David Gracias Johns Hopkins University
Oliver G. Schmidt IFW Dresden
Paul W. K. Rothemund California Institute of Technology
Bartosz A. Grzybowski Northwestern University
OO1: Folding, Rolling, and Wrinkling Structures
Tuesday PM, April 06, 2010
Room 3020 (Moscone West)
9:00 AM - **OO1.1
Engineering Membranes: Nanostructured Origami, Applications, and Outgrowths.
George Barbastathis 1 2 , William Arora 3 , Wyatt Tenhaeff 4 , Christy Petruczok 5 , Se Young Yang 1 , Anthony Nichol 1 , Karen Gleason 5 , Henry Smith 6 1 Show Abstract
1 Mechanical Engineering, MIT, Cambridge, Massachusetts, United States, 2 Singapore-MIT Alliance for Research and Technology (SMART) Centre, MIT, Singapore Singapore, 3 , MC10, Inc., Waltham, Massachusetts, United States, 4 Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 5 Chemical Engineering, MIT, Cambrige, Massachusetts, United States, 6 Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts, United States
Three-dimensional nanomanufacturing and assembly methods present fundamental challenges. Here we outline the principles of Nanostructured Origami, an approach based on folding of nanopatterned membranes, and describe our progress in folding actuation and alignment techniques, and the application to chemical sensing. The approach consists of two steps. First, we nanopattern a membrane with functional features, e.g. swellable polymers deposited using the initiated Chemical Vapor Deposition (iCVD) process, diffraction gratings patterned using interference lithography, cobalt or nickel nanomagnets patterned with electron-beam lithography, carbon nanotubes, etc. The same step also includes the important task of defining the folding creases as bilayer or ion-implantation-induced stress, or as hinges. The second step actuates the hinges causing the membrane to fold to its final shape, e.g. by release of the pre-stressed cantilevers or via external magnetic forces acting on the magnets patterned on the membranes. Silicon nitride, coated on a silicon substrate with low-pressure chemical vapor deposition (LPCVD), may be folded to a radius of curvature as tight as 2μm with the ion-implantation method. The LPCVD process under optimized conditions results in membranes that are essentially free of defects and, hence, lack nucleation centers from which cracks could develop. Implantation with helium minimized the damage to the membrane.To achieve accuracy in folding, we developed methods of latching and alignment, both coarse and fine. For fine alignment between intimately adjacent folded layers, we used the forces that develop between nanomagnets on opposing folding segments. As the folding angle approaches 180 degrees, the inter-magnet forces exceed the force due to the external field, forcing the moving segment to settle in the aligned configuration. Our best result to date demonstrated that using this technique 100μm x 100μm segments settle to within 30nm of their ideal position. The application to chemical sensing was somewhat accidental in the sense that it did not require folding, but was enabled by our experience in engineering membranes for experiments on folding. We patterned 100nm-thick silicon nitride cantilevers using the same LPCVD process mentioned above, coated them with titanium and gold and released them, and performed iCVD of 75nm-thick Poly[maleic anhydride-alt-di(ethylene glycol) di(vinyl ether)] [poly(Ma-D)] film, selected for its specific reactivity to hexylamine. Detection results when the polymer swells due to reaction with the analyte, which in turn deforms the cantilever in a controllable fashion and shorts a circuit. A benefit of this design is that it consumes no electrical power until the detection event occurs.
9:30 AM - OO1.2
Ion Sensitive Field Effect Transistor Based on Wrinkled Nanochannels Integrated on a Chip.
Stefan Harazim 1 , Yongfeng Mei 1 , Oliver Schmidt 1 Show Abstract
1 Institute for Integrative Nanosciences, IFW Dresden, Dresden, Saxony, Germany
An on-chip device for active ion transport control with three integrated ion sensitive field effect transistors (ISFET) based on wrinkled nanochannels is presented, and we highlight the advantages of deterministic layer wrinkling towards the ISFET assembling process. The wrinkling of strained InGaAs layers allows us to create channel systems of various configurations ranging from a single nanochannel to symmetric nanochannel systems with multiple entrances. Additionally, it is possible to define location and orientation of these nanochannels on the chip for later logical integrated electrical circuits combined with nano fluidic networks. Our wrinkled channels have a characteristic length of about 6µm and an inner diameter of about 25nm. The inner diameter can be tuned by an atomic layer deposition method (ALD). The accuracy of this ALD is in the angstrom range depending on the used oxide to deposit. For our device it is necessary to use the tri-methylaluminum precursor due to easy handling and the good isolating properties of the deposited Al2O3 layer. The resulting sensitivity of our device is at about 25pA by using biases between -1V and +1V and a gate electrode range from -1V to +1V. The used electrolyte for functionality demonstration is high diluted KCl. Our work relies on easy to handle fabrication methods like standard photolithography, e-beam evaporation and atomic layer deposition. The gate effect on the ion transport behaviour is shown clearly for three separate transistors on a single chip.
9:45 AM - OO1.3
Self-folding of Lithographically Patterned Nanopolyhedra.
Jeong-Hyun Cho 1 , David Gracias 1 Show Abstract
1 Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States
Patterning can dramatically alter the physical and chemical properties of nanoparticles. Additionally, patterned building blocks are needed to direct the bottom-up self-assembly of integrated structures. However, present day three dimensional fabrication is greatly limited on the nanoscale; most nanoparticles such as nanowires and nanoparticles have homogenous surfaces or very limited patterns. We describe a new strategy based on self-folding of nanoscale panels with tin (Sn) hinges. The process can be used to transform e-beam patterned templates into 3D objects with precise surface patterning. We utilize multiple layers of electron beam lithography to pattern specifically defined patterns, faces, and hinges of 2D templates with nanoscale precision on a sacrificial layer. Through self-assembly process, we realized specific patterns with widths as small as 15 nm on 100 nm scale nanoparticles, composed of either nickel (metal) and alumina (dielectric material). The particles are very stable and the process is versatile and requires only simple thin film deposition techniques. We will also describe preliminary applications of these self assembled particles in optical and biological applications. Reference: Self-assembly of lithographically patterned nanoparticles J. H. Cho and D. H. Gracias, Nanoletters (2009) DOI:10.1021/nl9022176
10:00 AM - **OO1.4
Rolled-up Inorganic Nanomembranes.
Yongfeng Mei 1 Show Abstract
1 Institute for Integrative Nanosciences, IFW Dresden, Dresden Germany
The deterministic release and rearrangement of thin solid films or inorganic nanomembranes on substrate surfaces offers exciting possibilities toward advanced integration strategies on a single chip, such as rolled-up nanotechnology, micro- and nano-origami, stretchable electronics, and thin membrane transfer. When a pre-stressed layer is released from substrate, it will be deformed as certain shapes by rolling or wrinkling. With appropriate methods of deposition and post-treatments, rolled-up micro-/nanotubes can be placed where they are needed on a chip. This method may leads to hybrid material heterostructure and superlattice systems with interdisciplinary functionalities in electronics, optics, as well as nanomechanics and nanofluidity. In this talk, the details of such technology will be described as well as conceptual demonstrations for potential applications like bioanalytic systems, optofluidics, metamaterials, energy storage, and micro-/nanoscale motions.
10:30 AM - **OO1.5
Rolled-up Helical Nanobelts: From Fabrication to Swimming Microrobots.
Li Zhang 1 , Jake Abbott 1 2 , Lixin Dong 1 3 , Kathrin Peyer 1 , Bradley Kratochvil 1 , Bradley Nelson 1 Show Abstract
1 Institute of Robotics and Intelligent Systems, ETH Zurich, Zurich Switzerland, 2 Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah, United States, 3 Department of Electrical & Computer Engineering, Michigan State University, East Lansing, Michigan, United States
A strategy that combines “top-down” and “bottom-up” approaches for fabricating 3D micro-/nanostructures has recently been introduced [1-2]. This method is based on the coiling of strained 2D thin films to form 3D structures after the films detach from the substrate by selective etching, a type of self-assembly. To fabricate rolled-up helical nanobelts, the 2-D films are patterned into ribbon-like mesas. Compared to nanohelices grown solely from "bottom-up" processes, these rolled-up helical nanobelts can be designed with a specific geometrical shape, i.e., their diameter, chirality, pitch, helicity angle and length can be precisely controlled [3-4]. Nanorobotic manipulation shows that the as-fabricated helical nanobelts are highly flexible and retain a strong “memory” of their original shape. Inspired by the helical-shaped flagella of bacteria, we have developed artificial bacterial flagella (ABFs) as wireless swimming microrobots [5-6]. An ABF consists of a rolled-up helical nanobelt similar to a natural flagellum in both size and shape, and a thin soft-magnetic head for magnetic actuation. Experimental investigation shows that an ABF can be propelled and steered in 3D with micrometer precision by a low-strength, rotating magnetic field. Moreover, the swimming properties are tunable by changing the input magnetic field frequency and the shape of the ABF. Swarm-like behavior of multiple ABFs as a single entity is also demonstrated under the control of the magnetic field, and two approaches can be applied to decouple or immobilize an individual ABF from the swarm, i.e. using the step-out frequency in a high frequency range or the wobbling effect at low frequencies. These miniaturized devices made of helical nanobelts provide a mechanism for mimicking and investigating many natural micro-organisms, and can be used as magnetically driven wireless manipulators for medical and biological applications in fluid environments, such as cell manipulation and removal of tissue. Due to its large surface to volume ratio, surface functionalized ABFs have the potential to sense and transmit inter- or intracellular information, and to perform targeted drug delivery. V. Prinz et al., Physica E 6, 828, 2000.  O.G. Schmidt et al., Nature 410, 168, 2001.  L. Zhang et al., Nanotechnology 16, 655, 2005.  L. Zhang et al., Nano Lett. 6, 1311, 2006.  L. Zhang et al., Appl. Phys. Lett. 94, 064107, 2009.  L. Zhang et al., Nano Lett. 9, 3663, 2009.
11:00 AM - OO1: Fold
11:30 AM - OO1.6
Hands Free Origami With Bidirectional Curvature for Microassembly of Complex Structures.
Noy Bassik 1 2 , George Stern 1 , David Gracias 1 3 Show Abstract
1 Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States, 2 School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States, 3 Chemistry, Johns Hopkins University, Baltimore, Maryland, United States
Complex structures are difficult to assemble manually at sub-millimeter size scales. An attractive approach is to use origami, the Japanese art of paper folding, to design a self-assembly process. Such a process is suitable for forming advanced materials and complex three-dimensional (3D) devices. Previous work has shown that thin films of metals, semiconductors, and polymers can be made to assemble via folding. We have extended thin film folding approaches to design a system with specific angles of positive and negative curvature. Our approach is a combination of origami, the art of paper folding, and kirigami, which utilizes paper cutting. We create flexible hinges of mountain or valley type, rigid panels, and hollow regions, all in 2D. This design framework achieves spontaneous bidirectional folds with any desired angle. We show theoretical design and experimental realization of +90°, −90°, +180°, and −180° folds. In addition, we fold a complex corrugated origami tessellation, commonly known as a cubic core, involving >4500 elements simultaneously. This framework utilizes conventional microfabrication and is inherently versatile and parallel. Reference: Microassembly based on Hands Free Origami with Bidirectional Curvature N. Bassik, G. Stern and D. H. Gracias, Applied Physics Letters 95, 9, 091901/1-3 (2009) [Featured on the Cover].
11:45 AM - **OO1.7
Metamaterial Hyperlenses and Spin-wave Resonators Fabricated by Rolled-up Nanotech.
Markus Broell 1 , Stephan Schwaiger 1 , Felix Balhorn 1 , Sebastian Mansfeld 1 , Jesco Topp 1 , Wolfgang Hansen 1 , Detlef Heitmann 1 , Stefan Mendach 1 Show Abstract
1 , Institute of Applied Physics, Hamburg Germany
Rolled-up nanotech, i.e. the method of self-rolling strained layers, which was pioneered by Prinz  and Schmidt  for semiconductor material, offers the unique possibility to obtain radial superlattices of high quality alternating semiconductor and metal layers [3, 4]. As two recent examples of utilizing such metal/semiconductor radial superlattices we here present metamaterial hyperlenses and spin wave resonators.Our metamaterial hyperlenses are produced from well-defined radial Ag/InGaAs superlattices with accurately tuneable curvature, lattice constants and layer thickness aspect ratios. For wavelengths much larger than the lattice constant (typically some ten nanometers) the transmission through the superlattice can be described by the effective permittivity tensor which shows a strong anisotropy with respect to the radial component εr and the tangential component εt. Finite difference time domain simulations confirm in accordance with the effective medium picture of hyperlenses  that sub-wavelength imaging is obtained in our structures for an operating wavelength λO chosen such that εr >> εt = 0. Transmission measurements show that the working wavelength λO with εr >> εt = 0 can be tuned over a broad range in the visible and near infrared by varying the Ag and InGaAs layer thickness ratio .Furthermore, we present a completely new type of spin-wave resonator based on rolled-up Permalloy/InGaAs layers . This device resembles the universal concept of whispering-gallery modes as discovered by Lord Rayleigh in 1910, and well known from acoustics and optics, for spin waves. The homogeneous magnetization in our rolled-up structures resembles the refractive index in optical resonators or the stiffness in acoustic materials and can be tuned simply by changing the external magnetic field. Microwave absorption measurements reveal that our structures exhibit well separated sharp whispering gallery modes, which exist over a broad magnetic field range and can be tuned over several GHz, which makes them particularly appealing as tuneable spin wave filters in future spintronic devices. References: V. Ya. Prinz, V. A. Seleznev, A. K. Gutakovsky, A. V. Chekhovskiy, V. V. Preobrazhenskii, M. A. Putyato, and T. A. Gavrilova, Physica E 6, 828 (2000). O. G. Schmidt and K. Eberl, Nature 410, 168 (2001) O. Schumacher, S. Mendach, H. Welsch, A. Schramm, Ch. Heyn and W. Hansen, Appl. Phys. Lett. (2005). C. Deneke, J. Schumann1, R. Engelhard, J. Thomas, W. Sigle, U. Zschieschang, H. Klauk, A. Chuvilin, and O. G. Schmidt, phys. stat. sol. (c) 5, 2704 (2008). X. Jacob, L.V. Alekseyev, and E. Narimanov, Opt.Express 14, 8247 (2006). S. Schwaiger, M. Bröll, A. Krohn, A. Stemmann, C. Heyn, Y. Stark, D. Stickler, D. Heitmann, and S. Mendach, Phys. Rev. Lett. 102, 163903 (2009). S. Mendach, J. Podbielski, J. Topp, W. Hansen, and D. Heitmann, Appl. Phys. Lett. 93, 262501 (2008).
12:15 PM - OO1.8
Rolled-up Composite Nanomembranes for Improved Electrochemical Energy Storage.
Hengxing Ji 1 , Yongfeng Mei 1 , Oliver Schmidt 1 Show Abstract
1 , Institute for Integrative Nanosciences, IFW Dresden, Dresden Germany
Nanotechnology has become one of the most promising approaches to improve the performance of electrochemical storage devices such as supercapacitors and lithium-ion batteries. Winding up appropriate layers is an industrial standard technique to manufacture commercial batteries on the macro scale. On the micro- and nanoscale, highly strained layers (or nanomembranes) can roll-up on a substrate by themselves upon release from the substrate, which has produced a manifold of applications in various research fields. The strained layers are deposited by methods compatible to industrial needs such as e-beam evaporation or sputtering deposition. It has thus become extremely convenient to choose various material combinations for different demands.Here, we show that rolled-up technology can combine different functional materials into nano-/microstructures, which are beneficial for electrode materials in lithium-ion battery. For example, the multifunctional nanomembrane tubes are strain free, the tubular structure can accommodate large volume variations and offers continues electron conduction networks so as to enhance the lithium battery stability.Moreover, by tailoring the composition, individual rolled-up nanomembranes reveal super capacitive characteristics with controlled proton diffusion behavior, and could therefore serve as one-dimensional micro-scale power sources for microchips.
12:30 PM - **OO1.9
Polymer Tubes by Rolling of Polymer Bilayers.
Manfred Stamm 1 , Kamlesh Kumar 1 , Valeriy Luchnikov 2 Show Abstract
1 , Leibniz-Institut fuer Polymerforschung, Dresden Germany, 2 Institute de Chimie des Surfaces et Interfaces, CNRS, Mulhouse France
The self-rolling approach for the formation of polymeric, metallic and ceramic micro and submicron size objects has been demonstrated. The tubes are fabricated by strain driven self-rolling phenomena of P4VP/PS thin bilayer films. Swelling of P4VP layer is achieved in acidic solution. Photolithography route is used for formation of polymer roll-up tubes in high quantity and quality. The position and arrangement of the tubes on the substrate are precisely defined by UV-photolithograhy. Directional rolling of crosslinked layer was performed by asymmetric photopatterning for the production of single tubes. UV-radiation crosslinking the bilayer, is used stepwise in order to create asymmetric patterns of polymer layers. By special procedures also metal containing, ceramic and polymer tubes are produced. Complex geometries like toroids and triangles may also be fabricated using this strain driven self-rolling approach of polymer films.
OO2: Complex Particle-based Self-Assembly
Tuesday PM, April 06, 2010
Room 3020 (Moscone West)
2:30 PM - **OO2.1
Roughness-controlled Depletion Attractions for Assembling Shape-designed Colloidal Particles.
Thomas Mason 1 Show Abstract
1 Chemistry & Biochemistry, UCLA, Los Angeles, California, United States
Surface roughness can profoundly affect depletion attractions between custom-shaped microscale particles. When the heights of nanoscale surface asperities on the faces of lithographically fabricated microplatelets become significantly larger than the size of a nanoscale depletion agent, entropic depletion attractions between the platelets can be strongly suppressed. By controlling the size of the depletion agent relative to the surface roughness, we obtain a universal phase diagram that describes the observed face-to-face aggregation of platelets into columns. Moreover, by designing and making Janus platelets, which have different surface roughness on opposite faces, we can direct thermodynamic self-assembly of a pure dimer phase. The interaction between flat plates can be modeled by a smooth plate coated by hemispheroids having controlled sizes and densities, relative to those of a spherical depletion agent, and the results of these calculations are consistent with experiments. For Janus particles, the model also reveals a new type of distinguishable columnar phase that we have now observed experimentally. We will briefly discuss the behavior of an assembly containing many pentagonal platelets held near a flat smooth wall by roughness controlled depletion attractions. Overall, these studies provide significant insight into directing the self-assembly of colloidal particles through purely entropic interactions.
3:00 PM - OO2.2
Hybrid Nanoparticle Assemblies: Synthesis, Stability and Applications.
Laura Fabris 1 2 , Brandon Berke 1 , Bryan Paladini 1 , Daniel Naftalovich 1 Show Abstract
1 Materials Science and Engineering, Rutgers University, Piscataway, New Jersey, United States, 2 Institute for Advanced Materials Devices and Nanotechnology, Rutgers University, Piscataway, New Jersey, United States
The wide variety of core materials, along with the possibility to synthesize them with different sizes and shapes, render nanoparticles (NPs) an excellent platform for a broad range of applications that span from biological sensing, to materials engineering . Spheres, shells, rods, and stars are only few of the several shapes that can be obtained by exploiting solution-based synthetic protocols for the preparation of metallic nanostructures, and new procedures continue to appear . Intrinsically related to the shape of metal NP are their plasmonic properties: By breaking the symmetry and lowering the degeneracy of these systems, both longitudinal and transverse plasmon modes appear that cover a wide range of wavelengths in the UV-Vis-NIR spectrum. This result can be achieved by modifying the shape of the NPs but also by synthesizing organized multidimensional assemblies . The simplest approach to creating organization is the preparation of dimers, trimers and tetramers and their application has been reported in connection to Surface Enhanced Raman Spectroscopy (SERS) and plasmon coupling . Higher order aggregates such as 1D linear assemblies have also been reported . The plasmonic properties of closely spaced, linearly assembled metal NPs are considered to represent the connecting point between those of localized and propagating plasmons. The use of di-thiolated small organic molecules and biomolecules, polymers and biopolymers, allows to carry out the assembly with a high degree of control, that can ultimately lead to the ability of tailoring the plasmonic properties of the assemblies. Moreover, if the linking units possess high Raman cross sections, then these assemblies can be used as imaging tools or for sensing applications. Finally, the possibility of easily functionalizing the NP surface with biomolecules such as amino acids, oligonucleotides and proteins, makes these systems useful in bio-related applications. Herein we report on our recent progress in the synthesis and characterization of hybrid NP assemblies. Spheres, shells, rods and other shapes are synthesized and assembled as dimers, trimers and 1D linear aggregates. Their stability in different solvents is evaluated and their plasmonic properties are studied. Procedures for bioconjugation are optimized and preliminary results are reported for their use in bio-related applications. Katz, E.; Willner, I. Angew. Chem. Int. Ed. 2004, 43, 6042. Sau, T.K.; Murphy, C. J. Am. Chem. Soc. 2004, 126, 8648. Liz-Marzan, L.M. Langmuir, 2006, 22, 32. Fabris, L.; Dante, M.; Nguyen, T.Q.; Tok, J.B.H.; Bazan, G.C. Adv. Funct. Mater. 2008, 18, 2518. DeVries, G.A.; Brunnbauer, M.; Hu, Y.; Jackson, A.M.; Long, B.; Neltner, B.T.; Uzun, O.; Wunsch, B.H.; Stellacci, F. Science, 2007, 315, 358.
3:15 PM - OO2.3
Self-assembly of Complex Crystal Structures: Influence of Shape and Particle Interactions.
Michael Engel 1 , Sharon Glotzer 1 2 Show Abstract
1 Chemical Engineering, University of Michigan, Ann Arbor, Michigan, United States, 2 Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan, United States
Ordered arrangements of meso- and nanoscopic building blocks play an important role in the search for new functional materials because of their distinctive physical properties. For practical purposes it is desirable to discover routes to assemble crystals with increasingly higher complexity. Whereas simple structures like fcc, hcp, bcc, and others are achieved relatively easily, synthesizing more complex crystals is still tedious work and often a result of a trial-and-error approach. Structural complexity can be achieved by optimizing the interactions and the shapes of the building blocks -- parameters that often cannot be varied independently in experiments. In theory, however, the problem can be split into two parts: (i) isotropic particles with varying pair potentials [1,2]; (ii) hard particles with varying shapes . In this contribution we give examples of both situations where structural complexity occurs naturally and growth from the disordered fluid phase has been observed computationally using particle-based simulations. The self-assembled crystals are periodic with complicated, non-trivial unit cells and quasicrystals in two and three dimensions. Our results show that both energy and entropy alone can independently produce highly complex, ordered structures. Engel, M. and Trebin, H.-R. Self-assembly of complex crystals and quasicrystals with a double-well interaction potential, Phys. Rev. Lett. 98, 225505 (2007). Engel, M. and Trebin, H.-R. Structural complexity in monodisperse systems of isotropic particles, Z. Kristallogr. 223, 721 (2009). Glotzer, S.C. and Solomon, M.J. Anisotropy of building blocks and their assembly into complex structures, Nature Mat. 6, 567 (2007).
3:30 PM - OO2.4
Confinement-controlled Ordering of Colloids With Simultaneous Isotropic and Anisotropic Cross-section.
Erin Riley 1 , Chekesha Liddell 1 Show Abstract
1 Materials Science and Engineering, Cornell University, Ithaca, New York, United States
The pursuit to determine the realizable structures formed by anisotropic particles is foundational to colloidal solutions for correlating structure and properties for photonics. Confinement has proven to be a powerful structure directing technique for molecular-based materials including block copolymers, where complex morphologies are induced by surface separations on the length scale of the microphase domains. A mildly expanded range of phase stability has also been demonstrated for spherical colloids under wedge-shaped confinement geometry. In addition to hexagonal (hex) and square symmetry, rhombic and buckled structures have been reported in the transition regions between one and two particle layers. Here, we investigate the promotion of greater structural diversity utilizing nonspherical colloids and confinement. Particularly, the mushroom-cap shaped particles employed in this study have features of both isotropic and anisotropic colloids. Results from fast confocal microscopy imaging of particles’ gravitational sedimentation in a wedge cell into a range of mono- and bilayer structures under 2D and quasi-2D confinement will be described. Particle tracking routines enable quantitative analysis of positional and orientational correlations in the order. The sequence of phases tracked with increasing confinement height includes those cited for spheres, as well as the more complex rotator and orientation-dependent phases observed for the class of short rod-like building blocks (i.e., major axis re-orients with respect to the substrate). Closest packing considerations provide rationale for the observed 1hex-1buckled-1rotator (oblique)-2square-2hex-2rotator (oblique) phase behavior with height. Photonic band structure simulations of the experimental particle arrangements will be presented to characterize the optical properties.
3:45 PM - OO2.5
Self-assembly of Reconfigurable Nanorod Structures.
Trung Nguyen 1 , Sharon Glotzer 1 2 Show Abstract
1 Chemical Engineering, University of Michigan, Ann Arbor, Michigan, United States, 2 Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan, United States
Reconfigurable nanostructures represent an exciting new direction for nanomaterials. Applications of reversible transformations between nanostructures can be found in a broad range of advanced technologies including smart materials, electromagnetic sensors, and drug delivery. In this work, we propose two model nanostructures assembled by laterally tethered nanorods that are able to reversibly reconfigure in response to changes in environmental conditions and/or nanorod shape. In the first model, we show that pre-assembled flat bilayer sheet scrolls into distinct helical morphologies depending on the solvent selectivity. The local packing of the rods within the sheet and the tether length are shown to be key factors that guide the helix handedness, radius and pitch. When the effective solvent condition is switched,, either externally or via changes in the building block, the helices transform from one morphology to another. In the second model, we report a reversible transformation between two ordered structures assembled by laterally tethered rods with different rod lengths. When the rod segments are expanded or shortened in a short period of time as compared to the system relaxation time, a reversible transformation between those structures is induced. The kinetic effects due to rod shortening and expanding are shown to enhance the transformation process over the counterpart self-assembly process from disorder states. These models serve both to inspire the fabrication of laterally tethered nanorods for assembling higher order nanostructures at nanometer scales and as a proof-of-concept for engineering reconfigurable nanomaterials via hierarchical self-assembly.References T. D. Nguyen, S. C. Glotzer, Switchable helical structures formed by the hierarchical self-assembly of laterally-tethered nanorods, Small 5, 2092, 2009. T. D. Nguyen, S. C. Glotzer, Reversible morphological transformation between assembled structures by laterally tethered shape-changing nanorods, Preprint.
4:00 PM - OO2: Part
4:30 PM - OO2.6
Mesoscopic Self-assembly of Colloidal Nanoparticle Suspensions into Superstructures.
Philip Born 1 , Johann Lacava 1 , Tobias Kraus 1 Show Abstract
1 Structure Formation, INM – Leibniz Institute for New Materials, Saarbruecken, Saarland, Germany
Research on the self-assembly behaviour of colloidal nanoparticles will foster the understanding of self-assembly across multiple lengths scales, as the dynamics of nanoparticle self-assembly are related to processes known from atomic self-assembly as well as effects and processes leading to order in macroscopic granular media.Colloidal nanoparticles often resemble atoms in their behaviour. The various interparticle interactions  lead to a phase diagram which is akin the thermodynamic phase diagram of atomic gases, including instability regions and possible gas-liquid and gas-solid transitions . In the atomic-gas-like state of colloidal suspensions, assembly is driven by the strength and directionality of the interparticle potentials, whose range is large compared to the particle size. However, Foffi et al. showed that the phase diagram alters drastically when the ratio between the particle size and the range of the interparticle forces increases . The liquid phase vanishes with increasing ratio, and the system eventually exhibits the temperature-independent jamming phase diagram of macroscopic granular media. In the granular-media-like state, the range of the interparticle forces is small compared to the size of the particles and mobility and friction among the particles dominate the ordering process . Here, we use sterically stabilized gold nanoparticles as a model system to explore experimentally the thermodynamic concentration-temperature (c-T) phase diagram of a colloidal suspension. We focus on the ordering of the emerging superstructures after quenching the system to the instable regime. By exchanging the capping layer of the gold particles the ratio between particle size and interaction potential range and the interactions among the ligand shells of particles can be changed. By systematically increasing the capping layer thickness, the transition from a rather atom-like to a granular media-like state can be observed. The interactions among the ligand shells of the particles change the interparticle friction and inhibit rearrangement. Our results contribute to the controlled design of particle superstructures from colloidal systems using multidimensional phase diagrams that include parameters such as particle size and interaction potential.K. J. M. Bishop, C. E. Wilmer, S. Soh, and B. A. Grzybowski, Small 2009, 5, pp. 1600 – 1630P. Born, E. Murray, and T. Kraus, J. Phys. Chem. Solids 2009, In Press, doi:10.1016/j.jpcs.2009.09.011G. Foffi, G. D. McCullagh, A. Lawlor, E. Zaccarelli, K. A. Dawson, F. Sciortino, P. Tartaglia, D. Pini, and G. Stell, Phys. Rev E 2002, 65, pp. 031407-1 - 031407-17 C. Song, P. Wang, and H. A. Makse, Nature 2008, 453, pp. 629 - 632
4:45 PM - **OO2.7
Magnetic and Capillary Forces for Microscale Self-assembled Systems.
Christopher Morris 1 , Kate Laflin 2 1 , David Gracias 2 Show Abstract
1 , U.S. Army Research Laboratory, Adelphi, Maryland, United States, 2 , Johns Hopkins University, Baltimore, Maryland, United States
Self-assembly is a promising technique to overcome fundamental limitations with integrating, packaging, and generally handling individual electronic-related components which are smaller than about 300 µm. Existing scientific literature extensively documents various aspects of fluidic self-assembly, where parts suspended in a fluid and are attracted to intended binding sites by one or more types of forces. These types include capillary and electromagnetic forces, with each approach entailing certain advantages and disadvantages. We present methods which employ the long range attraction of electromagnetic forces, the scaling advantages of short-range capillary forces, and the novel combination of both. Three examples demonstrate the utility of these methods. First, the assembly of microfabricated silicon blocks on silicon templates represents a model system to develop appropriate fabrication methods and to study the yield resulting from these processes. This development will allow the application of these methods to the integration of other semiconductor materials, with numerous potential applications in next generation, high performance transistors for CMOS, and the integration of a variety of optoelectronic, polymeric, or even energetic materials with conventional silicon MEMS and electronics. Second, as a specific example of integration between different materials, we will show the integration of commercially available, sub-millimeter scale RFID-like chips with self-actuating, metallic hinged structures. Lastly, the development of a self-assembled, three-dimensional (3-D) circuit architecture effectively connects top-down, micro-fabrication methods with bottom-up self-assembly. We will show the self-assembly of these parts into 3-D structures and test their electrical connectivity.
5:15 PM - OO2.8
Hierarchical Self-assembly of Nano- and Micro-particles Using Forces Mediated by Liquid Crystalline Solvents.
Nicholas Abbott 1 Show Abstract
1 Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States
This presentation will address the hierarchical self-assembly of nano- and micro-particles using forces mediated by liquid crystalline solvents. Whereas many past studies have investigated hierarchical self-assembly in isotropic liquids, recently, new types of inter-colloidal interactions have been unmasked when using liquid crystalline solvents: the long-range ordering of the liquid crystal (LC), as well as defects within the LC, mediates inter-colloidal interactions with symmetries that differ from those observed with isotropic liquids. In this presentation, hierarchical assembly processes will be described at interfaces formed between aqueous phases and nematic LCs. At these interfaces, particles assemble into chains with controlled interparticle spacing, consistent with the dipolar symmetry of the defects observed to form about each particle. Addition of a molecular surfactant to the aqueous phase results in a continuous ordering transition in the LC, which triggers reorganization of the particles, first by increasing the spacing between particles within chains, and ultimately by forming two-dimensional arrays with local hexagonal symmetry. The ordering transition of the particles is reversible, and is driven by surfactant-induced changes in the symmetry of the topological defects induced by the particles. Differences between LC-driven assembly processes involving micro- and nano-particles will be highlighted.
5:30 PM - OO2.9
Reversible Attachment of Platinum Alloy Nanoparticles to Non-functionalized Carbon Nanotubes.
Christian Klinke 1 , Beate Ritz 1 , Hauke Heller 1 , Anton Myalitsin 1 , Andreas Kornowski 1 , Beatriz H. Juarez 2 , Horst Weller 1 , Francisco J. Martin-Martinez 3 , Santiago Melchor 3 , Jose A. Dobado 3 Show Abstract
1 Institute of Physical Chemistry, University of Hamburg, Hamburg Germany, 2 , IMDEA Nanoscience, Madrid Spain, 3 Department of Organic Chemistry, University of Granada, Granada Spain
There are an increasing number of potential applications for materials with dimensions in the nanometer range. In particular catalytic processes can be lead with enhanced efficiency. We will discuss the formation of monodisperse, tunable sized, alloyed nanoparticles of Ni, Co, or Fe with Pt and pure Pt nanoparticles attached to carbon nanotubes. Following homogeneous nucleation, nanoparticles attach directly to non-functionalized singlewall and multiwall carbon nanotubes during nanoparticle synthesis as a function of ligand nature and the nanoparticle work function. These ligands not only provide a way to tune the chemical composition, size and shape of the nanoparticles but also control a strong reversible interaction with carbon nanotubes and the nanoparticle coverage. Detailed Raman investigations show that the sp2 hybridization of the carbon lattice is not modified by the attachment, but charge-transfer is verifiable. The degree of charging scales with the difference between the work functions of the carbon nanotubes and nanoparticles. The experimental findings are supported by extensive DFT simulations. The understanding of the interaction between the directly attached nanoparticles and the non-functionalized carbon nanotubes is very advantageous in terms of further integration of these systems into applications involving catalytic processes and energy storage.
OO3: Poster Session: Hierarchical assembly Self-assembly of Functional Materials -- from Nanoscopic to Mescoscopic Length Scales
Tuesday PM, April 06, 2010
Exhibition Hall (Moscone West)
6:00 PM - OO3.1
Building Bridges Between Nanoparticles: Simulation and Experiment.
Paul Mark 1 , Laura Fabris 1 Show Abstract
1 Materials Science and Engineering, Rutgers University, Piscataway, New Jersey, United States
Metallic nanoparticles (NPs) hold great promise for use in many fields. Their small and regular size, large surface area and the capability of multifunctional surface groups allow for a wide variety of possible uses. Efficient biosensing requires the capability of recognizing the presence of the analyte with high specificity and sensitivity. Such capability can be achieved using Raman spectroscopy, by which analytes are selectively identified based on their specific vibrational pattern. However, due to its low cross-section, Raman is not sensitive enough to detect small amounts of target molecules with high sensitivity. Nevertheless, a strong increase in signal intensity can be achieved with surface enhanced Raman spectroscopy (SERS), which takes advantage of local field enhancements near metallic nanostructures. This is a valuable tool in many biological applications of nanotechnology. The NIR laser beam, required for the Raman signal excitation in biological applications, penetrates the tissue allowing for in vivo imaging. SERS has also many proven uses in drug delivery and cancer treatment. Due to the signal attenuation exerted from the tissue, a large input excitation or a long collection time are required to obtain a good signal to noise ratio. A large input excitation is not a possibility when working with living tissues. However, by closely spacing metallic NPs the SERS signal from a molecular linker positioned in the intermetallic junction can be further increased. There is a separation that results in a maximum field enhancement between the NPs, above and below which the field decreases. One way to tightly constrain that separation so as to maximize the field is the use of a molecular linker that bridges two NPs, forming a dimer. This dimer will have a separation closely tied to the length of the bridging surface group. In this study the effect of bridging groups in NP aggregation is simulated using a modified molecular dynamics approach. Simulations are done by modeling the interactions between NPs in solution using Langevin dynamics with future position and velocities computed using Beeman’s algorithm [1,2]. The effects of surface groups on the NP-NP interactions are explicitly modeled simultaneously with surface group adsorption and desorption. The bridging is also modeled explicitly as a stiff spring linked between the particles. Several bridging groups are considered including 2,6-napthalene dithiol, 1,5-napthalene dithiol, 2,7 naphthalene dithiol and biphenyl dithiol. The evolution of the system is studied for varying concentration and temperature profiles. At certain times in the simulation the system is excited with monochromatic radiation and the field enhancement is calculated. These simulations are compared to results from experiments imaged with TEM, AFM and SERS. References:1. Schlick, T.; Skeel, R.D.; et al. Comput. Phys. 1999, 151, 9.2. Beeman, D. J. Comput. Phys. 1976, 20, 130.
6:00 PM - OO3.10
Artificial Membrane Constructed by One-dimensional Nanostructure Using DNA Origami.
Ian Robertson 2 , Ken Uchida 2 3 , Shunri Oda 1 2 3 Show Abstract
2 Physical Electronics, Tokyo Institute of Technology, Tokyo Japan, 3 , JST SORST, Tokyo Japan, 1 Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, Tokyo Japan
One-dimensional nanostructure, such as nanowires, nanorods and, nanotubes has rapidly gained popularity among industry and academic institution. Given their unique ability to confine electrons in a one directional path and able to interconnect, it is no wonder that such structures have shown great potential for various applications in electronic, material and sensor devices. Though, one of the most common issues constantly being faced is the methodology of assembling the nanostructures together. There are many resolutions in working with this issue such as direct-assembly or electromagnetic guidance. Yet such method can be limited to a number of patterns being constructed and having the ability to construct patterns in a low cost desirable fashion gives rise to the ability of control. Recent advancements in DNA technology such as DNA origami, has made molecular self-assembly an attractable and promising tool for future assembly technology . DNA origami, first introduced by Paul W. K. Rothemund, is way to shape a scaffolding DNA such as an M13mp18 bacteria virus, into variety of shapes by using specified single strand DNA (ssDNA) as staples . In our experiment we study how DNA origami can be used as a template to organize silicon nanowires (SiNW) onto a silicon (Si) substrate. We use silicon material for our nanowires since many biosensor case studies have shown that SiNW can be readily functionalized . Let alone silicon is still part of electronic industry and its application factor for CMOS devices still makes it an attractable material. In our preparation for our experiment we use an open-source software, Nanorex founded by Mark Sims, to construct our pattern shape. After the geometric shape is completed, a list of sequential ssDNA can be generated from which we joint the virtual strands accordingly to how the ssDNA would bind to a viral DNA. We can then send the list of sequential ssDNA to Biotechnology Company for synthesization and upon receiving we can readily attach it to the silicon nanowires. After which, we can hybridize the functional SiNW on to the M13mp18 for self assembling by using a polymerase chain reaction (PCR) unit. Using an atomic force microscope (AFM) we can then observe our pattern results. Silicon nanowires are grown through Low-Pressure Chemical Vapor Deposition (LPCVD) using gold particles as catalysts. The nanowires are about a micron long and a diameter between 5 – 10nm.1. Douglas S. M., Dietz H., Liedl T., Högberg B., Graf F. and Shih W. M. Self-assembly of DNA into nanoscale three-dimensional shapes. Nature 459, 414–418 (2009)2. Rothemund, P. W. Folding DNA to create nanoscale shapes and patterns. Nature 440, 297–302 (2006)3. Cui Yi, Wei Q., Park H. and Lieber C. M. Nanowire Nanosensor for highly sensitive and selective detection of biological and chemical sensor. Science 17, 1289-1292 (2001)
6:00 PM - OO3.12
Porous Carbon Materials from Block Copolymer Precursors for Supercapacitor Applications.
John McGann 1 , Eun Kyung Kim 1 , Lynne McCullough 1 , Krzystof Matyjaszewski 1 , Tomasz Kowalewski 1 , Jay Whitacre 1 Show Abstract
1 Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
High performance electrochemical capacitors (i.e. supercapacitors) represent one of the major energy storage solutions as they generally store significantly more energy (~5 Wh g-1) than conventional capacitors and offer much higher power delivery or uptake (10 kW kg-1) than Li ion batteries. In contrast to batteries and fuel cells, in supercapacitors electrical charge is stored in the electrical double layer, which forms at the electrode/electrolyte interface mainly by electrostatic attraction. Porous carbons, such as activated carbons, are considered to be particularly suitable as high performance materials for supercapacitors due to their high surface area and chemical stability.In recent years we have developed a number of synthetic and processing routes to a new class of porous nanostructured carbon materials which combine high surface area with well defined nanostructure.1-3 Our approach relies on the use of macromolecular carbon precursors, such as polyacrylonitrile, which through the process of self assembly and directed self assembly organize into well defined nanoscale morphologies. After their nanostructure is fixed through chemical crosslinking, these materials are converted into porous nanographenes with morphology resembling that of the starting material.This presentation will demonstrate the advantages of macromolecular self assembly in creating nanoporous graphitic materials exhibiting superior supercapacitor performance. The key feature of all synthetic routes based on our approach is that the precursor polymer chains are oriented perpendicularly to the interface which becomes the pore wall after removal of the sacrificial phase. The orientation of polymer chains prior to graphitization assures that resultant pyrolytic nanographenes are oriented perpendicular to pore walls, leading to high graphitic edge exposure to the pores. As a result, the specific capacitance per unit area in these materials significantly exceeds one reported for conventional porous carbons. For example, porous nanographenes from polyacrylonitrile-b-poly(n-butyl acrylate) precursors show specific capacitance values comparable to activated carbons (>160 F/g), already at much lower specific surface area (400 m2/g vs. >1000 m2/g). This represents more than twofold increase of specific capacitance per unit area in comparison with conventional materials (~35 μF/cm2 vs. ~15 μF/cm2). 1.Tang, C. B.; Tracz, A.; Kruk, M.; Zhang, R.; Smilgies, D. M.; Matyjaszewski, K.; Kowalewski, T. J. Am. Chem. Soc. 2005, 127, 6918-6919.2.Kruk, M.; Dufour, B.; Celer, E. B.; Kowalewski, T.; Jaroniec, M.; Matyjaszewski, K. J. Phys. Chem. B 2005, 109, 9216-9225.3.Tang, C.; Bombalski, L.; Kruk, M.; Jaroniec, M.; Matyjaszewski, K.; Kowalewski, T. Adv. Mater. 2008, 20, 1516-1522.
6:00 PM - OO3.13
Solution Self-assembly Behavior of Block Copolymer Blends With the Same Hydrophilic Block but Different Hydrophobic Blocks.
Jiahua Zhu 1 , Ke Zhang 2 , Karen Wooley 3 , Darrin Pochan 1 Show Abstract
1 Department of Materials Science and Engineering, University of Delaware, Newark, Delaware, United States, 2 Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, United States, 3 Department of Chemistry, Texas A&M University, College Station, Texas, United States
Novel micellar structures due to segregation of unlike hydrophobic domains trapped within the same micelle core have been produced via self-assembly of block copolymer blends in tetrahydrofuran/water solution. The blend is composed of two/or more block copolymers with distinctive hydrophobic blocks but the same poly(acrylic acid) (PAA) hydrophilic block. By taking advantage of the complexation in the hydrophilic corona between the acid side chains of the PAA block and added organoamine molecules, unlike hydrophobic blocks are trapped in the same micelle core and consequently, locally segregate. This segregation gives rise to a branch of new multi-compartment micelle structures, such as hemisphere-hemisphere connector, AB/ABA sphere-cylinder connectors, etc. The volume and shape of each compartment can be well controlled by changing the blending ratio, block length and kinetic pathways. The interesting arrangement of hydrophilic PAA block and varied hydrophobic blocks within the micelles makes them potential templates for multi-functional composite nanomaterials via putting varied nanoparticles into targeting domains. Transmission electron, cryogenic transmission electron, and atomic force microscopy along with x-ray and neutron scattering have been applied to characterize the assembled structures.
6:00 PM - OO3.15
Programmable Self-assembly of DNA Origami Across Length Scales.
Sungwook Woo 1 , Paul W. K. Rothemund 2 3 Show Abstract
1 Bioengineering, California Institute of Technology, Pasadena, California, United States, 2 Computer Science, California Institute of Technology, Pasadena, California, United States, 3 Computation & Neural Systems, California Institute of Technology, Pasadena, California, United States
We demonstrate that the base stacking interactions between blunt-ended DNA helices on the edges of DNA origami can be employed to join origami together in a programmable fashion. Structures built by the DNA origami method are typically 100 nm by 100 nm in area and can be designed to create patterns with roughly 200 features at a spatial resolution of about 6 nm. We aim to combine origami structures to create larger scale structures that can expand the area and pattern space. Further, we explore the base stacking interactions between DNA origami as a new basis for molecular recognition, a new method for attaining specific binding reactions beyond the usual Watson-Crick DNA binding interactions. To achieve specificity in the stacking interactions, we take two approaches: introducing geometric shapes along the edges of origami, where a pair of complementary geometric shapes becomes a type of bond, and changing the composition of the edge staples along the edge of an origami of fixed geometry, e.g. a rectangle. Using these approaches, multiple bond types that exhibit mutual orthogonality are demonstrated. The base stacking interactions between blunt-ended DNA helices may become a promising method for hierarchical construction of complex structures based on DNA self-assembly across various length scales.
6:00 PM - OO3.2
The Morphology of Integrated Self-assembled Monolayers and Their Impact on Devices - A Computational and Experimental Approach.
Michael Novak 1 , Christof Jaeger 2 , Tim Clark 2 , Marcus Halik 1 Show Abstract
1 Institute of Polymer Materials, University Erlangen-Nürnberg, Erlangen Germany, 2 Computer Chemistry Center, University Erlangen-Nürnberg, Erlangen Germany
Self-organizing molecules are promising components in high performance, low cost, and flexible electronic devices. Due to the molecular induced driving force of voluntary film formation the process of self-assembly has the advantage of local selectivity, yielding highly ordered monomolecular films.We have investigated the divergence from theoretical dependence of alkyl chain length variation in thin-film devices with molecular gate dielectrics. We explain this divergence observed in capacitors and transistors with a change in self-assembled monolayer (SAM) morphology from amorphous layers for short alkyl chains (C6) to a pronounced 2D-crystalline behavior proceeding from C10 to C18 alkyl chains. Molecular Dynamics (MD) simulations and STM investigations prove these effects, which impact on the leakage current and the mobility obtained from the devices. The morphology and device characteristics of SAMs of n-alkyl phosphonic acids (C6-, C10-, C14- and C18-n-alkyl chains) were investigated on 2 nm thick atomic layer deposited AlOx on single crystalline silicon to benefit from the smooth surface and ensure that the self-assembly is not affected by the surface roughness. In low-voltage organic pentacene transistors with hybrid dielectrics (ALD-AlOx/SAM) hole mobilities up to 0.3 cm^2/Vs (at -1V) and ON/OFF-ratios around 1e4 were obtained. Thereby, device parameters such as leakage current (IG) do not follow the monotonously increasing of the chain length as expected. A more pronounced anomaly in current density was observed in capacitor devices (Si/AlD-AlOx/SAM/Au). The experimental results were correlated to the Simmons model to calculate the effective monolayer thickness. With results from MD simulation (10 ns) and STM measurements we explain these effects with changes in SAM morphology. We propose that the self-assembling of molecules with shorter alkyl chain is dominated by the footprint of the phosphonic acid, yielding amorphous monolayers. Molecules with longer alkyl chains organize in highly ordered 2D crystals separated by gaps, due to a competition between the space requirements of the phosphonic acid and Van der Waals interactions of the alkyl chain. Considering the impact on different SAM morphologies (depending on the chain length), the SAM leakage behavior is in good agreement with experimental and theoretical results, and the effects on the morphology (grain size) subsequent pentacene or gold layer could be explained. Therefore, an increased number of nucleation centres (yielding from the edges on the gaps in the 2D crystals) translates directly to smaller grain sizes in penatcene layers on C18-SAMs.Our study shows that the molecular interaction in molecular scale electronics is of enormous importance and also tuneable by the molecular structure (anchor group, chain, or possible “active” head group).
6:00 PM - OO3.3
Design and Self Assembly of Functional Boron Network Materials.
Takao Mori 1 Show Abstract
1 WPI Materials Nanoachitechtonics Center (MANA), National Institute for Materials Science (NIMS), Tsukuba Japan
Boron is an interesting element, tending to form 2D atomic nets and clusters in materials . In this sense it is similar to carbon, which has been much more extensively studied for such materials as fullerenes, nanotubes, and graphite related materials (graphene, GICs). A rich vein of materials science potential remains to be tapped and this is illustrated quite well by the recent discoveries of striking phenomena in compounds containing boron, such as the superconductivity of MgB2  and boron-doped diamonds , the strong magnetic coupling in magnetically dilute insulators , and the formation of a novel elemental structure of boron .Boron has one less electron than carbon and thus is electron deficient when forming atomic networks, but this causes it to have a special affinity with the rare earth elements and as a result, it forms myriad compounds. This is an excellent combination, because the rare earth atoms supply electrons to the boron atomic framework to stabilize and form novel structures, while the shell of f electrons will supply interesting properties like magnetism. From an application standpoint, the strong covalent boron cluster framework supplies a light robust "armor” which is acid and corrosion resistant and can withstand high temperatures. Attractive electronic, magnetic, and thermal properties [1,5] can be developed from the "inside" through metal atom constituents to utilize the protective properties of this network for applications. I will review state of the art of synthesis methods, focusing on the role of “bridging sites” through which novel boron network structures can be built up. The discovery of intrinsic “tiling” defects and their large effect on physical properties in 2D flat boron polygon materials will also be presented. Mori T.; “Higher Borides” in Handbook on the Physics and Chemistry of Rare Earths, Vol. 38, ed. K. A. Gschneidner Jr., J. -C. Bunzli, and V. Pecharsky, (North-Holland, Amsterdam, 2008) pp. 105-173. Nagamatsu, J.; Nakagawa, N.; Muranaka, T.; Zenitani, Y.; Akimitsu, J.; Nature, 2001, 410, 63. Ekimov, E.A.; Sidorov V.A.; Bauer E.D.; Mel'nik, N.N.; Curro N.J.; Thompson J.D.; Stishov, S.M.; Nature, 2004, 428, 542 Oganov, A.R.; Chen, J.; Gatti, C.; Ma, Y.; Glass, C.W.; Liu, Z.; Yu, T.; Kurakevych, O.O.; Solozhenko, V.L.; Nature 2009, 457, 863. Mori, T., “High Temperature Boron-based Thermoelectric Materials”, Material Matters 4, 37-39 (2009).
6:00 PM - OO3.5
Supramolecular Fibrous Gel Fabricated by Using a Microfluidic Channel.
Daisuke Kiriya 1 , Hiroaki Onoe 1 , Masato Ikeda 2 , Itaru Hamachi 2 , Shoji Takeuchi 1 Show Abstract
1 Institute of Industrial Science, The University of Tokyo, Tokyo Japan, 2 Graduate School of Engineering, Kyoto University, Kyoto Japan
This presentation describes the formation of a micro-scale gel strand constructed with the molecular-assembly of supramolecular fibers fabricated in a microfluidic channel. We find that the supramolecular fibers are highly aligned along the axis of the gel strand; this morphology is very different from the bulk gel. Moreover we find that the supramolecular fibers in these strands are able to diffuse small molecules along the supramolecular-fiber's axis. We believe that these gel strands could be a useful material to transport small molecules based on the supramolecular interaction. Supramolecular gels are hierarchical materials made from small molecules (monomers) that are assembled to form nano-sized fibers, which in turn are assembled to form macroscopic hydrogels. The weak non-covalent interactions between molecules in the fibers enable the incorporation of other molecules into the fiber structure, itself. In addition, their weak interactions allow for molecular diffusion along the axis. These properties could be useful as molecular sensors or transporters. However, this fascinating characteristic incorporate a disadvantage: the gels are weak due to the non-covalent-bonding nature of the molecular assembly. To utilize these gels as a sensor or transporting material several basic drawbacks need to be improved: 1) fragility of the hydrogel; and 2) the low degree of alignment of the supramolecular fibers. We overcome these problems to form robust gel strands containing highly aligned supramolecular fibers by using alginate as a shell to enhance the mechanical strength and generate the gel strands in a laminar flow within a microfluidic channel to align the supramolecular fibers. The building block of our supramolecular gel fibers is an amphiphilic synthetic molecule having a phosphate moiety. Coaxial micro-scale gel strands were fabricated with a double coaxial flow device constructed by three glass tubes and connectors fabricated by using stereolithographic modeling machine. The double coaxial flow geometry enables us to obtain the 50 um diameter coaxial gel strands; the strands have enough mechanical strength so that we can easily handle by tweezers. One of the important properties of supramolecular fibers is the ability to incorporate amphiphilic dye molecules so that we can examine the detailed structure of the fiber network. By staining supramolecular fibers with fluorescent lipid dye, we can clearly observe the alignment of supramolecular fibers along the gel strand. Then by using FRAP (Fluorescence Recovery After Photobleaching) experiment, we examined the fluidic nature for the aligned supramolecular fibers. The fluorescence intensity recovery curve and pictures in this process demonstrate the slow diffusion within the gel fiber. These data indicate the possibility of aligning nano-sized fibers in microfluidic channel and these fibers as --molecular highways--.
6:00 PM - OO3.6
A Composite Poly(ethylene glycol)-Based Hydrogel and Poly(dimethylsiloxane) Material for Active Soft Structures.
Rebecca Kramer 1 , Robert Wood 1 , Philseok Kim 1 , Lauren Zarzar 2 , Joanna Aizenberg 1 2 Show Abstract
1 School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States, 2 Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States
A pliable self-folding actuator, driven by environmental changes in humidity, has been fabricated from layers of cross-linked poly(ethylene glycol) (PEG) diacrylate -based hydrogel and poly(dimethylsiloxane) (PDMS). The swelling behavior of PEG-based hydrogel bonded by surface chemical processes to PDMS was studied. Polyglycidyl methacrylate (PGMA) dissolved into a mixture of MEK (2-butanone) : DMSO (dimethyl sulfoxide) (10:1 v:v), when applied to a thin plasma-treated PDMS substrate, forms a surface layer that is rich in reactive glycidyl groups allowing for the grafting of acrylate-based hydrogels . A layer of PEG (MW 2000) gel grafted to the substrate via PGMA was formed by photo-initiated crosslinking of PEG-diacrylate and the glycidyl anchoring groups. A hydrogel/PDMS bilayered device can be reversibly actuated by exposure to changes in humidity. In air, a bilayered PEG/PDMS device will remain flat. When it is brought into contact with a solvent, the hydrogel imbibes the solvent and swells, causing volumetric expansion of the hydrogel layer and forcing the elastomeric PDMS layer to bend. For a bilayered assembly with a width:length ratio of 0.19 and PEG:PDMS thickness ratios of 0.28 and 0.37, submersion in deionized water yielded radii of curvature of about 4.08cm and 3.75cm, respectively. These results confirm the intuitive notion that for a constant hydrogel thickness, a reduction in PDMS thickness yields lessened stiffness and increased curvature. The mechanics of a two-layer material bending actuator have been explored analytically by laminate plate theory . We assume no external forces and neglect mid-plane stresses to define a relationship between curvature and corresponding moments, given as: [M] = [D][k], where [M], [D] and [k] are the moment matrix, effective stiffness matrix and device curvatures (we assume curvature only exists in-plane), respectively. We therefore can predict local moments within the device generated by hydrogel swelling as a function of known material elasticities, geometries and curvatures. In addition to a bilayered system, several hybrid hydrogel/PDMS actuator devices, enabled by PGMA-assisted bonding and selective pre-patterned photo-initiated binding sites, have been considered. The use of a mask allows for direct photopatterning of liquid phase hydrogel for simple discriminatory patterning and fabrication . The hybrid material and devices described here allow for dynamic control over the movement and orientation of thin films of PDMS, which may be integrated with microfluidic systems and have applications in the emerging field of soft robotics. Sidorenko et. al. Science 315 (2007) p.487-490 Wood et. al. Sensors and Actuators 199 (2005) p.476-488 Beebe et. al. Nature 404 (2000) p. 588-590
6:00 PM - OO3.7
Predictive Modeling of Microscale Self Assembly.
Gary Hendricks 1 , James Tuckerman 1 , Nathan Crane 1 Show Abstract
1 Mechanical Engineering, University of South Florida, Tampa, Florida, United States
Self assembly relies on random interactions to combine components into desired configurations. It is analogous to chemical reaction processes. As such, the system energy level (analogous to temperature), bond energies, interaction frequencies, and the number of components play a key role. Unlike chemical reactions which are limited to combinations of a small set of elements, the basic components available for self assembly are limitless. However, basic scaling relationships tend to dramatically reduce the rates of microscale self assembly processes. Achieving acceptable rates requires careful design of the components and the system that brings them together. Predictive process models are also critical to developing self assembly processes and scaling them from laboratory demonstrations to commercial manufacturing. We will present a framework for developing a predictive model based on a simple parameter set and report on experimental data collected in support of this model. Current work focuses on surface tension-driven self assembly, but the approach is applicable to other self-assembly forces.
6:00 PM - OO3.8
Photoactive Supramolecular Scaffolds for Directed Nanoparticle Assembly.
Jeffrey Alston 1 , Jordan Poler 1 Show Abstract
1 Nanoscale Science Ph.D. Program, UNC Charlotte, Charlotte, North Carolina, United States
A well known goal of nanoscale science is to incorporate nanoscale materials into functional assemblies, devices and machines that utilize the interesting phenomena and properties of that material. However, a significant challenge exists for those applications in which nanoscale materials must be processed and then manipulated to be incorporated into a device. Solution based processing is one potential pathway and answer to that challenge. Ru coordination complexes have long been shown to be optically active molecules that can be utilized in supramolecular chemistry for photoinduced electron and energy transfer. Our research focuses on a specific family of Ru coordination complexes that contain multiple Ru centers coordinated with polypyridine ligands forming rigid complexes with well defined nanoscale features. We have shown that these nanoscale features contribute to interactions with nanoscale materials in solution. These interactions have a direct effect on nanoparticle assembly/aggregation within solutions with the added benefit of the Ru complex’s photosensitivity by which control can be augmented with light. Based on the binding phenomena observed in these studies, functional yet surprisingly simple assemblies can be constructed. Thin conducting pathways can be built with nanoscale materials, fastened by optically active Ru complexes combining both the nanoscale attributes of a particular material with the photointeractive character of the Ru coordination complex. The processing of these assemblies will be presented as well as several of the nanoscale phenomena that can be translated to this device will be shown, ie. translation of chirality to surface plasmon resonance and optical gating.
6:00 PM - OO3.9
Effect of Self-assembly on Structure and Properties of Freeze-cast Hybrid Materials.
Philipp Hunger 1 , Amalie Oroho 1 , Jenell Smith 1 , Michael Wang 1 , Ulrike G. Wegst 1 Show Abstract
1 Materials Science & Engineering, Drexel University, Philadelphia, Pennsylvania, United States
Natural composites like bone, antler and nacre possess exceptional sets of mechanical properties combining high Young’s modulus and strength with high toughness. It is generally observed that the ‘mechanical property amplification’ of these biological materials occurs in a non-additive manner. They go well beyond the simple composite ‘rule of mixture’ and are thought to be intricately linked to the multi-level hierarchical composite structure present in these material systems. In nature, complex microstructures and material architectures are achieved by self-assembly and relatively slow growth. For technical applications, which require fast and high volume production, the challenge persists to develop manufacturing processes with which it is possible to synthesize materials that mimic both structure and performance of their biological counterparts. One process with which it is possible to manufacture such hybrid materials is freeze-casting. It utilizes two intricate processes, directional solidification and self-assembly, to create structures that can be controlled across several length-scales. As a result, freeze-casting permits to create from well chosen constituents highly porous materials with mechanical properties that are an order of magnitude better than those with the same overall porosity and cell walls of identical composition but more random structure. Depending on the choice and combination of materials, whether polymer, ceramic or metal, the self-assembly induced by freeze-casting permits to create complex materials with a diverse spectrum of properties and multifunctionality that can be custom-designed and carefully controlled. Examples will be presented that illustrate their potential for use in biomedical, optical, thermal and electronic applications.
David Gracias Johns Hopkins University
Oliver G. Schmidt IFW Dresden
Paul W. K. Rothemund California Institute of Technology
Bartosz A. Grzybowski Northwestern University
OO4: Biomaterials for Engineering: DNA, Peptide, and Phage-based Self-Assembly I
Wednesday AM, April 07, 2010
Room 3020 (Moscone West)
9:30 AM - OO4.1
DNA-mediated Assembly of Anisotropic Nano-objects.
Stephanie Vial 1 2 , Dmytro Nykypanchuk 1 , Oleg Gang 1 Show Abstract
1 , Brookhaven National Laboratory, Upton, New York, United States, 2 , International Iberian Nanotechnology Laboratory, Braga Portugal
DNA-based approach for nano-object assembly allows programming of self-assembly behavior and establishes design rules for nanoscale fabrication. The addressability of DNA's binding was utilized in recently demonstrated assembly of well-defined 2D and 3D structures. While the most of the studies were focused on assembly of spherical particles, many of nano-objects with optical, electrical and magnetic functionalities are anisotropic. The anisotropy can significantly contribute to geometrical and entropic constrains, thus, influencing particles assembly. An understanding of these effects in 3D structures formed by DNA directed nano-objects is the focus of the presented studies. We investigated self-assembly behavior of system containing model anisotropic nano-object, gold nano-rods; in particular, the effect of DNA linkage design on the assembled structures. The thermodynamic properties and structure of assembled systems were probed by small-angle x-ray scattering, optical methods, and electron microscopy. A behavior associated with liquid-crystal effects in this type of nano-objects was observed.
9:45 AM - OO4.2
Designed Peptide Conjugates for Directing the Simultaneous Synthesis and Assembly of Inorganic Nanoparticles.
Nathaniel Rosi 1 , Chun-Long Chen 1 , Chengyi Song 1 , Leekyoung Hwang 1 Show Abstract
1 Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
A new strategy for directing the synthesis and self-assembly of nanoparticles will be presented. This strategy relies on the preparation of specific peptide conjugate molecules that are designed to direct not only the synthesis but also the self-assembly of nanoparticles into complex nanoparticle superstructures. We show how this method can be used to prepare various topologically complex nanoparticle superstructures, including gold nanoparticle chains, double helices, and capsules. Further, we show how various synthetic parameters can be tuned to carefully control the nanoparticle size and interparticle spacing within the superstructures and the overall metrics of the nanoparticle superstructure.
10:00 AM - **OO4.3
Self-assembly of a Nanoscale DNA Box With Controlled Functions.
Ebbe Andersen 1 2 3 , Morten Nielsen 1 2 3 , Kasper Jahn 1 2 3 , Reza Zadegan 1 2 3 , Rasmus Sorensen 1 2 3 , Victoria Birkedal 1 4 , Flemming Besenbacher 1 2 4 , Kurt Gothelf 1 2 5 , Jorgen Kjems 1 2 3 Show Abstract
1 Interdisciplinary Nanoscience Center, Aarhus University, Aarhus Denmark, 2 Danish National Research Foundation: Centre for DNA Nanotechnology, Aarhus University, Aarhus Denmark, 3 Department of Molecular Biology, Aarhus University, Aarhus Denmark, 4 Department of Physics and Astronomy, Aarhus University, Aarhus Denmark, 5 Department of Chemistry, Aarhus University, Aarhus Denmark
DNA molecules can be programmed by their specific nucleotide sequence to self-assemble into complex predefined nanostructures. The scaffolded ‘DNA origami‘ method allows high-yield assembly of DNA nanostructures of abitrary shape with unique surface addressability (Rothemund, 2006). We have developed a software package for the semi-automated design of DNA origami structures and demonstrated its applicability by the design of a DNA nano-dolphin with a flexible tail (Andersen et al., 2008). Recently, we have extended the DNA origami method into 3D by the design and characterization of a fully addressable 3D DNA box with dimensions of 42 × 36 × 36 nm3 that can be opened in response to external ‘key‘ signals (Andersen et al., 2009). Here we show further development of ‘key-lock‘ systems for the DNA box and monitor opening of the lid optically by fluorescence resonance energy transfer. It is shown that the DNA box can be made responsive to a signature of multiple microRNA sequences or to ultra-violet light, which demonstrates that the DNA box has potential as a single-molecule diagnostic sensor for cancer-specific microRNA expression profiles and for intracelluar controlled drug delivery in response to sequences or light. Rothemund. Folding DNA to create nanoscale shapes and patterns. Nature 2006, 440, 297-302. Andersen et al. DNA Origami Design of Dolphin-Shaped Structures with Flexible Tails. ACS nano 2008, Andersen et al. Self-assembly of a nano-scale DNA box with a controllable lid. Nature 2009, 459, 73-76.
10:30 AM - **OO4.4
DNA Nanostructures and Molecular Machinery.
Andrew Turberfield 1 Show Abstract
1 Department of Physics, University of Oxford, Oxford United Kingdom
DNA is a wonderful material for nanoscale construction: its self-assembly can be programmed by making use of its information-carrying capability, and its hybridization or hydrolysis can be used as to provide energy for molecular devices. I shall describe our recent work on self-assembled molecular structures and on molecular machinery, including free-running bipedal molecular motors inspired by the motor protein kinesin. An autonomous molecular motor that does not alter its track needs an external energy source: if it uses a chemical fuel, it must be a catalyst that couples chemical change to mechanical motion. We have demonstrated the mechanism of a chemically fuelled motor that is designed to transport a load on a reusable track and to operate without intervention until it runs out of fuel. The motor is built from DNA, and the free energy required for directional motion is obtained by catalyzing hybridization of a DNA fuel. Its two-footed structure is inspired by kinesin and myosin V, protein motors with two feet (or ‘‘heads’’) that are driven along cytoskeletal filaments by ATP hydrolysis. The DNA motor’s feet are coordinated by means of competition where their binding sites on the track overlap: competition exposes different ends of the identical feet so that the left and right feet interact with the fuel at different rates. We show how the catalytic activities of the two feet can be coordinated to create a Brownian ratchet that is in principle capable of directional and processive movement. References Turberfield, A.J., Mitchell, J.C., Yurke, B., Mills, A.P., Blakey, M.I. & Simmel, F.C. DNA fuel for free-running nanomachines. Phys. Rev. Lett. 90, 4 (2003) Bath, J. & Turberfield, A.J. DNA nanomachines. Nature Nanotech. 2, 275-284 (2007) Green, S.J., Bath, J. & Turberfield, A.J. Coordinated Chemomechanical Cycles: a Mechanism for Autonomous Molecular Motion. Phys. Rev. Lett. 101, 238101 (2008) Bath, J., Green, S.J., Allen, K.E. & Turberfield, A.J., Mechanism for a Directional, Processive, and Reversible DNA Motor. Small 5, 1513-1516 (2009)
11:30 AM - **OO4.5
Self-assembly of DNA into Nanoscale Three-dimensional Shapes.
William Shih 1 2 3 Show Abstract
1 Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States, 2 Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States, 3 Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States
I will present a general method for solving a key challenge for nanotechnology: programmable self-assembly of complex, three-dimensional nanostructures. Previously, scaffolded DNA origami had been used to build arbitrary flat shapes 100 nm in diameter and almost twice the mass of a ribosome. We have succeeded in building custom three-dimensional structures that can be conceived as stacks of nearly flat layers of DNA. Successful extension from two-dimensions to three-dimensions in this way depended critically on calibration of folding conditions. This general capability for building complex, three-dimensional nanostructures will pave the way for the manufacture of sophisticated devices bearing features on the nanometer scale.
12:00 PM - **OO4.6
Exciting Positional Control With DNA Origami: Onwards Nanoscale Gadgets for Science and Technology.
Hendrik Dietz 1 Show Abstract
1 Physics Dept., Technische Universität München, Garching near Munich Germany
I will present how DNA origami can be tweaked for the construction of intricate nanoscale shapes that bend and twist. Taken together with other recent advances, DNA origami offers now phenomenal positional control on the nanoscale. I will discuss our efforts and ideas to harness this positional control in nano-gadgets for applications in the molecular biosciences.
12:30 PM - OO4.7
Controlled Alignment of Multiple Proteins and Nanoparticles via Backbone Modified Phosphorothioate DNA Templates.
Ngo Yin Wong 1 , Jung Heon Lee 3 , Zidong Wang 1 , Yi Lu 1 2 Show Abstract
1 Materials Science and Engineering, University of Illinois at Urbana Champaign, Urbana, Illinois, United States, 3 , Northwestern University, Evanston, Illinois, United States, 2 Chemistry, University of Illinois at Urbana Champaign, Urbana, Illinois, United States
One of the fundamental challenges of nanotechnology is the ability to pattern functional and relevant nanosized objects in a directed and technologically meaningful way. In the past decades, nanotechnology focused much of its attention on “top-down” approaches, where smaller objects are fabricated from bulk materials using mainly optical lithography techniques. Citing a fundamental limit to optical resolution, however, there has been a paradigm shift toward nanotechnology from the “bottom-up.” While many different strategies have been explored and reported, DNA structural nanotechnology takes a biological approach and exploits the highly programmable and rigid nature of double stranded DNA to build periodic as well as discrete structures in 1, 2, and 3 dimensions. We have previously reported an iodine/thiol bi-functional linker that can specifically conjugate with a single phosphothiolate modification on the backbone of DNA and gold nanoparticles, allowing the programmable attachment of nanoparticles to DNA with nanometer precision in 1 dimension. In the current work, we have extended this technique to directing the assembly of 2 different proteins and nanoparticles, as well as expanding from 1 dimension into 2 dimensions. This work represents an important extension in DNA structural nanotechnology by increasing the stability of the DNA nano-template as well as allowing the directed assembly of more diverse nanomaterials, critical towards the development of applications using DNA structural nanotechnology.
OO5: Biomaterials for Engineering: DNA, Peptide, and Phage-based Self-assembly II
Wednesday PM, April 07, 2010
Room 3020 (Moscone West)
2:30 PM - **OO5.1
Designer DNA Architectures for Nanobiotechnology.
Hao Yan 1 Show Abstract
1 , Arizona State University, Tempe, Arizona, United States
Naturally existing biological systems, from the simplest unicellular diatom to the most sophisticated organ such as human brain, are functional self-assembled architectures. Scientists have long been dreaming about building artificial nanostructures that can mimic such elegance in nature. Structural DNA nanotechnology, which uses DNA as blueprint and building material to organize matter with nanometer precision, represents an appealing solution to this challenge. Based on the knowledge of helical DNA structure and Watson-Crick base pairing rules, we are now able to construct DNA nanoarchitectures with a large variety of geometries, topologies and periodicities with considerably high yields. Modified by functional groups, those DNA nanostructures can serve as scaffolds to control the positioning of other molecular species, which opens opportunities to study inter-molecular synergies, such as protein-protein interactions, as well as to build artificial multi-component nano-machines. In this talk, I will describe our recent progress in designing and implementing designer DNA architectures for directed self-assembly, biosensing and molecular robotics and discuss some potential applications of structural DNA nanotechnology.
3:00 PM - OO5.2
Low-cost, High-throughput Nanoscale Patterning of DNA for Nanomaterial Assembly.
Hyunwoo Noh 1 2 , Albert Hung 2 , Chulmin Choi 1 3 , Sungho Jin 1 2 3 , Jennifer Cha 1 2 3 Show Abstract
1 Materials Science and Engineering, UCSD, La Jolla, California, United States, 2 Nanoengineering, UCSD, La Jolla, California, United States, 3 Mechanical and aerospace Engineering, UCSD, La Jolla, California, United States
A facile, scalable, and cost-effective approach for fabricating sub-100nm features of DNA and templating the deposition of nanoscale materials is reported. Despite their unique physical properties, nanoscale materials have faced serious roadblocks toward technological impact owing to the inherent difficulties of engineering wafer-level arrays inexpensively with nanoscale precision. By patterning DNA arrays over macroscopic domains with sub-100nm resolution, nanoscale materials may be assembled into functional architectures with high yield and fidelity. To address nanoscale features via facile and inexpensive fabrication, we report here a printing method that enables repeated patterning of nanoscale arrays of DNA strands over 16 mm2 areas with 50 nm resolution. DNA hybridization is then shown to direct the assembly of 10 nm gold nanoparticles onto the DNA patterns to create highly ordered two-dimensional nanocrystal arrays. The entire printing and assembly process requires only three fabrication steps and a single lithographically generated silicon stamp that can be used repeatedly. The inexpensive procedures developed here to generate nanoscale DNA patterns expected to extend toward roll-to-roll assembly of nanoscale materials with sub-50 nm resolution and fidelity.
3:15 PM - OO5.3
Self-assembly of Genetically Engineered Bacteriophages into 2D Matrices and Their Bio/Optical Application.
Woojae Chung 1 2 , Mark Sena 1 , Seung-Wuk Lee 1 2 Show Abstract
1 Bioengineering, UC Berkeley, Berkeley, California, United States, 2 , Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley Nanoscience and Nanoengineering Institute, Berkeley, California, United States
Designing biomimetic matrices with precisely controlled structural organization that provides (bio)chemical and physical cues is critical for the development of smart materials applicable to tissue engineering scaffold and optical device materials. We have developed novel liquid crystalline film matrices/patterns made from genetically engineered M13 bacteriophages that exhibit the ability to control and guide cell behavior for tissue regenerating applications. To facilitate adhesion between the viruses and cells and modulate the virus assembly on the substrate, 2700 copies of the M13 major coat protein were genetically engineered to display functional peptide motifs with integrin-binding activity or different net charges. In addition, the viral pattern film, which was created by meniscus-driven self-assembly of the liquid crystalline phage solution, was demonstrated that it would provide great opportunities for developing various optical devices such as color filters and diffraction grating as well as tissue regenerating scaffolds.
3:30 PM - OO5.4
Synthesis and Characterization of Single Organic Molecule-bis(micron-sized DNA) Triblock Supramolecule: Towards Nanoelectronics.
JungKyu Lee 1 , Alex Neuhausen 2 , Zhenan Bao 3 , Daive Goldhaber-Gordon 2 Show Abstract
1 Chemistry, Stanford University, Stanford, California, United States, 2 Physics, Stanford University, Stanford, California, United States, 3 Chmeical Engineering, Stanford University, Stanford, California, United States
We report the synthesis of single organic molecule-bis(micron-sized DNA) triblock supramolecules and the optical and structural characterization of the construct at the single-molecule level. A single organic molecule-bis(oligodeoxynucleotide) triblock was synthesized via the amide-coupling reaction. Subsequent protocols of DNA hybridization-ligation were developed to form the supramolecular triblock structure with lambda-DNA fragments on the micrometer length scale. The successful synthesis of the micron-sized DNA-single organic molecule-DNA supramolecule was confirmed by agarose gel electrophoresis with fluorescence imaging under UV excitation. Single triblock structures were directly imaged by combined scanning force microscopy (SFM) and single-molecule fluorescence microscopy, and provided unambiguous confirmation of the existence of the single fluorophore inserted in the middle of the long DNA. This type of triblock structure is a step closer to providing a scaffold for single-molecule electronic devices after metallization of the DNAs.
3:45 PM - OO5.5
Design Rules for Self-assembly of Artificial Microtubules.
Mark Stevens 1 Show Abstract
1 , Sandia National Labs, Albuquerque, New Mexico, United States
Biological materials often have a hierarchical structure which enables complex functionality. Biopolymers such as microtubules and actin have monomers which are proteins that contain a rich variety of feature incorporated into the basic building block. In development of materials that mimic aspects of natural systems, we will need to develop basic building blocks that have a range of features. A promise of nanoscience is the creation of such complex nanoparticles, after all proteins are nanoparticles. We are working to understand the fewest and most fundamental features of the monomers that will yield the geometry and dynamic properties of interest. In particular the focus of the modeling effort is determining design principles for assembly of tubular structures from monomers that mimic microtubules formed from the protein tubulin. We will discuss the role of symmetry of the interaction sites on the surface of the monomer with respect to forming self-assembled structures. We will discuss the results of simulations that show our monomer models can self-assembled into tubular structures including helical geoemetry without a chiral character in the monomeric building block. The role of the interactions in the dynamic assembly is critical in the assembly process with respect to defect tolerance. A key goal is to achieve some of the reconfigurable self-assembly of microtubules and methods to include such features in the models will be given.
OO6/LL6: Joint Session: Biomimetic and Hybrid Materials
Wednesday PM, April 07, 2010
Room 3020 (Moscone West)
4:30 PM - OO6.1/LL6.1
Directed Assembly of Patterned Mono and Multi-layered Cell Clusters Towards the Development of a Bioengineered Artificial Pancreas.
Adam Mendelsohn 1 , Tejal Desai 1 2 Show Abstract
1 Joint Graduate Group in Bioengineering, UCSF/UC Berkeley, San Francisco, California, United States, 2 Bioengineering and Therapeutic Sciences, UCSF, San Francisco, California, United States
In the treatment of type I diabetes, there is significant effort towards development of a therapy that provides effective blood-glucose homeostasis without requiring frequent patient action. Current standard of care treatments all require frequent needle-pricks for blood-glucose detection or glucose sensor calibration in addition to precise insulin delivery to achieve effective disease management. Transplantation of insulin-secreting pancreatic β-cell clusters or islets promises to obviate the need for needle- pricks and insulin delivery devices to provide the patient with an effective cure. The majority of therapies under development attempt to transplant human cadaver islets which after removal from the dense network of blood vessels in a healthy pancreas are often too large to maintain cell viability on the inside of large clusters. As a result, control over the size of transplanted clusters has recently emerged as an important factor determining clinical efficacy. The goal of this work is to provide a method for creating cell clusters of precisely defined dimensions for transplantation and to evaluate the effect that cluster size has on function. In this work, we functionalized glass cover slips with an aldehyde through a step-by-step covalent attachment of self-assembled monolayers. Extracellular matrix proteins that facilitate cell adhesion were covalently attached in defined areas through microcontact printing. The remaining exposed aldehydes were then covalently attached to mPEG-amine which inhibits cell attachment. The surfaces were characterized with water contact angle measurements, x-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and semi-quantitative fluorescence microscopy. 20-120 µm square protein patterns directed the assembly of monolayer cell clusters confined to the same area at low cell seeding densities, and multi-layered cell clusters at higher cell seeding densities. Semi-quantitative immunocytochemistry after glucose-stimulated insulin secretion revealed greater normalized insulin production from larger 2D clusters as well as multi-layered vs. mono-layered clusters confined to the same 2D area. Cluster sizes which exhibit optimal insulin production and viability can be removed from the surface for transplantation. This work demonstrates that directed cell cluster assembly results in precisely defined 2D and 3D clusters that may contribute towards the development of a clinically successful artificial pancreas for treating type I diabetes.
4:45 PM - OO6.2/LL6.2
Structural Transitions of DNA-surfactant Films in Response to Hydration and Temperature.
Surekha Gajria 2 , Thorsten Neumann 1 , Luc Jaeger 2 , Matthew Tirrell 1 Show Abstract
2 Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, United States, 1 Bioengineering, University of California Berkeley, Berkeley, California, United States
Anionic biopolymers such as RNA and DNA can self-assemble with cationic lipids into water-insoluble complexes driven by electrostatic attraction which are capable of forming self-standing films when cast from an organic solvent.1-5We have previously investigated the mechanical properties and structure of a DNA-didodecylammonium bromide (DDAB) film by tensile tests, small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), circular dichroism (CD) and FT-IR-spectroscopy.4,5 Regardless of the type or length of nucleic acid chosen, the films have a lamellar structure with a repeat unit consisting of nucleic acid strands sandwiched between layers of DDAB.Recently we found that the structure of the films is flexible and undergoes a transition from monolayer of DDAB paired with single-stranded DNA when dry to double-stranded DNA and a bilayer of DDAB when wet.4 We have further probed the transition pathway of the structural switching that occurs as the film is exposed to varying levels of humidity and when doped with small interfering molecules like cholesterol and ethidium bromide.3 Heating the wet film above the melting temperature of the nucleic acid generates a third structural state which consists of single-stranded DNA and a bilayer of DDAB.This unique structural transition prompts further investigation into its cause and the extent to which it can be manipulated. To our knowledge no switching behavior as a function of water content such as we have seen for our films has been reported in the literature. This transition upon hydration could be used to manipulate the film into “on” and “off” states; i.e. biochemically inactive or “off” in dry state, and when hydrated changing its structure, possibly presenting therapeutic nucleic acids such as siRNA, peptides, or small molecules for release in vivo as the film degrades.We conclude that the state of DNA in the film depends on the surrounding water content and temperature, while the state of DDAB depends only on the water content. The structure of the film is flexible and can be altered by changing environmental conditions as well as the chemical ingredients. These films will have applications as responsive materials, e.g. in drug delivery. References:1.Hoshino, Y.; Tajima, S.; Nakayama, H.; Okahata, Y. Macromolecular Rapid Communications 2002, 23, 253-255.2.Ijiro, K.; Okahata, Y. Journal of the Chemical Society-Chemical Communications 1992, 1339-1341.3.Neumann, T.; Gajria, S.; Bouxsein, N. F.; Jaeger, L.; Tirrell, M. "Structural responses of DNA-DDAB films to varying hydration and temperature" (in preparation).4.Neumann, T.; Gajria, S.; Tirrell, M.; Jaeger, L. Journal of the American Chemical Society 2009, 131, 3440-3441.5.Smitthipong, W.; Neumann, T.; Gajria, S.; Li, Y.; Chworos, A.; Jaeger, L.; Tirrell, M. Biomacromolecules 2009, 10, 221-228.
5:00 PM - OO6.3/LL6.3
Towards Optically Active Hybrid Materials Using Bifunctional Inorganic Binding Peptides.
Turgay Kacar 1 2 , Yuhei Hayamizu 1 , Marketa Hnilova 1 , Emre Oren 1 , Candan Tamerler 1 2 , Mehmet Sarikaya 1 Show Abstract
1 Genetically Engineered Materials Science and Engineering Center, Materials Science and Engineering Dept. , University of Washington, Seattle, Washington, United States, 2 Molecular Biology and Genetics, Istanbul Technical University, Maslak - Istanbul Turkey
Genetically engineered peptides for inorganics (GEPIs), isolated through biocombinatorial approaches utilizing, e.g., phage display and cell surface display peptide libraries, were used as linkers for metal and metal oxide nanoparticle immobilization on inorganic surfaces for optically active nanostructures. Specifically, we developed bi-functional GEPIs that consist of gold binding peptide (AuBP) and quartz binding peptide (QBP) that were chemically conjugated to each other. Subsequently, either silica or gold nanoparticle assembly was successfully carried out on gold and glass surfaces, respectively, The solid surfaces are functionalized using these bifunctional peptides whose either the AuBP or QBP end acts as the material specific “glue” for the surface. Following nanoparticle attachment, the substrates were characterized by atomic force microscopy and dark-field (DF) imaging using a fluorescence microscope. Alkanethiols, aminoalkylalkoxysilanes, and other chemical reagents, are the most common used linkers in the literature for covalent attachment of the nanoparticle to inorganic surfaces. Here, our results demonstrate that bifunctional-GEPIs can be an attractive alternative approach for the immobilization of nano-metallic and -oxide particles on any given solid substrate The novel molecular bifunctional-GEPI platform has enormous potential in practical applications in nanobiotechnology, e.g., in functionalization of core-nanoshell particles, core-satellite nanoparticle systems, immobilization of nanoparticles on substrates and on biomacromolecules towards functional utilization. The research is supported by NSF-MRSEC Program through the University of Washington GEMSEC (DMR 0520567), NSF-BioMat.
5:15 PM - OO6.4/LL6.4
Particle/Fluid Interface Replication as a Means of Producing Topographically Patterned Surfaces: Substrates for Supported Lipid Bilayers.
Anand Subramaniam 1 , Sigolene Lecuyer 1 , Kumaran Ramamurthi 3 , Richard Losick 3 , Howard Stone 2 Show Abstract
1 School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States, 3 Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States, 2 Department of Mechanical and Aerospace Engineering, Princeton University, Cambridge, New Jersey, United States
There is intense interest in the role of geometry in the thermodynamics and dynamics of such systems as lipid bilayers, membrane proteins and block copolymers. Topographically patterned surfaces that impose well-defined gradients of curvature on surface adsorbed layers are a potential model to study these geometrical effects. Here we report a method for producing topographically patterned surfaces by replicating a fluid-fluid interface studded with colloidal particles. With this method we have fabricated geometrically simple surfaces, such as arrays of spherical features on planar surfaces and also surfaces with complex geometries such as replicas of whole bacterial cells, tubular nanoclays, and even multi-walled carbon nanotubes. Furthermore, chemically heterogeneous surfaces composed of silica, polystyrene, epoxy or poly(dimethyl)siloxane (PDMS), and chemically homogeneous surfaces composed of PDMS or epoxy can be made. As an example of the potential applications of these surfaces, we show that lipid bilayers that are supported on all-PDMS topographically patterned substrates undergo curvature-modulated phase separation.
5:30 PM - OO6.5/LL6.5
Isotropic Diffraction from a Two-dimensional Biomimetic Self-assembled `moth-eye’ Grating.
Petros Stavroulakis 1 , Stuart Boden 1 , Darren Bagnall 1 Show Abstract
1 School of Electronics and Computer Science, University of Southampton, Southampton, Hampshire, United Kingdom
The cornea of some species of night flying moth is covered in protuberances organized in close-packed tessellated structures, which create an effective grated refractive index metamaterial layer. This discovery from Bernard  has since spearheaded the concept of using subwavelength gratings as alternative methods to thin film layers for achieving optical antireflection. In this work, interest is focused on the pattern itself by studying it’s 2D Fourier transform. It is shown that this type of moth-eye pattern appears to be a naturally-evolved counter-intuitive method of realising very high optical rotational symmetry which was confirmed by analysis of the grating’s optical diffraction pattern. A close-packed tessellated two dimensional diffraction grating, consisting of silicon pillars in air, was defined via self-assembly of polystyrene nanospheres on the surface of the silicon substrate followed by anisotropic etching. This pattern was compared to the sunflower pattern which is another heavily studied biomimetic pattern, with very high optical rotational symmetry, whose diffraction pattern consists of circular Bragg rings . A sunflower pattern diffraction grating was created in silicon by e-beam lithography and anisotropic etching. A white-light laser reflectometry system was used to measure and compare the diffraction pattern from both structures. It was confirmed that, owing to the fact that the close-packed structure has been tessellated randomly, the diffraction pattern from the structure is isotropic compared to the six fold symmetry of the underlying close-packed pattern it consists of. The diffraction pattern observed from the nanosphere sample is less homogeneous but equally isotropic to the one observed from the sunflower pattern.The moth-eye biomimetic sample was created on a large area (~2x2cm2) and hence the assumption that the isotropic nature of the moth eye pattern is not sensitive to the point of contact with the incident beam, was also confirmed by measuring the isotropic nature of the diffraction pattern in multiple locations on the sample. The opposite behaviour that is suggested for the sunflower pattern  was not confirmed due to the very small size of the pattern. A main advantage of the moth-eye biomimetic pattern is that it can be manufactured, as shown in this work, via nanosphere lithography which is a cheap and massively parallel self-assembly nanomanufacturing technique.C.G. Bernard, "Structural and functional adaptation in a visual system," Endeavour, vol. 26, 1967, pp. 79-84.A. Agrawal, N. Kejalakshmy, J. Chen, B.M. Rahman, and K.T. Grattan, "Golden spiral photonic crystal fiber: polarization and dispersion properties," Optics Letters, vol. 33, 2008, p. 2716.M.E. Pollard and G.J. Parker, "Low-contrast bandgaps of a planar parabolic spiral lattice," Optics Letters, vol. 34, 2009, p. 2805.
5:45 PM - OO6.6LL6.6
Formation of Helical Cylindrical Micelles via Kinetic Self-assembly of Block Copolymer in Solution.
Sheng Zhong 1 , Ke Zhang 2 , Karen Wooley 2 , Darrin Pochan 1 Show Abstract
1 Materials Science and Engineering, University of Delaware, Newark, Delaware, United States, 2 Center for Materials Innovation, Department of Chemistry and Department of Radiology, Washington University in Saint Louis, Saint Louis, Missouri, United States
One dimensional polymeric helical micelle is a perfect example of the importance in self-assembly of macromolecules for nanotechnology. We report here that multimicrometer-long, helical cylinders can be produced from co-assembly of poly(acrylic acid)-block-poly(methyl acrylate)-block-polystyrene (PAA-b-PMA-b-PS) triblock copolymers with an excessive amount of multivalent amino molecules in THF/water mixtures. The key to generate such helical nanostructures is the control of the assembly kinetics. Cryogenic transmission electron microscope (cryo-TEM) studies clearly revealed that the kinetic pathway underwent a complex but reproducible structural transition from the long-range stacking of branched cylinders at early stage to the interconnection of these branched cylinders and then to the helical nano-cylinders. We hypothesized that this evolution process involved a redistribution of the excess multivalent amino molecules around hydrophilic corona. We also found that the final assemblies were greatly influenced by the type and amount of the amino molecules, the volume ratio of water in THF as well as the block length of polystyrene block. Further study indicates the mechanical properties of assembled polymeric nanostructures are greatly subject to the composition and architecture of the block copolymers.