-lipophilic balance (HLB). This suggests a strong contribution from end groups to the hydration as the initial step of the self-assembly process, and could be conveniently used to guide the particle morphology and size. Additionally, for polymers with those head groups which drive vesicular structures, differences in membrane organization affect their physical properties, such as permeability.The terminal groups of amphiphilic block copolymers are shown to control macromolecular self-assembly in aqueous solutions, in the micellar/lamellar region of the phase diagram. At the same concentration and using the same self-assembly conditions, dramatic differences are observed in polymer hydration and the resulting nano-/microstructure for two series of polymers with identical block chemistry and hydrophilic-lipophilic balance (HLB). This suggests a strong contribution from end groups to the hydration as the initial step of the self-assembly process, and could be conveniently used to guide the particle morphology and size. Additionally, for polymers with those head groups which drive vesicular structures, differences in membrane organization affect their physical properties, such as permeability. Electronic supplementary information (ESI) available: Fig. S1: Particle diameters for hydrated NH2-ABA-NH2 polymers with different degrees of functionalization; Fig. S2: TEM characterization of compound micelles from BA-OH polymer after extrusion; Fig. S3: Cryo-TEM and stopped flow characterization of lipid vesicles; Fig. S4 and S5: NMR spectra for ABA and BA polymers

  4. The statistical mechanics of dynamic pathways to self-assembly.

    Science.gov (United States)

    Whitelam, Stephen; Jack, Robert L

    2015-04-01

    This review describes some important physical characteristics of the pathways (i.e., dynamical processes) by which molecular, nanoscale, and micrometer-scale self-assembly occurs. We highlight the existence of features of self-assembly pathways that are common to a wide range of physical systems, even though those systems may differ with respect to their microscopic details. We summarize some existing theoretical descriptions of self-assembly pathways and highlight areas-notably, the description of self-assembly pathways that occur far from equilibrium-that are likely to become increasingly important.

  5. Template-Directed Self-Assembly of Alkanethiol Monolayers: Selective Growth on Preexisting Monolayer Edges

    NARCIS (Netherlands)

    Sharpe, Ruben B.A.; Burdinski, Dirk; Huskens, Jurriaan; Zandvliet, Harold J.W.; Reinhoudt, David N.; 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. n-Oct

  6. Metal-Directed Protein Self Assembly

    Science.gov (United States)

    SALGADO, ERIC N.; RADFORD, ROBERT J.

    2010-01-01

    CONSPECTUS Proteins are Nature’s premier building blocks for constructing sophisticated nanoscale architectures that carry out complex tasks and chemical transformations. It is estimated that 70–80% of all proteins are permanently oligomeric, that is, they are composed of multiple proteins that are held together in precise spatial organization through non-covalent interactions. While it is of great fundamental interest to understand the physicochemical basis of protein self-assembly, the mastery of protein-protein interactions (PPIs) would also allow access to novel biomaterials using Nature’s favorite and most versatile building block. With this possibility in mind, we have developed a new approach, Metal Directed Protein Self-Assembly (MDPSA), which utilizes the strength, directionality and selectivity of metal-ligand interactions to control PPIs. At its core, MDPSA is inspired by supramolecular coordination chemistry which exploits metal coordination for the self-assembly of small molecules into discrete, more-or-less predictable higher-order structures. Proteins, however, are not exactly small molecules or simple metal ligands: they feature extensive, heterogeneous surfaces that can interact with each other and with metal ions in unpredictable ways. We will start this Account by first describing the challenges of using entire proteins as molecular building blocks. This will be followed by our work on a model protein (cytochrome cb562) to both highlight and overcome those challenges toward establishing some ground rules for MDPSA. Proteins are also Nature’s metal ligands of choice. In MDPSA, once metal ions guide proteins into forming large assemblies, they are by definition embedded within extensive interfaces formed between protein surfaces. These complex surfaces make an inorganic chemist’s life somewhat difficult, yet they also provide a wide platform to modulate the metal coordination environment through distant, non-covalent interactions

  7. Self-Assembled Magnetic Surface Swimmers

    Science.gov (United States)

    Snezhko, A.; Belkin, M.; Aranson, I. S.; Kwok, W.-K.

    2009-03-01

    We report studies of novel self-assembled magnetic surface swimmers (magnetic snakes) formed from a dispersion of magnetic microparticles at a liquid-air interface and energized by an alternating magnetic field. We show that under certain conditions the snakes spontaneously break the symmetry of surface flows and turn into self-propelled objects. Parameters of the driving magnetic field tune the propulsion velocity of these snakelike swimmers. We find that the symmetry of the surface flows can also be broken in a controlled fashion by attaching a large bead to a magnetic snake (bead-snake hybrid), transforming it into a self-locomoting entity. The observed phenomena have been successfully described by a phenomenological model based on the amplitude equation for surface waves coupled to a large-scale hydrodynamic mean flow equation.

  8. Self Assembly and Elasticity of Nuclear Pasta

    Science.gov (United States)

    Caplan, Matthew; Horowitz, Chuck; Berry, Don; da Silva Schneider, Andre

    2015-10-01

    While the outer crust of a neutron star is likely a solid ion lattice, the core consists of uniform nuclear matter at or above saturation density. In between, nuclei adopt exotic non-spherical geometries called ``nuclear pasta'' in order to minimize the nuclear attraction and Coulomb repulsion between protons. These structures have been well studied with both classical and quantum molecular dynamics, and their geometry can be predicted from the density, temperature, and proton fraction. Recent classical molecular dynamics simulations find evidence for a phase transition at T ~ 0 . 5 MeV, where simulations with low proton fractions undergo a solid-liquid phase transition, while simulations with high proton fractions under a glass-rubber phase transition. This is expected to have nontrivial consequences for the elastic properties of the pasta. Additionally, recent observations indicate that the structure of nuclear pasta may be related to structures observed in biophysics, specifically self assembling lipid membranes.

  9. Smart self-assembled hybrid hydrogel biomaterials.

    Science.gov (United States)

    Kopeček, Jindřich; Yang, Jiyuan

    2012-07-23

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

  10. 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.

  11. Capillary self-assembly of floating bodies

    Science.gov (United States)

    Jung, Sunghwan; Thompson, Paul; Bush, John

    2007-11-01

    We study the self-assembly of bodies supported on the water surface by surface tension. Attractive and repulsive capillary forces exist between menisci of, respectively, the same and opposite signs. In nature, floating objects (e.g. mosquito larvae) thus interact through capillary forces to form coherent packings on the water surface. We here present the results of an experimental investigation of such capillary pattern formation. Thin elliptical metal sheets were designed to have variable shape, flexibility and mass distribution. On the water surface, mono-, bi-, or tri-polar menisci could thus be achieved. The influence of the form of the menisci on the packings arising from the interaction of multiple floaters is explored. Biological applications are discussed.

  12. Supramolecular Self-Assembly Induced Adjustable Multiple Gating States of Nanofluidic Diodes.

    Science.gov (United States)

    Fang, Ruochen; Zhang, Huacheng; Yang, Liulin; Wang, Huanting; Tian, Ye; Zhang, Xi; Jiang, Lei

    2016-12-21

    Artificial nanochannels, inheriting smart gating functions of biological ion channels, promote the development of artificial functional nanofluidic devices for high-performance biosensing and electricity generation. However, gating states of the artificial nanochannels have been mainly realized through chemical modification of the channels with responsive molecules, and their gating states cannot be further regulated once the nanochannel is modified. In this work, we employed a new supramolecular layer-by-layer (LbL) self-assembly method to achieve reversible and adjustable multiple gating features in nanofluidic diodes. Initially, a self-assembly precursor was modified into a single conical nanochannel, then host molecule-cucurbit[8]uril (CB[8]) and guest molecule, a naphthalene derivative, were self-assembled onto the precursor through an LbL method driven by host-enhanced π-π interaction, forming supramolecular monolayer or multilayers on the inner surface of the channel. These self-assemblies with different layer numbers possessed remarkable charge effects and steric effects, exhibiting a capability to regulate the surface charge density and polarity, the effective diameter, and the geometric asymmetry of the single nanochannel, realizing reversible gating of the single nanochannel among multiple rectification and ion-conduction states. As an example of self-assembly of supramolecular networks in nanoconfinements, this work provides a new approach for enhancing functionalities of artificial nanochannels by LbL supramolecular self-assemblies. Meanwhile, since the host molecule, CB[8], used in this work can interact with different kinds of biomolecules and stimuli-responsive chemical species, this work can be further extended to build a novel stable multiple-state research platform for a variety of uses such as sensing and controllable release.

  13. Controlled self-assembly in homopolymer and diblock copolymer

    Science.gov (United States)

    Zhuang, Lei

    This thesis work studies the process, mechanism and control of self-assembly in homopolymers and diblock copolymers. These studies are aimed at finding novel patterning methods that can lead to low cost lithography technologies capable of creating micrometer to nanometer patterns over a large area. We first present a new phenomenon called Lithographically-Induced Self-Assembly (LISA) that can create ordered arrays of pillars in a homopolymer film with a mask placed close to its surface. We demonstrate that the shape, size and morphology of the ordered pillar arrays can be controlled with a patterned mask. A model is developed based on the instability in a fluidic film induced by the Coulomb force from charge accumulation in the polymer film and the mask. Experimental results are shown to support the model. We also investigate the behavior of defects that destroy the ordering of the LISA array and propose ways to prevent them. This self-assembly phenomenon is used as a patterning technique to define the active area of an organic light emitting diode (OLED). The device shows significantly improved lifetime due to the restriction of defect growth. Another patterning technology that is closely related to LISA, Lithographically-Induced Self-Construction (LISC), is also introduced. LISC can form mesas of polymer from the initial thin film and they inherit the shape and size of the mask patterns. A model based on the dynamics of LISA pillar formation and mass conservation is presented and provides a guideline for choosing LISC process parameters. In the final part of the thesis, we study a technique to control the orientation of diblock copolymer phase separation in a thin film by applying a pressure on the film through a flat mask. The result is a well-ordered grating pattern of the phase separation with a period of tens of nanometers. The effect of pressure and film thickness on the final pattern is investigated by experiments. We suggest that the increased ordering is

  14. Role of peripheral phenanthroline groups in the self-assembly of self-assembled molecular triangles

    Indian Academy of Sciences (India)

    Mili C Naranthatta; V Ramkumar; Dillip Kumar Chand

    2015-02-01

    Self-assembled molecular triangles [Pd3(phen)3(imidazolate)3](NO3)3, 1a and [Pd3(phen)3 (imidazolate)3](PF6)3, 1b are prepared by the combination of imidazole with Pd(phen)(NO3)2 and Pd(phen) (PF6)2, respectively. Imidazole was deprotonated during the complexation reactions and the imidazolate so formed acted as a bis-monodentate bridging ligand to form the bowl-shaped trinuclear architectures of 1a/b. Relative orientation of the imidazolate moieties can be best described as syn,anti,anti as observed in the crystal structure of 1b. However, in solution state, slow conformational changes are assumed on the basis of 1HNMR spectral data. The molecular triangles are crafted with three peripheral phen units capable of − stacking interactions. Well-fashioned intermolecular − interactions are observed in the solid-state, wherein further self-assembly of already self-assembled triangle is observed.

  15. Competition between self-assembly and surface adsorption

    Science.gov (United States)

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

    2009-02-01

    We investigate a minimal equilibrium polymerization model for the competition between self-assembly on a boundary and in solution that arises when an assembling system is in the presence of an adsorbing interface. Adsorption generally occurs upon cooling, but assembly (equilibrium polymerization) may arise either upon cooling or heating. Both cases are shown to exhibit a coupling between adsorption and self-assembly. When both assembly and adsorption proceed upon cooling, a change in the ratio of the enthalpy of adsorption to the enthalpy of assembly in solution can switch the system between a predominance of self-assembly in solution to assembly on the substrate. If assembly is promoted by heating and adsorption by cooling, as in many self-assembling proteins in aqueous solution, then a self-assembly analog of a closed loop phase boundary is found. In particular, the order parameter for assembly on the surface exhibits a peak as a function of temperature. As demonstrated by illustrative examples, the coupling between surface adsorption and self-assembly provides a powerful means of switching self-assembly processes on and off. Understanding and controlling this switching phenomenon will be useful in designing and directing self-assembly processes on surfaces for applications to nanomanufacturing and in developing treatments for diseases arising from pathological adsorption-induced assembly.

  16. Self-Assembly of Magnetic Colloids in Soft Confinement

    NARCIS (Netherlands)

    Liu, P.

    2016-01-01

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

  17. Synthetic self-assembled models with biomimetic functions

    NARCIS (Netherlands)

    Fiammengo, Roberto; Crego-Calama, Mercedes; Reinhoudt, David N.

    2001-01-01

    Self-assembly can be considered a powerful tool in the hand of chemists for the understanding, modeling and mimicking of biological systems. The possibility of reproducing biological functions in synthetic systems obtained by self-assembly is envisioned as a modest but very important step towards th

  18. Self-assembled nanofiber coatings for controlling cell responses

    NARCIS (Netherlands)

    Barros, Raquel C.; Gelens, Edith; Bulten, Erna; Tuin, Annemarie; de Jong, Menno R; Kuijer, Roel; van Kooten, Theo G

    Nanofibers are thought to enhance cell adhesion, growth, and function. We demonstrate that the choice of building blocks in self-assembling nanofiber systems can be used to control cell behavior. The use of 2 D-coated, self-assembled nanofibers in controlling lens epithelial cells, fibroblasts, and

  19. Supramolecular chemistry: Unexplored territory for self-assembly

    Science.gov (United States)

    Beuerle, Florian

    2016-12-01

    Cage-like structures can self-assemble from suitable metal ions and organic linkers, but the size of the assemblies was limited. The surprise discovery of a new series of cages opens up fresh horizons for self-assembly. See Letter p.563

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

    NARCIS (Netherlands)

    Graveland-Bikker, Johanna Frederike

    2005-01-01

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

  1. Self-Assembly of Optical Molecules with Supramolecular Concepts

    Directory of Open Access Journals (Sweden)

    Ken Okamoto

    2009-04-01

    Full Text Available Fabrication of nano-sized objects is one of the most important issues in nanoscience and nanotechnology. Soft nanomaterials with flexible properties have been given much attention and can be obtained through bottom-up processing from functional molecules, where self-assembly based on supramolecular chemistry and designed assembly have become crucial processes and techniques. Among the various functional molecules, dyes have become important materials in certain areas of nanotechnology and their self-assembling behaviors have been actively researched. In this short review, we briefly introduce recent progress in self-assembly of optical molecules and dyes, based mainly on supramolecular concepts. The introduced examples are classified into four categories: self-assembly of (i low-molecular-weight dyes and (ii polymeric dyes and dye self-assembly (iii in nanoscale architectures and (iv at surfaces.

  2. Self-Assembly: From Amphiphiles to Chromophores and Beyond

    Directory of Open Access Journals (Sweden)

    Jonathan P. Hill

    2014-06-01

    Full Text Available Self-assembly has been recognised as a ubiquitous aspect of modern chemistry. Our understanding and applications of self-assembly are substantially based on what has been learned from biochemical systems. In this review, we describe various aspects of self-assembly commencing with an account of the soft structures that are available by assembly of surfactant amphiphiles, which are important scientific and industrial materials. Variation of molecular design using rules defined by surfactant self-assembly permits synthesis of functional nanostructures in solution and at surfaces while increasing the strength of intermolecular interactions through π-π stacking, metal cation coordination and/or hydrogen bonding leads to formation of highly complex bespoke nanostructured materials exemplified by DNA assemblies. We describe the origins of self-assembly involving aggregation of lipid amphiphiles and how this subject has been expanded to include other highly advanced chemical systems.

  3. Self-assembly into temperature dependent micro-/nano-aggregates of 5,10,15,20-tetrakis(4-carboxyl phenyl)-porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qingyun, E-mail: qyliu@sdust.edu.cn [School of Chemistry and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266510 (China); Zhou, Hangyue; Zhu, Jiqin; Yang, Yanting; Liu, Xiaodong; Wang, Dongmei [School of Chemistry and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266510 (China); Zhang, Xiaomei [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Zhuo, Linhai, E-mail: lhzhuo@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 (China)

    2013-12-01

    Various nanostructures of 5,10,15,20-tetrakis(4-carboxyl phenyl)-porphyrin (H{sub 2}TCPP) can be easily synthesized by a surfactant-assisted self-assembly (SAS) method at different temperatures. When the DMF solution of porphyrin monomer was injected into cetyltimethylammonium bromide (CTAB) aqueous solution by a syringe, diverse H{sub 2}TCPP nanostructures dependent on the different temperatures, including hollow nanospheres, solid nanospheres and nanospheres with holes, were successfully obtained. As a result, the suitable concentration of the CTAB aqueous solution used to form nanostructues of porphyrin ranges from 0.15 to 0.2 mM. The various morphologies of porphyrin nanostructures were characterized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). UV–vis adsorption spectra showed that the micro-/nano-aggregate properties of porphyrin transformed from H-aggretates to J-aggregates during the process of self-assembly of porphyrin at different temperatures. Fluorescence spectra revealed a greater fluorescence quenching of various micro-/nano-aggregatess of porphyrin formed at different temperatures in aqueous solution, compared to the DMF solution of porphyrin monomer. - Graphical abstract: Temperature dependent morphologies of nanoaggregates of 5,10,15,20-tetra(4-carboxyl phenyl)-porphyrin (H{sub 2}TCPP) can be easily prepared by a surfactant-assisted self-assembly method. - Highlights: • Temperature dependent aggregates of H{sub 2}TCPP can be fabricated by self-assembly method. • The aggregate properties transformed from H to J aggregates with different speed. • A possible explanation for the formation of nanoaggregates has been proposed. • Fluorescence spectra revealed a greater fluorescence quenching of nanoaggregates.

  4. Solid state nanofibers based on self-assemblies : from cleaving from self-assemblies to multilevel hierarchical constructs

    NARCIS (Netherlands)

    Ikkala, Olli; Ras, Robin H. A.; Houbenov, Nikolay; Ruokolainen, Janne; Paakko, Marjo; Laine, Janne; Leskela, Markku; Berglund, Lars A.; Lindstrom, Tom; ten Brinke, Gerrit; Iatrou, Hermis; Hadjichristidis, Nikos; Faul, Charl F. J.; Pääkkö, Marjo; Leskelä, Markku; Lindström, Tom

    2009-01-01

    Self-assemblies and their hierarchies are useful to construct soft materials with structures at different length scales and to tune the materials properties for various functions. Here we address routes for solid nanofibers based on different forms of self-assemblies. On the other hand, we discuss r

  5. RNA self-assembly and RNA nanotechnology.

    Science.gov (United States)

    Grabow, Wade W; Jaeger, Luc

    2014-06-17

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

  6. Large-scale self-assembly of uniform submicron silver sulfide material driven by precise pressure control

    Science.gov (United States)

    Qi, Juanjuan; Chen, Ke; Zhang, Shuhao; Yang, Yun; Guo, Lin; Yang, Shihe

    2017-03-01

    The controllable self-assembly of nanosized building blocks into larger specific structures can provide an efficient method of synthesizing novel materials with excellent properties. The self-assembly of nanocrystals by assisted means is becoming an extremely active area of research, because it provides a method of producing large-scale advanced functional materials with potential applications in the areas of energy, electronics, optics, and biologics. In this study, we applied an efficient strategy, namely, the use of ‘pressure control’ to the assembly of silver sulfide (Ag2S) nanospheres with a diameter of approximately 33 nm into large-scale, uniform Ag2S sub-microspheres with a size of about 0.33 μm. More importantly, this strategy realizes the online control of the overall reaction system, including the pressure, reaction time, and temperature, and could also be used to easily fabricate other functional materials on an industrial scale. Moreover, the thermodynamics and kinetics parameters for the thermal decomposition of silver diethyldithiocarbamate (Ag(DDTC)) are also investigated to explore the formation mechanism of the Ag2S nanosized building blocks which can be assembled into uniform sub-micron scale architecture. As a method of producing sub-micron Ag2S particles by means of the pressure-controlled self-assembly of nanoparticles, we foresee this strategy being an efficient and universally applicable option for constructing other new building blocks and assembling novel and large functional micromaterials on an industrial scale.

  7. Large-scale self-assembly of uniform submicron silver sulfide material driven by precise pressure control.

    Science.gov (United States)

    Qi, Juanjuan; Chen, Ke; Zhang, Shuhao; Yang, Yun; Guo, Lin; Yang, Shihe

    2017-03-10

    The controllable self-assembly of nanosized building blocks into larger specific structures can provide an efficient method of synthesizing novel materials with excellent properties. The self-assembly of nanocrystals by assisted means is becoming an extremely active area of research, because it provides a method of producing large-scale advanced functional materials with potential applications in the areas of energy, electronics, optics, and biologics. In this study, we applied an efficient strategy, namely, the use of 'pressure control' to the assembly of silver sulfide (Ag2S) nanospheres  with a diameter of approximately 33 nm into large-scale, uniform Ag2S sub-microspheres with a size of about 0.33 μm. More importantly, this strategy realizes the online control of the overall reaction system, including the pressure, reaction time, and temperature, and could also be used to easily fabricate other functional materials on an industrial scale. Moreover, the thermodynamics and kinetics parameters for the thermal decomposition of silver diethyldithiocarbamate (Ag(DDTC)) are also investigated to explore the formation mechanism of the Ag2S nanosized building blocks which can be assembled into uniform sub-micron scale architecture. As a method of producing sub-micron Ag2S particles by means of the pressure-controlled self-assembly of nanoparticles, we foresee this strategy being an efficient and universally applicable option for constructing other new building blocks and assembling novel and large functional micromaterials on an industrial scale.

  8. Optical orientation in self assembled quantum dots

    CERN Document Server

    Stevens, G C

    2002-01-01

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

  9. Self-assembly of smallest magnetic particles.

    Science.gov (United States)

    Mehdizadeh Taheri, Sara; Michaelis, Maria; Friedrich, Thomas; Förster, Beate; Drechsler, Markus; Römer, Florian M; Bösecke, Peter; Narayanan, Theyencheri; Weber, Birgit; Rehberg, Ingo; Rosenfeldt, Sabine; Förster, Stephan

    2015-11-24

    The assembly of tiny magnetic particles in external magnetic fields is important for many applications ranging from data storage to medical technologies. The development of ever smaller magnetic structures is restricted by a size limit, where the particles are just barely magnetic. For such particles we report the discovery of a kind of solution assembly hitherto unobserved, to our knowledge. The fact that the assembly occurs in solution is very relevant for applications, where magnetic nanoparticles are either solution-processed or are used in liquid biological environments. Induced by an external magnetic field, nanocubes spontaneously assemble into 1D chains, 2D monolayer sheets, and large 3D cuboids with almost perfect internal ordering. The self-assembly of the nanocubes can be elucidated considering the dipole-dipole interaction of small superparamagnetic particles. Complex 3D geometrical arrangements of the nanodipoles are obtained under the assumption that the orientation of magnetization is freely adjustable within the superlattice and tends to minimize the binding energy. On that basis the magnetic moment of the cuboids can be explained.

  10. Dissipative adaptation in driven self-assembly.

    Science.gov (United States)

    England, Jeremy L

    2015-11-01

    In a collection of assembling particles that is allowed to reach thermal equilibrium, the energy of a given microscopic arrangement and the probability of observing the system in that arrangement obey a simple exponential relationship known as the Boltzmann distribution. Once the same thermally fluctuating particles are driven away from equilibrium by forces that do work on the system over time, however, it becomes significantly more challenging to relate the likelihood of a given outcome to familiar thermodynamic quantities. Nonetheless, it has long been appreciated that developing a sound and general understanding of the thermodynamics of such non-equilibrium scenarios could ultimately enable us to control and imitate the marvellous successes that living things achieve in driven self-assembly. Here, I suggest that such a theoretical understanding may at last be emerging, and trace its development from historic first steps to more recent discoveries. Focusing on these newer results, I propose that they imply a general thermodynamic mechanism for self-organization via dissipation of absorbed work that may be applicable in a broad class of driven many-body systems.

  11. Self-assembled nanostructures via electrospraying

    Science.gov (United States)

    Jayasinghe, S. N.

    2006-07-01

    A concentrated nanoparticulate-based ethylene glycol suspension was prepared and electrosprayed at optimum and stable cone-jet mode conditions. Using laser spectroscopy, the droplets were measured and found to range within ∼0.23-3.8 μm. In parallel to spectroscopy-assisted sizing, a volume equivalence route for estimating droplet sizes was carried out by measuring contact angles and diameters of the deposits. The electrosprayed nanosuspension relics were examined using optical and transmission electron microscopy. These deposits were further characterized using energy-dispersive X-rays and selected area electron diffraction. Simultaneously deposits were formed by a controlled route through needle deposition without the presence of an electric field. The structures formed in this non-electric field driven route are compared with those formed with electric fields. Thus, elucidating electrosprays as a competing nanofabrication route for forming self-assemblies with a wide range of nanomaterials in the nanoscale for top-down based bottom-up assembly of structures.

  12. Self-assembly models for lipid mixtures

    Science.gov (United States)

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

    2006-03-01

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

  13. 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.

  14. Self-assembly programming of DNA polyominoes.

    Science.gov (United States)

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

    2016-10-20

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

  15. Stochastic self-assembly of incommensurate clusters

    Science.gov (United States)

    DÓ Rsogna, Maria; Lakatos, Greg; Chou, Tom

    2013-03-01

    We examine the classic problem of homogeneous nucleation and self-assembly by deriving and analyzing a fully discrete stochastic master equation. We enumerate the highest probability steady-states, and derive exact analytical formulae for quenched and equilibrium mean cluster size distributions. Upon comparison with results obtained from the associated the mass-action Becker-Döring (BD) equations, we find striking differences between the two corresponding equilibrium mean cluster concentrations. These differences depend primarily on the divisibility of the total available mass by the maximum allowed cluster size, and the remainder. When such mass ``incommensurability'' arises, a single remainder particle can ``emulsify'' the system by significantly broadening the equilibrium mean cluster size distribution. This discreteness-induced broadening effect is periodic in the total mass of the system but arises even when the system size is asymptotically large, provided the ratio of the total mass to the maximum cluster size is finite. Our findings define a new scaling regime in which results from classic mass-action theories are qualitatively inaccurate, even in the limit of large total system size. This work supported by NSF DMS-1021818 and DMS-1021850

  16. Functional Self-Assembled Nanofibers by Electrospinning

    Science.gov (United States)

    Greiner, A.; Wendorff, J. H.

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

  17. What promotes derected self assembly (DSA)?

    Science.gov (United States)

    Nakagawa, S. T.

    2016-09-01

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

  18. Mechanistic investigation into the spontaneous linear assembly of gold nanospheres

    KAUST Repository

    Yang, Miaoxin

    2010-01-01

    Understanding the mechanism of nanoparticle self-assembly is of critical significance for developing synthetic strategies for complex nanostructures. By encapsulating aggregates of Au nanospheres in shells of polystyrene-block- poly(acrylic acid), we prevent the dissociation and aggregation typically associated with the drying of solution samples on TEM/SEM substrates. In our study of the salt-induced aggregation of 2-naphthalenethiol-functionalized Au nanospheres in DMF, the trapping of the solution species under various experimental conditions permits new insights in the mechanism thereof. We provide evidence that the spontaneous linear aggregation in this system is a kinetically controlled process and hence the long-range charge repulsion at the "transition state" before the actual contact of the Au nanospheres is the key factor. Thus, the charge repulsion potential (i.e. the activation energy) a nanosphere must overcome before attaching to either end of a nanochain is smaller than attaching on its sides, which has been previously established. This factor alone could give rise to the selective end-on attachment and lead to the linear assembly of originally isotropic Au nanospheres. © 2010 the Owner Societies.

  19. Controlling Self-Assembly of Engineered Peptides on Graphite by Rational Mutation

    Science.gov (United States)

    So, Christopher R.; Hayamizu, Yuhei; Yazici, Hilal; Gresswell, Carolyn; Khatayevich, Dmitriy; Tamerler, Candan; Sarikaya, Mehmet

    2012-01-01

    Self-assembly of proteins on surfaces is utilized in many fields to integrate intricate biological structures and diverse functions with engineered materials. Controlling proteins at bio-solid interfaces relies on establishing key correlations between their primary sequences and resulting spatial organizations on substrates. Protein self-assembly, however, remains an engineering challenge. As a novel approach, we demonstrate here that short dodecapeptides selected by phage display are capable of self-assembly on graphite and form long-range ordered biomolecular nanostructures. Using atomic force microscopy and contact angle studies, we identify three amino-acid domains along the primary sequence that steer peptide ordering and lead to nanostructures with uniformly displayed residues. The peptides are further engineered via simple mutations to control fundamental interfacial processes, including initial binding, surface aggregation and growth kinetics, and intermolecular interactions. Tailoring short peptides via their primary sequence offers versatile control over molecular self-assembly, resulting in well-defined surface properties essential in building engineered, chemically rich, bio-solid interfaces. PMID:22233341

  20. Shuttle-like supramolecular nanostructures formed by self-assembly of a porphyrin via an oil/water system

    Directory of Open Access Journals (Sweden)

    Guo Peipei

    2011-01-01

    Full Text Available Abstract In this paper, in terms of the concentration of an aqueous solution of a surfactant, we investigate the self-assembly behavior of a porphyrin, 5, 10, 15, 20-tetra(4-pyridyl-21H, 23H-porphine [H2TPyP], by using an oil/water system as the medium. We find that when a chloroform solution of H2TPyP is dropwise added into an aqueous solution of cetyltrimethylammonium bromide [CTAB] with a lower concentration, a large amount of irregular nanoarchitectures, together with a small amount of well-defined shuttle-like nanostructures, hollow nanospheres, and nanotubes, could be produced. While a moderate amount of shuttle-like nanostructures accompanied by a few irregular nanoarchitectures, solid nanospheres, and nanorods are produced when a CTAB aqueous solution in moderate concentration is employed, in contrast, a great quantity of shuttle-like nanostructures together with a negligible amount of solid nanospheres, nanofibers, and irregular nanostructures are manufactured when a high-concentration CTAB aqueous solution is involved. An explanation on the basis of the molecular geometry of H2TPyP and in terms of the intermolecular π-π interactions between H2TPyP units, and hydrophobic interactions between CTAB and H2TPyP has been proposed. The investigation gives deep insights into the self-assembly behavior of porphyrins in an oil/water system and provides important clues concerning the design of appropriate porphyrins when related subjects are addressed. Our investigation suggests that an oil/aqueous system might be an efficient medium for producing unique organic-based nanostructures.

  1. Shuttle-like supramolecular nanostructures formed by self-assembly of a porphyrin via an oil/water system.

    Science.gov (United States)

    Guo, Peipei; Chen, Penglei; Liu, Minghua

    2011-09-23

    In this paper, in terms of the concentration of an aqueous solution of a surfactant, we investigate the self-assembly behavior of a porphyrin, 5, 10, 15, 20-tetra(4-pyridyl)-21H, 23H-porphine [H2TPyP], by using an oil/water system as the medium. We find that when a chloroform solution of H2TPyP is dropwise added into an aqueous solution of cetyltrimethylammonium bromide [CTAB] with a lower concentration, a large amount of irregular nanoarchitectures, together with a small amount of well-defined shuttle-like nanostructures, hollow nanospheres, and nanotubes, could be produced. While a moderate amount of shuttle-like nanostructures accompanied by a few irregular nanoarchitectures, solid nanospheres, and nanorods are produced when a CTAB aqueous solution in moderate concentration is employed, in contrast, a great quantity of shuttle-like nanostructures together with a negligible amount of solid nanospheres, nanofibers, and irregular nanostructures are manufactured when a high-concentration CTAB aqueous solution is involved. An explanation on the basis of the molecular geometry of H2TPyP and in terms of the intermolecular π-π interactions between H2TPyP units, and hydrophobic interactions between CTAB and H2TPyP has been proposed. The investigation gives deep insights into the self-assembly behavior of porphyrins in an oil/water system and provides important clues concerning the design of appropriate porphyrins when related subjects are addressed. Our investigation suggests that an oil/aqueous system might be an efficient medium for producing unique organic-based nanostructures.

  2. The Lost Work in Dissipative Self-Assembly

    Science.gov (United States)

    Koper, G. J. M.; Boekhoven, J.; Hendriksen, W. E.; van Esch, J. H.; Eelkema, R.; Pagonabarraga, I.; Rubí, J. M.; Bedeaux, D.

    2013-07-01

    A general thermodynamic analysis is given of dissipative self-assembly (DSA). Subsequently, the analysis is used to quantify the lost work in a recently published chemical realization of DSA (Boekhoven et al., Angew Chem Int Ed 49:4825, 2010) where a formation reaction produces the monomers that subsequently self-assemble and are finally annihilated by means of a destruction reaction. For this example, the work lost in self-assembly itself is found to be negligibly small compared to the work lost in the reactions driving the non-spontaneous formation reaction and the kinetically hindered destruction reaction.

  3. Self-assembly of latex particles for colloidal crystals

    Institute of Scientific and Technical Information of China (English)

    Zhirong Li; Jingxia wang; Yanlin Song

    2011-01-01

    Self-assembly of latex particles is of great importance for fabricating various functional colloidal crystals.In this paper,we review recent research on the self-assembly of latex particles for colloidal crystals,covering the assembly forces and various assembly approaches of latex particles,including self-assembly by gravity sedimentation,vertical deposition,physical confinement,electric field,and magnetic field.Furthermore,some simple methods for assembling latex particles such as spin coating,spray coating,and printing are also summarized.

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

    Science.gov (United States)

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

    2016-01-01

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

  5. 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...... components were tested and observed to affect the diameter, which ranged from 100 to 500 nm, and morphology of the self-assembled nanofibers. The release of diclofenac, as model drug, from self-assembled xanthan-chitosan nanofibers was demonstrated, suggesting that these nanostructures can be used...

  6. Dynamic self-assembly of 'living' polymeric chains

    Science.gov (United States)

    Deng, Binghui; Shi, Yunfeng

    2017-01-01

    We report a dynamic self-assembly system of 'living' polymeric chains sustained by chemistry using reactive molecular dynamics simulations. The linear polymeric chains consist of self-assembled nanoparticles connected by metastable linker molecules. As such, the polymeric chains, once assembled, undergo spontaneous dissociation driven by thermodynamics. However, with a continuous supply of linker molecules and the stored chemical energy therein, the polymeric chains can survive and maintain a steady state averaged chain length. These dynamically self-assembled polymeric chains are analogous to biological systems that both are thermodynamically metastable, yet dynamically stable upon continuous influx of matter and energy.

  7. Magnetic manipulation of self-assembled colloidal asters.

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-01

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

  8. Inspection of directed self-assembly defects

    Science.gov (United States)

    Ito, Chikashi; Durant, Stephane; Lange, Steve; Harukawa, Ryota; Miyagi, Takemasa; Nagaswami, Venkat; Rincon Delgadillo, Paulina; Gronheid, Roel; Nealey, Paul

    2014-03-01

    Directed Self-Assembly (DSA) is considered as a potential patterning solution for future generation devices. One of the most critical challenges for translating DSA into high volume manufacturing is to achieve low defect density in the DSA patterning process. The defect inspection capability is fundamental to defect reduction in any process, particularly the DSA process, as it provides engineers with information on the numbers and types of defects. While the challenges of other candidates of new generation lithography are well known (for example, smaller size, noise level due to LER etc.), the DSA process causes certain defects that are unique. These defects are nearly planar and in a material which produces very little defect scattering signal. These defects, termed as "dislocation" and "disclination" have unique shapes and have very little material contrast. While large clusters of these unique defects are easy to detect, single dislocation and disclination defects offer considerable challenge during inspection. In this investigation, etching the DSA pattern into a silicon (Si) substrate structure to enhance defect signal and Signal-to-Noise Ratio (SNR) is studied. We used a Rigorous Coupled-Wave Analysis (RCWA) method for solving Maxwell's equations to simulate the DSA unique defects and calculate inspection parameters. Controllable inspection parameters include various illumination and collection apertures, wavelength band, polarization, noise filtering, focus, pixel size, and signal processing. From the RCWA simulation, we compared SNR between "Post-SiN etch" and "Post-SiN+Si-substrate etch" steps. The study is also extended to investigate wafer-level data at post etch inspection. Both the simulations and inspection tool results showed dramatic signal and SNR improvements when the pattern was etched into the SiN+Si substrate allowing capture of DSA unique defect types.

  9. 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.

  10. Strain mediated self-assembly of ceramic nano islands

    Science.gov (United States)

    Rauscher, Michael

    This dissertation presents the first observations of self-assembled arrays of epitaxial nano islands in ceramic systems, based on RF sputtering and thermal processing of Gadolinia-doped ceria (GDC) thin films on an yttria-stabilized zirconia (YSZ) single crystal substrate. In contrast to the conventional semiconductor nano island self-assembly systems, the island arrays in the GDC-YSZ system provide materials with categorically different physical properties and functionalities, and they exhibit a stronger ordering at a larger characteristic length scale. The initial focus of this study was on the processing and characterization of thin GDC layers on YSZ, which are used in SOFCs as barriers to prevent the reaction of some cathode materials with the YSZ electrolyte. Chapter 3 of this document describes studies on relatively thin (300 nm) were found to fail by spalling from the YSZ substrate, leaving behind patches of unspalled film and exposing a sputter-mixed GDC-YSZ surface. Upon annealing, the modified surface spontaneously broke up into two-dimensional arrays of epitaxial islands with sub-micron dimensions, exhibiting order in spacing and alignment. In addition to the classical local effects that drive dewetting processes, the self-assembly of the epitaxial GDC-bearing islands is driven by elastic interactions between them, and these interactions are mediated by the elastically anisotropic underlying YSZ substrate. The stresses in the initial mixed surface layers are modified by two factors: The thermal-expansion mismatch leads to stresses, depending on temperature and heating rates. The lattice-parameter mismatch leads to coherency stresses, depending on chemical composition variations and interdiffusion rates. When the initial surface layers cannot relieve their stress by other mechanisms, they break up by surface diffusion to introduce stress-free surfaces and relax the stresses in their vicinity, at the expense of increasing surface area and energy. The

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

    Data.gov (United States)

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

  12. Self-Assembled Nanostructured Health Monitoring Sensors Project

    Data.gov (United States)

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

  13. Self-assembled peptide nanostructures for functional materials

    Science.gov (United States)

    Sardan Ekiz, Melis; Cinar, Goksu; Aref Khalily, Mohammad; Guler, Mustafa O.

    2016-10-01

    Nature is an important inspirational source for scientists, and presents complex and elegant examples of adaptive and intelligent systems created by self-assembly. Significant effort has been devoted to understanding these sophisticated systems. The self-assembly process enables us to create supramolecular nanostructures with high order and complexity, and peptide-based self-assembling building blocks can serve as suitable platforms to construct nanostructures showing diverse features and applications. In this review, peptide-based supramolecular assemblies will be discussed in terms of their synthesis, design, characterization and application. Peptide nanostructures are categorized based on their chemical and physical properties and will be examined by rationalizing the influence of peptide design on the resulting morphology and the methods employed to characterize these high order complex systems. Moreover, the application of self-assembled peptide nanomaterials as functional materials in information technologies and environmental sciences will be reviewed by providing examples from recently published high-impact studies.

  14. Predicting self-assembled patterns on spheres with multicomponent coatings.

    Science.gov (United States)

    Edlund, Erik; Lindgren, Oskar; Jacobi, Martin Nilsson

    2014-05-01

    Patchy colloids are promising candidates for building blocks in directed self-assembly, but large scale synthesis of colloids with controlled surface patterns remains challenging. One potential fabrication method is to self-assemble the surface patterns themselves, allowing complex morphologies to organize spontaneously. For this approach to be competitive, prediction and control of the pattern formation process are necessary. However, structure formation in many-body systems is fundamentally hard to understand, and new theoretical methods are needed. Here we present a theory for self-assembling pattern formation in multi-component systems on the surfaces of colloidal particles, formulated as an analytic technique that predicts morphologies directly from the interactions in an effective model. As a demonstration we formulate an isotropic model of alkanethiols on gold, a suggested system for directed self-assembly, and predict its morphologies and transitions as a function of the interaction parameters.

  15. Directed flexibility: self-assembly of a supramolecular tetrahedron.

    Science.gov (United States)

    Ludlow, James M; Xie, Tingzheng; Guo, Zaihong; Guo, Kai; Saunders, Mary Jane; Moorefield, Charles N; Wesdemiotis, Chrys; Newkome, George R

    2015-03-01

    Self-assembly of a tribenzo-27-crown-9 ether functionalized with six terpyridines generated (85%) an expanded tetrahedral structure comprised of four independent triangular surfaces interlinked by crown ether vertices.

  16. Molecular Recognition Directed Self-Assembly of Supramolecular Polymers

    Science.gov (United States)

    1994-06-30

    demonstrated that various substituted gallic acid derivatives can be used to constmict exo-receptors with a tapered shape. "Tihis paper will review...understood self-assembled biological system [3ab.5]. Therefore, we believe it provides an ideal model to be used for the understanding of the principles...governing the self-assembly of synthetic supraimolecular architectures. Synthetic Strategy Used In The Design Of TMV-Like Supramolecular Architectures fl

  17. Self-assembly drugs: from micelles to nanomedicine.

    Science.gov (United States)

    Messina, Paula V; Besada-Porto, Jose Miguel; Ruso, Juan M

    2014-03-01

    Self-assembly has fascinated many scientists over the past few decades. Rapid advances and widespread interest in the study of this subject has led to the synthesis of an ever-increasing number of elegant and intricate functional structures with sizes that approach nano- and mesoscopic dimensions. Today, it has grown into a mature field of modern science whose interfaces with many disciplines have provided invaluable opportunities for crossing boundaries for scientists seeking to design novel molecular materials exhibiting unusual properties, and for researchers investigating the structure and function of biomolecules. Consequently, self-assembly transcends the traditional divisional boundaries of science and represents a highly interdisciplinary field including nanotechnology and nanomedicine. Basically, self-assembly focuses on a wide range of discrete molecules or molecular assemblies and uses physical transformations to achieve its goals. In this Review, we present a comprehensive overview of the advances in the field of drug self-assembly and discuss in detail the synthesis, self-assembly behavior, and physical properties as well as applications. We refer the reader to past reviews dealing with colloidal molecules and colloidal self-assembly. In the first part, we will discuss, compare, and link the various bioinformatic procedures: Molecular Dynamics and Quantitative Structure Activity Relationship. The second section deals with the self-assembly behavior in more detail, in which we focus on several experimental techniques, selected according to the depth of knowledge obtained. The last part will review the advances in drug-protein assembly. Nature provides many examples of proteins that form their substrate binding sites by bringing together the component pieces in a process of self-assembly. We will focus in the understanding of physical properties and applications developing thereof.

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

    Science.gov (United States)

    Shestopalov, N. V.; Henkelman, G.; Powell, C. T.; Rodin, G. J.

    2009-05-01

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

  19. Electronic polymers and DNA self-assembled in nanowire transistors.

    Science.gov (United States)

    Hamedi, Mahiar; Elfwing, Anders; Gabrielsson, Roger; Inganäs, Olle

    2013-02-11

    Aqueous self-assembly of DNA and molecular electronic materials can lead to the creation of innumerable copies of identical devices, and inherently programmed complex nanocircuits. Here self-assembly of a water soluble and highly conducting polymer PEDOT-S with DNA in aqueous conditions is shown. Orientation and assembly of the conducting DNA/PEDOT-S complex into electrochemical DNA nanowire transistors is demonstrated.

  20. 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....

  1. 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).

  2. Mesoscopic Self-Assembly: A Shift to Complexity

    Directory of Open Access Journals (Sweden)

    Massimo eMastrangeli

    2015-06-01

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

  3. Self-assembled tunable networks of sticky colloidal particles

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-07-18

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

  4. Self-assembled magnetic nanospheres with three-dimensional magnetic vortex

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min-Kwan; Dhak, Prasanta; Lee, Ha-Youn; Lee, Jae-Hyeok; Yoo, Myoung-Woo; Lee, Jehyun; Kim, Sang-Koog, E-mail: sangkoog@snu.ac.kr [National Creative Research Initiative Center for Spin Dynamics and Spin-Wave Devices, Nanospinics Laboratory, Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Jin, Kyoungsuk; Chu, Arim; Nam, Ki Tae; Kim, Miyoung [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Park, Hyun Soon [Department of Materials Science and Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Aizawa, Shinji [Center for Emergent Matter Science (CEMS), RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Tanigaki, Toshiaki [Center for Emergent Matter Science (CEMS), RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Hitachi, Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395 (Japan); Shindo, Daisuke [Center for Emergent Matter Science (CEMS), RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2014-12-08

    We report the electron holography images of spin configurations in peculiar assemblies of soft magnetic nanoparticles in single-, double-, triple-, or quadruple-sphere geometrical arrangements, in which each particle has a three-dimensional (3D) magnetic-vortex structure. Micromagnetic numerical calculations reveal that the uniqueness of the nanoparticles' 3D vortex structure plays a crucial role in their assembly, especially in terms of the contrasting contributions of the exchange and dipolar interactions to their binding energies. The results represent physical insights into the assembly of 3D-vortex-structure magnetic nanoparticles in different geometrical configurations and offer a practical means of controlling those assemblies.

  5. Absorption enhancement in nanostructured silicon fabricated by self-assembled nanosphere lithography

    Science.gov (United States)

    Li, Qiang; Gao, Jinsong; Li, Zizheng; Yang, Haigui; Liu, Hai; Wang, Xiaoyi; Li, Yudong

    2017-08-01

    In this work, we give a detailed experimental and theoretical analysis of a nano cone array on silicon wafer, which can greatly enhance the absorption compared with the polished silicon. The experimental absorptance can reach 98.7% in the wavelength ranging from 400 nm to 1100 nm. The mechanism of absorption enhancement is attributed to the nano cone array that can suppress the reflection by building a grade index from air to silicon surface. Moreover, an ultrathin 13 nm thickness gold film was sputtered on the nano cone array, by which surface plasmon can be excited and the absorption in the near-infrared region can be greatly enhanced. We also give a deep comprehending on the physics mechanism of such high absorption. This kind of nano cone array can be fabricated by a simple and low-cost colloidal sphere lithography and reactive ion etching, which makes it a more appropriate candidate for photovoltaics, spectroscopy, photodetectors, sensor, especially for the silicon-based application in the near-infrared region.

  6. Structures Self-Assembled Through Directional Solidification

    Science.gov (United States)

    Dynys, Frederick W.; Sayir, Ali

    2005-01-01

    dry plasma etch. The wet chemical etches the silicon away, exposing the TiSi2 rods, whereas plasma etching preferentially etches the Si-TiSi2 interface to form a crater. The porous architectures are applicable to fabricating microdevices or creating templates for part fabrication. The porous rod structure can serve as a platform for fabricating microplasma devices for propulsion or microheat exchangers and for fabricating microfilters for miniatured chemical reactors. Although more work is required, self-assembly from DSE can have a role in microdevice fabrication.

  7. 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 (properties. We observe the BaTiO3 nanocrystals crystallize with evidence of tetragonality. Electric field dependent polarization measurements show spontaneous polarization and hysteresis, indicating ferroelectric behavior for the BaTiO 3 nanocrystalline films with grain sizes in the range of 10--30 nm. Dielectric measurements of the films show dielectic constants in the range of 85--90 over the 1 kHz--100 kHz, with low loss. We present nanocrystals as initial building blocks for the preparation of thin films which exhibit uniform nanostructured morphologies and grain sizes. In the second part of this chapter, a nonhydrolytic alcoholysis route to study the preparation of well-crystallized size-tunable BaTiO3 nanocrystals is presented. Different surfactants of amines, carboxylic acids, and alcohols were used to study the effect of size and morphological control over the nanocrystals. Techniques including X-ray diffraction, transmission

  8. Self-Assembling Peptide Amphiphiles for Targeted Drug Delivery

    Science.gov (United States)

    Moyer, Tyson

    The systemic delivery of therapeutics is currently limited by off-target side effects and poor drug uptake into the cells that need to be treated. One way to circumvent these issues is to target the delivery and release of therapeutics to the desired location while limiting systemic toxicity. Using self-assembling peptide amphiphiles (PAs), this work has investigated supramolecular nanostructures for the development of targeted therapies. Specifically, the research has focused on the interrelationships between presentation of targeting moeities and the control of nanostructure morphology in the context of systemic delivery for targeting cancer and vascular injuries. The self-assembly region of the PA was systematically altered to achieve control of nanostructure widths, from 100 nm to 10 nm, by the addition of valine-glutamic acid dimers into the chemical structure, subsequently increasing the degree of nanostructure twist. For the targeting of tumors, a homing PA was synthesized to include a dimeric, cyclic peptide sequence known to target the cancer-specific, death receptor 5 (DR5) and initiate apoptosis through the oligomerization of DR5. This PA presented a multivalent display of DR5-binding peptides, resulting in improved binding affinity measured by surface plasmon resonance. The DR5-targeting PA also showed enhanced efficacy in both in vitro and in vivo tumor models relative to non-targeted controls. Alternative modifications to the PA-based antitumor therapies included the use of a cytotoxic, membrane-lytic PA coassembled with a pegylated PA, which showed enhanced biodistribution and in vivo activity after coassembly. The functionalization of the hydrophobic core was also accomplished through the encapsulation of the chemotherapy camptothecin, which was shown to be an effective treatment in vivo. Additionally, a targeted PA nanostructure was designed to bind to the site of vascular intervention by targeting collagen IV. Following balloon angioplasty

  9. Ion-induced erosion of organic self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Cyganik, P. E-mail: cyganik@castor.if.uj.edu.pl; Postawa, Z.; Meserole, C.A.; Vandeweert, E.; Winograd, N

    1999-01-02

    Laser post-ionization mass spectrometry combined with Scanning Tunneling Microscopy (STM) has been used to investigate processes of ion-stimulated erosion of self-assembled monolayers (SAM) of phenethyl mercaptan C{sub 6}H{sub 5}CH{sub 2}CH{sub 2}S (PEM) deposited on gold. Results indicate that only PEM fragments are emitted from the surface. Most of the PEM fragments (predominantly C{sub 6}H{sub 5}CH{sub 2}CH{sub 3} with m/z=106) are emitted with thermal kinetic energies. STM images collected on 8 keV H{sup +}{sub 2}-irradiated surfaces with a system tuned to probe electronic states of sulfur atoms show no additional damage induced by irradiation. This indicates that sulfur atoms are not removed from the surface during hydrogen bombardment. It is proposed that the emission of SAM molecules is initiated by chemical reactions which gently break C-S bonds.

  10. Investigate the Effect of Thawing Process on the Self-Assembly of Silk Protein for Tissue Applications

    Science.gov (United States)

    Tran, Hien Anh; Huynh, Khon Chan; Vo, Toi Van

    2017-01-01

    Biological self-assembly is a process in which building blocks autonomously organize to form stable supermolecules of higher order and complexity through domination of weak, noncovalent interactions. For silk protein, the effect of high incubating temperature on the induction of secondary structure and self-assembly was well investigated. However, the effect of freezing and thawing on silk solution has not been studied. The present work aimed to investigate a new all-aqueous process to form 3D porous silk fibroin matrices using a freezing-assisted self-assembly method. This study proposes an experimental investigation and optimization of environmental parameters for the self-assembly process such as freezing temperature, thawing process, and concentration of silk solution. The optical images demonstrated the possibility and potential of −80ST48 treatment to initialize the self-assembly of silk fibroin as well as controllably fabricate a porous scaffold. Moreover, the micrograph images illustrate the assembly of silk protein chain in 7 days under the treatment of −80ST48 process. The surface morphology characterization proved that this method could control the pore size of porous scaffolds by control of the concentration of silk solution. The animal test showed the support of silk scaffold for cell adhesion and proliferation, as well as the cell migration process in the 3D implantable scaffold.

  11. Label-free optical characterization methods for detecting amine silanization-driven gold nanoparticle self-assembly.

    Science.gov (United States)

    Roy, Shibsekhar; Dixit, Chandra K; Woolley, Robert; O'Kennedy, Richard; McDonagh, Colette

    2011-09-06

    Fluorescence lifetime correlation spectroscopy (FLCS) is presented as a single-step label-free detection method for probing the amine silanization-driven spontaneous 3D self-assembly of freestanding gold nanoparticles (GNPs) in solution. Unlike the conventional methods of studying self-assembly, for example, UV-vis spectroscopy and electron microscopy, FLCS utilizes the intrinsic gold fluorescence. The significance of this approach is to amalgamate the measurement of optical and hydrodynamic size properties simultaneously to achieve a more coherent description of the self-assembly pathway. GNP self-assembly has two-stage kinetics. Electrostatic interaction drives the initial amine silanization, and this is followed by siloxane bond formation between hydrolyzed ethoxy groups of GNP-attached APTES, resulting in the formation of micrometer-sized superstructures. The self-assembly has resulted in a 5-fold increase in the fluorescence lifetime (FL), and the FLCS study has shown an 8- to 10-fold increase in the diffusion coefficient using the pure diffusion model. This result is consistent with the transmission electron microscopy (TEM) observation, which shows a few hundred fold increase in the diameter due to assembly formation by the GNPs.

  12. Hydrogels constructed via self-assembly of beta-hairpin molecules

    Science.gov (United States)

    Ozbas, Bulent

    There is a recent and growing interest in hydrogel materials that are formed via peptide self-assembly for tissue engineering applications. Peptide based materials are excellent candidates for diverse applications in biomedical field due to their responsive behavior and complex self-assembled structures. However, there is very limited information on the self-assembly and resultant network and mechanical properties of these types of hydrogels. The main goal of this dissertation is to investigate the self-assembly mechanism and viscoelastic properties of hydrogels that can be altered by changing solution conditions as well as the primary structure of the peptide. These hydrogels are formed via intramolecular folding and consequent self-assembly of 20 amino acid long beta-hairpin peptide molecules (Max1). The peptide molecules are locally amphiphilic with two linear strands of alternating hydrophobic valine and hydrophilic lysine amino acids connected with a Dproline-LProline turn sequence. Circular dichroism and FTIR spectroscopy show that at physiological conditions peptides are unfolded in the absence of salt. By raising the ionic strength of the solution electrostatic interactions between charged lysines are screened and the peptide arms are forced into a beta-sheet secondary structure stabilized by the turn sequence. These folded molecules intermolecularly assemble via hydrophobic collapse and hydrogen bonding into a three dimensional network. Folding and self-assembly of these molecules can also be triggered by increasing temperature and/or pH of the peptide solution. In addition, the random-coil to beta-sheet transition of the beta-hairpin peptides is pH and, with proper changes in the peptide sequence, thermally reversible. Rheological measurements demonstrate that the resultant supramolecular structure forms an elastic material, whose structure, and thus modulus, can be tuned by magnitude of the stimulus. Hydrogels recover their initial viscoelastic

  13. Self-assembly of proteins and their nucleic acids

    Directory of Open Access Journals (Sweden)

    Terrett Jon

    2003-01-01

    Full Text Available Abstract We have developed an artificial protein scaffold, herewith called a protein vector, which allows linking of an in-vitro synthesised protein to the nucleic acid which encodes it through the process of self-assembly. This protein vector enables the direct physical linkage between a functional protein and its genetic code. The principle is demonstrated using a streptavidin-based protein vector (SAPV as both a nucleic acid binding pocket and a protein display system. We have shown that functional proteins or protein domains can be produced in vitro and physically linked to their DNA in a single enzymatic reaction. Such self-assembled protein-DNA complexes can be used for protein cloning, the cloning of protein affinity reagents or for the production of proteins which self-assemble on a variety of solid supports. Self-assembly can be utilised for making libraries of protein-DNA complexes or for labelling the protein part of such a complex to a high specific activity by labelling the nucleic acid associated with the protein. In summary, self-assembly offers an opportunity to quickly generate cheap protein affinity reagents, which can also be efficiently labelled, for use in traditional affinity assays or for protein arrays instead of conventional antibodies.

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

    Science.gov (United States)

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

    2015-06-23

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

  15. Self-assembly of DNA-functionalized colloids

    Directory of Open Access Journals (Sweden)

    P.E. Theodorakis

    2015-06-01

    Full Text Available Colloidal particles grafted with single-stranded DNA (ssDNA chains can self-assemble into a number of different crystalline structures, where hybridization of the ssDNA chains creates links between colloids stabilizing their structure. Depending on the geometry and the size of the particles, the grafting density of the ssDNA chains, and the length and choice of DNA sequences, a number of different crystalline structures can be fabricated. However, understanding how these factors contribute synergistically to the self-assembly process of DNA-functionalized nano- or micro-sized particles remains an intensive field of research. Moreover, the fabrication of long-range structures due to kinetic bottlenecks in the self-assembly are additional challenges. Here, we discuss the most recent advances from theory and experiment with particular focus put on recent simulation studies.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-06

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

  17. Self-Assembly in Biosilicification and Biotemplated Silica Materials

    Directory of Open Access Journals (Sweden)

    Francisco M. Fernandes

    2014-09-01

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

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

    Directory of Open Access Journals (Sweden)

    Katja Petkau-Milroy

    2013-10-01

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

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

    Science.gov (United States)

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

    2014-09-04

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

  20. Investigating collagen self-assembly with optical tweezers microrheology

    Science.gov (United States)

    Forde, Nancy; Shayegan, Marjan; Altindal, Tuba

    Collagen is the fundamental structural protein in vertebrates. Assembled from individual triple-helical proteins to make strong fibres, collagen is a beautiful example of a hierarchical self-assembling system. Using optical tweezers to perform microrheology measurements, we explore the dynamics of interactions between collagens responsible for their self-assembly and examine the development of heterogeneous mechanics during assembly into fibrillar gels. Telopeptides, short non-helical regions that flank the triple helix, have long been known to facilitate fibril self-assembly. We find that their removal not only slows down fibril nucleation but also results in a significant frequency-dependent reduction in the elastic modulus of collagens in solution. We interpret these results in terms of a model in which telopeptides facilitate transient intermolecular interactions, which enhance network connectivity in solution and lead to more rapid assembly in fibril-forming conditions. Current address: Department of Physics, McGill University.

  1. Controlled crystallization of hydroxyapatite under hexadecylamine self-assembled monolayer

    Institute of Scientific and Technical Information of China (English)

    黄苏萍; 周科朝; 刘咏; 黄伯云

    2003-01-01

    The role of self-assembled monolayer in inducing the crystal growth was investigated by X-ray diffractions (XRD), and scanning electron microscopy (SEM). Results show that crystallization in the absence of monolayer results in a mixture of poorly crystallized calcium phosphates, including hydroxyapatite (HAP) and octacalcium phosphate (OCP), while the presence of self-assembled monolayer gives rise to oriented and well crystallized HAP crystals. Moreover, the HAP crystal grows very quickly under the self-assembled monolayer, whereas very little calcium phosphate crystals grow without the monolayer. It is rationalized that the hexadecylamine monolayer with high polarity and charged density leads to increase supersaturation and lower the interfacial energy, which attributes to the HAP crystals nucleation. On the other hand, the positive headgroups construct the ordered "recognized site" with distinct size and topology, which results in the oriented HAP crystals deposit.

  2. A novel autonomous self-assembly distributed swarm flying robot

    Institute of Scientific and Technical Information of China (English)

    Wei Hongxing; Li Ning; Liu Miao; Tan Jindong

    2013-01-01

    Swarm intelligence embodied by many species such as ants and bees has inspired scholars in swarm robotic researches.This paper presents a novel autonomous self-assembly distributed swarm flying robot-DSFR,which can drive on the ground,autonomously accomplish self-assembly and then fly in the air coordinately.Mechanical and electrical designs ofa DSFR module,as well as the kinematics and dynamics analysis,are specifically investigated.Meanwhile,this paper brings forward a generalized adjacency matrix to describe configurations of DSFR structures.Also,the distributed flight control model is established for vertical taking-off and horizontal hovering,which can be applied to control of DSFR systems with arbitrary configurations.Finally,some experiments are carried out to testify and validate the DSFR design,the autonomous self-assembly strategy and the distributed flight control laws.

  3. Enhanced light extraction efficiency of plastic scintillator by photonic crystal prepared with a self-assembly method

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinliang [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Radiation Detection Research Center, Northwest Institute of Nuclear Technology, Xi’an, 710024 (China); Zhu, Zhichao [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Chen, Liang; Ouyang, Xiaoping [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Radiation Detection Research Center, Northwest Institute of Nuclear Technology, Xi’an, 710024 (China); Liu, Bo, E-mail: lbo@tongji.edu.cn [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Cheng, Chuanwei [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Hu, Jing; He, Shiyi [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Radiation Detection Research Center, Northwest Institute of Nuclear Technology, Xi’an, 710024 (China); Wang, Zewei [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Radiation Detection Research Center, Northwest Institute of Nuclear Technology, Xi’an, 710024 (China); College of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Gu, Mu; Chen, Hong [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China)

    2015-09-21

    Plastic scintillators are extensively used in various radiation measurement systems. However the total internal reflection decreases the scintillation light output, leading to a low detection efficiency especially in these weak signal detection situations. In the present investigation, we have designed a light extraction scheme based on the photonic crystal formed with a monolayer periodic array of polystyrene nanospheres by a self-assembly method. The photonic crystal coated on the surface of plastic scintillator can significantly enhance the light extraction by 120% compared with the plain reference sample under X-ray excitation, which is achieved by the principle of the coupling of evanescent field near the scintillator-air interface with the photonic crystal.

  4. Self-assembled microtubes and rhodamine 6G functionalized Raman-active gold microrods from 1-hydroxybenzotriazole

    Indian Academy of Sciences (India)

    Ravula Thirupathi; Erode N Prabhakaran

    2011-05-01

    1-Hydroxybenzotriazole spontaneously self-assembles to form hollow, linear microtubes initiated by controlled evaporation from water. The tube cavities act as thermo-labile micromoulds for the synthesis of linear gold microrods. Rhodamine 6G-labelled gold microrods, exhibiting surface enhanced resonance Raman activity, have been synthesized using the HOBT microtubes.

  5. Self-Assembled DNA Templated Nano-wires and Circuits

    Science.gov (United States)

    Braun, Erez

    2000-03-01

    The realization that conventional microelectronics is approaching its miniaturization limits has motivated the search for an alternative route based on self-assembled nanometer-scale electronics. We have recently proposed a new approach based on the hybridization of biological and electronic materials (Braun E., Eichen Y., Sivan U. and Ben-Yoseph G., Nature 391, 775 (1998)). The concept relies on a two-step self-assembly process. The inherent molecular recognition capabilities of DNA molecules are first utilized to construct a network that serves as a template for the subsequent assembly of electronic materials into a circuit. The utilization of DNA and its associated enzymatic machinery enables: (a) self-assembly of complex substrates, (b) specific molecular addresses for the localization of electronic materials (e.g., gold colloids) by standard molecular biology techniques, (c) interdevice wiring and (d) bridging the microscopic structures to the macroscopic world. The self-assembly of nanometer scale electronics relies on two complementary developments. First, the ability to convert DNA molecules into thin conductive wires and second, the self-assembly of complex extended DNA templates. Our progress in these two directions will be presented. Regarding the first issue, a physical process resulting in condensation of gold colloids onto DNA molecules enables the assembly of thin gold wires (around 100-200 A wide) having, in principle, unlimited extensions. The second issue is developed in the context of recombinant DNA which allows the self-assembly of precise molecular junctions and networks. Specifically, we use RecA protein, which is the main protein responsible for genetic recombination in E. Coli bacteria, to construct DNA junctions at pre-designed addresses (sequences) on the molecules. The integration of these processes allows advancing nanometer-scale electronics. A realistic fabrication scheme for a room-temperature single-electron transistor

  6. Emerin self-assembly mechanism: role of the LEM domain.

    Science.gov (United States)

    Samson, Camille; Celli, Florian; Hendriks, Kitty; Zinke, Maximilian; Essawy, Nada; Herrada, Isaline; Arteni, Ana-Andreea; Theillet, François-Xavier; Alpha-Bazin, Béatrice; Armengaud, Jean; Coirault, Catherine; Lange, Adam; Zinn-Justin, Sophie

    2017-01-01

    At the nuclear envelope, the inner nuclear membrane protein emerin contributes to the interface between the nucleoskeleton and the chromatin. Emerin is an essential actor of the nuclear response to a mechanical signal. Genetic defects in emerin cause Emery-Dreifuss muscular dystrophy. It was proposed that emerin oligomerization regulates nucleoskeleton binding, and impaired oligomerization contributes to the loss of function of emerin disease-causing mutants. We here report the first structural characterization of emerin oligomers. We identified an N-terminal emerin region from amino acid 1 to amino acid 132 that is necessary and sufficient for formation of long curvilinear filaments. In emerin monomer, this region contains a globular LEM domain and a fragment that is intrinsically disordered. Solid-state nuclear magnetic resonance analysis identifies the LEM β-fragment as part of the oligomeric structural core. However, the LEM domain alone does not self-assemble into filaments. Additional residues forming a β-structure are observed within the filaments that could correspond to the unstructured region in emerin monomer. We show that the delK37 mutation causing muscular dystrophy triggers LEM domain unfolding and increases emerin self-assembly rate. Similarly, inserting a disulfide bridge that stabilizes the LEM folded state impairs emerin N-terminal region self-assembly, whereas reducing this disulfide bridge triggers self-assembly. We conclude that the LEM domain, responsible for binding to the chromatin protein BAF, undergoes a conformational change during self-assembly of emerin N-terminal region. The consequences of these structural rearrangement and self-assembly events on emerin binding properties are discussed. © 2016 The Authors Journal compilation © 2016 FEBS.

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

    Directory of Open Access Journals (Sweden)

    Øystein Stakkestad

    2017-07-01

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

  8. Biomimetic Remineralization of Carious Lesions by Self-Assembling Peptide.

    Science.gov (United States)

    Kind, L; Stevanovic, S; Wuttig, S; Wimberger, S; Hofer, J; Müller, B; Pieles, U

    2017-07-01

    Caries is the most common disease in the world. Great efforts have been undertaken for prevention and to identify a regenerative treatment solution for dental caries. Self-assembling β-sheet forming peptides have previously shown to form 3-dimensional fiber networks supporting tissue regeneration. In particular, the self-assembling peptide P11-4 has shown potential in the treatment and prevention of dental caries. It has previously been shown that application of monomeric P11-4 solution to early carious lesions can increase net mineral gain by forming de novo hydroxyapatite crystals. The hypothesis for the mode of action was that monomeric self-assembling peptide P11-4 diffuses into the subsurface lesion body and assembles therein into higher order fibrils, facilitating mineralization of the subsurface volume by mimicking the natural biomineralization of the tooth enamel, and it remains within the lesion body as a scaffold built-in by the newly formed hydroxyapatite. The aim of the present study was to investigate the mechanism of action of the self-assembling peptide P11-4 supporting mineralization of carious enamel. By various analytical methods, it could be shown that the self-assembling peptide P11-4 diffuses into the subsurface lesion, assembles into higher formed aggregates throughout the whole volume of the lesion, and supports nucleation of de novo hydroxyapatite nanocrystals and consequently results in increased mineral density within the subsurface carious lesion. The results showed that the application of self-assembling peptide P11-4 can facilitate the subsurface regeneration of the enamel lesion by supporting de novo mineralization in a similar mode of action as has been shown for the natural formation of dental enamel.

  9. Artificial nanograting woven by self-assembled nanowires.

    Science.gov (United States)

    Liu, Feng-Qi; Shao, Ye; Huang, Xiu-Qi; Wang, Zhan-Guo

    2005-10-01

    We report on a new simple route to realize a high resolution nanograting. By adopting an InAlGaAs matrix and strain-compensated technique, we have proved that a uniform self-assembled InAs nanowire array can be fabricated by molecular beam epitaxy (MBE). A nanograting woven by self-assembled semiconductor nanowires shows a conspicuous diffraction feature. The good agreement between the theoretical and experimental values of diffraction peak positions indicates that a uniform nanowire array is a promising nanograting. This simple one-step MBE growth method will open exciting opportunities for the field of clever optics design.

  10. Self-assembly and manipulation of particles on drop surfaces

    Science.gov (United States)

    Janjua, M.; Fischer, I. S.; Singh, P.

    2013-11-01

    We have recently shown that particles adsorbed on the surface of a drop can be self-assembled at the poles or the equator of the drop by applying a uniform electric field, and that this method can be used to separate on the surface of a drop particles experiencing positive dielectrophoresis from those experiencing negative dielectrophoresis. In this talk we show that the frequency of the electric field is an important parameter which can be used to modify the distribution of self-assembled monolayers.

  11. Designing isotropic interactions for self-assembly of complex lattices.

    Science.gov (United States)

    Edlund, E; Lindgren, O; Jacobi, M Nilsson

    2011-08-19

    We present a direct method for solving the inverse problem of designing isotropic potentials that cause self-assembly into target lattices. Each potential is constructed by matching its energy spectrum to the reciprocal representation of the lattice to guarantee that the desired structure is a ground state. We use the method to self-assemble complex lattices not previously achieved with isotropic potentials, such as a snub square tiling and the kagome lattice. The latter is especially interesting because it provides the crucial geometric frustration in several proposed spin liquids. © 2011 American Physical Society

  12. Directional Self-assembly in Archaerhodopsin-Reconstituted Phospholipid Liposomes

    Institute of Scientific and Technical Information of China (English)

    吴佳; 黄力; 刘坚; 明明; 李庆国; 丁建东

    2005-01-01

    This paper reports, for the first time, that Archaerhodopsin-4 (AR4) could be reconstituted into phospholipid liposomes by self-assembly. AR4 is a new membrane protein isolated from halobacteria H.sp. xz515 in a salt lake of Tibet, China. This is a bacteriorhodopsin (bR) like protein, function as a light-driven proton pump. Experimental measurements verified that similar to bR, AR not only remains its biological activity in pmteoliposome, but also keeps a preferred orientation in self-assembly.

  13. Self-assembly of flagellin on Au(111) surfaces.

    Science.gov (United States)

    González Orive, Alejandro; Pissinis, Diego E; Diaz, Carolina; Miñán, Alejandro; Benítez, Guillermo A; Rubert, Aldo; Daza Millone, Antonieta; Rumbo, Martin; Hernández Creus, Alberto; Salvarezza, Roberto C; Schilardi, Patricia L

    2014-11-01

    The adsorption of flagellin monomers from Pseudomonas fluorescens on Au(111) has been studied by Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy (STM), X-ray Photoelectron Spectroscopy (XPS), Surface Plasmon Resonance (SPR), and electrochemical techniques. Results show that flagellin monomers spontaneously self-assemble forming a monolayer thick protein film bounded to the Au surface by the more hydrophobic subunit and exposed to the environment the hydrophilic subunit. The films are conductive and allow allocation of electrochemically active cytochrome C. The self-assembled films could be used as biological platforms to build 3D complex molecular structures on planar metal surfaces and to functionalize metal nanoparticles.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-04

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

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

    Science.gov (United States)

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

    2017-04-04

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

  16. Self-assembly of two-dimensional DNA crystals

    Institute of Scientific and Technical Information of China (English)

    SONG Cheng; CHEN Yaqing; WEI Shuai; YOU Xiaozeng; XIAO Shoujun

    2004-01-01

    Self-assembly of synthetic oligonucleotides into two-dimensional lattices presents a 'bottom-up' approach to the fabrication of devices on nanometer scale. We report the design and observation of two-dimensional crystalline forms of DNAs that are composed of twenty-one plane oligonucleotides and one phosphate-modified oligonucleotide. These synthetic sequences are designed to self-assemble into four double-crossover (DX) DNA tiles. The 'sticky ends' of these tiles that associate according to Watson-Crick's base pairing are programmed to build up specific periodic patterns upto tens of microns. The patterned crystals are visualized by the transmission electron microscopy.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-09-01

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

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

    Science.gov (United States)

    Lin, Milo M.

    2017-09-01

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

  19. Large-Scale Self-Assembled Ag Nanotubes

    Institute of Scientific and Technical Information of China (English)

    WEI Guodan; NAN Cewen; YU Dapeng

    2005-01-01

    A high yield of silver nanotubes with large aspect ratio were conveniently synthesized via an organic-assist solvothermal preparation technique using polyvinyl pyrrolidone (PVP) as a capping reagent and architecture soft-template. The molecular ratio between the repeating unit of PVP and AgNO3 plays a crucial role in determining the geometric shape of the product. Such novel-type Ag nanotubes were self-assembled by Ag nanoparticles, which had largely similar crystallographic orientation, forming a texture. The fact that nanoparticles without anisotropic crystal structures can form such superstructures by self-assembly may open a window for understanding a range of nanotube formation processes.

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

    Science.gov (United States)

    Halverson, Jonathan; Tkachenko, Alexei

    2012-02-01

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

  1. Composition and method for self-assembly and mineralization of peptide-amphiphiles

    Science.gov (United States)

    Stupp, Samuel I [Chicago, IL; Beniash, Elia [Newton, MA; Hartgerink, Jeffrey D [Pearland, TX

    2012-02-28

    The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.

  2. Composition and method for self-assembly and mineralization of peptide amphiphiles

    Science.gov (United States)

    Stupp, Samuel I.; Beniash, Elia; Hartgerink, Jeffrey D.

    2009-06-30

    The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.

  3. Supramolecular Self-Assembled Chaos: Polyphenolic Lignin’s Barrier to Cost-Effective Lignocellulosic Biofuels

    Directory of Open Access Journals (Sweden)

    Shawn Matthew Dirk

    2010-11-01

    Full Text Available Phenylpropanoid metabolism yields a mixture of monolignols that undergo chaotic, non-enzymatic reactions such as free radical polymerization and spontaneous self-assembly in order to form the polyphenolic lignin which is a barrier to cost-effective lignocellulosic biofuels. Post-synthesis lignin integration into the plant cell wall is unclear, including how the hydrophobic lignin incorporates into the wall in an initially hydrophilic milieu. Self-assembly, self-organization and aggregation give rise to a complex, 3D network of lignin that displays randomly branched topology and fractal properties. Attempts at isolating lignin, analogous to archaeology, are instantly destructive and non-representative of in planta. Lack of plant ligninases or enzymes that hydrolyze specific bonds in lignin-carbohydrate complexes (LCCs also frustrate a better grasp of lignin. Supramolecular self-assembly, nano-mechanical properties of lignin-lignin, lignin-polysaccharide interactions and association-dissociation kinetics affect biomass deconstruction and thereby cost-effective biofuels production.

  4. Enriching PMMA nanospheres with adjustable charges as novel templates for multicolored dye-PMMA nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xumei; Xu Shuping; Xu Weiqing [State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012 (China); Liang Chongyang; Li Hongrui; Sun Fei, E-mail: xuwq@jlu.edu.cn [Institute of Frontier Medical Science, Jilin University, Changchun 130021 (China)

    2011-07-08

    Multicolored fluorescent dye loaded PMMA nanospheres were synthesized by the electrostatic adsorption of dye molecules on the charged PMMA nanospheres, whose charges were adjusted by choosing different initiators. The charged PMMA nanospheres have a wider capacity and advantage for combining the charged dyes. The fluorescent dye-PMMA composite nanospheres possess the advantages of higher brightness, longer lifetime and stronger resistance to photobleaching relative to dye molecules. Dye leakage remained lower than 5% over one week. These fluorescent nanospheres have been used in biological labels in cell imaging. They can easily stain blood cancer cells without further surface modification.

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

    Directory of Open Access Journals (Sweden)

    Francesco Di Stasio

    2013-10-01

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

  6. Self-Assembly of Nano Hydroxyapatite or Aragonite Induced by Molecular Recognition to Soy Globulin 7S or 11S.

    Science.gov (United States)

    Liu, Dagang; Tian, Huafeng; Kumar, Rakesh; Zhang, Lina

    2009-09-01

    Molecular self-assembly is emerging as a viable 'bottom-up' approach to build stable organic/inorganic nanometer-scale blocks. Herein, under the conditions of appropriate pH and ionic strength, soy globulin 7S or 11S were coprecipitated with hydroxyapatite (HAp) or aragonite (Arag), respectively, to fabricate two organic/inorganic hybrids: 7S/HAp and 11S/Arag. Results from high-resolution transmission electron microscopy show that the hybrids exhibit a nanosized core-shell structure with globulin monomer 7S or 11S as core and HAp or Arag as shells. 7S/HAp and 11S/Arag present a disk and hexagon shape, respectively. After calcinations, monodispersed HAp without support from globulins existed as nanospheres. It was revealed that the globulin as host induces the self-assembly and growth layer by layer of HAp or Arag nanocrystals. The factors of molecular recognition and surface potential definitely affected the size and shape of the hierarchical blocks. This work provided a novel pathway to controllably synthesize a wide variety of precise plant protein/biomineral hybrid biomaterials.

  7. A switchable self-assembling and disassembling chiral system based on a porphyrin-substituted phenylalanine-phenylalanine motif

    Science.gov (United States)

    Charalambidis, Georgios; Georgilis, Evangelos; Panda, Manas K.; Anson, Christopher E.; Powell, Annie K.; Doyle, Stephen; Moss, David; Jochum, Tobias; Horton, Peter N.; Coles, Simon J.; Linares, Mathieu; Beljonne, David; Naubron, Jean-Valère; Conradt, Jonas; Kalt, Heinz; Mitraki, Anna; Coutsolelos, Athanassios G.; Balaban, Teodor Silviu

    2016-09-01

    Artificial light-harvesting systems have until now not been able to self-assemble into structures with a large photon capture cross-section that upon a stimulus reversibly can switch into an inactive state. Here we describe a simple and robust FLFL-dipeptide construct to which a meso-tetraphenylporphyrin has been appended and which self-assembles to fibrils, platelets or nanospheres depending on the solvent composition. The fibrils, functioning as quenched antennas, give intense excitonic couplets in the electronic circular dichroism spectra which are mirror imaged if the unnatural FDFD-analogue is used. By slightly increasing the solvent polarity, these light-harvesting fibres disassemble to spherical structures with silent electronic circular dichroism spectra but which fluoresce. Upon further dilution with the nonpolar solvent, the intense Cotton effects are recovered, thus proving a reversible switching. A single crystal X-ray structure shows a head-to-head arrangement of porphyrins that explains both their excitonic coupling and quenched fluorescence.

  8. A switchable self-assembling and disassembling chiral system based on a porphyrin-substituted phenylalanine–phenylalanine motif

    Science.gov (United States)

    Charalambidis, Georgios; Georgilis, Evangelos; Panda, Manas K.; Anson, Christopher E.; Powell, Annie K.; Doyle, Stephen; Moss, David; Jochum, Tobias; Horton, Peter N.; Coles, Simon J.; Linares, Mathieu; Beljonne, David; Naubron, Jean-Valère; Conradt, Jonas; Kalt, Heinz; Mitraki, Anna; Coutsolelos, Athanassios G.; Balaban, Teodor Silviu

    2016-01-01

    Artificial light-harvesting systems have until now not been able to self-assemble into structures with a large photon capture cross-section that upon a stimulus reversibly can switch into an inactive state. Here we describe a simple and robust FLFL-dipeptide construct to which a meso-tetraphenylporphyrin has been appended and which self-assembles to fibrils, platelets or nanospheres depending on the solvent composition. The fibrils, functioning as quenched antennas, give intense excitonic couplets in the electronic circular dichroism spectra which are mirror imaged if the unnatural FDFD-analogue is used. By slightly increasing the solvent polarity, these light-harvesting fibres disassemble to spherical structures with silent electronic circular dichroism spectra but which fluoresce. Upon further dilution with the nonpolar solvent, the intense Cotton effects are recovered, thus proving a reversible switching. A single crystal X-ray structure shows a head-to-head arrangement of porphyrins that explains both their excitonic coupling and quenched fluorescence. PMID:27582363

  9. Lubrication of polysilicon micromechanisms with self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-06-01

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

  10. Controllable fabrication of 2D colloidal-crystal films with polystyrene nanospheres of various diameters by spin-coating

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian; Dong, Peitao [College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha, Hunan, 410073 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Science (China); Di, Di; Wang, Chaoguang; Wang, Haoxu; Wang, Junfeng [College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha, Hunan, 410073 (China); Wu, Xuezhong, E-mail: xzwu@nudt.edu.cn [College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha, Hunan, 410073 (China)

    2013-04-01

    Monolayer and bilayer colloidal-crystal films are used as physical mask in nanosphere lithography (NSL). So far, spin-coating experiments have mainly been designed to form nanosphere monolayer with one given size or obtain small areas of polystyrene (PS) nanosphere monolayer which limited the application of these films used as physical masks. The development of NSL required more study focused on the preparation of colloidal-crystal films with large-scale, high ordering degree and nanospheres of different diameters. In this study, PS nanospheres were self-assembled to form monolayer and bilayer colloidal-crystal films by employing spin-coating technology. Based on our experiments, we have built an experiment system of PS nanospheres of certain size ranging from 200 nm to 1300 nm. To give an instance, we have chosen PS nanospheres of four diameters (223 nm, 347 nm, 509 nm, 1300 nm) to fabricate colloidal-crystal films by adjusting the spin speed and acceleration, and we have investigated the relationship between the monolayer coverage areas and spin parameters by designing different spin speed and acceleration for 509 nm nanosphere. Results revealed that monolayer and bilayer films of PS nanospheres with four different diameters were prepared successfully and the single structure where PS nanospheres were in hexagonal close-packed (HCP) order dominated the surface morphologies of both monolayer and bilayer colloidal-crystal films. For 509 nm PS nanosphere, as the spin speed and acceleration increasing, the monolayer coverage areas increase firstly then decrease and at spin speed 1750 rpm and acceleration 600 rpm/s, the areas reaches the biggest.

  11. Increase in stability of cellulase immobilized on functionalized magnetic nanospheres

    Science.gov (United States)

    Zhang, Wenjuan; Qiu, Jianhui; Feng, Huixia; Zang, Limin; Sakai, Eiichi

    2015-02-01

    Functionalized magnetic nanospheres were prepared by co-condensation of tetraethylorthosilicate with three different amino-silanes: 3-(2-aminoethylamino propyl)-triethoxysilane (AEAPTES), 3-(2-aminoethylamino propyl)-trimethoxysilane (AEAPTMES) and 3-aminopropyltriethoxysilane (APTES). Then three functionalized magnetic nanospheres were used as supports for immobilization of cellulase. The three functionalized magnetic nanospheres with core-shell morphologies exhibited higher capacity for cellulase immobilization than unfunctionalized magnetic nanospheres. The increasing of surface charge of functionalized magnetic nanospheres leads to an enhancement of the capacity of cellulase immobilization. Particularly, AEAPTMES with methoxy groups was favored to be hydrolyzed and grafted on unfunctionalized magnetic nanospheres than the others. AEAPTMES functionalized magnetic nanospheres with the highest zeta potential (29 mV) exhibited 87% activity recovery and the maximum amount of immobilized cellulase was 112 mg/g support at concentration of initial cellulase of 8 mg/mL. Immobilized cellulase on AEAPTMES functionalized magnetic nanospheres had higher temperature stability and broader pH stability than other immobilized cellulases and free cellulase. In particular, it can be used in about 40 °C, demonstrating the potential of biofuel production using this immobilized cellulase.

  12. Long lived coherence in self-assembled quantum dots

    DEFF Research Database (Denmark)

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

    2001-01-01

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

  13. 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-assem...

  14. Effect of alkyl substitutions on self-assembly

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The self-assemblies of 4-hexadecyloxybenzoic acid and 3,4,5-trihexadecyloxybenzoic acid have been studied by using scanning tunneling microscopy (STM). The well-ordered assemblies with different arrangement have been investigated. The structural change is attributed to the different number of substituted alkyl chains on periphery.

  15. Self-assembled three-dimensional non-volatile memories

    NARCIS (Netherlands)

    Abelmann, Leon; Tas, Niels; Berenschot, Erwin; Elwenspoek, Miko

    2010-01-01

    The continuous increase in capacity of non-volatile data storage systems will lead to bit densities of one bit per atom in 2020. Beyond this point, capacity can be increased by moving into the third dimension. We propose to use self-assembly of nanosized elements, either as a loosely organised assoc

  16. 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

  17. 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...

  18. Self-assembling peptides form nanodiscs that stabilize membrane proteins

    DEFF Research Database (Denmark)

    Midtgaard, Søren Roi; Pedersen, Martin Cramer; Kirkensgaard, Jacob Judas Kain;

    2014-01-01

    New methods to handle membrane bound proteins, e.g. G-protein coupled receptors (GPCRs), are highly desirable. Recently, apoliprotein A1 (ApoA1) based lipoprotein particles have emerged as a new platform for studying membrane proteins, and it has been shown that they can self-assemble in combinat...

  19. 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....... In particular we use EFM to investigate the structures of diphenylalanine peptide tubes, particles, and CSGAITIG peptide particles placed on pre-fabricated SiO2 surfaces with a backgate. We show that the cavity in the peptide tubes could be to the presence of water residues. Additionally we show that self......-assembled amyloid peptides form spherical solid structures containing the same self-assembled peptide in its interior. In both cases transmission electron microscopy is used to verify these structures. Further, the limitations of the EFM technique are discussed, especially when the observed structures become small...

  20. Chirality controlled responsive self-assembled nanotubes in water

    NARCIS (Netherlands)

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

    2017-01-01

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

  1. Fluorescent self-assembled monolayers as new sensing materials

    NARCIS (Netherlands)

    Basabe Desmonts, Lourdes

    2006-01-01

    Fluorescent self-assembled monolayers (SAMs) on glass surfaces have been studied as a new material for chemical sensing. The new sensing system presented in this thesis is a label-free sensing approach suitable for metal ion and inorganic anions sensing in both organic solvents and aqueous solution.

  2. 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...... der Waals (vdW) interaction and the coupling of C-H/π/C-F interaction and π/π interaction are proven to offer the continuous driving force of self-assembly of J-GN. The results show that J-GN can self-assemble into various J-NSs structures, including arcs, multi-wall J-NS and arm-chair-like J......-NS by manipulating its original geometry (size and aspect ratio). Moreover, we also investigated self-assembly of hydrofluorinated J-GN and Fe nanowires (NWs), suggesting that Fe NW is a good alternative to activate J-GN to form J-NS. Differently, the strong vdW interaction between J-GN and Fe NW provides the main...

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

    NARCIS (Netherlands)

    de Boer, B; Hadipour, A; Foekema, R; van Woudenbergh, T; Mandoc, MM; Mihailetchi, VD; Blom, PWM; Heremans, PL; Muccini, M; Hofstraat, H

    2004-01-01

    Tuning the work functions of metals was demonstrated by chemically modifying the metal surface through the formation of chemisorbed self-assembled monolayers (SAMs) derived from 1H,1H,2H,2H-perfluorinated alkanethiols and hexadecanethiol. The ordering inherent in the SAMs creates an effective, molec

  4. Self-assembly and semiconductivity of an oligothiophene supergelator

    NARCIS (Netherlands)

    Pratihar, P.; Ghosh, S.; Stepanenko, V.; Patwardhan, S.; Grozema, F.C.; Siebbeles, L.D.A.; Würthner, F.

    2010-01-01

    A bis(trialkoxybenzamide)-functionalized quaterthiophene derivative was synthesized and its self-assembly properties in solution were studied. In non-polar solvents such as cyclohexane, this quaterthiophene π-system formed fibril aggregates with an H-type molecular arrangement due to synergistic eff

  5. Multiphonon capture processes in self-assembled quantum dots

    DEFF Research Database (Denmark)

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

    2001-01-01

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

  6. Photocontrol over cooperative porphyrin self-assembly with phenylazopyridine ligands.

    Science.gov (United States)

    Hirose, Takashi; Helmich, Floris; Meijer, E W

    2013-01-02

    The cooperative self-assembly of chiral zinc porphyrins is regulated by a photoresponsive phenylazopyridine ligand. Porphyrin stacks depolymerize into dimers upon axial ligation and the strength of the coordination is regulated by its photoinduced isomerization, which shows more than 95 % conversion ratio for both photostationary states.

  7. Equation of State for Phospholipid Self-Assembly

    DEFF Research Database (Denmark)

    Marsh, Derek

    2016-01-01

    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...

  8. Controlled self-assembly of hydrophobic quantum dots through silanization.

    Science.gov (United States)

    Yang, Ping; Ando, Masanori; Murase, Norio

    2011-09-01

    We demonstrate the formation of one-, two-, and three-dimensional nanocomposites through the self-assembly of silanized CdSe/ZnS quantum dots (QDs) by using a controlled sol-gel process. The self-assembly behavior of the QDs was created when partially hydrolyzed silicon alkoxide monomers replaced hydrophobic ligands on the QDs. We examined systematically self-assembly conditions such as solvent components and QD sizes in order to elucidate the formation mechanism of various QD nanocomposites. The QD nanocomposites were assembled in water phase or on the interface of water and oil phase in emulsions. The partially hydrolyzed silicon alkoxides act as intermolecules to assemble the QDs. The QD nanocomposites with well-defined solid or hollow spherical, fiber-like, sheet-like, and pearl-like morphologies were prepared by adjusting the experimental conditions. The high photoluminescence efficiency of the prepared QD nanocomposites suggests partially hydrolyzed silicon alkoxides reduced the surface deterioration of QDs during self-assembly. These techniques are applicable to other hydrophobic QDs for fabricating complex QD nanocomposites.

  9. Photoresponsive self-assemblies based on fatty acids.

    Science.gov (United States)

    Fameau, A-L; Arnould, A; Lehmann, M; von Klitzing, R

    2015-02-18

    Photoresponsive surfactant system based on fatty acids has been developed by the introduction in aqueous solution of a photoacid generator (PAG). Self-assembly transitions are triggered by UV irradiation due to a pH change induced by the presence of PAG.

  10. Self-assembled materials from thermosensitive and biohybrid block copolymers

    NARCIS (Netherlands)

    de Graaf, A.J.

    2012-01-01

    In this research, several block copolymers were synthesized and characterized with regard to possible pharmaceutical applications. All block copolymers were thermosensitive and self-assembled at 37 °C into structures like micelles and hydrogels, which can be used for innovative drug delivery purpose

  11. New Metal-organic Polymers Through Subcomponent Self-Assembly

    Science.gov (United States)

    2012-07-27

    material using subcomponent self-assembly. We developed the synthesis of double helical polymeric species according to the general procedure...to use - diketones as subcomponents for polymers. She then shifted her efforts to other projects, funded by the European Research Council. Because

  12. 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

  13. Anisotropic Nanocolloids: self-assembly, interfacial adsorption, and electrostatic screening

    NARCIS (Netherlands)

    de Graaf, J.

    2012-01-01

    In this thesis we consider the influence of anisotropy on the behaviour of colloids using theory and simulations. The recent increase in the ability to synthesize anisotropic particles (cubes, caps, octapods, etc.) has led to samples of sufficient quality to perform self-assembly experiments. Our in

  14. Self-assembled peptide nanostructures for functional materials.

    Science.gov (United States)

    Ekiz, Melis Sardan; Cinar, Goksu; Khalily, Mohammad Aref; Guler, Mustafa O

    2016-10-07

    Nature is an important inspirational source for scientists, and presents complex and elegant examples of adaptive and intelligent systems created by self-assembly. Significant effort has been devoted to understanding these sophisticated systems. The self-assembly process enables us to create supramolecular nanostructures with high order and complexity, and peptide-based self-assembling building blocks can serve as suitable platforms to construct nanostructures showing diverse features and applications. In this review, peptide-based supramolecular assemblies will be discussed in terms of their synthesis, design, characterization and application. Peptide nanostructures are categorized based on their chemical and physical properties and will be examined by rationalizing the influence of peptide design on the resulting morphology and the methods employed to characterize these high order complex systems. Moreover, the application of self-assembled peptide nanomaterials as functional materials in information technologies and environmental sciences will be reviewed by providing examples from recently published high-impact studies.

  15. Electrostatic Self-Assembled Multilayers from Side Chain Azo Polyelectrolytes

    Institute of Scientific and Technical Information of China (English)

    庹新林; 陈峥; 邓永红; 王晓工; 刘德山

    2002-01-01

    Photoresponsive behavior and self-assembly properties of three side chain azo polyelectrolytes, poly (2-(4-phenylazophenoxy) ethanol-co-acrylic acid) (PPAPE), poly (2-(4-(4′-nitrophenylazo) phenoxy) ethanol-co-acrylic acid) (PNAPE), and poly (2-(4-(4′-ethoxyphenylazo) phenoxy) ethanol-co-acrylic acid) (PEAPE), were studied. These polyelectrolytes with different degrees of functionalization of azo chromophores were fabricated into nano-composite multilayers using two types of dipping solutions through a layer-by-layer electrostatic self-assembling process. Results show that the ratio between tetrahydrofuran (THF) and H2O significantly influences the photoresponsive behavior of PNAPE in THF-H2O mixture. The THF-H2O dipping solution, used in this work for self-assembly of hydrophobic polyelectrolytes, is proved to be as applicable as aqueous dipping solution for normal self-assembly of hydrophobic polyelectrolytes. However, significant differences in the multilayer growth between the two systems were also observed, which resulted from the remarkable difference of the existing forms of the polyelectrolytes in these two dipping solutions.

  16. Probabilistic Analysis of Pattern Formation in Monotonic Self-Assembly.

    Science.gov (United States)

    Moore, Tyler G; Garzon, Max H; Deaton, Russell J

    2015-01-01

    Inspired by biological systems, self-assembly aims to construct complex structures. It functions through piece-wise, local interactions among component parts and has the potential to produce novel materials and devices at the nanoscale. Algorithmic self-assembly models the product of self-assembly as the output of some computational process, and attempts to control the process of assembly algorithmically. Though providing fundamental insights, these computational models have yet to fully account for the randomness that is inherent in experimental realizations, which tend to be based on trial and error methods. In order to develop a method of analysis that addresses experimental parameters, such as error and yield, this work focuses on the capability of assembly systems to produce a pre-determined set of target patterns, either accurately or perhaps only approximately. Self-assembly systems that assemble patterns that are similar to the targets in a significant percentage are "strong" assemblers. In addition, assemblers should predominantly produce target patterns, with a small percentage of errors or junk. These definitions approximate notions of yield and purity in chemistry and manufacturing. By combining these definitions, a criterion for efficient assembly is developed that can be used to compare the ability of different assembly systems to produce a given target set. Efficiency is a composite measure of the accuracy and purity of an assembler. Typical examples in algorithmic assembly are assessed in the context of these metrics. In addition to validating the method, they also provide some insight that might be used to guide experimentation. Finally, some general results are established that, for efficient assembly, imply that every target pattern is guaranteed to be assembled with a minimum common positive probability, regardless of its size, and that a trichotomy exists to characterize the global behavior of typical efficient, monotonic self-assembly systems

  17. Probabilistic Analysis of Pattern Formation in Monotonic Self-Assembly.

    Directory of Open Access Journals (Sweden)

    Tyler G Moore

    Full Text Available Inspired by biological systems, self-assembly aims to construct complex structures. It functions through piece-wise, local interactions among component parts and has the potential to produce novel materials and devices at the nanoscale. Algorithmic self-assembly models the product of self-assembly as the output of some computational process, and attempts to control the process of assembly algorithmically. Though providing fundamental insights, these computational models have yet to fully account for the randomness that is inherent in experimental realizations, which tend to be based on trial and error methods. In order to develop a method of analysis that addresses experimental parameters, such as error and yield, this work focuses on the capability of assembly systems to produce a pre-determined set of target patterns, either accurately or perhaps only approximately. Self-assembly systems that assemble patterns that are similar to the targets in a significant percentage are "strong" assemblers. In addition, assemblers should predominantly produce target patterns, with a small percentage of errors or junk. These definitions approximate notions of yield and purity in chemistry and manufacturing. By combining these definitions, a criterion for efficient assembly is developed that can be used to compare the ability of different assembly systems to produce a given target set. Efficiency is a composite measure of the accuracy and purity of an assembler. Typical examples in algorithmic assembly are assessed in the context of these metrics. In addition to validating the method, they also provide some insight that might be used to guide experimentation. Finally, some general results are established that, for efficient assembly, imply that every target pattern is guaranteed to be assembled with a minimum common positive probability, regardless of its size, and that a trichotomy exists to characterize the global behavior of typical efficient, monotonic

  18. Irregular shaping of polystyrene nanosphere array by plasma etching

    National Research Council Canada - National Science Library

    Luo, Hao; Liu, Tingting; Ma, Jun; Wang, Wei; Li, Heng; Wang, Pengwei; Bai, Jintao; Jing, Guangyin

    2013-01-01

    .... Here, by plasma etching, the controllable tailoring of the nanosphere is realized and its morphology dependence on the initial shape, microscopic roughness, and the etching conditions is investigated quantitatively...

  19. The impact of substrate interaction in directed self-assembly of symmetric diblock copolymer thin films

    Science.gov (United States)

    Seidel, Robert

    ) and size of process window. It also introduces an analysis technique for evaluating assembly kinetics with an emphasis on defect annihilation. The fifth chapter seeks to identify more thoroughly the root causes of LER in BCP line/space DSA by investigating a number of factors. The sixth and final full chapter describes initial success in the effort to extend the concepts of BCP DSA on patterned planar substrates to flexible or three-dimensional substrates (for roll-to-roll applications) by using functional layer-by-layer deposited films. Our final conclusion touches on the ideas of nucleation of self-assembled BCP structures and how they relate to kinetic pathways and timescales of assembly.

  20. Hierarchical self-assembly: Self-organized nanostructures in a nematically ordered matrix of self-assembled polymeric chains

    Science.gov (United States)

    Mubeena, Shaikh; Chatterji, Apratim

    2015-03-01

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

  1. Hierarchical self-assembly: Self-organized nanostructures in a nematically ordered matrix of self-assembled polymeric chains.

    Science.gov (United States)

    Mubeena, Shaikh; Chatterji, Apratim

    2015-03-01

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

  2. Development of self-assembling nanowires containing electronically active oligothiophenes

    Science.gov (United States)

    Tsai, Wei-Wen

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

  3. Self-Organization in Coordination-Driven Self-Assembly

    Science.gov (United States)

    Northrop, Brian H.; Zheng, Yao-Rong; Chi, Ki-Whan; Stang, Peter J.

    2009-01-01

    Conspectus Self-assembly allows for the preparation of highly complex molecular and supramolecular systems from relatively simple starting materials. Typically, self-assembled supramolecules are constructed by combining complementary pairs of two highly symmetric molecular components, thus limiting the chances of forming unwanted side products. Combining asymmetric molecular components or multiple complementary sets of molecules in one complex mixture can produce myriad different ordered and disordered supramolecular assemblies. Alternatively, spontaneous self-organization phenomena can promote the formation of specific product(s) out of a collection of multiple possibilities. Self-organization processes are common throughout much of nature and are especially common in biological systems. Recently, researchers have studied self-organized self-assembly in purely synthetic systems. This Account describes our investigations of self-organization in the coordination-driven self-assembly of platinum(II)-based metallosupramolecules. The modularity of the coordination-driven approach to self-assembly has allowed us to systematically study a wide variety of different factors that can control the extent of supramolecular self-organization. In particular, we have evaluated the effects of the symmetry and polarity of ambidentate donor subunits, differences in geometrical parameters (e.g. the size, angularity, and dimensionality) of Pt(II)-based acceptors and organic donors, the influence of temperature and solvent, and the effects of intermolecular steric interactions and hydrophobic interactions on self-organization. Our studies have shown that the extent of self-organization in the coordination-driven self-assembly of both 2D polygons and 3D polyhedra ranges from no organization (a statistical mixture of multiple products), to amplified organization (wherein a particular product or products are favored over others), and all the way to the absolute self-organization of

  4. Self-organization in coordination-driven self-assembly.

    Science.gov (United States)

    Northrop, Brian H; Zheng, Yao-Rong; Chi, Ki-Whan; Stang, Peter J

    2009-10-20

    Self-assembly allows for the preparation of highly complex molecular and supramolecular systems from relatively simple starting materials. Typically, self-assembled supramolecules are constructed by combining complementary pairs of two highly symmetric molecular components, thus limiting the chances of forming unwanted side products. Combining asymmetric molecular components or multiple complementary sets of molecules in one complex mixture can produce myriad different ordered and disordered supramolecular assemblies. Alternatively, spontaneous self-organization phenomena can promote the formation of specific product(s) out of a collection of multiple possibilities. Self-organization processes are common throughout much of nature and are especially common in biological systems. Recently, researchers have studied self-organized self-assembly in purely synthetic systems. This Account describes our investigations of self-organization in the coordination-driven self-assembly of platinum(II)-based metallosupramolecules. The modularity of the coordination-driven approach to self-assembly has allowed us to systematically study a wide variety of different factors that can control the extent of supramolecular self-organization. In particular, we have evaluated the effects of the symmetry and polarity of ambidentate donor subunits, differences in geometrical parameters (e.g., the size, angularity, and dimensionality) of Pt(II)-based acceptors and organic donors, the influence of temperature and solvent, and the effects of intermolecular steric interactions and hydrophobic interactions on self-organization. Our studies have shown that the extent of self-organization in the coordination-driven self-assembly of both 2D polygons and 3D polyhedra ranges from no organization (a statistical mixture of multiple products) to amplified organization (wherein a particular product or products are favored over others) and all the way to the absolute self-organization of discrete

  5. Plasmon-enhanced optical absorption and photocurrent in organic bulk heterojunction photovoltaic devices using self-assembled layer of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Woo-Jun; Jung, Kyung-Young; Teixeira, Fernando L. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, OH 43210 (United States); Liu, Jiwen; Duraisamy, Thirumalai; Revur, Rao; Sengupta, Suvankar [MetaMateria Partners, 1275 Kinnear Road, Columbus, OH 43212 (United States); Berger, Paul R. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, OH 43210 (United States); Department of Physics, Ohio State University, Columbus, OH 43210 (United States)

    2010-02-15

    Improved optical absorption and photocurrent for polythiophene-fullerene bulk heterojunction photovoltaic devices is demonstrated using a unique self-assembled monolayer of Ag nanoparticles formed from a colloidal solution. With the presence of suitable nanoparticle organic capping groups that inhibit its propensity to agglomerate, the particle-to-particle spacing can be tailored. Transmission electron microscopy reveals the self-assembled Ag nanospheres are highly uniform with an average diameter of {proportional_to}4 nm and controllable particle-to-particle spacing. The localized surface plasmon resonance peak is {proportional_to}465 nm with a narrow full width at half maximum (95 nm). In the spectral range of 350-650 nm, where the organic bulk heterojunction photoactive film absorbs, an enhanced optical absorption is observed due to the increased electric field in the photoactive layer by excited localized surface plasmons within the Ag nanospheres. Under the short-circuit condition, the induced photo-current efficiency (IPCE) measurement demonstrates that the maximum IPCE increased to {proportional_to}51.6% at 500 nm for the experimental devices with the self-assembled layer of Ag nanoparticles, while the IPCE of the reference devices without the plasmon-active Ag nanoparticles is {proportional_to}45.7% at 480 nm. For the experimental devices under air mass 1.5 global filtered illuminations with incident intensity of 100 mW/cm{sup 2}, the increased short-circuit current density is observed due to the enhancement of the photogeneration of excitons near the plasmon resonance of the Ag nanoparticles. (author)

  6. Zirconium phosphonate/1,4,5,8-naphthalenediimides self-assembled films

    Directory of Open Access Journals (Sweden)

    MAGALI A. RODRIGUES

    2000-03-01

    Full Text Available The formation and characterization of self-assembled films of zirconium phosphonate / N,N'-di(2-phosphonoethyl-1,4,5,8-naphthalenediimide (DPN is presented. The films were produced on glass substrates by deposition of alternating layers of Zr+4 and DPN. Films containing up to 16 layers on each side of the substrate were obtained and monitored by absorption spectroscopy and ellipsometry. When irradiated, the initially colorless films turned to a persistent pinky color reminiscent of that of DPN anion radical. These films are a promising material to the development of photovoltaic devices.

  7. Characterization of Formation Kinetics of Self-Assembled Thiol Monolayers on Gold by Electrochemical Impedance Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Self-assembled monolayers of octadecanethiol (ODT) on gold have been studied by electrochemical impedance spectroscopy (EIS). The fractional coverage has been examined as a function of immersion time of Au in ODT deposition solution. The fractional coverage exhibits two distinct adsorption steps: an initial rapid step followed by a slow one. The fractional coverage of ODT monolayer increases sharply from zero to more than 99% of its maximum within the first minute. However, it takes a day for the fractional coverage to approach its final value.

  8. Attachment of Algal Cells to Zwitterionic Self-Assembled Monolayers Comprised of Different Anionic Compounds.

    Science.gov (United States)

    Bauer, S; Finlay, J A; Thomé, I; Nolte, K; Franco, S C; Ralston, E; Swain, G E; Clare, A S; Rosenhahn, A

    2016-06-07

    The influence of zwitterionic self-assembled monolayers on settlement and removal of algae was studied. The monolayers were constructed either from zwitterionic thiols or from solutions of positively and negatively charged thiols. The cationic component was composed of quaternary ammonium terminated thiols and the anionic component contained sulfate or carboxylate termination. During assembly, all surfaces showed a strong tendency for equilibration of the surface charge. Settlement and adhesion assays with zoospores of Ulva linza and the diatom Navicula incerta, and field tests of the initial surface colonization revealed the relevance of charge equilibration for the biological inertness of the prepared surfaces.

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

    DEFF Research Database (Denmark)

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

    2002-01-01

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

  10. Self-assembling functionalizable polydiacetylenes and their optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Sukwattanasinitt, M.; Wang, X.; Lee, D.C.; Li, L.; Kumar, J.; Tripathy, S.K.; Sandman, D.J.

    1998-07-01

    The alkoxycarbonylmethylurethanes of 9-(N-methyl-N-phenylamino)-5,7-nonadiyn-1-ol were synthesized and polymerized by {sup 60}Co gamma radiation. The resulting polydiacetylenes (PDA) are soluble, processable, and self-assemble into an acentric array. These PDAs are susceptible to postpolymerization functionalization via its dialkylaniline and ester groups, and hence comprise the most versatile PDA system for systematic chemical modification reported to date. Dialkylaniline functionalization via tetracyanoethylene and diazonium salt coupling led, respectively, to materials with interesting second order nonlinear optical properties and that exhibit directly photofabricated regular surface relief gratings. The latter materials provide the first example of a rigid rod polymer (lacking a detectable glass transition) to exhibit such phenomena. Moreover, these PDAs can form self-assembled multilayer structure in water by ester hydrolysis.

  11. Self-assembly of double helical nanostructures inside carbon nanotubes.

    Science.gov (United States)

    Lv, Cheng; Xue, Qingzhong; Shan, Meixia; Jing, Nuannuan; Ling, Cuicui; Zhou, Xiaoyan; Jiao, Zhiyong; Xing, Wei; Yan, Zifeng

    2013-05-21

    We use molecular dynamics (MD) simulations to show that a DNA-like double helix of two poly(acetylene) (PA) chains can form inside single-walled carbon nanotubes (SWNTs). The computational results indicate that SWNTs can activate and guide the self-assembly of polymer chains, allowing them to adopt a helical configuration in a SWNT through the combined action of the van der Waals potential well and the π-π stacking interaction between the polymer and the inner surface of SWNTs. Meanwhile both the SWNT size and polymer chain stiffness determine the outcome of the nanostructure. Furthermore, we also found that water clusters encourage the self-assembly of PA helical structures in the tube. This molecular model may lead to a better understanding of the formation of a double helix biological molecule inside SWNTs. Alternatively, it could form the basis of a novel nanoscale material by utilizing the 'empty' spaces of SWNTs.

  12. Self-Assembled Magnetic Surface Swimmers: Theoretical Model

    Science.gov (United States)

    Aranson, Igor; Belkin, Maxim; Snezhko, Alexey

    2009-03-01

    The mechanisms of self-propulsion of living microorganisms are a fascinating phenomenon attracting enormous attention in the physics community. A new type of self-assembled micro-swimmers, magnetic snakes, is an excellent tool to model locomotion in a simple table-top experiment. The snakes self-assemble from a dispersion of magnetic microparticles suspended on the liquid-air interface and subjected to an alternating magnetic field. Formation and dynamics of these swimmers are captured in the framework of theoretical model coupling paradigm equation for the amplitude of surface waves, conservation law for the density of particles, and the Navier-Stokes equation for hydrodynamic flows. The results of continuum modeling are supported by hybrid molecular dynamics simulations of magnetic particles floating on the surface of fluid.

  13. 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...

  14. Self-reproduction of nanoparticles through synergistic self-assembly.

    Science.gov (United States)

    Ikeda, Keisuke; Nakano, Minoru

    2015-01-01

    We describe a self-reproduction mechanism of nanometer-sized particles (i.e., nanodiscs) through chemical ligation of the precursors and self-assembly of the building blocks. The ligation reaction was accelerated on lipid bilayer surfaces, and the products spontaneously assembled into nanodiscs with lipid molecules. With the increase in the number of nanodiscs, a rapid proliferation of the nanodiscs occurred through the spatial rearrangements of the molecules between the pre-existing nanodiscs and the unreacted materials, rather than template- or complex-enhanced ligation of the precursors. The subsequent process of surface-enhanced ligation of integrated precursors matured the nanoparticles into identical copies of the pre-existing assembly. Our study showed that the synergistic self-assembly mechanism probably underlie the self-replication principles for heterogeneous multimolecular systems.

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

    Science.gov (United States)

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

    2015-08-12

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

  16. Biomolecular decision-making process for self assembly.

    Energy Technology Data Exchange (ETDEWEB)

    Osbourn, Gordon Cecil

    2005-01-01

    The brain is often identified with decision-making processes in the biological world. In fact, single cells, single macromolecules (proteins) and populations of molecules also make simple decisions. These decision processes are essential to survival and to the biological self-assembly and self-repair processes that we seek to emulate. How do these tiny systems make effective decisions? How do they make decisions in concert with a cooperative network of other molecules or cells? How can we emulate the decision-making behaviors of small-scale biological systems to program and self-assemble microsystems? This LDRD supported research to answer these questions. Our work included modeling and simulation of protein populations to help us understand, mimic, and categorize molecular decision-making mechanisms that nonequilibrium systems can exhibit. This work is an early step towards mimicking such nanoscale and microscale biomolecular decision-making processes in inorganic systems.

  17. The collagen assisted self-assembly of silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Salhi, Billel; Vaurette, Francois; Grandidier, Bruno; Stievenard, Didier [IEMN, UMR8520, Department ISEN, 41 Boulevard Vauban, 59046 Lille Cedex (France); Melnyk, Oleg [IBL, UMR8161, Institut Pasteur de Lille, Universite de Lille Nord de France, 1 rue du Professeur Calmette, 59021 Lille (France); Coffinier, Yannick; Boukherroub, Rabah [IRI, USR3078, c/o IEMN, Cite Scientifique, BP60069, 59652 Villeneuve d' Ascq (France)], E-mail: didier.stievenard@isen.iemn.univ-lille1.fr

    2009-06-10

    The paper reports on self-assembly of silicon nanowire junctions assisted by protocollagen, a low cost soluble long fiber protein and precursor of collagen fibrils. First, the collagen was combed on an octadecyl-terminated silicon surface with gold electrodes. Then the combed surface was exposed to an aqueous suspension of silicon nanowires. In order to increase electrostatic interactions between the positively charged collagen and the nanowires, the nanowires were chemically modified with negatively charged sulfonate groups. The interaction of collagen with the sulfonated nanowires, which mimics the native collagen/heparin sulfate interaction, induced self-assembly of the nanowires localized between gold electrodes. The proof of concept for the formation of spontaneous electrode-nanowire-electrode junctions using collagen as a template was supported by current-voltage measurements.

  18. Stable doping of carbon nanotubes via molecular self assembly

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.; Chen, Y.; Podzorov, V., E-mail: podzorov@physics.rutgers.edu [Department of Physics and Institute for Advanced Materials and Devices for Nanotechnology, Rutgers University, New Jersey 08854 (United States); Cook, A.; Zakhidov, A. [Department of Physics and NanoTech Institute, University of Texas at Dallas, Richardson, Texas 75083 (United States)

    2014-10-14

    We report a novel method for stable doping of carbon nanotubes (CNT) based on methods of molecular self assembly. A conformal growth of a self-assembled monolayer of fluoroalkyl trichloro-silane (FTS) at CNT surfaces results in a strong increase of the sheet conductivity of CNT electrodes by 60–300%, depending on the CNT chirality and composition. The charge carrier mobility of undoped partially aligned CNT films was independently estimated in a field-effect transistor geometry (~100 cm²V⁻¹s⁻¹). The hole density induced by the FTS monolayer in CNT sheets is estimated to be ~1.8 ×10¹⁴cm⁻². We also show that FTS doping of CNT anodes greatly improves the performance of organic solar cells. This large and stable doping effect, easily achieved in large-area samples, makes this approach very attractive for applications of CNTs in transparent and flexible electronics.

  19. Self-Assembled Monolayer of Mixed Gold and Nickel Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Yanni Jie; Huiqing Fan; Wei You

    2012-01-01

    Forming a monolayer of mixed nickel and gold nanoparticles through self-assembly via simple solu-tion processing constitutes an important step toward inexpensive nanoparticle-based carbon nanofiber growth. In this work, mixed gold and nickel nanoparticles were anchored on the silicon wafer using self-assembled monolayers (SAMs) as a template. SAMs of 3-mercaptopropyl trimethoxysilane (MPTS-SAMs) were formed on silicon wafer, with the exposed thiol functionality providing ligand exchange sites to form the mixed mono-layer of nickel and gold nanoparticles via a two-step sequential soaking approach. The densities of the nickel and gold nanoparticles on the surface can be varied by adjusting the soaking sequence.

  20. Self Assembled Structures by Directional Solidification of Eutectics

    Science.gov (United States)

    Dynys, Frederick W.; Sayir, Ali

    2004-01-01

    Interest in ordered porous structures has grown because of there unique properties such as photonic bandgaps, high backing packing density and high surface to volume ratio. Inspired by nature, biometric strategies using self assembled organic molecules dominate the development of hierarchical inorganic structures. Directional solidification of eutectics (DSE) also exhibit self assembly characteristics to form hierarchical metallic and inorganic structures. Crystallization of diphasic materials by DSE can produce two dimensional ordered structures consisting of rods or lamella. By selective removal of phases, DSE is capable to fabricate ordered pore arrays or ordered pin arrays. Criteria and limitations to fabricate hierarchical structures will be presented. Porous structures in silicon base alloys and ceramic systems will be reported.

  1. Communication: Self-assembly of semiflexible-flexible block copolymers

    Science.gov (United States)

    Kumar, N. Arun; Ganesan, Venkat

    2012-03-01

    We apply the methodology of self-consistent Brownian dynamics simulations to study the self-assembly behavior in melts of semiflexible-flexible diblock copolymers as a function of the persistence length of the semiflexible block. Our results reveal a novel progression of morphologies in transitioning from the case of flexible-coil to rod-coil copolymers. At even moderate persistence lengths, the morphologies in the semiflexible-block rich region of the phase diagram transform to liquid crystalline phases. In contrast, the phases in the flexible-block rich region of the phase diagram persist up to much larger persistence lengths. Our analysis suggests that the development of orientational order in the semiflexible block to be a critical factor influencing the morphologies of self-assembly.

  2. Self-assembly of semiflexible-flexible block copolymers

    Science.gov (United States)

    Kumar, Arun; Ganesan, Venkat

    2012-02-01

    We apply self-consistent Brownian dynamics simulations to study the self-assembly behavior of semiflexible-flexible block copolymers. A Maier-Saupe interaction model was applied for the orientational interactions between the semiflexible polymers, while the enthalpic interactions between semiflexible and flexible polymers were modeled through a standard Flory-Huggins approach. To develop a physical understanding of the phases and their regimes of occurrence as a function of varying persistence length of the semiflexible block, we computed the 2D phase diagram for our model. We quantify the progression of the self-assembly morphologies in transitioning from coil-coil block copolymers on the one hand to rod-coil block copolymers on the other hand. The results obtained are in qualitative agreement with the existing experimental and numerical results.

  3. Design of Self-Assembling Protein-Polymer Conjugates.

    Science.gov (United States)

    Carter, Nathan A; Geng, Xi; Grove, Tijana Z

    Protein-polymer conjugates are of particular interest for nanobiotechnology applications because of the various and complementary roles that each component may play in composite hybrid-materials. This chapter focuses on the design principles and applications of self-assembling protein-polymer conjugate materials. We address the general design methodology, from both synthetic and genetic perspective, conjugation strategies, protein vs. polymer driven self-assembly and finally, emerging applications for conjugate materials. By marrying proteins and polymers into conjugated bio-hybrid materials, materials scientists, chemists, and biologists alike, have at their fingertips a vast toolkit for material design. These inherently hierarchical structures give rise to useful patterning, mechanical and transport properties that may help realize new, more efficient materials for energy generation, catalysis, nanorobots, etc.

  4. Self-Assembly and Hydrogelation of Peptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Wahyudi Priyono Suwarso

    2012-04-01

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

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

    Science.gov (United States)

    Barry, Rachael; Gitai, Zemer

    2011-01-01

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

  6. Advances in self-assembled ultrathin polyoxomolybdates multilayers

    Institute of Scientific and Technical Information of China (English)

    Liang-bao YANG; Xiu-fang WANG; An-jian XIE; Gang HU; Yu-bua SHEN

    2009-01-01

    The research on the assembly and function of organized molecular films has gained more and more interest. Electrostatic interactions can be employed to assemble polyoxomolybdates in surface confined multi-layers. Ultrathin multilayer films of polyoxomolybdates and organic molecules by the self-assembly method have been reviewed. At the same time, self-assemblies in aqueous solution are also reported, such as wheel-shaped clusters (Mo154), hollow spherical "blackberry"-like vesicles (Mo72Fe30) and Keggin structures. Polyoxomo-lybdate multilayers are promising candidates for diverse applications including electrocatalytic, photo- and electro-chromic systems. The development in this particular field of materials science may be highlighted in the future.

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

    Directory of Open Access Journals (Sweden)

    Chandrashekhar V. Kulkarni

    2016-10-01

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

  8. An information-bearing seed for nucleating algorithmic self-assembly.

    Science.gov (United States)

    Barish, Robert D; Schulman, Rebecca; Rothemund, Paul W K; Winfree, Erik

    2009-04-14

    Self-assembly creates natural mineral, chemical, and biological structures of great complexity. Often, the same starting materials have the potential to form an infinite variety of distinct structures; information in a seed molecule can determine which form is grown as well as where and when. These phenomena can be exploited to program the growth of complex supramolecular structures, as demonstrated by the algorithmic self-assembly of DNA tiles. However, the lack of effective seeds has limited the reliability and yield of algorithmic crystals. Here, we present a programmable DNA origami seed that can display up to 32 distinct binding sites and demonstrate the use of seeds to nucleate three types of algorithmic crystals. In the simplest case, the starting materials are a set of tiles that can form crystalline ribbons of any width; the seed directs assembly of a chosen width with >90% yield. Increased structural diversity is obtained by using tiles that copy a binary string from layer to layer; the seed specifies the initial string and triggers growth under near-optimal conditions where the bit copying error rate is complexity is achieved by using tiles that generate a binary counting pattern; the seed specifies the initial value for the counter. Self-assembly proceeds in a one-pot annealing reaction involving up to 300 DNA strands containing >17 kb of sequence information. In sum, this work demonstrates how DNA origami seeds enable the easy, high-yield, low-error-rate growth of algorithmic crystals as a route toward programmable bottom-up fabrication.

  9. Controlling guest-host interactions in self-assembled materials

    Science.gov (United States)

    Steinbeck, Christian Alexander

    Aqueous solutions of self-assembling macromolecules can be found in many industrial formulations, as well as in many living organisms. Regardless of the specific system, the self-assembling macromolecules are rarely found in the absence of other solutes or guest species. Such components may include fragrance molecules incorporated into block-copolymer micelles for use in detergents, dyes included in micellar precursor solutions for the synthesis of mesostructured silica-block copolymer composites, or specifically designed additives for controlling protein folding and activity. A detailed understanding of the structures and dynamic molecular interactions among the various species in solution and their influences on macromolecule aggregation and phase behaviors is of paramount importance for designing systems with improved properties and performance. Unambiguous measurements of the loci of interaction and solubilization of small molecule species (e.g., dyes or surfactants) within self-assembling block-copolymer species or proteins in aqueous solutions have been established. This has been achieved by exploiting powerful correlative multidimensional nuclear magnetic resonance (NMR) spectroscopy techniques, including pulsed-field-gradient diffusion measurements, which provide detailed molecular insights into a variety of heterogeneous self-assembled systems. Furthermore, these insights and measurements enable the solution conditions to be established that permit the control and release of such guest molecules from association with macromolecular carrier species into the surrounding solution. Specifically, the use of temperature to control the distribution of porphyrin guest-species in a block-copolymer host and the light-dependent folding and unfolding of bovine serum albumin through varying interactions with an azo-benzene functionalized surfactant are demonstrated. In the absence of long-range order in these complex systems, advanced NMR spectroscopy methods provide

  10. Hydrophobic Interactions Modulate Self-Assembly of Nanoparticles

    OpenAIRE

    Sánchez-Iglesias, Ana; Grzelczak, Marek; Altantzis, Thomas; Goris, Bart; Pérez-Juste, Jorge; Bals, Sara; Van Tendeloo, Gustaaf; Donaldson, Stephen H.; Chmelka, Bradley F.; Israelachvili, Jacob N.; Liz-Marzán, Luis M.

    2012-01-01

    Abstract: Hydrophobic interactions constitute one of the most important types of nonspecific interactions in biological systems, which emerge when water molecules rearrange as two hydrophobic species come close to each other. The prediction of hydrophobic interactions at the level of nanoparticles (Brownian objects) remains challenging because of uncontrolled diffusive motion of the particles. We describe here a general methodology for solvent-induced, reversible self-assembly of gold nanopar...

  11. Coherence and dephasing in self-assembled quantum dots

    DEFF Research Database (Denmark)

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

    2003-01-01

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

  12. Self-Assembling Protein Materials for Metal Nanoparticle Templation

    Science.gov (United States)

    2015-05-01

    ion trap formed by a ring of conserved glutamines, which has been shown to bind chlorine ,119 all-trans-retinol, vitamin D3,95 as well as several fatty...helical Pre-fabricated Au-TAsp NPs featuring thiol ligands, a tetra( ethylene glycol) segment, and a dianionic aspartate Increased from 10.2...hydrophobic helical peptide combined with a hydrophilic poly( ethylene glycol) unit to create an amphiphilic block copolymer that self-assembled into a

  13. 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

  14. Monodisperse magnesium hydride nanoparticles uniformly self-assembled on graphene.

    Science.gov (United States)

    Xia, Guanglin; Tan, Yingbin; Chen, Xiaowei; Sun, Dalin; Guo, Zaiping; Liu, Huakun; Ouyang, Liuzhang; Zhu, Min; Yu, Xuebin

    2015-10-21

    Monodisperse MgH2 nanoparticles with homogeneous distribution and a high loading percent are developed through hydrogenation-induced self-assembly under the structure-directing role of graphene. Graphene acts not only as a structural support, but also as a space barrier to prevent the growth of MgH2 nanoparticles and as a thermally conductive pathway, leading to outstanding performance.

  15. SELF-ASSEMBLING AMPHIPHILIC POLYELECTROLYTES AND THEIR NANOSTRUCTURES

    Institute of Scientific and Technical Information of China (English)

    Yotaro Morishima

    2000-01-01

    The self-assembling behavior of random copolymers of sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS)and hydrophobic comonomers possessing dodecyl groups linked by various spacer bonds was discussed with a focus on the effect of the spacer. The characterization of association behavior of such polymers in water using quasielastic light scattering,capillary electrophoresis, NMR relaxation, various fluorescence, and viscoelastic methods was described. These copolymers form a variety of self-assembled nanostructures depending on the type of the spacer. Random copolymers of AMPS and Ndodecylmethacrylamide show a strong preference for intrapolymer self-association even in concentrated aqueous solutions forming single-macromolecular self-assemblies (unimolecular micelles). In contrast, random copolymers of AMPS and dodecyl methacrylate are prone to undergo interpolymer associations yielding multipolymer micelles. In random copolymers of AMPS and a methacrylate substituted a nonionic surfactant (HO(CH2CH2O)25C12H25) (C12E25), dodecyl groups are much less restricted by the polymer backbone because they are linked via a long, flexible hydrophilic spacer. Thus, the polymerbound C12E25 surfactant moieties form micelles similar to those formed by discrete surfactants, but they are bridged by polymer chains forming a network structure.

  16. Three dimensional self-assembly at the nanoscale

    Science.gov (United States)

    Gracias, D. H.

    2013-05-01

    At the nanoscale, three dimensional manipulation and assembly becomes extremely challenging and also cost prohibitive. Self-assembly provides an attractive and possibly the only highly parallel methodology to structure truly three dimensional patterned materials and devices at this size scale for applications in electronics, optics, robotics and medicine. This is a concise review along with a perspective of an important and exciting field in nanotechnology and is related to a Nanoengineering Pioneer Award that I received at this SPIE symposium for my contributions to the 3D selfassembly of nanostructures. I detail a historical account of 3D self-assembly and outline important developments in this area which is put into context with the larger research areas of 3D nanofabrication, assembly and nanomanufacturing. A focus in this review is on our work as it relates to the self-assembly with lithographically patterned units; this approach provides a means for heterogeneous integration of periodic, curved and angled nanostructures with precisely defined three dimensional patterns.

  17. Simulation Methods for Self-Assembled Polymers and Rings

    Science.gov (United States)

    Kindt, James T.

    2003-11-01

    New off-lattice grand canonical Monte Carlo simulation methods have been developed and used to model the equilibrium structure and phase diagrams of equilibrium polymers and rings. A scheme called Polydisperse Insertion, Removal, and Resizing (PDIRR) is used to accelerate the equilibration of the size distribution of self-assembled aggregates. This method allows the insertion or removal of aggregates (e.g., chains) containing an arbitrary number of monomers in a single Monte Carlo move, or the re-sizing of an existing aggregate. For the equilibrium polymer model under semi-dilute conditions, a several-fold increase in equilibration rate compared with single-monomer moves is observed, facilitating the study of the isotropic-nematic transition of semiflexible, self-assembled chains. Combined with the pivot-coupled GCMC method for ring simulation, the PDIRR approach also allows the phenomenological simulation of a polydisperse equilibrium phase of rings, 2-dimensional fluid domains, or flat self-assembled disks in three dimensions.

  18. Dynamic self-assembly and control of microfluidic particle crystals

    Science.gov (United States)

    Lee, Wonhee; Amini, Hamed; Stone, Howard A.; Di Carlo, Dino

    2010-01-01

    Engineered two-phase microfluidic systems have recently shown promise for computation, encryption, and biological processing. For many of these systems, complex control of dispersed-phase frequency and switching is enabled by nonlinearities associated with interfacial stresses. Introducing nonlinearity associated with fluid inertia has recently been identified as an easy to implement strategy to control two-phase (solid-liquid) microscale flows. By taking advantage of inertial effects we demonstrate controllable self-assembling particle systems, uncover dynamics suggesting a unique mechanism of dynamic self-assembly, and establish a framework for engineering microfluidic structures with the possibility of spatial frequency filtering. Focusing on the dynamics of the particle–particle interactions reveals a mechanism for the dynamic self-assembly process; inertial lift forces and a parabolic flow field act together to stabilize interparticle spacings that otherwise would diverge to infinity due to viscous disturbance flows. The interplay of the repulsive viscous interaction and inertial lift also allow us to design and implement microfluidic structures that irreversibly change interparticle spacing, similar to a low-pass filter. Although often not considered at the microscale, nonlinearity due to inertia can provide a platform for high-throughput passive control of particle positions in all directions, which will be useful for applications in flow cytometry, tissue engineering, and metamaterial synthesis. PMID:21149674

  19. Epitaxial photostriction-magnetostriction coupled self-assembled nanostructures.

    Science.gov (United States)

    Liu, Heng-Jui; Chen, Long-Yi; He, Qing; Liang, Chen-Wei; Chen, Yu-Ze; Chien, Yung-Shun; Hsieh, Ying-Hui; Lin, Su-Jien; Arenholz, Elke; Luo, Chih-Wei; Chueh, Yu-Lun; Chen, Yi-Chun; Chu, Ying-Hao

    2012-08-28

    Self-assembled vertical nanostructures take advantage of high interface-to-volume ratio and can be used to design new functionalities by the choice of a proper combination of constituents. However, most of the studies to date have emphasized the functional controllability of the nanostructures using external electric or magnetic fields. In this study, to introduce light (or photons) as an external control parameter in a self-assembled nanostructure system, we have successfully synthesized oxide nanostructures with CoFe(2)O(4) nanopillars embedded in a SrRuO(3) matrix. The combination of photostrictive SrRuO(3) and magnetostrictive CoFe(2)O(4) in the intimately assembled nanostructures leads to a light-induced, ultrafast change in magnetization of the CoFe(2)O(4) nanopillars. Our work demonstrates a novel concept on oxide nanostructure design and opens an alternative pathway for the explorations of diverse functionalities in heteroepitaxial self-assembled oxide nanostructures.

  20. Directed self-assembly of a colloidal kagome lattice.

    Science.gov (United States)

    Chen, Qian; Bae, Sung Chul; Granick, Steve

    2011-01-20

    A challenging goal in materials chemistry and physics is spontaneously to form intended superstructures from designed building blocks. In fields such as crystal engineering and the design of porous materials, this typically involves building blocks of organic molecules, sometimes operating together with metallic ions or clusters. The translation of such ideas to nanoparticles and colloidal-sized building blocks would potentially open doors to new materials and new properties, but the pathways to achieve this goal are still undetermined. Here we show how colloidal spheres can be induced to self-assemble into a complex predetermined colloidal crystal-in this case a colloidal kagome lattice-through decoration of their surfaces with a simple pattern of hydrophobic domains. The building blocks are simple micrometre-sized spheres with interactions (electrostatic repulsion in the middle, hydrophobic attraction at the poles, which we call 'triblock Janus') that are also simple, but the self-assembly of the spheres into an open kagome structure contrasts with previously known close-packed periodic arrangements of spheres. This open network is of interest for several theoretical reasons. With a view to possible enhanced functionality, the resulting lattice structure possesses two families of pores, one that is hydrophobic on the rims of the pores and another that is hydrophilic. This strategy of 'convergent' self-assembly from easily fabricated colloidal building blocks encodes the target supracolloidal architecture, not in localized attractive spots but instead in large redundantly attractive regions, and can be extended to form other supracolloidal networks.

  1. Highly conductive self-assembled nanoribbons of coordination polymers.

    Science.gov (United States)

    Welte, Lorena; Calzolari, Arrigo; Di Felice, Rosa; Zamora, Felix; Gómez-Herrero, Julio

    2010-02-01

    Organic molecules can self-assemble into well-ordered structures, but the conductance of these structures is limited, which is a disadvantage for applications in molecular electronics. Conductivity can be improved by using coordination polymers-in which metal centres are incorporated into a molecular backbone-and such structures have been used as molecular wires by self-assembling them into ordered films on metal surfaces. Here, we report electrically conductive nanoribbons of the coordination polymer [Pt(2)I(S(2)CCH(3))(4)](n) self-assembled on an insulating substrate by direct sublimation of polymer crystals. Conductance atomic force microscopy is used to probe the electrical characteristics of a few polymer chains ( approximately 10) within the nanoribbons. The observed currents exceed those previously sustained in organic and metal-organic molecules assembled on surfaces by several orders of magnitude and over much longer distances. These results, and the results of theoretical calculations based on density functional theory, confirm coordination polymers as candidate materials for applications in molecular electronics.

  2. Synthesis and self-assembly of glycal-based bolaforms.

    Science.gov (United States)

    Bozell, Joseph J; Tice, Nathan C; Sanyal, Nibedita; Thompson, David; Kim, Jong-Mok; Vidal, Sébastien

    2008-11-21

    Glycal-based bolaforms serve as synthetically flexible components of molecular self-assembly. The compounds are prepared in good yield by a Ferrier reaction between triacetylglucal or -galactal or diacetylxylal and a long chain alpha,omega-diol, followed by deacetylation under Zemplen conditions. The reactions are stereoselective and preferentially afford the alpha-diastereomer. The bolaforms undergo self-assembly in water or water/dioxane solution to give a variety of nanostructures. In solution, bolaforms with C8 or C10 chains between glucal headgroups form nanoscale vesicles. In contrast, bolaforms with C12 chains exhibit lower solubility and a dynamic self-assembly, forming several different nanoscale structures. However, the solid-state structures of C12 bolaform isomers adopt shapes very similar to those of bolaforms possessing more extensive hydrogen-bonding networks, indicating that multiple hydrogen bonds in solution are important to formation of stable, discrete nanostructures but that only a few key intermolecular interactions between bolaform headgroups are necessary to determine the structure in the solid state. The diversity and differentiation of the functional groups present in glycal-based bolaforms suggest that they could be useful probes of the various noncovalent forces controlling the structure of new nanomaterials.

  3. Probabilistic inverse design for self-assembling materials

    Science.gov (United States)

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

    2017-05-01

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

  4. Algorithmic self-assembly of DNA Sierpinski triangles.

    Directory of Open Access Journals (Sweden)

    Paul W K Rothemund

    2004-12-01

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

  5. 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.

  6. Nucleation of apatite crystals in vitro by self-assembled dentin matrix protein 1

    Science.gov (United States)

    He, Gen; Dahl, Tom; Veis, Arthur; George, Anne

    2003-08-01

    Bones and teeth are biocomposites that require controlled mineral deposition during their self-assembly to form tissues with unique mechanical properties. Acidic extracellular matrix proteins play a pivotal role during biomineral formation. However, the mechanisms of protein-mediated mineral initiation are far from understood. Here we report that dentin matrix protein 1 (DMP1), an acidic protein, can nucleate the formation of hydroxyapatite in vitro in a multistep process that begins by DMP1 binding calcium ions and initiating mineral deposition. The nucleated amorphous calcium phosphate precipitates ripen and nanocrystals form. Subsequently, these expand and coalesce into microscale crystals elongated in the c-axis direction. Characterization of the functional domains in DMP1 demonstrated that intermolecular assembly of acidic clusters into a β-sheet template was essential for the observed mineral nucleation. Protein-mediated initiation of nanocrystals, as discussed here, might provide a new methodology for constructing nanoscale composites by self-assembly of polypeptides with tailor-made peptide sequences.

  7. Simulation of macromolecule self-assembly in solution: A multiscale approach

    Energy Technology Data Exchange (ETDEWEB)

    Lavino, Alessio D., E-mail: alessiodomenico.lavino@studenti.polito.it; Barresi, Antonello A., E-mail: antonello.barresi@polito.it; Marchisio, Daniele L., E-mail: daniele.marchisio@polito.it [Dipartimento di Scienza Applicata e Tecnologia, Istituto di Ingegneria Chimica, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Pasquale, Nicodemo di, E-mail: nicodemo.dipasquale@manchester.ac.uk [School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UnitedKingdom (United Kingdom); Carbone, Paola, E-mail: paola.carbone@manchester.ac.uk [School of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester M13 9PL, UnitedKingdom (United Kingdom)

    2015-12-17

    One of the most common processes to produce polymer nanoparticles is to induce self-assembly by using the solvent-displacement method, in which the polymer is dissolved in a “good” solvent and the solution is then mixed with an “anti-solvent”. The polymer ability to self-assemble in solution is therefore determined by its structural and transport properties in solutions of the pure solvents and at the intermediate compositions. In this work, we focus on poly-ε-caprolactone (PCL) which is a biocompatible polymer that finds widespread application in the pharmaceutical and biomedical fields, performing simulation at three different scales using three different computational tools: full atomistic molecular dynamics (MD), population balance modeling (PBM) and computational fluid dynamics (CFD). Simulations consider PCL chains of different molecular weight in solution of pure acetone (good solvent), of pure water (anti-solvent) and their mixtures, and mixing at different rates and initial concentrations in a confined impinging jets mixer (CIJM). Our MD simulations reveal that the nano-structuring of one of the solvents in the mixture leads to an unexpected identical polymer structure irrespectively of the concentration of the two solvents. In particular, although in pure solvents the behavior of the polymer is, as expected, very different, at intermediate compositions, the PCL chain shows properties very similar to those found in pure acetone as a result of the clustering of the acetone molecules in the vicinity of the polymer chain. We derive an analytical expression to predict the polymer structural properties in solution at different solvent compositions and use it to formulate an aggregation kernel to describe the self-assembly in the CIJM via PBM and CFD. Simulations are eventually validated against experiments.

  8. Spontaneous luminescence of Eu3+ ions in porous Y2O3 nanospheres

    Science.gov (United States)

    Zaitsev, S. V.; Ermolaeva, Yu. V.; Matveevskaya, N. A.; Zver'kova, I. I.; Tolmachev, A. V.

    2017-06-01

    A study of the luminescence of Eu3+ ions in Y2O3 nanospheres indicates a significant influence of the porous structure of nanoparticles on the luminescence of dopant ions. It is shown that filling the nanopores of initially porous Y2O3 nanospheres shortens the decay time of the spontaneous luminescence of doping europium ions. The change in the decay time is associated with the change in the effective refractive index of the porous nanospheres.

  9. Design technology co-optimization assessment for directed self-assembly-based lithography: design for directed self-assembly or directed self-assembly for design?

    Science.gov (United States)

    Lai, Kafai; Liu, Chi-Chun; Tsai, Hsinyu; Xu, Yongan; Chi, Cheng; Raghunathan, Ananthan; Dhagat, Parul; Hu, Lin; Park, Oseo; Jung, Sunggon; Cho, Wooyong; Morillo, Jaime; Pitera, Jed; Schmidt, Kristin; Guillorn, Mike; Brink, Markus; Sanders, Daniel; Felix, Nelson; Bailey, Todd; Colburn, Matthew

    2017-01-01

    We report a systematic study of the feasibility of using directed self-assembly (DSA) in real product design for 7-nm fin field effect transistor (FinFET) technology. We illustrate a design technology co-optimization (DTCO) methodology and two test cases applying both line/space type and via/cut type DSA processes. We cover the parts of DSA process flow and critical design constructs as well as a full chip capable computational lithography framework for DSA. By co-optimizing all process flow and product design constructs in a holistic way using a computational DTCO flow, we point out the feasibility of manufacturing using DSA in an advanced FinFET technology node and highlight the issues in the whole DSA ecosystem before we insert DSA into manufacturing.

  10. Self-assembled multicompartment liquid crystalline lipid carriers for protein, peptide, and nucleic acid drug delivery.

    Science.gov (United States)

    Angelova, Angelina; Angelov, Borislav; Mutafchieva, Rada; Lesieur, Sylviane; Couvreur, Patrick

    2011-02-15

    Lipids and lipopolymers self-assembled into biocompatible nano- and mesostructured functional materials offer many potential applications in medicine and diagnostics. In this Account, we demonstrate how high-resolution structural investigations of bicontinuous cubic templates made from lyotropic thermosensitive liquid-crystalline (LC) materials have initiated the development of innovative lipidopolymeric self-assembled nanocarriers. Such structures have tunable nanochannel sizes, morphologies, and hierarchical inner organizations and provide potential vehicles for the predictable loading and release of therapeutic proteins, peptides, or nucleic acids. This Account shows that structural studies of swelling of bicontinuous cubic lipid/water phases are essential for overcoming the nanoscale constraints for encapsulation of large therapeutic molecules in multicompartment lipid carriers. For the systems described here, we have employed time-resolved small-angle X-ray scattering (SAXS) and high-resolution freeze-fracture electronic microscopy (FF-EM) to study the morphology and the dynamic topological transitions of these nanostructured multicomponent amphiphilic assemblies. Quasi-elastic light scattering and circular dichroism spectroscopy can provide additional information at the nanoscale about the behavior of lipid/protein self-assemblies under conditions that approximate physiological hydration. We wanted to generalize these findings to control the stability and the hydration of the water nanochannels in liquid-crystalline lipid nanovehicles and confine therapeutic biomolecules within these structures. Therefore we analyzed the influence of amphiphilic and soluble additives (e.g. poly(ethylene glycol)monooleate (MO-PEG), octyl glucoside (OG), proteins) on the nanochannels' size in a diamond (D)-type bicontinuous cubic phase of the lipid glycerol monooleate (MO). At body temperature, we can stabilize long-living swollen states, corresponding to a diamond cubic phase

  11. Tobacco mosaic virus adsorption on self-assembled and Langmuir–Blodgett monolayers studied by TIRF and SFM

    OpenAIRE

    Britt, David W.; Buijs, Jos; Hlady, V.

    1998-01-01

    The adsorption of tobacco mosaic virus (TMV) on self-assembled and Langmuir–Blodgett monolayers was investigated using total internal reflection fluorescence (TIRF) spectroscopy and scanning force microscopy (SFM). Substrates were chosen to probe electrostatic, hydrophobic and surface fluidity effects on TMV adsorption. Positively charged and hydrophobic surfaces demonstrated similar initial rates of TMV adsorption; however, their respective surface TMV coverages differed greatly. Likewise, p...

  12. Self-assembly of amphiphilic molecules in organic liquids

    Science.gov (United States)

    Tung, Shih-Huang

    2007-12-01

    Amphiphilic molecules are well-known for their ability to self-assemble in water to form structures such as micelles and vesicles. In comparison, much less is known about amphiphilic self-assembly in nonpolar organic liquids. Such "reverse" self assembly can produce many of the counterparts to structures found in water. In this dissertation, we focus on the formation and dynamics of such reverse structures. We seek to obtain fundamental insight into the driving forces for reverse self-assembly processes. Three specific types of reverse structures are studied: (a) reverse wormlike micelles, i.e., long, flexible micellar chains; (b) reverse vesicles, i.e., hollow containers enclosed by reverse bilayers; and (c) organogel networks. While our focus is on the fundamentals, we note that reverse structures can be useful in a variety of applications ranging from drug delivery, controlled release, hosts for enzymatic reactions, and templates for nanomaterials synthesis. In the first part of this study, we describe a new route for forming reverse wormlike micelles in nonpolar organic liquids. This route involves the addition of trace amounts of a bile salt to solutions of the phospholipid, lecithin. We show that bile salts, due to their unique "facially amphiphilic" structure, can promote the aggregation of lecithin molecules into these reverse micellar chains. The resulting samples are viscoelastic and show interesting rheological properties. Unusual trends are seen in the temperature dependence of their rheology, which indicates the importance of hydrogen-bonding interactions in the formation of these micelles. Another remarkable feature of their rheology is the presence of strain-stiffening, where the material becomes stiffer at high deformations. Strain-stiffening has been seen before for elastic gels of biopolymers; here, we demonstrate the same properties for viscoelastic micellar solutions. The second reverse aggregate we deal with is the reverse vesicle. We present a

  13. Self-assembly behaviour of hetero-nuclear Janus dumbbells.

    Science.gov (United States)

    O'Toole, Patrick; Munaò, Gianmarco; Giacometti, Achille; Hudson, Toby S

    2017-09-05

    We investigate the fluid structure and self-assembly of a system of Janus dumbbells by means of aggregation-volume-bias Monte Carlo simulations and Simulated Annealing techniques. In our approach, Janus dumbbells model asymmetric colloidal particles constituted by two tangent (touching) spheres (labelled as h and s) of different sizes and interaction properties: specifically, the h spheres interact with all other spheres belonging to different dumbbells via hard-sphere potentials, whereas two s spheres interact via a square-well potential. By introducing a parameter α ∈ [0,2] that controls the size ratio between the h and s spheres, we are able to investigate the overall phase behaviour of Janus dumbbells as a function of α. In a previous paper (O'Toole et al., Soft Matter, 2017, 13, 803) we focused on the region where the s sphere is larger than the h sphere (α > 1), documenting the presence of a variety of phase behaviours. Here we investigate a different regime of size ratios, predominantly where the hard sphere is larger than (or comparable to) the attractive one. Under these conditions, we observe the onset of many different self-assembled super-structures. Depending on the specific value of α we document the presence of spherical clusters (micelles) progressively evolving into more exotic structures including platelets, filaments, networks and percolating fluids, sponge structures and lamellar phases. We find no evidence of a gas-liquid phase separation for α ≤ 1.1, since under these conditions it is pre-empted by the development of self-assembled phases.

  14. Self-Assembled Conjugated Polymer Nanometer Scale Devices

    Institute of Scientific and Technical Information of China (English)

    Wenping Hu; Hiroshi Nakashima; Keiichi Torimitsu; Yunqi Liu; Daoben Zhu

    2005-01-01

    @@ 1Introduction Nanometer scale devices, as the next generation devices of electronics, have got a worldwide attention and rapid development recently. Simultaneously, conjugated polymers have been applied in organic electronics successfully because of their outstanding electronic-photonic properties. However, as far as we know few reports have dealt with the fabrication of nanometer scale devices by using conjugated polymers, although the combination of nanometer scale devices and polymers will not only extend conjugated polymers to Nanoelectronics, but also excavate the behaviors of polymer molecules at nano-molecular level, such as the electron transport through polymer molecules. One reason for this case is due to the lack of rigidity for most polymers.It results in the failure to bridge them between electrodes or to stand on substrates, therefore, fails to be characterized by scanning probe microscopy. Another reason is that the non-functionalized end-group of most polymers is impossible to graft on substrates through chemical bonds. Here, we introduce a self-assembled conjugated polymer can be used to fabricate nanodevices by self-assembly. The conjugated polymer is a derivative of poly(p-phenyleneethynylene)s (PPE) with thioacetyl end groups (Fig. 1). In general, it is known that for self-assembling ideal nanojunctions the materials should possess: a) conductivity, b) rigidity (for wiring and bridging between electrodes), and c) connectivity (for covalent attachment to metallic or semiconductor solid surfaces). PPE provides good conductivity owing to its special π-conjugated configuration. It is also believed that in principle PPE molecules possess rigidity because of the presence of the triple bond in their molecules,which prevents the rotation of adjacent phenyl rings with respect to each other.

  15. Bottlebrush Polymers: Synthesis, Rheology, and Self-Assembly

    Science.gov (United States)

    Dalsin, Samuel J.

    Bottlebrush polymers are comb-like molecules with a high density of side chains grafted along a central backbone. Due to their unique conformational properties, bottlebrush polymers have become attractive candidates for developing new photonic bandgap materials, nanotubes and nanowires, or drug delivery vehicles, to name a few. This dissertation primarily investigates the rheological properties and self-assembly behavior of bottlebrush polymer molecules made using a variety of different polymerization routes. A considerable portion of the work is directed towards the linear rheology of model, polyolefin-based bottlebrush polymers with independently varied branch and backbone lengths. These studies demonstrate how the tight spacing between branch points effectively precludes backbone entanglement in the polymer melts, but it does not inhibit the formation of entanglements among the branched side chains. Furthermore, the relaxation profiles reveal transient scaling behavior in which the dynamics transition from Zimm-like to Rouse-like at increasing relaxation times. These results highlight the distinct conformational character of bottlebrushes at different length scales. The latter parts of this work report on the self-assembly behavior of bottlebrush diblock polymers composed of atactic polypropylene and polystyrene side chains. The diblock samples are analyzed using small-angle X-ray scattering and atomic force microscopy. Nearly all of the samples display strong segregation between the two blocks, owing to the large molar mass of typical bottlebrush polymers. Consequently, only one experimental sample displays an accessible order-disorder transition temperature. The strong segregation is also shown to affect the ability of large bottlebrush diblocks to readily achieve well-ordered nanostructures by self-assembly. Finally, results of the most symmetric (by volume fraction) diblock samples are compared with predictions of a newly developed self-consistent field

  16. Platelets self-assemble into porous nacre during freeze casting.

    Science.gov (United States)

    Hunger, Philipp M; Donius, Amalie E; Wegst, Ulrike G K

    2013-03-01

    Nacre possesses a remarkable combination of mechanical properties. Its high stiffness, strength and toughness are attributed to a highly aligned structure of aragonite platelets "glued" together by a small fraction (∼5vol%) of polymer; theoretically it can be described by a shear-lag model of staggered tensile elements between which loads are transferred via shear. Despite extensive research, it has not been possible yet to manufacture this aligned structure as a bulk material of considerable volume with a fast and easy production process. Particularly porous materials would benefit from enhanced wall material properties to compensate for performance loss due to their high porosity. An important application for such porous materials are tissue scaffolds for bone substitution. Bone, like nacre, exhibits excellent mechanical properties, particularly an exceptionally high toughness, because of its composite structure of hydroxyapatite platelets aligned in a ∼35vol% polymer matrix. Through the freeze casting process, which results in a fast and straightforward self-assembly of platelet-shaped particles during directional solidification, highly porous bulk materials with nacre-like cell walls can now be created. This porous nacre outperforms by a factor of 1.5-4 in terms of stiffness, strength and toughness materials that have the same amount of porosity but do not exhibit the nacre-like microarchitecture. The self-assembly process presented in this study thus has tremendous potential for the creation of highly porous, yet mechanically strong tissue scaffolds for low or medium load bearing bone substitute materials. Due to the versatility of the freeze casting process, materials with a self-assembled cell wall structure can be created from high-aspect ratio particles of all material classes. This enables material optimization for a great variety of applications such as impact protection, filtration, catalysis, energy generation and storage, in addition to those with

  17. Directed self-assembly defectivity assessment. Part II

    Science.gov (United States)

    Bencher, Chris; Yi, He; Zhou, Jessica; Cai, Manping; Smith, Jeffrey; Miao, Liyan; Montal, Ofir; Blitshtein, Shiran; Lavi, Alon; Dotan, Kfir; Dai, Huixiong; Cheng, Joy Y.; Sanders, Daniel P.; Tjio, Melia; Holmes, Steven

    2012-03-01

    The main concern for the commercialization of directed self-assembly (DSA) for semiconductor manufacturing continues to be the uncertainty in capability and control of defect density. Our research investigates the defect densities of various DSA process applications in the context of a 300mm wafer fab cleanroom environment; this paper expands substantially on the previously published DSA defectivity study by reporting a defect density process window relative to chemical epitaxial pre-pattern registration lines; as well as investigated DSA based contact hole shrinking and report critical dimension statistics for the phase separated polymers before and after etch, along with positional accuracy measurements and missing via defect density.

  18. Out of the cleanroom, self-assembled magnetic artificial cilia.

    Science.gov (United States)

    Wang, Ye; Gao, Yang; Wyss, Hans; Anderson, Patrick; den Toonder, Jaap

    2013-09-01

    Micro-sized hair-like structures, such as cilia, are abundant in nature and have various functionalities. Many efforts have been made to mimic the fluid pumping function of cilia, but most of the fabrication processes for these "artificial cilia" are tedious and expensive, hindering their practical application. In this paper a cost-effective in situ fabrication technique for artificial cilia is demonstrated. The cilia are constructed by self-assembly of micron sized magnetic beads and encapsulated with soft polymer coatings. Actuation of the cilia induces an effective fluid flow, and the cilia lengths and distribution can be adjusted by varying the magnetic bead concentration and fabrication parameters.

  19. Self-assembled antimicrobial and biocompatible copolymer films on titanium.

    Science.gov (United States)

    Pfaffenroth, Cornelia; Winkel, Andreas; Dempwolf, Wibke; Gamble, Lara J; Castner, David G; Stiesch, Meike; Menzel, Henning

    2011-11-10

    Copolymers of 4-vinyl-N-hexylpyridinium bromide and dimethyl(2-methacryloyloxyethyl) phosphonate self-assemble to form ultrathin layers on titanium surfaces that show antimicrobial activity, and biocompatibility. The copolymer layers are characterized by contact angle measurements, ellipsometry and XPS. Antibacterial activity is assessed by investigation of adherence of S. mutans. Biocompatibility is rated based on human gingival fibroblast adhesion and proliferation. By balancing the opposing effects of the chemical composition on biocompatibility and antimicrobial activity, copolymer coatings are fabricated that are able to inhibit the growth of S. mutans on the surface but still show attachment of gingival fibroblasts, and therefore might prevent biofilm formation on implants.

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

    Science.gov (United States)

    2015-05-15

    MONITORING AGENCY NAME(S) AND ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park , NC 27709-2211 DNA, nanoscience, self-assembly... themes of our other accomplishments: (1) proof of concept high-density optical memory, (2) a physical key based information assurance system, (3) a...provide defect tolerance by self‐organizing into irregular  topologies . In this scenario, simple static  routing algorithms based on regular physical

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

    Directory of Open Access Journals (Sweden)

    Kathrin Barbe

    2014-08-01

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

  2. Preparation and self-assembly of amphiphilic polylysine dendrons

    DEFF Research Database (Denmark)

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

    2016-01-01

    with alkyl chain lengths above C12 are ascribed to intermicellar aggregates stabilized by hydrophobic and electrostatic forces in accordance with the observed pH effect. Finally, the cytotoxicity of the dendrons was evaluated in mouse fibroblast (NIH/3T3) and human embryonic kidney (HEK 293T) cells at 5, 10...... 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...

  3. 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.

  4. Self-assembling peptide amphiphile nanostructures for cancer therapy

    Science.gov (United States)

    Soukasene, Stephen

    The application of nanotechnology to cancer therapy shows great promise for reducing the burden of the disease. By virtue of their size, nanoscale objects preferentially accumulate in tumor tissue through an enhanced permeability and retention (EPR) effect. However, to fully overcome the issues that limit current cancer treatments, viable nanostructures must also impart multifunctionality and be fully compatible with their biological surrounds. The self-assembling peptide amphiphile (PA) materials studied extensively in the Stupp Research Group form very biocompatible high aspect ratio nanostructures that meet these criteria. This thesis investigates the development of PA nanostructures designed to treat cancer. We first look to use the PA as a drug delivery vehicle by entrapping a small hydrophobic anti-cancer drug, camptothecin, in the core of the nanostructures. Using a solvent evaporation technique to load the drug into the PA nanofibers, we are able to improve the aqueous solubility of the molecule by nearly 30-fold. TEM and AFM studies show that entrapment of drug molecules does not disrupt the self-assembled morphology of the nanofiber. In vitro and in vivo studies are also conducted to demonstrate the bioactivity of the drug after its entrapment. As a potential platform for novel therapeutics, we next develop techniques for using light irradiation to trigger self-assembly inside the confined space of liposomes. We encapsulate PA monomers that assemble under acidic conditions along with a photoacid generator inside liposomes. Upon exposure to 254 nm light, the PA monomers self assemble inside the liposome to form nanostructures, which we observe through a quick freeze/deep etch technique that allows us to look inside the liposomes by SEM and TEM. Last of all, the development and discovery of epitopes for targeting PA nanostructures to tumors are explored. Using phage display technology we generate two groups of peptide sequences, one of which can potentially

  5. 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.

  6. Electrically addressing a single self-assembled quantum dot

    CERN Document Server

    Ellis, D J P; Atkinson, P; Ritchie, D A; Shields, A J

    2006-01-01

    We report on the use of an aperture in an aluminum oxide layer to restrict current injection into a single self-assembled InAs quantum dot, from an ensemble of such dots within a large mesa. The insulating aperture is formed through the wet-oxidation of a layer of AlAs. Under photoluminescence we observe that only one quantum dot in the ensemble exhibits a Stark shift, and that the same single dot is visible under electroluminescence. Autocorrelation measurements performed on the electroluminescence confirm that we are observing emission from a single quantum dot.

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

    DEFF Research Database (Denmark)

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

    2002-01-01

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

  8. 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-15

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

  12. 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.

  13. Understanding recognition and self-assembly in biology using the chemist's toolbox. Insight into medicinal chemistry.

    Science.gov (United States)

    Quirolo, Z B; Benedini, L A; Sequeira, M A; Herrera, M G; Veuthey, T V; Dodero, V I

    2014-01-01

    Medicinal chemistry is intimately connected with basic science such as organic synthesis, chemical biology and biophysical chemistry among other disciplines. The reason of such connections is due to the power of organic synthesis to provide designed molecules; chemical biology to give tools to discover biological and/or pathological pathways and biophysical chemistry which provides the techniques to characterize and the theoretical background to understand molecular behaviour. The present review provides some selective examples of these research areas. Initially, template dsDNA organic synthesis and the spatio-temporal control of transcription are presenting following by the supramolecular entities used in drug delivery, such as liposomes and liquid crystal among others. Finally, peptides and protein self-assembly is connected with biomaterials and as an important event in the balance between health and disease. The final aim of the present review is to show the power of chemical tools not only for the synthesis of new molecules but also to improve our understanding of recognition and self-assembly in the biological context.

  14. Localized dealloying corrosion mediated by self-assembled monolayers used as an inhibitor system.

    Science.gov (United States)

    Shrestha, B R; Bashir, A; Ankah, G N; Valtiner, M; Renner, F U

    2015-01-01

    The structure and chemistry of thiol or selenol self-assembled organic monolayers have been frequently addressed due to the unique opportunities in functionalization of materials. Such organic films can also act as effective inhibition layers to mitigate oxidation or corrosion. Cu-Au alloy substrates covered by self-assembled monolayers show a different dealloying mechanism compared to bare surfaces. The organic surface layer inhibits dealloying of noble metal alloys by a suppression of surface diffusion at lower potentials but at higher applied potentials dealloying proceeds in localized regions due to passivity breakdown. We present an in situ atomic force microscopy study of a patterned thiol layer applied on Cu-Au alloy surfaces and further explore approaches to change the local composition of the surface layers by exchange of molecules. The pattern for the in situ experiment has been applied by micro-contact printing. This allows the study of corrosion protection with its dependence on different molecule densities at different sites. Low-density thiol areas surrounding the high-density patterns are completely protected and initiation of dealloying proceeds only along the areas with the lowest inhibitor concentration. Dealloying patterns are highly influenced and controlled by molecular thiol to selenol exchange and are also affected by introducing structural defects such as scratches or polishing defects.

  15. A proposed simulation method for directed self-assembly of nanographene

    Science.gov (United States)

    Geraets, J. A.; Baldwin, J. P. C.; Twarock, R.; Hancock, Y.

    2017-09-01

    A methodology for predictive kinetic self-assembly modeling of bottom-up chemical synthesis of nanographene is proposed. The method maintains physical transparency in using a novel array format to efficiently store molecule information and by using array operations to determine reaction possibilities. Within a minimal model approach, the parameter space for the bond activation energies (i.e. molecule functionalization) at fixed reaction temperature and initial molecule concentrations is explored. Directed self-assembly of nanographene from functionalized tetrabenzanthracene and benzene is studied with regions in the activation energy phase-space showing length-to-width ratio tunability. The degree of defects and reaction reproducibility in the simulations is also determined, with the rate of functionalized benzene addition providing additional control of the dimension and quality of the nanographene. Comparison of the reaction energetics to available density functional theory data suggests the synthesis may be experimentally tenable using aryl-halide cross-coupling and noble metal surface-assisted catalysis. With full access to the intermediate reaction network and with dynamic coupling to density functional theory-informed tight-binding simulation, the method is proposed as a computationally efficient means towards detailed simulation-driven design of new nanographene systems.

  16. THE AMPHIPHILIC MULTIARM COPOLYMERS BASED ON HYPERBRANCHED POLYESTER AND LYSINE: SYNTHESIS AND SELF-ASSEMBLY

    Institute of Scientific and Technical Information of China (English)

    Jing Wang; Yuan Yao; Bing Ji; Wei Huang; Yong-feng Zhou; De-yue Yan

    2011-01-01

    The amphiphilic multiarm copolymers were synthesized through the modification of commercially available hyperbranched polyesters (Boltom H40) with N-ε-carbobenzoxy-L-Lysine N-carboxyanhydride (ZLys-NCA). After being condensed with N-Boc-phenylalanine (Boc-NPhe) and deprotected the Boc-groups in trifluoroacetic acid (TFA), the original terminal hydroxyl groups were transformed into the amino groups and then initiated the ring-opening polymerization of ZLys-NCA. The hydrophilic poly(L-lysine) was grafted to the surface of Boltorn H40 successfully after the protecting benzyl groups were removed by the HBr solution in glacial acetic acid (33 wt%). The resulting multiarm copolymers were characterized by the 1H-NMR, GPC and FTIR. The arm length calculated by NMR and GPC analysis was about 3 and 13 lysine-units for H40-Phe-PLysl and H40-Phe-PLys2 respectively. Due to the amphiphilic molecular structure, they displayed ability to self-assemble into spherical micelles in aqueous solution with the average diameter in the range from 70 nm to 250 nm. The CMC of H40-Phe-PLysl and H40-Phe-PLys2 was 0.013 mg/mL and 0.028 mg/mL, respectively,indicating that H40-Phe-PLysl with shorter arm length is easier to self-assemble than H40-Phe-PLys2 with longer arm length.

  17. Self-assembly of a supramolecular hexagram and a supramolecular pentagram

    Science.gov (United States)

    Jiang, Zhilong; Li, Yiming; Wang, Ming; Song, Bo; Wang, Kun; Sun, Mingyu; Liu, Die; Li, Xiaohong; Yuan, Jie; Chen, Mingzhao; Guo, Yuan; Yang, Xiaoyu; Zhang, Tong; Moorefield, Charles N.; Newkome, George R.; Xu, Bingqian; Li, Xiaopeng; Wang, Pingshan

    2017-05-01

    Five- and six-pointed star structures occur frequently in nature as flowers, snow-flakes, leaves and so on. These star-shaped patterns are also frequently used in both functional and artistic man-made architectures. Here following a stepwise synthesis and self-assembly approach, pentagonal and hexagonal metallosupramolecules possessing star-shaped motifs were prepared based on the careful design of metallo-organic ligands (MOLs). In the MOL design and preparation, robust ruthenium-terpyridyl complexes were employed to construct brominated metallo-organic intermediates, followed by a Suzuki coupling reaction to achieve the required ensemble. Ligand LA (VRu2+X, V=bisterpyridine, X=tetraterpyridine, Ru=Ruthenium) was initially used for the self-assembly of an anticipated hexagram upon reaction with Cd2+ or Fe2+ however, unexpected pentagonal structures were formed, that is, [Cd5LA5]30+ and [Fe5LA5]30+. In our redesign, LB [V(Ru2+X)2] was synthesized and treated with 60° V-shaped bisterpyridine (V) and Cd2+ to create hexagonal hexagram [Cd12V3LB3]36+ along with traces of the triangle [Cd3V3]6+. Finally, a pure supramolecular hexagram [Fe12V3LB3]36+ was successfully isolated in a high yield using Fe2+ with a higher assembly temperature.

  18. Molecular Design of Bioinspired Nanostructures for Biomedical Applications: Synthesis, Self-Assembly and Functional Properties

    Science.gov (United States)

    Xu, Hesheng Victor; Zheng, Xin Ting; Mok, Beverly Yin Leng; Ibrahim, Salwa Ali; Yu, Yong; Tan, Yen Nee

    2016-08-01

    Biomolecules are the nanoscale building blocks of cells, which play multifaceted roles in the critical biological processes such as biomineralization in a living organism. In these processes, the biological molecules such as protein and nucleic acids use their exclusive biorecognition properties enabled from their unique chemical composition, shape and function to initiate a cascade of cellular events. The exceptional features of these biomolecules, coupled with the recent advancement in nanotechnology, have led to the emergence of a new research field that focuses on the molecular design of bioinspired nanostructures that inherit the extraordinary function of natural biomaterials. These “bioinspired” nanostructures could be formulated by biomimetic approaches through either self-assembling of biomolecules or acting as a biomolecular template/precursor to direct the synthesis of nanocomposite. In either situation, the resulting nanomaterials exhibit phenomenal biocompatibility, superb aqueous solubility and excellent colloidal stability, branding them exceptionally desirable for both in vitro and in vivo biomedical applications. In this review, we will present the recent developments in the preparation of “bioinspired” nanostructures through biomimetic self-assembly and biotemplating synthesis, as well as highlight their functional properties and potential applications in biomedical diagnostics and therapeutic delivery. Lastly, we will conclude this topic with some personal perspective on the challenges and future outlooks of the “bioinspired” nanostructures for nanomedicine.

  19. Self-assembling SAS-6 multimer is a core centriole building block.

    Science.gov (United States)

    Gopalakrishnan, Jayachandran; Guichard, Paul; Smith, Andrew H; Schwarz, Heinz; Agard, David A; Marco, Sergio; Avidor-Reiss, Tomer

    2010-03-19

    Centrioles are conserved microtubule-based organelles with 9-fold symmetry that are essential for cilia and mitotic spindle formation. A conserved structure at the onset of centriole assembly is a "cartwheel" with 9-fold radial symmetry and a central tubule in its core. It remains unclear how the cartwheel is formed. The conserved centriole protein, SAS-6, is a cartwheel component that functions early in centriole formation. Here, combining biochemistry and electron microscopy, we characterize SAS-6 and show that it self-assembles into stable tetramers, which serve as building blocks for the central tubule. These results suggest that SAS-6 self-assembly may be an initial step in the formation of the cartwheel that provides the 9-fold symmetry. Electron microscopy of centrosomes identified 25-nm central tubules with repeating subunits and show that SAS-6 concentrates at the core of the cartwheel. Recombinant and native SAS-6 self-oligomerizes into tetramers with approximately 6-nm subunits, and these tetramers are components of the centrosome, suggesting that tetramers are the building blocks of the central tubule. This is further supported by the observation that elevated levels of SAS-6 in Drosophila cells resulted in higher order structures resembling central tubule morphology. Finally, in the presence of embryonic extract, SAS-6 tetramers assembled into high density complexes, providing a starting point for the eventual in vitro reconstruction of centrioles.

  20. Shape-induced separation of nanospheres and aligned nanorods.

    Science.gov (United States)

    Ahmad, I; Zandvliet, H J W; Kooij, E S

    2014-07-15

    We studied the phase separation and spatial arrangement of gold nanorods and nanospheres after evaporative self-assembly from aqueous suspension. Depending on the position relative to the contact line of the drying droplet, spheres and rods separate into various liquid-crystalline phases. Nanorods exhibit a strong preference for side-by-side alignment, giving rise to smectic phases; spheres in solution are forced out of these regions and form close-packed arrays. We discuss this self-separation into nanorod- and sphere-rich phases in terms of various interactions, including electrostatic, van der Waals, and deplection interactions forces. The experimental results are compared to quantitative calculations of the colloidal interaction energies. We also describe and discuss the role of the surfactant on the different crystal facets of the nanorods on the assembly process.

  1. Early-time, beta-hairpin peptide self-assembly and hydrogelation: Structure, kinetics, and shear-recovery

    Science.gov (United States)

    Yucel, Tuna

    Recently, there has been growing interest in the supramolecular self-assembly and hydrogelation of peptides for potential biomaterials applications. However, there has been limited work on the physicochemical characterization of these systems that will be crucial for the development of these materials for future applications. The main objective of this dissertation was to provide a solid understanding of the self-assembly kinetics, hydrogelation pathways and the physical origins of the shear-recovery behavior of a self-assembled, peptidic hydrogel system. The MAX1 peptide, (VK)4-VDPPT-(KV)4-NH 2 is unfolded, and completely soluble in acidic to neutral aqueous solution. Increasing the pH or ionic strength of the solution triggers intramolecular peptide folding into beta-hairpins and concomitant intermolecular self-assembly into bilayered nanofibrils. Combined static and dynamic light scattering experiments revealed a direct transition from the initial, monomeric state to self-assembled nanofibrils, without an intermediate self-assembly step. The energy barrier associated with MAX1 self-assembly suggested that the self-assembly process involved intramolecular peptide folding events and cluster reorganization to facilitate intermolecular self-assembly. The assembly kinetics could be modeled using Smoluchowski's equation which indicated an essentially diffusion-limited assembly process. The analysis of early-stage dependence of apparent mass on size and the concentration dependence of assembly kinetics gave different fractal dimension values: The former indicated that the nanofibrils behaved locally as rigid rods, while the latter analysis suggested an increase in the apparent fractal dimension at larger length scales. Cryogenic transmission electron microscopy indicated that the increase in the apparent fractal dimension could be attributed to the formation of branched clusters of well-defined (uniform, 3 nm cross section), semi-flexible, beta-sheet-rich nanofibrils

  2. Impact of film thickness on the morphology of mesoporous carbon films using organic-organic self-assembly.

    Science.gov (United States)

    Vogt, Bryan D; Chavez, Vicki L; Dai, Mingzhi; Arreola, M Regina Croda; Song, Lingyan; Feng, Dan; Zhao, Dongyuan; Perera, Ginusha M; Stein, Gila E

    2011-05-03

    Mesoporous polymer and carbon thin films are prepared by the organic-organic self-assembly of an oligomeric phenolic resin with an amphiphilic triblock copolymer template, Pluronic F127. The ratio of resin to template is selected such that a body-centered cubic (Im3m) mesostructure is formed in the bulk. However, well-ordered mesoporous films are not always obtained for thin films (body-centered cubic symmetry with a preferential orientation of the closest-packed (110) plane parallel to the substrate. Film thickness and initial composition of the carbonizable precursors in the template are critical factors in determining the morphology of mesoporous carbon films. These results provide insight into why difficulties have been reported in producing ultrathin ordered mesoporous carbon films using cooperative organic-organic self-assembly.

  3. 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 synthes...... and 20 μM concentrations. The dendrons showed low cytotoxicity, displaying cell viability well above 80%....... 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...... with alkyl chain lengths above C12 are ascribed to intermicellar aggregates stabilized by hydrophobic and electrostatic forces in accordance with the observed pH effect. Finally, the cytotoxicity of the dendrons was evaluated in mouse fibroblast (NIH/3T3) and human embryonic kidney (HEK 293T) cells at 5, 10...

  4. 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.

  5. Self-assembling and self-limiting monolayer deposition

    Science.gov (United States)

    Foest, Rüdiger; Schmidt, Martin; Gargouri, Hassan

    2014-02-01

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

  6. 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.

  7. Parallelism and Time in Hierarchical Self-Assembly

    CERN Document Server

    Chen, Ho-Lin

    2011-01-01

    We study the role that parallelism plays in time complexity of Winfree's abstract Tile Assembly Model (aTAM), a model of molecular algorithmic self-assembly. In the "hierarchical" aTAM, two assemblies, both consisting of multiple tiles, are allowed to aggregate together, whereas in the "seeded" aTAM, tiles attach one at a time to a growing assembly. Adleman, Cheng, Goel, and Huang ("Running Time and Program Size for Self-Assembled Squares", STOC 2001) showed how to assemble an n x n square in O(n) time in the seeded aTAM using O(log n / log log n) unique tile types, where both of these parameters are optimal. They asked whether the hierarchical aTAM could allow a tile system to use the ability to form large assemblies in parallel before they attach to break the Omega(n) lower bound for assembly time. We show that there is a tile system with the optimal O(log n / log log n) tile types that assembles an n x n square using O(log^2 n) parallel "stages", which is close to the optimal Omega(log n) stages, forming t...

  8. 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

  9. 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.

  10. Self-Assembly of Supramolecular Composites under Cylindrical Confinement

    Science.gov (United States)

    Bai, Peter; Thorkelsson, Kari; Ercius, Peter; Xu, Ting

    2014-03-01

    Block copolymer (BCP) or BCP-based supramolecules are useful platforms to direct nanoparticle (NP) assemblies. However, the variety of NP assemblies is rather limited in comparison to those shown by DNA-guided approach. By subjecting supramolecular nanocomposites to 2-D cylindrical confinement afforded by anodic aluminum oxide membranes, a range of new NP assemblies such as stacked rings, and single and double helices can be readily obtained, as confirmed by TEM and TEM tomography. At low NP loadings (3 v%), the nanostructure conforms to the supramolecule morphology. However, at higher NP loadings (6-9 v%), the nanostructure deviates significantly from the morphology of supramolecular nanocomposites in bulk or in thin film, suggesting that frustrated NP packing, in addition to simple supramolecule templating, may play a significant role in the self-assembly process. The present studies demonstrate that 2-D confinement can be an effective means to tailor self-assembled NP structures and may open further opportunities to manipulate the macroscopic properties of NP assemblies.

  11. 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.

  12. 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.

  13. Self-assembling peptide nanofiber scaffolds accelerate wound healing.

    Directory of Open Access Journals (Sweden)

    Aurore Schneider

    Full Text Available Cutaneous wound repair regenerates skin integrity, but a chronic failure to heal results in compromised tissue function and increased morbidity. To address this, we have used an integrated approach, using nanobiotechnology to augment the rate of wound reepithelialization by combining self-assembling peptide (SAP nanofiber scaffold and Epidermal Growth Factor (EGF. This SAP bioscaffold was tested in a bioengineered Human Skin Equivalent (HSE tissue model that enabled wound reepithelialization to be monitored in a tissue that recapitulates molecular and cellular mechanisms of repair known to occur in human skin. We found that SAP underwent molecular self-assembly to form unique 3D structures that stably covered the surface of the wound, suggesting that this scaffold may serve as a viable wound dressing. We measured the rates of release of EGF from the SAP scaffold and determined that EGF was only released when the scaffold was in direct contact with the HSE. By measuring the length of the epithelial tongue during wound reepithelialization, we found that SAP scaffolds containing EGF accelerated the rate of wound coverage by 5 fold when compared to controls without scaffolds and by 3.5 fold when compared to the scaffold without EGF. In conclusion, our experiments demonstrated that biomaterials composed of a biofunctionalized peptidic scaffold have many properties that are well-suited for the treatment of cutaneous wounds including wound coverage, functionalization with bioactive molecules, localized growth factor release and activation of wound repair.

  14. Self-assembled biomimetic monolayers using phospholipid-containing disulfides.

    Science.gov (United States)

    Chung, Yi Chang; Chiu, Yi Hong; Wu, Yin Wei; Tao, Yu Tai

    2005-05-01

    Several phospholipid-based disulfide molecules were synthesized and attached onto the gold-coated silicon wafer using the self-assembling method. The syntheses of these surface-modifying agents were conducted by introducing bromoethylphosphorate (PBr), phosphorylcholine (PC) or phosphorylethanolamine (PE) groups on the terminals of a dialkyl disulfide. After disulfides adsorption onto gold substrate surfaces, the composition, the film thickness, and the conformational order of self-assembled monolayer surfaces were explored and discussed in detail based on reflection-absorption infrared spectroscopy, contact angle measurement, Auger electron spectroscopy, X-ray photoelectron spectroscopy, and so on. The monolayer having the PBr end group could also be converted to a PC surface by treating with trimethylamine. The model functional surfaces of Au-SC11-PC, -PE, -PBr, -OH or corresponding mixed layers were used to mimic biomembrane surfaces. The monolayer having PC groups was found to reduce fibrinogen adsorption as evaluated from protein adsorption experiments using quartz crystal microbalance. It also showed relatively low platelet adherence compare to the glass, PBr and PE surfaces. The cell viability test also revealed that the PC surface displayed lower cytotoxicity than other surfaces.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-03-23

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

  16. 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.

  17. Molecular self-assembly at metal-electrolyte interfaces.

    Science.gov (United States)

    Phan, Thanh Hai; Wandelt, Klaus

    2013-02-25

    The self-assembly of molecular layers has become an important strategy in modern design of functional materials. However, in particular, large organic molecules may no longer be sufficiently volatile to be deposited by vapor deposition. In this case, deposition from solution may be a promising route; in ionic form, these molecules may even be soluble in water. In this contribution, we present and discuss results on the electrochemical deposition of viologen- and porphyrin molecules as well as their co-adsorption on chloride modified Cu(100) and Cu(111) single crystal electrode surfaces from aqueous acidic solutions. Using in situ techniques like cyclic voltametry and high resolution scanning tunneling microscopy, as well as ex-situ photoelectron spectroscopy data the highly ordered self-assembled organic layers are characterized with respect to their electrochemical behavior, lateral order and inner conformation as well as phase transitions thereof as a function of their redox-state and the symmetry of the substrate. As a result, detailed structure models are derived and are discussed in terms of the prevailing interactions.

  18. Molecular Self-Assembly at Metal-Electrolyte Interfaces

    Directory of Open Access Journals (Sweden)

    Thanh Hai Phan

    2013-02-01

    Full Text Available The self-assembly of molecular layers has become an important strategy in modern design of functional materials. However, in particular, large organic molecules may no longer be sufficiently volatile to be deposited by vapor deposition. In this case, deposition from solution may be a promising route; in ionic form, these molecules may even be soluble in water. In this contribution, we present and discuss results on the electrochemical deposition of viologen- and porphyrin molecules as well as their co-adsorption on chloride modified Cu(100 and Cu(111 single crystal electrode surfaces from aqueous acidic solutions. Using in situ techniques like cyclic voltametry and high resolution scanning tunneling microscopy, as well as ex-situ photoelectron spectroscopy data the highly ordered self-assembled organic layers are characterized with respect to their electrochemical behavior, lateral order and inner conformation as well as phase transitions thereof as a function of their redox-state and the symmetry of the substrate. As a result, detailed structure models are derived and are discussed in terms of the prevailing interactions.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-22

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

  20. Delivery of therapeutics and molecules using self-assembled peptides.

    Science.gov (United States)

    Sundar, S; Chen, Y; Tong, Y W

    2014-01-01

    The use of nanobiotechnology in the formulation of drug carriers has been gaining popularity in recent years. Peptide self-assembly technology is a particularly attractive option due to its simplicity and programmability. Selfassembling peptide amphiphiles are surfactant-like molecules that are capable of spontaneous organization into a variety of nanostructures. The structural and functional features of these nanostructures can be designed through alterations to the peptide sequence. With a keen understanding of the supramolecular principles governing the non-covalent interactions involved, drug loading strategies can be customised. Hydrophobic drugs can be hidden within the core via aromatic interactions while gene-based therapeutics can be complexed with a cationic region of lysine residues. This review article focuses on the application of self-assembling peptide amphiphiles to drug delivery in the area of anti-cancer therapeutics, protein- and peptide-based therapeutics and nucleic acid-based therapeutics. Specific examples are used to discuss the various systems available and emphasis is given to the encapsulation and release mechanism.

  1. 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.

  2. Facile self-assembly and stabilization of metal oxide nanoparticles.

    Science.gov (United States)

    Charbonneau, Cecile; Holliman, Peter J; Davies, Matthew L; Watson, Trystan M; Worsley, David A

    2015-03-15

    This paper describes a facile method of self-assembling different metal oxide nanoparticles into nanostructured materials via di-carboxylate linkers (oxalic acid) using TiO2 as an example. In this method, the di-carboxylate linkers react with surface hydroxyls on metal oxide nanoparticles forming covalent, ester-like bonds, which enable the binding of two metal oxide particles, one at either end of the linker and facilitates efficient self-assembly of one group of metal oxide nanoparticles homogeneously distributed onto the surface of another group. The oxalate linkers can then be removed by thermal decomposition. This approach is shown to be effective using differently-sized TiO2 nanoparticles, namely in-house synthesized 3-5nm anatase nanocrystals and Degussa P25 titania particles (mean 21nm particle size). Our data show that the application of a high temperature heat treatment (450°C for 30min), conventionally applied to achieve a stable porous structure by thermal decomposition of the linker molecules and by inducing inter-particle necking, damages the surface area of the nanostructured material. However, here we show that sintering at 300°C for 30min or by flash near infrared radiation sintering for 12s efficiently decomposes the oxalate linkers and stabilizes the nanostructure of the material whilst maintaining its high surface area. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Development of self-assembled bacterial cellulose-starch nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Grande, Cristian J. [Faculty of Mechanical Engineering, Catholic University of Peru (PUCP), Lima 32 (Peru); Torres, Fernando G., E-mail: fgtorres@pucp.edu.pe [Faculty of Mechanical Engineering, Catholic University of Peru (PUCP), Lima 32 (Peru); Gomez, Clara M., E-mail: Clara.Gomez@uv.es [Departament de Quimica Fisica and Institut de Ciencia dels Materials, Dr Moliner 50, Universitat de Valencia, E-46100 Burjassot, Valencia (Spain); Troncoso, Omar P. [Faculty of Mechanical Engineering, Catholic University of Peru (PUCP), Lima 32 (Peru); Canet-Ferrer, Josep; Martinez-Pastor, Juan [Unit of Optoelectronic Materials and Devices of the University of Valencia, P.O. Box 22085, 46071 Valencia (Spain)

    2009-05-05

    A bioinspired bottom-up process was developed to produce self-assembled nanocomposites of cellulose synthesized by Acetobacter bacteria and native starch. This process takes advantage of the way some bacteria extrude cellulose nanofibres and of the transport process that occurs during the gelatinization of starch. Potato and corn starch were added into the culture medium and partially gelatinized in order to allow the cellulose nanofibrils to grow in the presence of a starch phase. The bacterial cellulose (BC)-starch gels were hot pressed into sheets that had a BC volume fraction higher than 90%. During this step starch was forced to further penetrate the BC network. The self-assembled BC-starch nanocomposites showed a coherent morphology that was assessed by Atomic Force Microscopy (AFM) and Environmental Scanning Electron Microscopy (ESEM). The nanocomposites structure was studied using X-ray diffraction and ATR-FTIR spectroscopy. The degree of crystallinity of the final nanocomposites was used to estimate the volume fraction of BC. The aim of this paper is to explore a new methodology that could be used to produce nanomaterials by introducing a different phase into a cellulose nanofibre network during its assembly.

  4. Self-assembly of organic films on a liquid metal

    Science.gov (United States)

    Magnussen, Olaf M.; Ocko, Benjamin M.; Deutsch, Moshe; Regan, Michael J.; Pershan, Peter S.; Abernathy, Douglas; Grübel, Gerhard; Legrand, Jean-François

    1996-11-01

    THE structure and phase behaviour of organic thin films result from the subtle interplay of intermolecular Van der Waals interactions, which promote self-assembly and long-ranged order, and the more complex interactions between the end groups of the organic chains and the substrate. The structure of molecular films of amphiphiles has been extensively studied on subphases of dielectric liquids, notably water (Langmuir mono-layers) and on solid surfaces (self-assembled monolayers, SAMs)1-4. Here we report structural studies, by synchrotron X-ray scattering, of an intermediate case: densely packed alka-nethiol films on the surface of liquid mercury. While, like SAMs, these films form strong chemical bonds to the subphase, this subphase is smooth and unstructured, as in the case of Langmuir monolayers. But unlike either of these1,2,5-7, our films have no in-plane long-range order. We suggest that the strong interaction of the thiol group with the underlying disordered liquid dominates here over the order-promoting interactions of the alkyl chains.

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

    Science.gov (United States)

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

    2015-03-01

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

  6. Functional self-assembled DNA nanostructures for molecular recognition

    Science.gov (United States)

    Zhang, Xiaojuan; Yadavalli, Vamsi K.

    2012-03-01

    Nucleic acids present a wonderful toolkit of structural motifs for nanoconstruction. Functional DNA nanostructures can enable protein recognition by the use of aptamers attached to a basic core shape formed by DNA self-assembly. Here, we present a facile, programmable strategy for the assembly of discrete aptamer-tagged DNA shapes and nanostructures that can function for molecular recognition and binding in an aqueous environment. These nanostructures, presented here to bind two different protein targets, are easily synthesized in large numbers, and are portable and stable over long periods of time. This construction modality can facilitate on-demand production of libraries of diverse shapes to recognize and bind proteins or catalyze reactions via functional nucleic acid tags.Nucleic acids present a wonderful toolkit of structural motifs for nanoconstruction. Functional DNA nanostructures can enable protein recognition by the use of aptamers attached to a basic core shape formed by DNA self-assembly. Here, we present a facile, programmable strategy for the assembly of discrete aptamer-tagged DNA shapes and nanostructures that can function for molecular recognition and binding in an aqueous environment. These nanostructures, presented here to bind two different protein targets, are easily synthesized in large numbers, and are portable and stable over long periods of time. This construction modality can facilitate on-demand production of libraries of diverse shapes to recognize and bind proteins or catalyze reactions via functional nucleic acid tags. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11711h

  7. Synthesis and Self-Assembly of Triangulenium Salts

    DEFF Research Database (Denmark)

    Shi, Dong

    This thesis describes the design and synthesis of asymmetrically substituted amphiphilic tis(dialkylamino)trioxiatriangulenium (ATOTA+) salts with different counter ions. Attention was focused on exploring the assembling properties of the ATOTA+ salts in aqueous media. A direct vortexing-processe......This thesis describes the design and synthesis of asymmetrically substituted amphiphilic tis(dialkylamino)trioxiatriangulenium (ATOTA+) salts with different counter ions. Attention was focused on exploring the assembling properties of the ATOTA+ salts in aqueous media. A direct vortexing......, highly ordered, and free-floating bilayer nanosheets through prolonged vigorous shaking. In this study, a mechanism for the self-assembly process agitated by prolonged vigorous shaking is proposed. It is proposed that the self-assembly is realized via a intermediated monolayer formed at the dynamic air......–water interfaces and lateral compression of the monolayer results in the collapsing toward the formation of bilayer nanosheets. The nanosheets showed excellent stability after standing over 10 months stocked in a close vial at ambient conditions due to the ionic atmosphere surrounding its charged surfaces...

  8. 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.

  9. Self assembled monolayers on silicon for molecular electronics.

    Science.gov (United States)

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

    2006-05-24

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

  10. Synthesis and simultaneous self-assembly of novel antibacterial polyurethanes

    Science.gov (United States)

    Duan, J. H.; Yin, F.; Jiang, G. C.

    2016-07-01

    Novel physically crosslinked polyurethane (PUII) based on isophorone diisocyanates (IPDI) was prepared by a conventional two step method. The chemical structures of the PUII were characterized by fourier transform infrared (FTIR), proton nuclear magnetic resonance (1H-NMR), gel permeation chromatography (GPC) and scanning electron microscopy (SEM). The PUII hydrogels were subjected to solvent-induced self-assembly in THF + water to construct a variety of morphologies. The self-assembly morphology of the PUII was observed by scanning electron microscopy (SEM). Different amounts (0.2%, 0.4%, 0.6%, 0.8%, 1.0%) of 1,3,5-Tris(2-hydroxyethyl)hexahydro-1,3,5-triazine (TNO) was added as antibacterial agent to the polyurethane prepolymers. The inhibiting capacity of the antibacterial films to the Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Gray mold has been studied. The inhibiting capacity of films for each strain effect became obvious with the increase of content of antibacterial agent and the sensitive degree to all kind of bacterial species was different.

  11. Tumor Bioimaging: Morphology-Tailoring of a Red AIEgen from Microsized Rods to Nanospheres for Tumor-Targeted Bioimaging (Adv. Mater. 16/2016).

    Science.gov (United States)

    Li, Yongsheng; Shao, Andong; Wang, Yao; Mei, Ju; Niu, Dechao; Gu, Jinlou; Shi, Ping; Zhu, Weihong; Tian, He; Shi, Jianlin

    2016-04-01

    Y. Li, W. Zhu, and co-workers develop a convenient and versatile "make-up" strategy to modulate the micro-sized rods of a near-infrared-emissive AIEgen probe integrated into nanospheres via a self-assembly encapsulation process, as presented on page 3187. The obtained nanospheres outperform microrods in terms of brightness, photostability, biocompatibility, tumor-accumulation, and targeting ability, making them perfect bioprobes for tumor-targeted bioimaging. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Molecular self-assembly: Design, synthesis, and characterization of peptidic materials for bio- and nano-technologies

    Science.gov (United States)

    Lamm, Matthew S.

    The research presented in this dissertation focuses on the design, synthesis, and characterization of amphiphilic peptides capable of self-assembling into beta-sheet fibrils under specific aqueous solution conditions. The peptide design consists of two beta-sheet forming strands of alternating valine and lysine residues, flanking a central tetrapeptide sequence that contains a diproline. Depending on the chirality of the prolines the peptide can assume either an intramolecularly folded or an extended conformation in the self-assembled state. For the peptide where intramolecular folding is designed against, the self-assembled nanostructure was found to exhibit a unique, nontwisted laminated morphology. Experimental techniques including transmission electron microscopy, atomic force microscopy, circular dichroism spectroscopy, Fourier transform infra-red spectroscopy and x-ray diffraction were employed to characterize the self-assembled structure and kinetics. With the understanding of the self-assembly process gained from these first peptides, other peptide sequences were rationally designed to assemble with a desired nanostructure. For example, the effect of peptide strand length in conserving the laminated morphology and controlling the fibril height was investigated. In addition, other peptides were designed so as to affect the self-assembled nanostructure by enforcing a parallel versus anti-parallel beta-sheet or by disrupting the registry of laminating beta-sheet filaments. In some cases, the peptides assembled into structures predicted by the initial design while other peptides assembled into unexpected fibril morphologies. The major conclusions from the research on these peptides is that the diproline sequence plays an important role in disrupting the beta-strand twist thereby resulting in a nontwisted laminated morphology. However, when the flanking beta-strands become long enough, the effect of the diproline sequence becomes diminished and the fibrils do

  13. A Coarse-Grained Molecular Dynamics Simulation Using NAMD Package to Reveal Aggregation Profile of Phospholipids Self-Assembly in Water

    Directory of Open Access Journals (Sweden)

    Dwi Hudiyanti

    2014-01-01

    Full Text Available The energy profile of self-assembly process of DLPE, DLPS, DOPE, DOPS, DLiPE, and DLiPS in water was investigated by a coarse-grained molecular dynamics simulation using NAMD package. The self-assembly process was initiated from random configurations. The simulation was carried out for 160 ns. This study presented proof that there were three major self-assembled arrangements which became visible for a certain duration when the simulation took place, that is, liposome, deformed liposome, and planar bilayer. The energy profile that shows plateau at the time of these structures emerge confirmed their stability therein. Our findings have highlighted the idea that liposomes and deformed liposomes are metastable phases which eventually will turn into planar bilayer, the stable one.

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

    Science.gov (United States)

    Rudzka, Katarzyna; Sanchez Treviño, Alda Y.; Rodríguez-Valverde, Miguel A.; Cabrerizo-Vílchez, Miguel A.

    2016-12-01

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

  15. Self-Assembled Peptide- and Protein-Based Nanomaterials for Antitumor Photodynamic and Photothermal Therapy.

    Science.gov (United States)

    Abbas, Manzar; Zou, Qianli; Li, Shukun; Yan, Xuehai

    2017-01-06

    Tremendous interest in self-assembly of peptides and proteins towards functional nanomaterials has been inspired by naturally evolving self-assembly in biological construction of multiple and sophisticated protein architectures in organisms. Self-assembled peptide and protein nanoarchitectures are excellent promising candidates for facilitating biomedical applications due to their advantages of structural, mechanical, and functional diversity and high biocompability and biodegradability. Here, this review focuses on the self-assembly of peptides and proteins for fabrication of phototherapeutic nanomaterials for antitumor photodynamic and photothermal therapy, with emphasis on building blocks, non-covalent interactions, strategies, and the nanoarchitectures of self-assembly. The exciting antitumor activities achieved by these phototherapeutic nanomaterials are also discussed in-depth, along with the relationships between their specific nanoarchitectures and their unique properties, providing an increased understanding of the role of peptide and protein self-assembly in improving the efficiency of photodynamic and photothermal therapy.

  16. Self-assembled dynamics of silver nanoparticles and self-assembled dynamics of 1,4-benzenedithiol adsorbed on silver nanoparticles: Surface-enhanced Raman scattering study.

    Science.gov (United States)

    Sun, Mengtao; Xia, Lixin; Chen, Maodu

    2009-10-01

    Self-assembled dynamics of silver nanoparticles and self-assembled dynamics of 1,4-benzenedithiol (1,4-BDT) adsorbed on silver nanoparticles were investigated experimentally with surface-enhanced Raman scattering (SERS) and theoretically with density functional theory (DFT) and finite difference time domain (FDTD) method. The absorption spectroscopy of 1,4-BDT in silver sol at different time intervals was measured, which give the indirect evidence of self-assembled dynamics of silver nanoparticles and self-assembled dynamics of 1,4-benzenedithiol (1,4-BDT) adsorbed on silver nanoparticles. To obtain the direct evidence of self-assembled dynamics of silver nanoparticles and self-assembled dynamics of 1,4-benzenedithiol (1,4-BDT) adsorbed on silver nanoparticles, the SERS of 1,4-BDT were measured experimentally and investigated theoretically. The appearances of S-S stretching band (revealing the formation of multilayers of 1,4-BDT), and strongly enhanced S-C stretching, C-C ring stretching vibrational modes clearly show self-assembled dynamics of 1,4-BDT.

  17. Effect of the Fabrication Parameters of the Nanosphere Lithography Method on the Properties of the Deposited Au-Ag Nanoparticle Arrays.

    Science.gov (United States)

    Liu, Jing; Chen, Chaoyang; Yang, Guangsong; Chen, Yushan; Yang, Cheng-Fu

    2017-04-03

    The nanosphere lithography (NSL) method can be developed to deposit the Au-Ag triangle hexagonal nanoparticle arrays for the generation of localized surface plasmon resonance. Previously, we have found that the parameters used to form the NSL masks and the physical methods required to deposit the Au-Ag thin films had large effects on the geometry properties of the nanoparticle arrays. Considering this, the different parameters used to grow the Au-Ag triangle hexagonal nanoparticle arrays were investigated. A single-layer NSL mask was formed by using self-assembly nano-scale polystyrene (PS) nanospheres with an average radius of 265 nm. At first, the concentration of the nano-scale PS nanospheres in the solution was set at 6 wt %. Two coating methods, drop-coating and spin-coating, were used to coat the nano-scale PS nanospheres as a single-layer NSL mask. From the observations of scanning electronic microscopy (SEM), we found that the matrixes of the PS nanosphere masks fabricated by using the drop-coating method were more uniform and exhibited a smaller gap than those fabricated by the spin-coating method. Next, the drop-coating method was used to form the single-layer NSL mask and the concentration of nano-scale PS nanospheres in a solution that was changed from 4 to 10 wt %, for further study. The SEM images showed that when the concentrations of PS nanospheres in the solution were 6 and 8 wt %, the matrixes of the PS nanosphere masks were more uniform than those of 4 and 10 wt %. The effects of the one-side lifting angle of substrates and the vaporization temperature for the solvent of one-layer self-assembly PS nanosphere thin films, were also investigated. Finally, the concentration of the nano-scale PS nanospheres in the solution was set at 8 wt % to form the PS nanosphere masks by the drop-coating method. Three different physical deposition methods, including thermal evaporation, radio-frequency magnetron sputtering, and e-gun deposition, were used to

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    Asaf Shahmoon

    2010-05-01

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

  20. Nanospheric Chemotherapeutic and Chemoprotective Agents

    Science.gov (United States)

    2008-09-01

    targeting the drug-nanosphere complex to diseased cells, thereby minimizing unwanted effects on healthy cells. This report describes the optimization of...military and civilian requirements for effective breast cancer chemotherapy : nontoxic administration, increased bioavailability, prolonged circulation...provide highly effective delivery of hydrophobic paclitaxel to human tumor cells in vitro; (b) tyrosine-derived nanospheres exhibit no toxicity as

  1. Principles Governing the Self Assembly of Polypeptide Nanoparticles

    Science.gov (United States)

    Wahome, Newton

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

  2. Molecular engineering and characterization of self-assembled biorecognition surfaces

    Science.gov (United States)

    Pan, Sheng

    The development of molecular engineering techniques for the fabrication of biomaterial surfaces is of importance in the field of biomaterials. It offers opportunities for better understanding of biological processes on material surfaces and rational design of contemporary biomaterials. Our work in this area aims to develop novel engineering strategies to design biorecognition surfaces via self-assembly and surface derivatization. Fundamental issues regarding self-assembled monolayer (SAM) structure, formation kinetics, and chemical derivatization were investigated systematically using electron spectroscopy for chemical analysis (ESCA), time-of-flight secondary ion mass spectrometry (TOF-SIMS), infrared reflection absorption spectroscopy (IRAS), atomic force microscopy (AFM), and contact angle measurements. Novel engineering concepts based on multifunctionality and statistical pattern matching were introduced and applied to develop biomimetic surfaces. Our study illustrated that molecules underwent structural transition and orientation development during self-assembly formation, from a disordered, low-density, more liquid-like structure to a highly ordered, closed-packed crystalline-like structure. Surface properties, such as wettability and the reactivity of outermost functional groups can be related to film structure, packing density, as well as molecular orientation. Given the order and organization of SAMs, the accessibility and reactivity of the outermost functional groups, reaction kinetics, stoichiometry, and SAMs stability were studied systematically by surface derivatization of trifluoroacetic anhydride (TFAA). The TFAA derivatization reactions exhibited rapid kinetics on the hydroxyl-terminated SAMs. The data from complementary surface analytical techniques consistently indicated a nearly complete surface reaction. Biomimetic surfaces were made by random immobilization of amino acid of arginine (R), glycine (G), and aspartic acid (D) on well-defined SAMs

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-01

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

  4. From self-assembly fundamental knowledge to nanomedicine developments.

    Science.gov (United States)

    Monduzzi, Maura; Lampis, Sandrina; Murgia, Sergio; Salis, Andrea

    2014-03-01

    This review highlights the key role of NMR techniques in demonstrating the molecular aspects of the self-assembly of surfactant molecules that nowadays constitute the basic knowledge which modern nanoscience relies on. The aim is to provide a tutorial overview. The story of a rigorous scientific approach to understand self-assembly in surfactant systems and biological membranes starts in the early seventies when the progresses of SAXRD and NMR technological facilities allowed to demonstrate the existence of ordered soft matter, and the validity of Tanford approach concerning self-assembly at a molecular level. Particularly, NMR quadrupolar splittings, NMR chemical shift anisotropy, and NMR relaxation of dipolar and quadrupolar nuclei in micellar solutions, microemulsions, and liquid crystals proved the existence of an ordered polar-apolar interface, on the NMR time scale. NMR data, rationalized in terms of the two-step model of relaxation, allowed to quantify the dynamic aspects of the supramolecular aggregates in different soft matter systems. In addition, NMR techniques allowed to obtain important information on counterion binding as well as on size of the aggregate through molecular self-diffusion. Indeed NMR self-diffusion proved without any doubt the existence of bicontinuous microemulsions and bicontinuous cubic liquid crystals, suggested by pioneering and brilliant interpretation of SAXRD investigations. Moreover, NMR self-diffusion played a fundamental role in the understanding of microemulsion and emulsion nanostructures, phase transitions in phase diagrams, and particularly percolation phenomena in microemulsions. Since the nineties, globalization of the knowledge along with many other technical facilities such as electron microscopy, particularly cryo-EM, produced huge progresses in surfactant and colloid science. Actually we refer to nanoscience: bottom up/top down strategies allow to build nanodevices with applications spanning from ICT to food

  5. Electrochemical Properties of Organosilane Self Assembled Monolayers on Aluminum 2024

    Science.gov (United States)

    Hintze, Paul E.; Calle, Luz Marina

    2004-01-01

    Self assembled monolayers are commonly used to modify surfaces. Within the last 15 years, self assembled monolayers have been investigated as a way to protect from corrosion[1,2] or biofouling.[3] In this study, self assembled monolayers of decitriethoxysilane (C10H21Si(OC2H5)3) and octadecyltriethoxysilane (C18H37Si(OC2H5)3) were formed on aluminum 2024-T3. The modified surfaces and bare Al 2024 were characterized by dynamic water contact angle measurements, x-ray photoelectron spectroscopy (XIPS) and infrared spectroscopy. Electrochemical impedance spectroscopy (EIS) in 0.5 M NaCl was used to characterize the monolayers and evaluate their corrosion protection properties. The advancing water contact angle and infrared measurements show that the mono layers form a surface where the hydrocarbon chains are packed and oriented away from the surface, consistent with what is found in similar systems. The contact angle hysteresis measured in these systems is relatively large, perhaps indicating that the hydrocarbon chains are not as well packed as monolayers formed on other substrates. The results of the EIS measurements were modeled using a Randle's circuit modified by changing the capacitor to a constant phase element. The constant phase element values were found to characterize the monolayer. The capacitance of the monolayer modified surface starts lower than the bare Al 2024, but approaches values similar to the bare Al 2024 within 24 hours as the monolayer is degraded. The n values found for bare Al 2024 quickly approach the value of a true capacitor and are greater than 0.9 within hours after the start of exposure. For the monolayer modified structure, n can stay lower than 0.9 for a longer period of time. In fact, n for the monolayer modified surfaces is different from the bare surface even after the capacitance values have converged. This indicates that the deviation from ideal capacitance is the most sensitive indicator of the presence of the monolayer.

  6. From dynamic self-assembly to networked chemical systems.

    Science.gov (United States)

    Grzybowski, Bartosz A; Fitzner, Krzysztof; Paczesny, Jan; Granick, Steve

    2017-07-13

    Although dynamic self-assembly, DySA, is a relatively new area of research, the past decade has brought numerous demonstrations of how various types of components - on scales from (macro)molecular to macroscopic - can be arranged into ordered structures thriving in non-equilibrium, steady states. At the same time, none of these dynamic assemblies has so far proven practically relevant, prompting questions about the field's prospects and ultimate objectives. The main thesis of this Review is that formation of dynamic assemblies cannot be an end in itself - instead, we should think more ambitiously of using such assemblies as control elements (reconfigurable catalysts, nanomachines, etc.) of larger, networked systems directing sequences of chemical reactions or assembly tasks. Such networked systems would be inspired by biology but intended to operate in environments and conditions incompatible with living matter (e.g., in organic solvents, elevated temperatures, etc.). To realize this vision, we need to start considering not only the interactions mediating dynamic self-assembly of individual components, but also how components of different types could coexist and communicate within larger, multicomponent ensembles. Along these lines, the review starts with the discussion of the conceptual foundations of self-assembly in equilibrium and non-equilibrium regimes. It discusses key examples of interactions and phenomena that can provide the basis for various DySA modalities (e.g., those driven by light, magnetic fields, flows, etc.). It then focuses on the recent examples where organization of components in steady states is coupled to other processes taking place in the system (catalysis, formation of dynamic supramolecular materials, control of chirality, etc.). With these examples of functional DySA, we then look forward and consider conditions that must be fulfilled to allow components of multiple types to coexist, function, and communicate with one another within the

  7. 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

  8. Charge conduction and breakdown mechanisms in self-assembled nanodielectrics.

    Science.gov (United States)

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

    2009-05-27

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

  9. Antitumor therapeutic application of self-assembled RNAi-AuNP nanoconstructs: Combination of VEGF-RNAi and photothermal ablation

    Science.gov (United States)

    Son, Sejin; Kim, Namho; You, Dong Gil; Yoon, Hong Yeol; Yhee, Ji Young; Kim, Kwangmeyung; Kwon, Ick Chan; Kim, Sun Hwa

    2017-01-01

    Nucleic acid-directed self-assembly provides an attractive method to fabricate prerequisite nanoscale structures for a wide range of technological applications due to the remarkable programmability of DNA/RNA molecules. In this study, exquisite RNAi-AuNP nanoconstructs with various geometries were developed by utilizing anti-VEGF siRNA molecules as RNAi-based therapeutics in addition to their role as building blocks for programmed self-assembly. In particular, the anti-VEGF siRNA-functionalized AuNP nanoconstructs can take additional advantage of gold-nanoclusters for photothermal cancer therapeutic agent. A noticeable technical aspect of self-assembled RNAi-AuNP nanoconstructs in this study is the precise conjugation and separation of designated numbers of therapeutic siRNA onto AuNP to develop highly sophisticated RNA-based building blocks capable of creating various geometries of RNAi-AuNP nano-assemblies. The therapeutic potential of RNAi-AuNP nanoconstructs was validated in vivo as well as in vitro by combining heat generation capability of AuNP and anti-angiogenesis mechanism of siRNA. This strategy of combining anti-VEGF mechanism for depleting angiogenesis process at initial tumor progression and complete ablation of residual tumors with photothermal activity of AuNP at later tumor stage showed effective tumor growth inhibition and tumor ablation with PC-3 tumor bearing mice. PMID:28042312

  10. Creating Sub-50 Nm Nanofluidic Junctions in PDMS Microfluidic Chip via Self-Assembly Process of Colloidal Particles.

    Science.gov (United States)

    Wei, Xi; Syed, Abeer; Mao, Pan; Han, Jongyoon; Song, Yong-Ak

    2016-03-13

    Polydimethylsiloxane (PDMS) is the prevailing building material to make microfluidic devices due to its ease of molding and bonding as well as its transparency. Due to the softness of the PDMS material, however, it is challenging to use PDMS for building nanochannels. The channels tend to collapse easily during plasma bonding. In this paper, we present an evaporation-driven self-assembly method of silica colloidal nanoparticles to create nanofluidic junctions with sub-50 nm pores between two microchannels. The pore size as well as the surface charge of the nanofluidic junction is tunable simply by changing the colloidal silica bead size and surface functionalization outside of the assembled microfluidic device in a vial before the self-assembly process. Using the self-assembly of nanoparticles with a bead size of 300 nm, 500 nm, and 900 nm, it was possible to fabricate a porous membrane with a pore size of ~45 nm, ~75 nm and ~135 nm, respectively. Under electrical potential, this nanoporous membrane initiated ion concentration polarization (ICP) acting as a cation-selective membrane to concentrate DNA by ~1,700 times within 15 min. This non-lithographic nanofabrication process opens up a new opportunity to build a tunable nanofluidic junction for the study of nanoscale transport processes of ions and molecules inside a PDMS microfluidic chip.

  11. Self-assembly modified-mushroom nanocomposite for rapid removal of hexavalent chromium from aqueous solution with bubbling fluidized bed

    Science.gov (United States)

    Xu, Fei; Liu, Xu; Chen, Yijiao; Zhang, Ke; Xu, Heng

    2016-05-01

    A self-assembled modified Pleurotus Cornucopiae material (SMPM) combined with improved Intermittent Bubbling Fluidized Bed (IBFB) was investigated to remove the hexavalent chromium ions in aqueous solution. After the modification, the powder-like raw material gradually self-assembled together to SMPM, which had crinkly porous structure, improved the Cr-accommodation ability in a sound manner. Optimized by Taguchi method, Cr(VI) removal efficiency was up to 75.91% and 48.01% for 100 mg/L and 500 mg/L initial concentration of Cr(VI), respectively. Results indicated that the metal removal was dependent on dosage of adsorbent, particle diameter and treatment time. The experimental data obtained from the biosorption process was successfully correlated with Freundlich isotherm model. Thermodynamic study indicated the endothermic nature of the process. The results confirmed that self-assembly modified Pleurotus Cornucopiae material could be applied for the removal of heavy metal from wastewater in continuous fluidized bed process.

  12. Studies on multivalent interactions of quantum dots-protein self-assemble using fluorescence coupled capillary electrophoresis

    Science.gov (United States)

    Wang, Jianhao; Li, Jingyan; Teng, Yiwan; Hu, Wei; Chai, Hong; Li, Jinchen; Wang, Cheli; Qiu, Lin; Jiang, Pengju

    2014-07-01

    Nanoparticle-biomolecules self-assembly is the key to the understanding of biomolecular coating of nanoparticle. However, the self-assembly of biomolecules with nanoparticles is still under-exploited because of the lack of an efficient method to detect the subtle changes in the surface of nanoparticles. In this study, we utilized fluorescence coupled capillary electrophoresis (CE-FL) to probe the binding interaction between a multivalent ligand (dBSA, denatured bovine serum albumin which contains multiple thiol groups) and CdSe/ZnS quantum dots (QDs, 5 nm in diameter). The yield of QDs-dBSA complex increased with increasing molar ratio of dBSA to QDs, which plateaued at a ratio of 8:1. Besides, QDs-dBSA complex showed good stability due to the multivalent interaction, revealing that dBSA is a superior ligand for QDs. The self-assembly kinetics of QDs with dBSA manifested a bi-phasic kinetics with a linear initial stage followed by a saturating stage. This work revealed for the first time that there exist two types of binding sites on the surface of QDs for dBSA: one type termed "high priority" binding sites, which preferentially bind to the protein, whereas the "low priority" sites are occupied only after the first-type binding sites are fully bound. Our work thereby represents the first example of systematic investigation on the details of the metal-affinity driven self-assembly between QDs and dBSA utilizing the high-resolution CE-FL. It also expanded the application of CE-FL in the study of nanoparticle-biomolecule interaction and kinetics analysis.

  13. Functional materials derived from block copolymer self-assembly

    DEFF Research Database (Denmark)

    Li, Tao

    is to fabricate interconnected and highly ordered metal oxide films by using a nano-porous polymer with gyroid morphology as the template. This unique structure is ideal for the solar cell application where a mesoscopic metal oxide scaffold functions as the electron collection and transport material. Two......The main objective of this project is to explore block copolymer self-assembly for generating functional materials with well-defined morphology on sub-20 nanometer length scale, which can be utilized in many important applications such as solar cells and nanolithography. One of the specific targets......-casting, the block copolymer self-organizes into monolayer packed sphere pattern, without any surface treatment of the substrate and annealing process. Arrays of nano-pillars and nanowells of various materials are fabricated in dry etch processes over wafer scale without defects. We also show an in situ Al2O3 hard...

  14. Self-Assembled PbSe Nanowire:Perovskite Hybrids.

    Science.gov (United States)

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

    2015-12-02

    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.

  15. Nanophotonic Fabrication Self-Assembly and Deposition Techniques

    CERN Document Server

    Yatsui, Takashi

    2012-01-01

    Nanophotonics, a novel optical technology, utilizes the local interaction between nanometric particles via optical near fields. The optical near fields are the elementary surface excitations on nanometric particles, i.e. dressed photons that carry material energy. Of the variety of qualitative innovations in optical technology realized by nanophotonics, this books focuses on fabrication. To fabricate nano-scale photonic devices with nanometer-scale controllability in size and position, we developed a self-assembly method for size- and position-controlled ultra-long nanodot chains using a novel effect of near-field optical desorption. A novel deposition and etching scheme under nonresonant conditions is also demonstrated and its origin is reviewed.

  16. Confined self-assembly approach to produce ultrathin carbon nanofibers.

    Science.gov (United States)

    Zhang, Weixia; Cui, Jiecheng; Tao, Cheng-An; Lin, Changxu; Wu, Yiguang; Li, Guangtao

    2009-07-21

    A surfactant containing a terminal carbon source moiety was synthesized and used simultaneously as both template molecule and carbon source. On the basis of this special structure-directing agent, an efficient strategy for producing uniform carbon nanowires with diameter below 1 nm was developed using a confined self-assembly approach. Besides the capability of producing ultralong and thin carbon wires inaccessible by the previously reported approaches, the method described here presents many advantages such as the direct use of residue iron complex as catalyst for carbonization and no requirement of conventional tedious infiltration process of carbon source into small channels. Different methods including SEM, TEM, XRD, Raman spectroscopy, and conductivity measurement were employed to characterize the formed ultrathin carbon nanofibers. Additionally, the described strategy is extendable. By designing an appropriate surfactant, it is also possible for the fabrication of the finely structured carbon network and ultrathin graphitic sheets through the construction of the corresponding cubic and lamellar mesostructured templates.

  17. IONIC SELF-ASSEMBLY AND HUMIDITY SENSITIVITY OF POLYELECTROLYTE MULTILAYERS

    Institute of Scientific and Technical Information of China (English)

    Hai-hu Yu; De-sheng Jiang

    2002-01-01

    Multilayer thin films of alternately adsorbed layers of polyelectrolytes PDDA and PS-119 were formed on both planar silica substrates and optical fibers through the ionic self-assembly technique. Intrinsic Fabry-Perot cavities were fabricated by stepwise assembling the polyelectrolytes onto the ends of optical fibers for the purposes of fiber optical device and sensor development. Ionically assembled polyelectrolyte multilayer thin films, in whichthere are hydrophilic side groups with strong affinity towards water molecules, are a category of humidity-sensitive functional materials. The polyelectrolyte multilayer thin film Fabry-Perot cavity-type fiber optical humidity sensor can work over a wide range from about 0% RH to about 100% RH with a response time less than 1 s.

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

    Directory of Open Access Journals (Sweden)

    Su Xiao-Zhou

    2014-01-01

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

  19. 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 10(17) 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.

  20. Controlling the photoconductivity: Graphene oxide and polyaniline self assembled intercalation

    Energy Technology Data Exchange (ETDEWEB)

    Vempati, Sesha, E-mail: svempati01@qub.ac.uk [UNAM-National Nanotechnology Research Centre, Bilkent University, Ankara 06800 (Turkey); Ozcan, Sefika [UNAM-National Nanotechnology Research Centre, Bilkent University, Ankara 06800 (Turkey); Department of Polymer Science and Technology, Middle East Technical University, Ankara 06800 (Turkey); Uyar, Tamer, E-mail: uyar@unam.bilkent.edu.tr [UNAM-National Nanotechnology Research Centre, Bilkent University, Ankara 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey)

    2015-02-02

    We report on controlling the optoelectronic properties of self-assembled intercalating compound of graphene oxide (GO) and HCl doped polyaniline (PANI). Optical emission and X-ray diffraction studies revealed a secondary doping phenomenon of PANI with –OH and –COOH groups of GO, which essentially arbitrate the intercalation. A control on the polarity and the magnitude of the photoresponse (PR) is harnessed by manipulating the weight ratios of PANI to GO (viz., 1:1.5 and 1:2.2 are abbreviated as PG1.5 and PG2.2, respectively), where ±PR = 100(R{sub Dark} – R{sub UV-Vis})/R{sub Dark} and R corresponds to the resistance of the device in dark or UV-Vis illumination. To be precise, the PR from GO, PANI, PG1.5, and PG2.2 are +34%, −111%, −51%, and +58%, respectively.

  1. 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.

  2. 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.

  3. Self-assembled tunable photonic hyper-crystals

    CERN Document Server

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

    2013-01-01

    We demonstrate a novel artificial optical material, a 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.

  4. 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.

  5. Molecular wires self-assembled on a graphite surface.

    Science.gov (United States)

    Riemann, Andreas; Nelson, Brittany

    2009-04-21

    We report a scanning tunneling microscopy study of the amino acid l-methionine on highly ordered pyrolytic graphite deposited under ambient conditions. Our experiments demonstrate the ability of l-methionine to form highly regular structures on the surface of the graphite template. By means of self-assembly, the amino acid arranges itself into an array of molecular wires, i.e., well-ordered stripes of uniform width and separation. The spacing of these wires can be controlled with the deposition amount of the amino acid, whereas the width stays constant. The width of the wires is determined by two methionine molecules arranged with their carboxyl group facing each other. The regular separation of individual wires suggest a long-range interaction among them. Molecular mechanics calculations are used to compare the experimental results with a basic model for the methionine configuration on the surface. A model for the adsorption geometry of methionine on graphite is presented.

  6. Composition maps in self-assembled alloy quantum dots.

    Science.gov (United States)

    Medhekar, N V; Hegadekatte, V; Shenoy, V B

    2008-03-14

    Nanoscale variations in composition arising from the competition between chemical mixing effects and elastic relaxation can substantially influence the electronic and optical properties of self-assembled alloy quantum dots. Using a combination of finite element and quadratic programming optimization methods, we have developed an efficient technique to compute the equilibrium composition profiles in strained quantum dots. We find that the composition profiles depend strongly on the morphological features such as the slopes and curvatures of their surfaces and the presence of corners and edges as well as the ratio of the strain and chemical mixing energy densities. More generally, our approach provides a means to quantitatively model the interplay among the composition variations, the temperature, the strain, and the shapes of small-scale lattice-mismatched structures.

  7. 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

  8. Self-Assembly of Cerium Oxide Nanostructures in Ice Molds

    Energy Technology Data Exchange (ETDEWEB)

    Karakoti, Ajay S.; Kuchibhatla, Satyanarayana V N T; Baer, Donald R.; Thevuthasan, Suntharampillai; Sayle, Dean C.; Seal, Sudipta

    2008-08-01

    The formation of nanorods, driven by the physico-chemical phenomena during the freezing of ceria nanoparticle suspension is reported. During freezing a dilute solution of CeO2 nanocrystals, some nuclei remain in solution while others are trapped inside the voids formed within the growing ice front. Over time the particles trapped within the constrained geometries combined by an oriented attachment process to form ceria nanorods. The experimental observations are further supported through Molecular Dynamics (MD) simulations. These observations suggest a new possible strategy for the templated formation of nanostructures through self assembly by exploiting natural phenomena such as freezing of water. "(A portion of) The research described in this paper (poster or presentation) was performed in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory."

  9. 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.

  10. Electrochemical metallization of self-assembled porphyrin monolayers.

    Science.gov (United States)

    Nann, Thomas; Kielmann, Udo; Dietrich, Christoph

    2002-04-01

    Multifunctional sensor systems are becoming increasingly important in electroanalytical chemistry. Together with ongoing miniaturization there is a need for micro- and nanopatterning tools for thin electroactive layers (e.g. self-assembling monolayers). This paper documents a method for production of a micro-array of different metal-porphyrin monolayers with different sensor properties. A new method has been developed for the selective and local metallization of bare porphyrin monolayers by cathodic pulsing and sweeping. The metal-porphyrin monolayers obtained were characterized by cyclic voltammetry. It was shown that porphyrin monolayers can be metallized with manganese, iron, cobalt, and nickel by use of the new method. It is expected that all types of metal-porphyrin monolayers can be produced in the same manner.

  11. Tribological properties of OTS self-assembled monolayers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs)were prepared on the substrates of silicon and glass. The tribological properties were tested with a self-made point-contact pure sliding micro tribometer. The effect of humidity on the tribological properties of both OTS SAMs and the naked substrates were studied. When the substrate is covered by OTS monolayer, the friction coefficient is reduced from 0.5 to 0.1 and the stick-slip phenomenon is weakened. OTS monolayer can keep its friction coefficient steady in a wide range of humidity, because it is highly hydrophobic and thus not sensitive to humidity. In addition, the OTS monolayer has a considerable anti-wear ability.

  12. Regulated growth of diatom cells on self-assembled monolayers

    Directory of Open Access Journals (Sweden)

    Kobayashi Koichi

    2007-03-01

    Full Text Available Abstract We succeeded in regulating the growth of diatom cells on chemically modified glass surfaces. Glass surfaces were functionalized with -CF3, -CH3, -COOH, and -NH2 groups using the technique of self-assembled monolayers (SAM, and diatom cells were subsequently cultured on these surfaces. When the samples were rinsed after the adhesion of the diatom cells on the modified surfaces, the diatoms formed two dimensional arrays; this was not possible without the rinsing treatment. Furthermore, we examined the number of cells that grew and their motility by time-lapse imaging in order to clarify the interaction between the cells and SAMs. We hope that our results will be a basis for developing biodevices using living photosynthetic diatom cells.

  13. Self-assembling hydrogel scaffolds for photocatalytic hydrogen production

    Science.gov (United States)

    Weingarten, Adam S.; Kazantsev, Roman V.; Palmer, Liam C.; McClendon, Mark; Koltonow, Andrew R.; Samuel, Amanda P. S.; Kiebala, Derek J.; Wasielewski, Michael R.; Stupp, Samuel I.

    2014-11-01

    Integration into a soft material of all the molecular components necessary to generate storable fuels is an interesting target in supramolecular chemistry. The concept is inspired by the internal structure of photosynthetic organelles, such as plant chloroplasts, which colocalize molecules involved in light absorption, charge transport and catalysis to create chemical bonds using light energy. We report here on the light-driven production of hydrogen inside a hydrogel scaffold built by the supramolecular self-assembly of a perylene monoimide amphiphile. The charged ribbons formed can electrostatically attract a nickel-based catalyst, and electrolyte screening promotes gelation. We found the emergent phenomenon that screening by the catalyst or the electrolytes led to two-dimensional crystallization of the chromophore assemblies and enhanced the electronic coupling among the molecules. Photocatalytic production of hydrogen is observed in the three-dimensional environment of the hydrogel scaffold and the material is easily placed on surfaces or in the pores of solid supports.

  14. Probing individual quantum dots: noise in self-assembled systems.

    Science.gov (United States)

    Vicaro, K O; Gutiérrez, H R; Seabra, A C; Schulz, P A; Cotta, M A

    2009-11-01

    In this work we explore the noise characteristics in lithographically-defined two terminal devices containing self-assembled InAs/InP quantum dots. The experimental ensemble of InAs dots show random telegraph noise (RTN) with tuneable relative amplitude-up to 150%-in well defined temperature and source-drain applied voltage ranges. Our numerical simulation indicates that the RTN signature correlates with a very low number of quantum dots acting as effective charge storage centres in the structure for a given applied voltage. The modulation in relative amplitude variation can thus be associated to the altered electrostatic potential profile around such centres and enhanced carrier scattering provided by a charged dot.

  15. Self-assembly of Janus particles under shear.

    Science.gov (United States)

    Nikoubashman, Arash; Bianchi, Emanuela; Panagiotopoulos, Athanassios Z; Nikoubashman, Arash

    2015-05-21

    We investigate the self-assembly of colloidal Janus particles under shear flow by employing hybrid molecular dynamics simulations that explicitly take into account hydrodynamic interactions. Under quiescent conditions, the amphiphilic colloids form spherical micellar aggregates of different sizes, where the solvophobic hemispheres are directed towards the core and the solvophilic caps are exposed to the solvent. When sufficiently strong shear is applied, the micelles disaggregate with a consequent decay of the average cluster size. Nonetheless, we find an intermediate shear rate regime where the balance between rearrangement and dissociation favors the growth of the aggregates. Additionally, our simulations show that clusters composed of either 6 or 13 particles are the most stable towards the shear flow due to their high geometric symmetry. Our findings open up a new range of applications for Janus particles, ranging from biotechnology to sensor systems.

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

    Science.gov (United States)

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

    2015-07-01

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

  17. Self-Assembled Enzyme Nanoparticles for Carbon Dioxide Capture.

    Science.gov (United States)

    Shanbhag, Bhuvana Kamath; Liu, Boyin; Fu, Jing; Haritos, Victoria S; He, Lizhong

    2016-05-11

    Enzyme-based processes have shown promise as a sustainable alternative to amine-based processes for carbon dioxide capture. In this work, we have engineered carbonic anhydrase nanoparticles that retain 98% of hydratase activity in comparison to their free counterparts. Carbonic anhydrase was fused with a self-assembling peptide that facilitates the noncovalent assembly of the particle and together were recombinantly expressed from a single gene construct in Escherichia coli. The purified enzymes, when subjected to a reduced pH, form 50-200 nm nanoparticles. The CO2 capture capability of enzyme nanoparticles was demonstrated at ambient (22 ± 2 °C) and higher (50 °C) temperatures, under which the nanoparticles maintain their assembled state. The carrier-free enzymatic nanoparticles demonstrated here offer a new approach to stabilize and reuse enzymes in a simple and cost-effective manner.

  18. Control of Nanomaterial Self-Assembly in Ultrasonically Levitated Droplets.

    Science.gov (United States)

    Seddon, Annela M; Richardson, Sam J; Rastogi, Kunal; Plivelic, Tomás S; Squires, Adam M; Pfrang, Christian

    2016-04-01

    We demonstrate that acoustic trapping can be used to levitate and manipulate droplets of soft matter, in particular, lyotropic mesophases formed from self-assembly of different surfactants and lipids, which can be analyzed in a contact-less manner by X-ray scattering in a controlled gas-phase environment. On the macroscopic length scale, the dimensions and the orientation of the particle are shaped by the ultrasonic field, while on the microscopic length scale the nanostructure can be controlled by varying the humidity of the atmosphere around the droplet. We demonstrate levitation and in situ phase transitions of micellar, hexagonal, bicontinuous cubic, and lamellar phases. The technique opens up a wide range of new experimental approaches of fundamental importance for environmental, biological, and chemical research.

  19. Random lasing actions in self-assembled perovskite nanoparticles

    CERN Document Server

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

    2015-01-01

    Solution-based perovskite nanoparticles have been intensively studied in past few years due to their applications in both photovoltaic and optoelectronic devices. Here, based on the common ground between the solution-based perovskite and random lasers, we have studied the mirrorless lasing actions in self-assembled perovskite nanoparticles. After the synthesis from solution, discrete lasing peaks have been observed from the optically pumped perovskites without any well-defined cavity boundaries. The obtained quality (Q) factors and thresholds of random lasers are around 500 and 60 uJ/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 as 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...

  20. 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.

  1. Using Markov State Models to Study Self-Assembly

    CERN Document Server

    Perkett, Matthew R

    2014-01-01

    Markov state models (MSMs) have been demonstrated to be a powerful method for computationally studying intramolecular processes such as protein folding and macromolecular conformational changes. In this article, we present a new approach to construct MSMs that is applicable to modeling a broad class of multi-molecular assembly reactions. Distinct structures formed during assembly are distinguished by their undirected graphs, which are defined by strong subunit interactions. Spatial inhomogeneities of free subunits are accounted for using a recently developed Gaussian-based signature. Simplifications to this state identification are also investigated. The feasibility of this approach is demonstrated on two different coarse-grained models for virus self-assembly. We find good agreement between the dynamics predicted by the MSMs and long, unbiased simulations, and that the MSMs can reduce overall simulation time by orders of magnitude.

  2. Fulleropeptide esters as potential self-assembled antioxidants

    Directory of Open Access Journals (Sweden)

    Mira S. Bjelaković

    2015-04-01

    Full Text Available The potential use of amphiphilic fullerene derivatives as a bionanomaterial was investigated by cyclic voltammetry (CV, scanning electron microscopy (SEM, and the ferrous ion oxidation–xylenol orange (FOX method. Despite the disrupted delocalization of the π-electronic system over the C60 sphere, its antioxidant capacity remained high for all twelve derivatives. The compounds expressed up to two-fold and 5–12-fold better peroxide quenching capacity as compared to pristine C60 and standard antioxidant vitamin C, respectively. During precipitation and slow evaporation of the solvent, all compounds underwent spontaneous self-assembly giving ordered structures. The size and morphology of the resulting particles depend primarily on the sample concentration, and somewhat on the side chain structure.

  3. Mechanism for Rapid Self-Assembly of Block Copolymer Nanoparticles

    Science.gov (United States)

    Johnson, Brian K.; Prud'Homme, Robert K.

    2003-09-01

    Amphiphilic block copolymers in solution spontaneously self-assemble when the solvent quality for one block is selectively decreased. We demonstrate that, for supersaturation ratio changes [d(S)/dt] over 105 per second from equilibrium, nanoparticles are obtained with a formation mechanism and size dependent on the jumping rate and magnitude. The threshold rate for homogeneous precipitation is determined by the induction time of a particle, equivalent to the diffusion limited fusion of copolymer chains to form a corona of overlapping soluble brushes. Via determination of the induction time with a novel confined impinging jets mixer and use of a scaling relation, the interfacial free energy of a block copolymer nanoparticle was measured for the first time.

  4. Mechanical characterization of carbon nanomembranes from self-assembled monolayers

    Directory of Open Access Journals (Sweden)

    Xianghui Zhang

    2011-12-01

    Full Text Available This paper reports on the mechanical characterization of carbon nanomembranes (CNMs with a thickness of 1 nm that are fabricated by electron-induced crosslinking of aromatic self-assembled monolayers (SAMs. A novel type of in situ bulge test employing an atomic force microscope (AFM is utilized to investigate their mechanical properties. A series of biphenyl-based molecules with different types of terminal and/or anchor groups were used to prepare the CNMs, such as 4'-[(3-trimethoxysilylpropoxy]-[1,1'-biphenyl]-4-carbonitrile (CBPS, 1,1'-biphenyl-4-thiol (BPT and 4-nitro-1,1'-biphenyl-4-thiol (NBPT. The elastic properties, viscoelastic behaviors and ultimate tensile strength of these biphenyl-based CNMs are investigated and discussed.

  5. Sequence dependent proton conduction in self-assembled peptide nanostructures

    Science.gov (United States)

    Lerner Yardeni, Jenny; Amit, Moran; Ashkenasy, Gonen; Ashkenasy, Nurit

    2016-01-01

    The advancement of diverse electrochemistry technologies depends on the development of novel proton conducting polymers. Inspired by the efficacy of proton transport through proteins, we show in this work that self-assembling peptide nanostructures may be a promising alternative for such organic proton conducting materials. We demonstrate that aromatic amino acids, which participate in charge transport in nature, unprecedentedly promote proton conduction under both high and low relative humidity conditions for d,l α-cyclic peptide nanotubes. For dehydrated networks long-range order of the assemblies, induced by the aromatic side chains, is shown to be a dominating factor for promoting conductivity. However, for hydrated networks this order of effect is less significant and conductivity can be improved by the introduction of proton donating carboxylic acid peptide side chains in addition to the aromatic side chains despite the lower order of the assemblies. Based on these observations, a novel cyclic peptide that incorporates non-natural naphthyl side chains was designed. Self-assembled nanotubes of this peptide show greatly improved dehydrated conductivity, while maintaining high conductivity under hydrated conditions. We envision that the demonstrated modularity and versatility of these bio inspired nanostructures will make them extremely attractive building blocks for the fabrication of devices for energy conversion and storage applications, as well as other applications that involve proton transport, whether dry or wet conductivity is desired.The advancement of diverse electrochemistry technologies depends on the development of novel proton conducting polymers. Inspired by the efficacy of proton transport through proteins, we show in this work that self-assembling peptide nanostructures may be a promising alternative for such organic proton conducting materials. We demonstrate that aromatic amino acids, which participate in charge transport in nature

  6. 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.

  7. Self-assembled platinum nanochains based on octreotide acetate

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiaoning; Gao, Dawei, E-mail: dwgao@ysu.edu.cn; Gao, Faming, E-mail: fmgao@ysu.edu.cn; Li, Na; Zhou, Jing [Yanshan University, Applying Chemistry Key Lab of Hebei Province (China); Hao, Jikui [Illinois Institute of Technology, Department of Chemical and Biological Engineering (United States)

    2013-09-15

    Biological scaffolds are used for the synthesis of inorganic materials due to their ability to self-assemble and nucleate crystal formation. We reported a facile method for preparing self-assembled Pt nanochains by using octreotide acetate (AOC) as bio-template in aqueous environment. The influence of solution pH was examined to define the optimal conditions for the formation of the AOC bio-templated Pt nanoparticles (PtNPs) arrays, the AOC has diameter about 55 nm at pH 2.0, for comparison, at pH 9.0, the diameter of AOC is about 25 nm. After 24-h incubation of AOC (pH 2.0) with PtCl{sub 4} and chemical reduction with borane-dimethyl-amine, uniform platinum nanoparticles (mean diameter 2.5 {+-} 0.5 nm) directed by AOC were formed. Preliminary characterizations of the synthesized PtNPs were performed using transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, and selected area of electron diffraction. The cytotoxicity of Pt/octreotide acetate complexes (PtNPs-AOC) and AOC was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The results indicated that the antiproliferative effect of PtNPs-AOC is as high as AOC. In addition, the nano-design architecture of the Pt particles plays a crucial role in a strong enhancement of the biological efficiency of radiations, making PtNPs-AOC a promising material for anticancer drug delivery in the future.

  8. 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.

  9. Dynamic self-assembly in living systems as computation.

    Energy Technology Data Exchange (ETDEWEB)

    Bouchard, Ann Marie; Osbourn, Gordon Cecil

    2004-06-01

    Biochemical reactions taking place in living systems that map different inputs to specific outputs are intuitively recognized as performing information processing. Conventional wisdom distinguishes such proteins, whose primary function is to transfer and process information, from proteins that perform the vast majority of the construction, maintenance, and actuation tasks of the cell (assembling and disassembling macromolecular structures, producing movement, and synthesizing and degrading molecules). In this paper, we examine the computing capabilities of biological processes in the context of the formal model of computing known as the random access machine (RAM) [Dewdney AK (1993) The New Turing Omnibus. Computer Science Press, New York], which is equivalent to a Turing machine [Minsky ML (1967) Computation: Finite and Infinite Machines. Prentice-Hall, Englewood Cliffs, NJ]. When viewed from the RAM perspective, we observe that many of these dynamic self-assembly processes - synthesis, degradation, assembly, movement - do carry out computational operations. We also show that the same computing model is applicable at other hierarchical levels of biological systems (e.g., cellular or organism networks as well as molecular networks). We present stochastic simulations of idealized protein networks designed explicitly to carry out a numeric calculation. We explore the reliability of such computations and discuss error-correction strategies (algorithms) employed by living systems. Finally, we discuss some real examples of dynamic self-assembly processes that occur in living systems, and describe the RAM computer programs they implement. Thus, by viewing the processes of living systems from the RAM perspective, a far greater fraction of these processes can be understood as computing than has been previously recognized.

  10. Coupling self-assembled quantum dots to nanostructures

    Science.gov (United States)

    Badolato, Antonio

    Self-assembled quantum dot (QD) grown by molecular beam epitaxy implements the ultimate quantum confined structure in the solid-state. Because electrons are confined in all three dimensions, QDs have shown delta-function-like energy dependence of the density of states. The identification of QDs as artificial atoms has been proven by the observation of fundamental exciton emission with perfect photon antibunching and with a linewidth limited by spontaneous emission. As artificial atoms that can be monolithically integrated with other functional devices in the setting of semiconductor technology, QDs have been the source of inspiration of several novel quantum devices. Nonetheless, QD self-assemble on random nucleation sites, whereas many proposals require precise positioning of a single QD. In this thesis, two new elements of design and control for coupling single QDs to single nanostructure will be presented: (i) a technique to control ab-initio the site nucleation of a single QD and (ii) a deterministic approach to the coupling of single QDs to single nanocavity modes. Chapter 1 is dedicated to a theoretical overview of the QD system, first, as a solid-state heterostructure that confines electrons and, second, as an artificial atom interacting with confined photons. Chapter 2 presents a technique to grow highly ordered QD arrays by engineering subsurface periodic strain templates. This technique achieved almost perfect registering of single QDs into a two-dimensional lattice. In Chapter 3 a deterministic approach to the realization of solid-state cavity quantum electrodynamics (QED) systems is demonstrated. Based on a precise spatial and spectral matching between a single QD and a PC microcavity, this approach yielded cavity QED effects (such as Purcell effect) in all fabricated nanostructures.

  11. 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.

  12. Origami Inspired Self-assembly of Patterned and Reconfigurable Particles

    Science.gov (United States)

    Pandey, Shivendra; Gultepe, Evin; Gracias, David H.

    2013-01-01

    There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two dimensional (2D) structures. These technologies are mature, offer high precision and many of them can be implemented in a high-throughput manner. We leverage the advantages of planar lithography and combine them with self-folding methods1-20 wherein physical forces derived from surface tension or residual stress, are used to curve or fold planar structures into three dimensional (3D) structures. In doing so, we make it possible to mass produce precisely patterned static and reconfigurable particles that are challenging to synthesize. In this paper, we detail visualized experimental protocols to create patterned particles, notably, (a) permanently bonded, hollow, polyhedra that self-assemble and self-seal due to the minimization of surface energy of liquefied hinges21-23 and (b) grippers that self-fold due to residual stress powered hinges24,25. The specific protocol described can be used to create particles with overall sizes ranging from the micrometer to the centimeter length scales. Further, arbitrary patterns can be defined on the surfaces of the particles of importance in colloidal science, electronics, optics and medicine. More generally, the concept of self-assembling mechanically rigid particles with self-sealing hinges is applicable, with some process modifications, to the creation of particles at even smaller, 100 nm length scales22, 26 and with a range of materials including metals21, semiconductors9 and polymers27. With respect to residual stress powered actuation of reconfigurable grasping devices, our specific protocol utilizes chromium hinges of relevance to devices with sizes ranging from 100 μm to 2.5 mm. However, more generally, the concept of such tether-free residual stress powered actuation can be used with alternate high-stress materials such as heteroepitaxially deposited semiconductor films5,7 to

  13. Programmed DNA Self-Assembly and Logic Circuits

    Science.gov (United States)

    Li, Wei

    DNA is a unique, highly programmable and addressable biomolecule. Due to its reliable and predictable base recognition behavior, uniform structural properties, and extraordinary stability, DNA molecules are desirable substrates for biological computation and nanotechnology. The field of DNA computation has gained considerable attention due to the possibility of exploiting the massive parallelism that is inherent in natural systems to solve computational problems. This dissertation focuses on building novel types of computational DNA systems based on both DNA reaction networks and DNA nanotechnology. A series of related research projects are presented here. First, a novel, three-input majority logic gate based on DNA strand displacement reactions was constructed. Here, the three inputs in the majority gate have equal priority, and the output will be true if any two of the inputs are true. We subsequently designed and realized a complex, 5-input majority logic gate. By controlling two of the five inputs, the complex gate is capable of realizing every combination of OR and AND gates of the other 3 inputs. Next, we constructed a half adder, which is a basic arithmetic unit, from DNA strand operated XOR and AND gates. The aim of these two projects was to develop novel types of DNA logic gates to enrich the DNA computation toolbox, and to examine plausible ways to implement large scale DNA logic circuits. The third project utilized a two dimensional DNA origami frame shaped structure with a hollow interior where DNA hybridization seeds were selectively positioned to control the assembly of small DNA tile building blocks. The small DNA tiles were directed to fill the hollow interior of the DNA origami frame, guided through sticky end interactions at prescribed positions. This research shed light on the fundamental behavior of DNA based self-assembling systems, and provided the information necessary to build programmed nanodisplays based on the self-assembly of DNA.

  14. Novel self assembly behavior for γ-alumina nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Osama Saber

    2012-01-01

    In this study,self assembly behavior was induced for γ-alumina nanoparticles by adsorption of dimethyl disulfide.Following this trend,we have developed a chemical process to obtain γ-alumina in the nano scale.Scanning electron microscopy images of the prepared γ-alumina showed big and strong agglomeration of the nanoparticles indicating that these nanoparticles have strong surface forces.Transmission electron microscopy images confirmed that the γ-alumina nanoparticles 3-7 nm in size were converted to uniform spherical shape in the size range of 1-2 mm after shaking with dimethyl disulfide in the presence of n-hexane at room temperature.This phenomenon did not appear in the case of alumina in the micro scale.The surface properties of the prepared γ-alumina in the nano scale were characterized and compared with the γ-alumina in the micro scale by using low temperature nitrogen adsorption-desorption system,indicating that the specific surface area of the prepared γ-alumina nanoparticles is larger than that of the γ-alumina in the micro scale.Furthermore,micro-and meso-pores were observed for the γ-alumina nanoparticles while only mesoporous structure was detected for the γ-alumina in the micro scale.These experimental results suggested that the self assembly behavior of the γ-alumina nanoparticles may be due to the selective adsorption of dimethyl disulfide in the micropores of these nanoparticles to act as bridge linking the nanoparticles.

  15. Chemically sensitive surface plasmon devices employing a self-assembled monolayer composite film

    Science.gov (United States)

    DePriest, J. C.; Meriaudeau, Fabrice; Oden, Patrick I.; Downey, Todd R.; Passian, A.; Wig, A. G.; Ferrell, Trinidad L.

    1998-12-01

    In this paper the results of detecting volatile organic compounds (VOC) employing surface plasmon-based sensors are presented. The initial step in preparing the sensing elements herein requires depositing Au degree(s) on a quartz slide. The sensing elements are based on either (1) freshly deposited Au degree(s) or (2) growth of a self assembled monolayer composite film (SAM) on to a freshly deposited Au degree(s) surface. The desired SAM is either (1) acid terminated using (omega) -mercaptoundecanoic acid (MUA-COOH) or (2) Cu2+ metal ion terminated yielding (omega) - mercaptoundecanoic acid-Cu2+ (MUA-Cu2+). The experimental apparatus shown here measures the reflectivity of the Au degree(s) surface as a function of time at a given angle. The response of this surface plasmon device to various VOC's is correlated to the composition of the SAM film.

  16. The magneto-elastica: from self-buckling to self-assembly

    KAUST Repository

    Vella, D.

    2013-12-04

    Spherical neodymium-iron-boron magnets are permanent magnets that can be assembled into a variety of structures owing to their high magnetic strength. A one-dimensional chain of these magnets responds to mechanical loadings in a manner reminiscent of an elastic rod. We investigate the macroscopic mechanical properties of assemblies of ferromagnetic spheres by considering chains, rings and chiral cylinders of magnets. Based on energy estimates and simple experiments, we introduce an effective magnetic bending stiffness for a chain of magnets and show that, used in conjunction with classic results for elastic rods, it provides excellent estimates for the buckling and vibration dynamics of magnetic chains. We then use this estimate to understand the dynamic self-assembly of a cylinder from an initially straight chain of magnets.

  17. Free-energy functional method for inverse problem of self assembly

    Science.gov (United States)

    Torikai, Masashi

    2015-04-01

    A new theoretical approach is described for the inverse self-assembly problem, i.e., the reconstruction of the interparticle interaction from a given structure. This theory is based on the variational principle for the functional that is constructed from a free energy functional in combination with Percus's approach [J. Percus, Phys. Rev. Lett. 8, 462 (1962)]. In this theory, the interparticle interaction potential for the given structure is obtained as the function that maximizes the functional. As test cases, the interparticle potentials for two-dimensional crystals, such as square, honeycomb, and kagome lattices, are predicted by this theory. The formation of each target lattice from an initial random particle configuration in Monte Carlo simulations with the predicted interparticle interaction indicates that the theory is successfully applied to the test cases.

  18. Fabrication of PEDOT/PSS-ZnO nanowire by self-assembly method under vacuum condition

    Institute of Scientific and Technical Information of China (English)

    QI Yingqun; WANG Tiejun; HU Xiujie; CHEN Ping

    2005-01-01

    In this paper, cable-like PEDOT/PSS-ZnO nanowires are successfully fabricated under vacuum condition by self-assembly of the PEDOT/PSS-ZnO composite initially prepared via sol-gel method. Characterized by TEM and EDX, the nanowire is found to have a polycrystalline ZnO inner core that is sheathed by the PEDOT/PSS blends and the nanowire has an outer diameter of ca. 100 nm. The results also indicate that the morphology of PEDOT/PSS- ZnO nanocomposite is greatly influenced by external vacuum condition and aging time. The feasible and simple approach that we have developed provides a new strategy for the synthesis of novel one-dimensional nanocomposites.

  19. Organoids and the genetically encoded self-assembly of embryonic stem cells.

    Science.gov (United States)

    Turner, David A; Baillie-Johnson, Peter; Martinez Arias, Alfonso

    2016-02-01

    Understanding the mechanisms of early embryonic patterning and the timely allocation of specific cells to embryonic regions and fates as well as their development into tissues and organs, is a fundamental problem in Developmental Biology. The classical explanation for this process had been built around the notion of positional information. Accordingly the programmed appearance of sources of Morphogens at localized positions within a field of cells directs their differentiation. Recently, the development of organs and tissues from unpatterned and initially identical stem cells (adult and embryonic) has challenged the need for positional information and even the integrity of the embryo, for pattern formation. Here we review the emerging area of organoid biology from the perspective of Developmental Biology. We argue that the events underlying the development of these systems are not purely linked to self-organization, as often suggested, but rather to a process of genetically encoded self-assembly where genetic programs encode and control the emergence of biological structures.

  20. Time dependent Bloch mode transmittance in self-assembled random photonic crystal for photonic time delay switching

    Science.gov (United States)

    Bingi, Jayachandra; Nair, Radhika V.; Vijayan, C.

    2017-02-01

    Light propagation and localization in a random structure with a periodic background is an upcoming paradigm for novel photonic applications. This paper demonstrates the phenomenon of time dependent transmittance of evanescent Bloch modes (EBM) in ZnS random photonic crystal (RPC) which forms the basis for photonic delay switching. The RPC is fabricated by colloidal self-assembly with ZnS nanospheres of size 215 nm. An anomalous reciprocity and time dependent transmission at EBM (mid band gap wavelength) are observed in coherent back scattering and transmission studies respectively. These are explained on the basis of restricted propagation of EBMs through random channels in the periodic background and enhanced field storage inside RPC. The channelized propagation of EBMs is evident from decreasing time delay of transmittance at reduced thicknesses. The proportionality between transmission time delay and incident power confirms photon (field) storage within the RPC. The results indicate that structures with systematically engineered EBM channels can work as wavelength selective delay switch and further provide a short time photon storage system under non-absorbing conditions.

  1. Fabrication of molecular nanopatterns at aluminium oxide surfaces by nanoshaving of self-assembled monolayers of alkylphosphonates.

    Science.gov (United States)

    El Zubir, Osama; Barlow, Iain; Leggett, Graham J; Williams, Nicholas H

    2013-11-21

    Nanoshaving, by tracing an atomic force microscope probe across a surface at elevated load, has been used to fabricate nanostructures in self-assembled monolayers of alkylphosphonates adsorbed at aluminium oxide surfaces. The simple process is implemented under ambient conditions. Because of the strong bond between the alkylphosphonates and the oxide surface, loads in excess of 400 nN are required to pattern the monolayer. Following patterning of octadecylphosphonate SAMs, adsorption of aminobutyl phosphonate yielded features as small as 39 nm. Shaving of monolayers of aryl azide-terminated alkylphosphonates, followed by attachment of polyethylene glycol to unmodified regions in a photochemical coupling reaction, yielded 102 nm trenches into which NeutrAvidin coated, dye-labelled, polymer nanospheres could be deposited, yielding bright fluorescence with little evidence of non-specific adsorption to other regions of the surface. Structures formed in alkylphosphonate films by nanoshaving were used to etch structures into the underlying metal. Because of the isotropic nature of the etch process, and the large grain size, some broadening was observed, but features 25-35 nm deep and 180 nm wide were fabricated.

  2. Ca(2+) Mediates the Self-Assembly of the Foot Proteins of Pinctada fucata from the Nanoscale to the Microscale.

    Science.gov (United States)

    Liu, Chuang; Xie, Liping; Zhang, Rongqing

    2016-10-10

    Bivalve animals such as mussels and pearl oysters secrete proteinaceous byssus from the foot to attach themselves to solid surfaces under seawater. Although the biomolecules of mussel byssus have been extensively studied, how they form insoluble threads underwater from soluble protein precursors and how they produce hierarchical microscale threads from biomolecules remains unclear. Here, using the pearl oyster Pinctada fucata as a model, metal ions rather than pH are found to play critical roles in the solidification process of the byssus. Particularly, Ca(2+) can induce self-assembly of the foot proteins and the byssal proteins, resulting in aggregate formation. At a concentration of 10 mM, protein fibers with a diameter of approximately 26 μm and a length ranging from 50 to 400 μm were formed. Moreover, the fibers are composed of 60-90 nm nanospheres, reminiscent of the ultrastructure sizes of threads. It is proposed that Ca(2+) can interact with byssal proteins such as thrombospondin-1 containing protein through phosphorylated serine and/or von Willebrand factor type A domains. This study provides insight into how the byssus forms from the soluble protein molecules into insoluble threads underwater and may inspire further biomaterial design for underwater use.

  3. 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.

  4. Synthetic Molecular Machines for Active Self-Assembly: Prototype Algorithms, Designs, and Experimental Study

    Science.gov (United States)

    Dabby, Nadine L.

    behaviors. This class of behaviors includes any behavior where a passive physical system simply does not have enough physical energy to perform the specified tasks in the requisite amount of time. As we will demonstrate and prove, a sufficiently expressive implementation of an "active" molecular self-assembly approach can achieve these behaviors. Using an external source of fuel solves part of the problem, so the system is not "energetically incomplete." But the programmable system also needs to have sufficient expressive power to achieve the specified behaviors. Perhaps surprisingly, some of these systems do not even require Turing completeness to be sufficiently expressive. Building on a large variety of work by other scientists in the fields of DNA nanotechnology, chemistry and reconfigurable robotics, this thesis introduces several research contributions in the context of active self-assembly. We show that simple primitives such as insertion and deletion are able to generate complex and interesting results such as the growth of a linear polymer in logarithmic time and the ability of a linear polymer to treadmill. To this end we developed a formal model for active-self assembly that is directly implementable with DNA molecules. We show that this model is computationally equivalent to a machine capable of producing strings that are stronger than regular languages and, at most, as strong as context-free grammars. This is a great advance in the theory of active self-assembly as prior models were either entirely theoretical or only implementable in the context of macro-scale robotics. We developed a chain reaction method for the autonomous exponential growth of a linear DNA polymer. Our method is based on the insertion of molecules into the assembly, which generates two new insertion sites for every initial one employed. The building of a line in logarithmic time is a first step toward building a shape in logarithmic time. We demonstrate the first construction of a synthetic

  5. Light-triggered self-assembly of a dichromonyl compound in water

    NARCIS (Netherlands)

    Velema, Willem A.; Stuart, Marc C. A.; Szymanski, Wiktor; Feringa, Ben L.

    2013-01-01

    External control over self-assembling structures is achieved by incorporating an azobenzene photoswitch into the structure of a dichromonyl compound. The self-assembly of dichromonyl compounds into fibers leads to the formation of a hydrogel and can be triggered with visible light.

  6. 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...

  7. 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...

  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 nanos...

  9. Ultra-Thin Self-Assembled Protein-Polymer Membranes : A New Pore Forming Strategy

    NARCIS (Netherlands)

    van Rijn, Patrick; Tutus, Murat; Kathrein, Christine; Mougin, Nathalie C.; Park, Hyunji; Hein, Christopher; Schuerings, Marco P.; Boeker, Alexander

    2014-01-01

    Self-assembled membranes offer a promising alternative for conventional membrane fabrication, especially in the field of ultrafiltration. Here, a new pore-making strategy is introduced involving stimuli responsive proteinpolymer conjugates self-assembled across a large surface area using dryingmedia

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

    NARCIS (Netherlands)

    Kim, B.J.; Liebau, M.; Huskens, J.; Reinhoudt, D.N.; 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 dodecyltrichlorosil

  11. Reversible Self-Assembly of Backbone-Thermoresponsive Long Chain Hyperbranched Poly(N-Isopropyl Acrylamide

    Directory of Open Access Journals (Sweden)

    Ting-Ting Liu

    2016-01-01

    Full Text Available In this paper, we mainly described the reversible self-assembly of a backbone-thermoresponsive, long-chain, hyperbranched poly(N-isopropyl acrylamide (LCHBPNIPAM in aqueous solution. Here, we revealed a reversible self-assembly behavior of LCHBPNIPAM aqueous solution derived from temperature. By controlling the temperature of LCHBPNIPAM aqueous solution, we tune the morphology of the LCHBPNIPAM self-assemblies. When the solution temperature increased from the room temperature to the lower critical solution temperature of PNIPAM segments, LCHBPNIPAM self-assembled from multi-compartment vesicles into solid micelles. The morphology of LCHBPNIPAM self-assemblies changed from solid micelles to multi-compartment vesicles again when the temperature decreased back to the room temperature. The size presented, at first, an increase, and then a decrease, tendency in the heating-cooling process. The above thermally-triggered self-assembly behavior of LCHBPNIPAM aqueous solution was investigated by dynamic/static light scattering, transmission electron microscopy, atomic force microscopy, fluorescence spectroscopy, 1H nuclear magnetic resonance in D2O, and attenuated total reflectance Fourier transform infrared spectroscopy. These results indicated that LCHBPNIPAM aqueous solution presents a reversible self-assembly process. The controlled release behaviors of doxorubicin from the vesicles and micelles formed by LCHBPNIPAM further proved the feasibility of these self-assemblies as the stimulus-responsive drug delivery system.

  12. Decorated self-assembling β(3)-tripeptide foldamers form cell adhesive scaffolds.

    Science.gov (United States)

    Luder, Kerstin; Kulkarni, Ketav; Lee, Huey Wen; Widdop, Robert E; Del Borgo, Mark P; Aguilar, Marie-Isabel

    2016-03-25

    A popular strategy to control cellular growth and differentiation is the employment of self-assembling peptides as biomaterials. In this study we decorated ultrashort helical N-acetylated β-tripeptides with cell adhesion signals IKVAV and RGD, which spontaneously self-assemble to give nanofibres with multiple signals, and form a bioscaffold that supports the growth of cells.

  13. 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.

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

    Science.gov (United States)

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

    2009-01-01

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

  15. Self-assembling microsphere-based dextran hydrogels for pharmaceutical applications

    NARCIS (Netherlands)

    Van Tomme, S.R.

    2007-01-01

    In this thesis novel self-assembling hydrogels, based on physical interactions between dextran microgels, potentially suitable for controlled drug delivery and tissue engineering, are presented. Two different approaches to self-assemble the hydrogels were investigated: ionic interactions and hydroph

  16. Self-assembled vesicles of urea-tethered foldamers as hydrophobic drug carriers.

    Science.gov (United States)

    Ingole, Tukaram S; Kale, Sangram S; Santhosh Babu, Sukumaran; Sanjayan, Gangadhar J

    2016-08-25

    Molecular self-assembly of nonamphiphilic α,β-hybrid foldamers based on urea-tethered anthranilic acid-proline (Ant-Pro) foldamers is reported. These self-assembled hollow vesicular architectures can take up and release the anticancer hydrophobic drug curcumin.

  17. Synthesis, characterization and self-assembly of Co3+ complexes appended with phenol and catechol groups

    Indian Academy of Sciences (India)

    Afsar Ali; Deepak Bansal; Rajeev Gupt

    2014-09-01

    This work presents the syntheses, characterization and hydrogen bonding based self-assembly of Co3+ complexes of pyridine-amide based bidentate ligands containing appended phenol and catechol groups. Placement of multiple hydrogen bond donors (phenolic OH and amidic NH groups) and acceptors (Oamide groups) in these molecules results in interesting self-assembled architectures.

  18. 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.

  19. Self-assembling tryptophan-based designer peptides as intracellular delivery vehicles.

    Science.gov (United States)

    Bhardwaj, Ishanki; Jha, Divya; Admane, Prasad; Panda, Amulya K; Haridas, V

    2016-01-15

    A series of tryptophan-based peptides W1a, b-W4a, b, with diverse architectures were designed and synthesized. These tryptophan containing peptides can self-assemble to spherical particle. This self-assembled system was demonstrated to encapsulate rhodamine B and penetrate the cell membrane.

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  1. Self-assembly of the hydrophobin SC3 proceeds via two structural intermediates

    NARCIS (Netherlands)

    Vocht, Marcel L. de; Reviakine, Ilya; Ulrich, Wolf-Peter; Bergsma-Schutter, Wilma; Wösten, Han A.B.; Vogel, Horst; Brisson, Alain; Wessels, Joseph G.H.; Robillard, George T.

    2002-01-01

    Hydrophobins self assemble into amphipathic films at hydrophobic–hydrophilic interfaces. These proteins are involved in a broad range of processes in fungal development. We have studied the conformational changes that accompany the self-assembly of the hydrophobin SC3 with polarization-modulation in

  2. Self-assembled cardanol azo derivatives as antifungal agent with chitin-binding ability.

    Science.gov (United States)

    Mahata, Denial; Mandal, Santi M; Bharti, Rashmi; Gupta, Vinay Krishna; Mandal, Mahitosh; Nag, Ahindra; Nando, Golok B

    2014-08-01

    Cardanol is a non-isoprenoic phenolic lipid-mixture of distilled cashew nut shell liquid obtained from Anacardium occidentale. Herein, cardanol is purified from cashew nut shell liquid (CNSL) and synthesized to new compounds with different azo amphiphiles. These synthesized compounds are allowed to self-assembled in hydrophobic environment and checked antifungal activity against Candida albicans. Self-assembled structure of CABA showed higher antifungal activity (16μg/mL) and chitin-binding ability in comparison to CAP and CANB. Furthermore, the self-assembled azo amphiphiles are immobilized with silver ions to prepare hydrogel which showed eight folds enhanced antifungal activity. Toxicity is reduced by several folds of self-assembled or hydrogel structure in comparison to pure compounds. Thus, the self-assembled structure of amphiphiles and their hydrogels have been found to be new macromolecules of interest with potential use as antifungal drugs.

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

    Science.gov (United States)

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

    2011-01-01

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

  4. TOPICAL REVIEW: Challenges and breakthroughs in recent research on self-assembly

    Directory of Open Access Journals (Sweden)

    Katsuhiko Ariga, Jonathan P Hill, Michael V Lee, Ajayan Vinu, Richard Charvet and Somobrata Acharya

    2008-01-01

    Full Text Available The controlled fabrication of nanometer-scale objects is without doubt one of the central issues in current science and technology. However, existing fabrication techniques suffer from several disadvantages including size-restrictions and a general paucity of applicable materials. Because of this, the development of alternative approaches based on supramolecular self-assembly processes is anticipated as a breakthrough methodology. This review article aims to comprehensively summarize the salient aspects of self-assembly through the introduction of the recent challenges and breakthroughs in three categories: (i types of self-assembly in bulk media; (ii types of components for self-assembly in bulk media; and (iii self-assembly at interfaces.

  5. Self-assembled peptide nanomaterials for biomedical applications: promises and pitfalls

    Science.gov (United States)

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

    2017-01-01

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

  6. Development of injectable organic/inorganic colloidal composite gels made of self-assembling gelatin nanospheres and calcium phosphate nanocrystals

    NARCIS (Netherlands)

    Wang, H.; Bongio, M.; Farbod, K.; Nijhuis, A.W.G.; Beucken, J.J. van den; Boerman, O.C.; Hest, J.C.M. van; Li, Y.; Jansen, J.A.; Leeuwenburgh, S.C.G.

    2014-01-01

    Colloidal gels are a particularly attractive class of hydrogels for applications in regenerative medicine, and allow for a "bottom-up" fabrication of multi-functional biomaterials by employing micro- or nanoscale particles as building blocks to assemble into shape-specific bulk scaffolds. So far, ho

  7. Lattice model of equilibrium polymerization. VII. Understanding the role of "cooperativity" in self-assembly.

    Science.gov (United States)

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

    2008-06-14

    Cooperativity is an emergent many-body phenomenon related to the degree to which elementary entities (particles, molecules, organisms) collectively interact to form larger scale structures. From the standpoint of a formal mean field description of chemical reactions, the cooperativity index m, describing the number of elements involved in this structural self-organization, is the order of the reaction. Thus, m for molecular self-assembly is the number of molecules in the final organized structure, e.g., spherical micelles. Although cooperativity is crucial for regulating the thermodynamics and dynamics of self-assembly, there is a limited understanding of this aspect of self-assembly. We analyze the cooperativity by calculating essential thermodynamic properties of the classical mth order reaction model of self-assembly (FAm model), including universal scaling functions describing the temperature and concentration dependence of the order parameter and average cluster size. The competition between self-assembly and phase separation is also described. We demonstrate that a sequential model of thermally activated equilibrium polymerization can quantitatively be related to the FAm model. Our analysis indicates that the essential requirement for "cooperative" self-assembly is the introduction of constraints (often nonlocal) acting on the individual assembly events to regulate the thermodynamic free energy landscape and, thus, the thermodynamic sharpness of the assembly transition. An effective value of m is defined for general self-assembly transitions, and we find a general tendency for self-assembly to become a true phase transition as m-->infinity. Finally, various quantitative measures of self-assembly cooperativity are discussed in order to identify experimental signatures of cooperativity in self-assembling systems and to provide a reliable metric for the degree of transition cooperativity.

  8. Engineering cellular fibers for musculoskeletal soft tissues using directed self-assembly.

    Science.gov (United States)

    Schiele, Nathan R; Koppes, Ryan A; Chrisey, Douglas B; Corr, David T

    2013-05-01

    Engineering strategies guided by developmental biology may enhance and accelerate in vitro tissue formation for tissue engineering and regenerative medicine applications. In this study, we looked toward embryonic tendon development as a model system to guide our soft tissue engineering approach. To direct cellular self-assembly, we utilized laser micromachined, differentially adherent growth channels lined with fibronectin. The micromachined growth channels directed human dermal fibroblast cells to form single cellular fibers, without the need for a provisional three-dimensional extracellular matrix or scaffold to establish a fiber structure. Therefore, the resulting tissue structure and mechanical characteristics were determined solely by the cells. Due to the self-assembly nature of this approach, the growing fibers exhibit some key aspects of embryonic tendon development, such as high cellularity, the rapid formation (within 24 h) of a highly organized and aligned cellular structure, and the expression of cadherin-11 (indicating direct cell-to-cell adhesions). To provide a dynamic mechanical environment, we have also developed and characterized a method to apply precise cyclic tensile strain to the cellular fibers as they develop. After an initial period of cellular fiber formation (24 h postseeding), cyclic strain was applied for 48 h, in 8-h intervals, with tensile strain increasing from 0.7% to 1.0%, and at a frequency of 0.5 Hz. Dynamic loading dramatically increased cellular fiber mechanical properties with a nearly twofold increase in both the linear region stiffness and maximum load at failure, thereby demonstrating a mechanism for enhancing cellular fiber formation and mechanical properties. Tissue engineering strategies, designed to capture key aspects of embryonic development, may provide unique insight into accelerated maturation of engineered replacement tissue, and offer significant advances for regenerative medicine applications in tendon

  9. Molecular self-assembly for biological investigations and nanoscale lithography

    Science.gov (United States)

    Cheunkar, Sarawut

    Small, diffusible molecules when recognized by their binding partners, such as proteins and antibodies, trigger enzymatic activity, cell communication, and immune response. Progress in analytical methods enabling detection, characterization, and visualization of biological dynamics at the molecular level will advance our exploration of complex biological systems. In this dissertation, analytical platforms were fabricated to capture membrane-associated receptors, which are essential proteins in cell signaling pathways. The neurotransmitter serotonin and its biological precursor were immobilized on gold substrates coated with self-assembled monolayers (SAMs) of oligo(ethylene glycol)alkanethiols and their reactive derivatives. The SAM-coated substrates present the biologically selective affinity of immobilized molecules to target native membrane-associated receptors. These substrates were also tested for biospecificity using antibodies. In addition, small-molecule-functionalized platforms, expressing neurotransmitter pharmacophores, were employed to examine kinetic interactions between G-protein-coupled receptors and their associated neurotransmitters. The binding interactions were monitored using a quartz crystal microbalance equipped with liquid-flow injection. The interaction kinetics of G-protein-coupled serotonin 1A receptor and 5-hydroxytyptophan-functionalized surfaces were studied in a real-time, label-free environment. Key binding parameters, such as equilibrium dissociation constants, binding rate constants, and dissociative half-life, were extracted. These parameters are critical for understanding and comparing biomolecular interactions in modern biomedical research. By integrating self-assembly, surface functionalization, and nanofabrication, small-molecule microarrays were created for high-throughput screening. A hybrid soft-lithography, called microcontact insertion printing, was used to pattern small molecules at the dilute scales necessary for highly

  10. Self-assembly studies of native and recombinant fibrous proteins

    Science.gov (United States)

    Wilson, Donna Lucille

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

  11. Self-assembly and interactions of biomimetic thin films

    Science.gov (United States)

    Handa, Hitesh

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

  12. Strong plasmon coupling in self-assembled superparamagnetic nanoshell chains

    Science.gov (United States)

    Xiong, Min; Jin, Xiulong; Ye, Jian

    2016-02-01

    Construction of ordered patterns of plasmonic nanoparticles is greatly important for nanophotonics relevant applications. We have reported a facile and low-cost magnetic field induced self-assembly approach to construct plasmonic superparamagnetic nanoshell (SN) chains up to several hundred micrometers in a few seconds in a large area without templates or other assistance processes. Experimental and theoretical investigations of the near- and far-field optical properties indicate that the super- and sub-radiant modes of the SN chains continuously redshift with the increase of SN number and the Fano resonance emerges in the infinite double- and triple-line SN chains. Strong plasmon coupling effects in the SN chains result in great electric field enhancements at visible and infrared wavelengths, which indicates that these chain structures potentially can be used as a common substrate for both surface enhanced Raman scattering (SERS) and surface-enhanced infrared absorption (SEIRA) application. This fabrication method also offers a general strategy alternative to top-down processing that enables the construction of nanostructures for metamaterials, electromagnetic energy transport, and optical waveguide.Construction of ordered patterns of plasmonic nanoparticles is greatly important for nanophotonics relevant applications. We have reported a facile and low-cost magnetic field induced self-assembly approach to construct plasmonic superparamagnetic nanoshell (SN) chains up to several hundred micrometers in a few seconds in a large area without templates or other assistance processes. Experimental and theoretical investigations of the near- and far-field optical properties indicate that the super- and sub-radiant modes of the SN chains continuously redshift with the increase of SN number and the Fano resonance emerges in the infinite double- and triple-line SN chains. Strong plasmon coupling effects in the SN chains result in great electric field enhancements at visible

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-24

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

  14. Self-assembly of Nanopatterns on Shape Memory Polymer Substrates

    Science.gov (United States)

    Chen, Zhongbi

    Periodic surface nanostructures provide unique acoustic, electronic, optical and mechanical properties, with potential applications to metamaterials, sensors, catalysis, medicine, etc. However, assembling nanometer scale constituents into engineering scale components or devices poses tremendous challenges such as cost reduction and scalability. In this work, we will introduce a novel directed self-assembly method that has the potential to address these challenges by forming unidirectional micro- and nano-wrinkles on engineering scale polymer substrates. The approach utilizes a smart material, shape memory polymer (SMP), as the substrate in a bi-layer thin-film/substrate system. With a specially-designed programming scheme, the SMP substrate can retract in one direction while expand in the perpendicular direction in a heating process. Consequently, the thin film corrugates and the wrinkling patterns are aligned. A parametric study that investigates how the system parameters influence the surface topology will be presented. Besides wrinkles, surface defects that occurred concurrently were also observed. We will present a progressive damage scheme and a microdomain-based model to understand and possibly help preventing the formation of defects. In addition, this work will also address our efforts in shrinking the wrinkle feature size from several microns to the tens of nanometer range. Two methods, through which the minimum wrinkle wavelength was reduced from one micron to 300 nm and further down to 35 nm will be elaborated. Such aligned wrinkles whose wavelength spanning two orders of magnitude from as small as 35 nm to as large as 5 mum will open up avenues for numerous exciting applications. The application of using the self-assembled wrinkled surface as the back-reflector in solar cells to improve the power conversion efficiency will be discussed as a case study. The long-term stability of the wrinkle topology, which is essential to efficiency boost will be

  15. Cryogenic Electron Microscopy Studies: Structure and Formation of Self-assembled Nanostructures in Solution

    Science.gov (United States)

    Lee, Han Seung

    Cryogenic electron microscopy (Cryo-EM) techniques are among the most powerful to characterize self-assembling soft materials (colloids, polymers, and microemulsions, etc.) at the nanometer scale, without any need for implicit models or assumptions about the structure. We can even visualize structure under dynamic conditions, capturing each stage of development. In this thesis, cryo-EM has been used to investigate the formation and structure of a variety of self-assembling soft materials. Visualization is complemented by small angle X-ray scattering (SAXS), dynamic light scattering, and conductivity measurements. In each case, cryo-EM provides new insights, not otherwise available, into the nanostructure development. Self-assembly phenomena at the molecular level are critical to the performance of tremendous number of applied systems ranging from personal care products to industrial products. To evaluate these self-assembled materials, multiple characterization techniques are required. We investigated aggregation behavior of cesium dodecyl sulfate (CsDS) ionic surfactant in aqueous solution. Coupled with the real space data from cryogenic transmission electron microscopy (Cryo-TEM) and the inverse space data from SAXS, the experimental result of CsDS in aqueous solution gave a new insight in CsDS micellar structures and their development as a function of concentration. Cryo-TEM showed the presence of the liquid-like hydrocarbon core in the CsDS micelles and relatively thick shell structures at a low CsDS concentration. The core-shell sphere structure micelle shifted to core-shell cylindrical micelle structure at high concentration. The morphology and structure of paclitaxel silicate (PTX) prodrug, encapsulated with amphiphilic poly(ethylene glycol)-b-poly(lactic-co-glycolic acid) diblock copolymers were studied. The six different silicate PTX prodrug candidates were characterized with cryo-TEM. Direct imaging with cryo-TEM illustrated structure of prodrug

  16. Structure-property relationships in self-assembling peptide hydrogels, homopolypeptides and polysaccharides

    Science.gov (United States)

    Hule, Rohan A.

    The main objective of this dissertation is to investigate quantitative structure-property relationships in a variety of molecular systems including de novo designed peptides, peptide amphiphiles, polysaccharides and high molecular weight polypeptides. Peptide molecules consisting of 20 amino acids were designed to undergo thermally triggered intramolecular folding into asymmetric beta-hairpins and intermolecular self-assembly via a strand swapping mechanism into physically crosslinked fibrillar hydrogels. The self-assembly mechanism was confirmed by multiple characterization techniques such as circular dichroism and FITR spectroscopy, atomic force and transmission electron microscopy and small angle neutron scattering. Three distinct fibrillar nanostructures, i.e. non-twisted, twisted and laminated were produced, depending on the degree of strand asymmetry and peptide registry. Differences in the fibrillar morphology have a direct consequence on the mechanical properties of the hydrogels, with the laminated hydrogels exhibiting a significantly higher elastic modulus as compared to the twisted or non-twisted fibrillar hydrogels. SANS and cryo-TEM data reveal that the self-assembled fibrils form networks that are fractal in nature. Models employed to elucidate the fractal behavior can relate changes in the correlation lengths, low q (network), and high q (fibrillar) fractal exponents to the distinct fibrillar nanomorphology. The fractal dimension of the networks varies significantly, from a mass to a surface fractal and can be directly related to the local fibrillar morphology and changes in the peptide concentration. Transitions in the fractal behavior seen in the high q regime can be attributed to self-assembly kinetics. An identical model can be used to establish a direct correlation between the bulk properties and changes in both, the network density and underlying morphology, of a modified peptide-based hydrogel. As in the case of asymmetric peptides, changes in

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-05-28

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

  18. 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.

  19. 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.

  20. Stoichiometric control of DNA-grafted colloid self-assembly.

    Science.gov (United States)

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

    2015-04-21

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

  1. Applications of self-assembled monolayers in materials chemistry

    Indian Academy of Sciences (India)

    Nirmalya K Chaki; M Aslam; Jadab Sharma; K Vijayamohanan

    2001-10-01

    Self-assembly provides a simple route to organise suitable organic molecules on noble metal and selected nanocluster surfaces by using monolayers of long chain organic molecules with various functionalities like -SH, -COOH, -NH2, silanes etc. These surfaces can be effectively used to build-up interesting nano level architectures. Flexibility with respect to the terminal functionalities of the organic molecules allows the control of the hydrophobicity or hydrophilicity of metal surface, while the selection of length scale can be used to tune the distant-dependent electron transfer behaviour. Organo-inorganic materials tailored in this fashion are extremely important in nanotechnology to construct nanoelctronic devices, sensor arrays, supercapacitors, catalysts, rechargeable power sources etc. by virtue of their size and shape-dependent electrical, optical or magnetic properties. The interesting applications of monolayers and monolayer-protected clusters in materials chemistry are discussed using recent examples of size and shape control of the properties of several metallic and semiconducting nanoparticles. The potential benefits of using these nanostructured systems for molecular electronic components are illustrated using Au and Ag nanoclusters with suitable bifunctional SAMs.

  2. Formation and size distribution of self-assembled vesicles

    Science.gov (United States)

    Huang, Changjin; Quinn, David; Suresh, Subra

    2017-01-01

    When detergents and phospholipid membranes are dispersed in aqueous solutions, they tend to self-assemble into vesicles of various shapes and sizes by virtue of their hydrophobic and hydrophilic segments. A clearer understanding of such vesiculation processes holds promise for better elucidation of human physiology and disease, and paves the way to improved diagnostics, drug development, and drug delivery. Here we present a detailed analysis of the energetics and thermodynamics of vesiculation by recourse to nonlinear elasticity, taking into account large deformation that may arise during the vesiculation process. The effects of membrane size, spontaneous curvature, and membrane stiffness on vesiculation and vesicle size distribution were investigated, and the critical size for vesicle formation was determined and found to compare favorably with available experimental evidence. Our analysis also showed that the critical membrane size for spontaneous vesiculation was correlated with membrane thickness, and further illustrated how the combined effects of membrane thickness and physical properties influenced the size, shape, and distribution of vesicles. These findings shed light on the formation of physiological extracellular vesicles, such as exosomes. The findings also suggest pathways for manipulating the size, shape, distribution, and physical properties of synthetic vesicles, with potential applications in vesicle physiology, the pathobiology of cancer and other diseases, diagnostics using in vivo liquid biopsy, and drug delivery methods. PMID:28265065

  3. Self-Assembled, Nanostructured, Tunable Metamaterials via Spinodal Decomposition.

    Science.gov (United States)

    Chen, Zuhuang; Wang, Xi; Qi, Yajun; Yang, Sui; Soares, Julio A N T; Apgar, Brent A; Gao, Ran; Xu, Ruijuan; Lee, Yeonbae; Zhang, Xiang; Yao, Jie; Martin, Lane W

    2016-11-22

    Self-assembly via nanoscale phase separation offers an elegant route to fabricate nanocomposites with physical properties unattainable in single-component systems. One important class of nanocomposites are optical metamaterials which exhibit exotic properties and lead to opportunities for agile control of light propagation. Such metamaterials are typically fabricated via expensive and hard-to-scale top-down processes requiring precise integration of dissimilar materials. In turn, there is a need for alternative, more efficient routes to fabricate large-scale metamaterials for practical applications with deep-subwavelength resolution. Here, we demonstrate a bottom-up approach to fabricate scalable nanostructured metamaterials via spinodal decomposition. To demonstrate the potential of such an approach, we leverage the innate spinodal decomposition of the VO2-TiO2 system, the metal-to-insulator transition in VO2, and thin-film epitaxy, to produce self-organized nanostructures with coherent interfaces and a structural unit cell down to 15 nm (tunable between horizontally and vertically aligned lamellae) wherein the iso-frequency surface is temperature-tunable from elliptic to hyperbolic dispersion producing metamaterial behavior. These results provide an efficient route for the fabrication of nanostructured metamaterials and other nanocomposites for desired functionalities.

  4. Temperature Triggered Structural Transitions in Surfactant organized Self Assemblies

    Science.gov (United States)

    Rose, J. Linet; Balamurugan, S.; Sajeevan, Ajin C.; Sreejith, Lisa

    2011-10-01

    Preparation & characterization of tunable fluids is an emerging area with potential application in many fields. Surfactants self assemble in aqueous solution to give a rich variety of phase structures, the size and shape of which can be tuned by additives like salts, alcohols, amines, aromatics etc or external stimuli such as light, temperature etc. The addition of long chain aliphatic alcohol has significant influence on the surfactant aggregation, as it promotes morphological growth of micelles. The cationic surfactant, Cetyl Trimethyl Ammonium Bromide (CTAB) with nonanol in presence of potassium bromide (KBr) shows thermo tunable viscosity behaviour and optical switching behaviour. The solution is visually observed to transform from a turbid and less viscous phase at low temperature to clear and considerably viscous phase at high temperature. Temperature induced changes in turbidity and viscosity are consistent with the transition from vesicle to worm like micelle. It is also worth emphasizing that the transition is thermo reversible, so that vesicles that are disrupted into micelles upon heating can be reformed upon cooling. The thermo tunable transition from turbid to transparent state and the concomitant changes in viscosity are promising for the use in smart windows, monitoring of tumor growth or in other stimuli based application.

  5. 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.

  6. Self assembled homodinuclear dithiocarbamates: One pot synthesis and spectral characterization

    Science.gov (United States)

    Nami, Shahab A. A.; Husain, Ahmad; Ullah, Irfan

    2014-01-01

    Several self assembled homodinuclear complexes of the type [M2(Ldtc)2·4H2O] derived from quadridentate ligand (Ldtc), where Ldtc = 2-aminobenzoylhydrazidebis(dithiocarbamate) and M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) have been reported. The in situ procedure gives high yield with the formation of single product as evident by TLC and various other physicochemical techniques. Elemental analysis, TGA, 1H NMR, 13C NMR, ESI mass spectrometry, EPR, UV-vis. and IR spectroscopy were used to characterize the homodinuclear complexes. The spectroscopic evidences and room temperature magnetic moment values suggest that all the complexes have octahedral geometry around the transition metal atom. A symmetrical bidentate coordination of the dithiocarbamato moiety has been observed in all the complexes. The energy-minimized structure of the molecule also showed that each metal atom acquires a distorted octahedral geometry. The complexes exhibit a three-step thermolytic pattern and are non-electrolyte in nature.

  7. 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.

  8. 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.

  9. Light-induced self-assembly of active rectification devices.

    Science.gov (United States)

    Stenhammar, Joakim; Wittkowski, Raphael; Marenduzzo, Davide; Cates, Michael E

    2016-04-01

    Self-propelled colloidal objects, such as motile bacteria or synthetic microswimmers, have microscopically irreversible individual dynamics-a feature they share with all living systems. The incoherent behavior of individual swimmers can be harnessed (or "rectified") by microfluidic devices that create systematic motions that are impossible in equilibrium. We present a computational proof-of-concept study showing that such active rectification devices could be created directly from an unstructured "primordial soup" of light-controlled motile particles, solely by using spatially modulated illumination to control their local propulsion speed. Alongside both microscopic irreversibility and speed modulation, our mechanism requires spatial symmetry breaking, such as a chevron light pattern, and strong interactions between particles, such as volume exclusion, which cause a collisional slowdown at high density. Together, we show how these four factors create a novel, many-body rectification mechanism. Our work suggests that standard spatial light modulator technology might allow the programmable, light-induced self-assembly of active rectification devices from an unstructured particle bath.

  10. Defect source analysis of directed self-assembly process

    Science.gov (United States)

    Delgadillo, Paulina Rincon; Suri, Mayur; Durant, Stephane; Cross, Andrew; Nagaswami, Venkat R.; Heuvel, Dieter Van Den; Gronheid, Roel; Nealey, Paul

    2013-07-01

    As design rule shrinks, it is essential that the capability to detect smaller and smaller defects should improve. There is considerable effort going on in the industry to enhance immersion lithography using directed self-assembly (DSA) for the 14-nm design node and below. While the process feasibility is demonstrated with DSA, material issues as well as process control requirements are not fully characterized. The chemical epitaxy process is currently the most-preferred process option for frequency multiplication, and it involves new materials at extremely small thicknesses. The image contrast of the lamellar line/space pattern at such small layer thicknesses is a new challenge for optical inspection tools. The study focuses on capability of optical inspection systems to capture DSA unique defects such as dislocations and disclination clusters over the system and wafer noise. The study is also extended to investigate wafer-level data at multiple process steps and to determine the contribution from each process step and materials using defect source analysis methodology. The added defect pareto and spatial distributions of added defects at each process step are discussed.

  11. 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.

  12. Thermodynamic balance of perylene self-assembly on Ag(110)

    Science.gov (United States)

    Bobrov, Kirill; Kalashnyk, Nataliya; Guillemot, Laurent

    2016-10-01

    We present a room temperature STM study of perylene adsorption on Ag(110) at the monolayer coverage regime. We found that structure and symmetry of the perylene monolayer are settled by thermodynamic balance of the three factors: (i) the ability of perylene molecules to recognize specific adsorption sites on the (110) lattice, (ii) the intermolecular interaction, and (iii) the accommodation of thermal motion of the molecules. The moderate strength of the site recognition and the intermolecular interaction, of the same order of magnitude as kT ˜ 25 meV, represents a key feature of the thermodynamic balance. It bestows to this system the unique quality to form the quasi-liquid monolayer of epitaxial as well as self-assembling character. The perylene monolayer accommodates the short-range motion of the molecules instead of quenching it. It precludes the formation of possible solid nuclei and maintains common registry of the included molecules. The surface registry of the quasi-liquid phase is provided by locking of a structure-related fraction of the perylene molecules into specific adsorption sites of the (110) lattice favorable in terms of intermolecular interaction.

  13. White-Emissive Self-Assembled Organic Microcrystals.

    Science.gov (United States)

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

    2017-03-10

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

  14. Artificial transmembrane ion channels from self-assembling peptide nanotubes

    Science.gov (United States)

    Ghadiri, M. Reza; Granja, Juan R.; Buehler, Lukas K.

    1994-05-01

    NATURALLY occurring membrane channels and pores are formed from a large family of diverse proteins, peptides and organic secon-dary metabolites whose vital biological functions include control of ion flow, signal transduction, molecular transport and produc-tion of cellular toxins. But despite the availability of a large amount of biochemical information about these molecules1, the design and synthesis of artificial systems that can mimic the bio-logical function of natural compounds remains a formidable task2-12. Here we present a simple strategy for the design of artifi-cial membrane ion channels based on a self-assembled cylindrical β-sheet peptide architecture13. Our systems-essentially stacks of peptide rings-display good channel-mediated ion-transport activ-ity with rates exceeding 107 ions s-1, rivalling the performance of many naturally occurring counterparts. Such molecular assemblies should find use in the design of novel cytotoxic agents, membrane transport vehicles and drug-delivery systems.

  15. Electronic nanodevices based on self-assembled metalloproteins

    Science.gov (United States)

    Rinaldi, Ross; Cingolani, Roberto

    2004-02-01

    A key challenge of the current research in nanoelectronics is the realization of biomolecular devices. The use of electron-transfer proteins, such as the blue copper protein azurin (Az), is particularly attractive because of their natural redox properties and self assembly capability. We present in this work our results about the fabrication, characterization and modeling of devices based on such redox protein. The prototypes of biomolecular devices operate in the solid state and in air . The charge transfer process in protein devices can be engineered by using proteins with different redox centers (metal atoms) and by controlling their orientation in the solid state through different immobilization methods. A biomolecular electron rectifier has been demonstrated by interconnecting two gold nanoelectrodes with an azurin monolayer immobilized on SiO 2. The device exhibits a clear rectifying behavior with discrete current steps in the positive wing of the current-voltage curve, which are ascribed to resonant tunnelling through the redox active center. On the basis of these results we have designed an azurin-based transistor. The three terminal device exhibits an ambipolar behavior as a function of the gate bias, thus opening the way to the implementation of a new generation of logic architecture, such as fully integrated biomolecular logic gate.

  16. Design directed self-assembly of donor-acceptor polymers.

    Science.gov (United States)

    Marszalek, Tomasz; Li, Mengmeng; Pisula, Wojciech

    2016-09-21

    Donor-acceptor polymers with an alternating array of donor and acceptor moieties have gained particular attention during recent years as active components of organic electronics. By implementation of suitable subunits within the conjugated backbone, these polymers can be made either electron-deficient or -rich. Additionally, their band gap and light absorption can be precisely tuned for improved light-harvesting in solar cells. On the other hand, the polymer design can also be modified to encode the desired supramolecular self-assembly in the solid-state that is essential for an unhindered transport of charge carriers. This review focuses on three major factors playing a role in the assembly of donor-acceptor polymers on surfaces which are (1) nature, geometry and substitution position of solubilizing alkyl side chains, (2) shape of the conjugated polymer defined by the backbone curvature, and (3) molecular weight which determines the conjugation length of the polymer. These factors adjust the fine balance between attractive and repulsive forces and ensure a close polymer packing important for an efficient charge hopping between neighboring chains. On the microscopic scale, an appropriate domain formation with a low density of structural defects in the solution deposited thin film is crucial for the charge transport. The charge carrier transport through such thin films is characterized by field-effect transistors as basic electronic elements.

  17. Intrinsic Electronic Transport through Alkanedithiol Self-Assembled Monolayer

    Science.gov (United States)

    Lee, Takhee; Wang, Wenyong; Reed, Mark A.

    2005-01-01

    Electronic transport through an alkanedithiol self-assembled monolayer (SAM) is investigated using a nanometer scale device. Temperature-independent current-voltage characteristics are observed, indicating tunneling is the main conduction mechanism. The measured current-voltage characteristics are analyzed with a metal-insulator-metal tunneling model. The inelastic electron tunneling spectroscopy (IETS) study on the octanedithiol device clearly shows the vibrational signatures of molecules. The pronounced IETS peaks correspond to vibrational modes perpendicular to the junction interface, which include the stretching modes of Au-S (at 33 mV) and C-C (at 133 mV), and wagging mode of CH2 (at 158 mV). Intrinsic linewidths are determined as 1.69 (upper limit), 3.73± 0.98, and 13.5± 2.4 meV for Au-S, C-C streching modes, and CH2 wagging mode, respectively. The observed peak intensities and peak widths are in good agreement with theoretical predictions.

  18. Self-assembling cyclic systems as drug carriers

    Science.gov (United States)

    Banerjee, A.; Yadav, A.

    2013-12-01

    Self-assembling cyclic systems have been of interest to researchers for over a decade now, and their wide variety applications have been explored from electronic devices to medicinal purposes. But still their discovery for newer innovative applications remains as valuable as before. In this study, ab initio Hartree-Fock molecular orbital calculations have been performed on peptidic and peptidomimetic cyclic compounds to identify characteristics required in compounds for efficient self-aggregation. The effect of these characteristics in determining the pore size and length of nanotube has been studied. Effect of backbone and substituents on environment of outer and inner surface and carriage properties has been studied in detail. Self-aggregating compounds (Ala)12 and (Ala)10 have been predicted to form a tubular structure with dimensions in nanoscale. They have been predicted to work as novel drug carriers having inert outer wall and inner pore. A peptidic self-aggregating compound (Ala)12 has been studied and suggested as carrier for antibiotic gentamicin to exemplify carriage properties of the designed compound. Such novel self-aggregatory systems are expected to help simplify the drug delivery process and increase bioavailability of various drugs.

  19. Characterization of self-assembled DNA concatemers from synthetic oligonucleotides

    Directory of Open Access Journals (Sweden)

    Lu Sun

    2014-08-01

    Full Text Available Studies of DNA–ligand interaction on a single molecule level provide opportunities to understand individual behavior of molecules. Construction of DNA molecules with repetitive copies of the same segments of sequences linked in series could be helpful for enhancing the interaction possibility for sequence-specific binding ligand to DNA. Here we report on the use of synthetic oligonucleotides to self-assembly into duplex DNA concatemeric molecules. Two strands of synthetic oligonucleotides used here were designed with 50-mer in length and the sequences are semi-complimentary so to hybridize spontaneously into concatemers of double stranded DNA. In order to optimize the length of the concatemers the oligonucleotides were incubated at different oligomer concentrations, ionic strengths and temperatures for different durations. Increasing the salt concentration to 200 mM NaCl was found to be the major optimizing factor because at this enhanced ionic strength the concatemers formed most quickly and the other parameters had no detectable effect. The size and shape of formed DNA concatemers were studied by gel electrophoresis in agarose, polyacrylamide gels and by AFM. Our results show that linear DNA constructs up to several hundred base pairs were formed and could be separated from a substantial fraction of non-linear constructs.

  20. Molecular Self-Assembly Strategy for Generating Catalytic Hybrid Polypeptides

    Science.gov (United States)

    Ikezoe, Yasuhiro; Pike, Douglas H.; Nanda, Vikas; Matsui, Hiroshi

    2016-01-01

    Recently, catalytic peptides were introduced that mimicked protease activities and showed promising selectivity of products even in organic solvents where protease cannot perform well. However, their catalytic efficiency was extremely low compared to natural enzyme counterparts presumably due to the lack of stable tertiary fold. We hypothesized that assembling these peptides along with simple hydrophobic pockets, mimicking enzyme active sites, could enhance the catalytic activity. Here we fused the sequence of catalytic peptide CP4, capable of protease and esterase-like activities, into a short amyloidogenic peptide fragment of Aβ. When the fused CP4-Aβ construct assembled into antiparallel β-sheets and amyloid fibrils, a 4.0-fold increase in the hydrolysis rate of p-nitrophenyl acetate (p-NPA) compared to neat CP4 peptide was observed. The enhanced catalytic activity of CP4-Aβ assembly could be explained both by pre-organization of a catalytically competent Ser-His-acid triad and hydrophobic stabilization of a bound substrate between the triad and p-NPA, indicating that a design strategy for self-assembled peptides is important to accomplish the desired functionality. PMID:27116246