Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session N30: Self-Assembly: Mostly Biopolymers, DNA and Nanoparticles |
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Sponsoring Units: DCMP Chair: Xiangyun Qiu, George Washington University Room: 338 |
Wednesday, March 20, 2013 11:15AM - 11:27AM |
N30.00001: Formation of Heterogeneous Toroidal-Spiral Particles -- by Drop Sedimentation and Interaction Ying Liu, Ludwig Nitsche, Richard Gemeinhart, Vishal Sharma, Magdalena Szymusiak, Hao Shen We describe self-assembly of polymeric particles, whereby competitive kinetics of viscous sedimentation, diffusion, and cross-linking yield a controllable toroidal-spiral (TS) structure. Precursor polymeric droplets are splashed through the surface of a less dense, miscible solution, after which viscous forces entrain the surrounding bulk solution into the sedimenting polymer drop to form TS channels. The intricate structure forms because low interfacial tension between the two miscible solutions is dominated by viscous forces. The biocompatible polymer, poly(ethylene glycol) diacrylate (PEG-DA), is used to demonstrate the solidification of the TS shapes at various configurational stages by UV-triggered cross-linking. The dimensions of the channels are controlled by Weber number during impact on the surface, and Reynolds number and viscosity ratio during subsequent sedimentation. Within the critical separation distance, interaction of multiple drops generates similar structure with more flexibility. Furthermore, the understanding of multiple drop interaction is essential for mass production of TS particles by using parallel and sequential arrays of drops. [Preview Abstract] |
Wednesday, March 20, 2013 11:27AM - 11:39AM |
N30.00002: ReaxFF Reactive Force Field Study of Oriented Attachment of TiO$_{2}$ Nanocrystals in Vacuum and Humid Environments Muralikrishna Raju, Kristen Fichthorn, Adri van Duin We use a ReaxFF reactive force field to study the aggregation of various titanium dioxide (anatase) nanocrystals in vacuum and humid environments. The nanocrystals are in the 2-6nm size range, with shapes dictated by the Wulff construction. In vacuum, the nanocrystals tend to merge along their direction of approach, resulting in a polycrystal. By contrast, in the presence of water vapor, the nanocrystals tend to reorient themselves and aggregate via the oriented attachment mechanism to form a single or twinned crystal. We find that adsorbed water molecules and hydroxyl groups play multiple roles in oriented attachment. As the nanocrystals approach one another closely, adsorbed water molecules and surface hydroxyls prevent their immediate aggregation. These adsorbed species create a hydrogen bonding network, which aligns the nanoparticles in registry. Upon the eventual elimination of these species, the nanoparticles fuse into a single-crystal or twinned aggregate. We observe this aggregation mechanism for anatase(101), anatase(112), and anatase(001) surfaces, as is also seen experimentally. This indicates the important role that solvent plays in nanocrystal aggregation and how solvent can be a powerful tool for directing and controlling nanocrystal growth. [Preview Abstract] |
Wednesday, March 20, 2013 11:39AM - 11:51AM |
N30.00003: Improving reaction rates by confinement within biocompatible polymers Cecile Malardier-Jugroot, Xia Li, Michael N. Groves, Manish Jugroot The most efficient catalysts have been developed and optimized by living systems. Indeed, in vivo enzyme-catalyzed reactions are several orders of magnitude more efficient than platinum based catalyzed reactions. However, the rate of reaction and equilibrium interactions are considerably reduced when the biological systems are studied in vitro. This phenomenon is largely attributed to the effect of confinement or macromolecular crowding present in the cell. This paper will present the comprehensive characterization of amphiphilic polymeric template with hydrophobic cores inducing 1D and 2D confinement on hydrophobic reactants diffusing within the templates. The paper will show that effect of confinement allows reactions to occur without external factors essential for these reactions to occur in the bulk. The products synthesized in a very controlled environment within amphiphilic polymeric nanotubes and nanosheets are monodispersed at the nanoscale ($\sim$ 2nm). The effect of confinement opens new possibilities for environmentally friendly synthesis of novel nanoscale materials. [Preview Abstract] |
Wednesday, March 20, 2013 11:51AM - 12:03PM |
N30.00004: Unraveling the Mechanism of Nanotube Formation by Chiral Self-Assembly of Amphiphiles Dganit Danino The self-assembly of \textit{nanotubes} from chiral amphiphiles and peptides is still poorly understood. Here, we present the first complete path to nanotubes by chiral self-assembly studied with C$_{12}$-$\beta_{12}$, a tailored molecule designed to have unique hybrid architecture. Using direct-imaging cryo-transmission electron microscopy (cryo-TEM) we show the time-evolution from micelles to closed nanotubes, passing through several types of 1-dimensional (1-D) intermediates such as elongated fibrils, twisted ribbons, and coiled helical ribbons. Scattering and diffraction techniques confirm that the fundamental unit is a monolayer lamella, with the hydrophobic tails in the gel state and beta-sheet arrangement. The lamellae are held together by a combination of hydrophobic interactions, and 2 sets of hydrogen bonding networks. Our data exclusively indicate that twisted ribbons are the precursors for coiled ribbons, and we show this transition is directly linked to the ribbon width. Furthermore, quantitative analysis shows that neither the ``growing width'' model nor the ``closing pitch'' model accurately describe the process of nanotube formation, and \textit{both} ribbon width and pitch grow with maturation, maintaining a linear growth in their ratio. We also show that chirality is a key requirement for nanotube formation. References: [1] Ziserman L et al., \textit{J Am Chem Soc} \textbf{133(8)}, 2511-2517 (2011) [2] Ziserman L et al., \textit{Phys Rev Lett} \textbf{106,} 238105 (2011) [Preview Abstract] |
Wednesday, March 20, 2013 12:03PM - 12:15PM |
N30.00005: Programmable Mesoscopic Architecture using Directionally-Functionalized Nanoparticles Jonathan Halverson, Alexei Tkachenko Nanoparticles that have been isotropically-functionalized with complementary DNA strands have been shown to self-assemble into a variety of crystalline morphologies. To produce a nanoparticle assembly with a finite size and arbitrary shape, the NPs must be endowed with directional interactions. Directionally-functionalized nanoparticles (dfNPs) can be constructed by grafting ssDNA at specific locations on the particles, and proof-of-principle experiments have successfully demonstrated the self-assembly of such particles. Using these building blocks we have previously demonstrated with numerical simulations that a variety of target mesoscopic structures, each with a programmed local morphology and complex overall shape, can be self-assembled in near perfect yield. Here we present a model to describe the kinetics of assembly of a structure composed on dfNPs. The capability to produce these structures can be utilized in a variety of applications where bottom-up construction of 3D nano-objects with well-defined composition and architecture is required (e.g., nanoplasmonics, nanomedicine, metamaterials). [Preview Abstract] |
Wednesday, March 20, 2013 12:15PM - 12:27PM |
N30.00006: Biomimetic DNA emulsions: specific, thermo-reversible and adjustable binding from a liquid-like DNA layer Lea-Laetitia Pontani, Lang Feng, Remi Dreyfus, Nadrian Seeman, Paul Chaikin, Jasna Brujic We develop micron-sized emulsions coated with specific DNA sequences and complementary sticky ends. The emulsions are stabilized with phospholipids on which the DNA strands are grafted through biotin-streptavidin interactions, which allows the DNA to diffuse freely on the surface. We produce two complementary emulsions: one is functionalized with S sticky ends and dyed with red streptavidin, the other displays the complementary S' sticky ends and green streptavidin. Mixing those emulsions reveals specific adhesion between them due to the short-range S-S' hybridization. As expected this interaction is thermo-reversible: the red-green adhesive droplets dissociate upon heating and reassemble after cooling. Here the fluid phospholipids layer also leads to diffusive adhesion patches, which allows the bound droplets to rearrange throughout the packing structure. We quantify the adhesion strength between two droplets and build a theoretical framework that captures the observed trends through parameters such as the size of the droplets, the DNA surface density, the various DNA constructs or the temperature. This colloidal-scale, specific, thermo-reversible biomimetic emulsion offers a new versatile and powerful tool for the development of complex self-assembled materials. [Preview Abstract] |
Wednesday, March 20, 2013 12:27PM - 12:39PM |
N30.00007: Hybridization dynamics to DNA guided crystallization Ting Li, Rastko Sknepnek, Monica Olvera de la Cruz DNA recognition inspires an elegant protocol to design versatile nanoparticle assemblies. Although great achievements in DNA programmed periodic structures have been obtained, it took over a decade to realize even the basic crystal structures like FCC and BCC in an experiment. We use molecular dynamics simulations to discuss the dynamic aspects of the assembly process and identify ingredients that are key to successfully assemble nanoparticle superlattices through DNA hybridizations. The scale-accurate coarse-grained model [1,2] faithfully captures the relevant dynamics of the DNA hybridization, and is able to recover the in situ formation of all to date experimentally reported binary superlattices (BCC, CsCl, AlB2, Cr3Si and Cs6C60 lattices). We used a multi-scale simulation approach to study the assembly mechanism in systems with up to $10^6$ degrees of freedom and found that the assembly process is enthalpy-driven. Finally, we investigated the optimal strength of DNA linkers, hybridization dynamics, and percentage of hybridizations for different binary systems. Based on these results, we suggest a protocol for future nanomaterial designs with versatile DNA interactions. [1] Knorowski, C., et al. P.R.L. 2011,106,215501; [2] Li, T.I.N.G., et al. Nano Letters 2012,12,2509. [Preview Abstract] |
Wednesday, March 20, 2013 12:39PM - 12:51PM |
N30.00008: When DNA Meets Depletion Kun-Ta Wu, Lang Feng, Paul Chaikin Depletion is a widely used tool in colloidal particle system for universal attraction. Recently, the rapid development of DNA-coated particles also opens a door to colloidal architecture due to the specificity of DNA hybridization. In our study, we combine these two techniques, depletion and DNA hybridization, in colloidal system and find out that DNA-coated particles in depletion system aggregate faster and have the higher melting temperature than the ones without depletion. We studied quantitatively how the kinetics and thermodynamics of DNA-coated particles are changed with the concentration of depletion and DNA. We also find out that by using the depletion-and-DNA coupled system, particle can form crystals within hours rather than days due to the catalysis effect from depletion. Our study illustrates how DNA and depletion can be used in the same system to create more various and unique systems, which can not be achieved by neither DNA nor depletion along. [Preview Abstract] |
Wednesday, March 20, 2013 12:51PM - 1:03PM |
N30.00009: Template-mediated catalysis of DNA tiles Corinna Maass, Xiaojin He, Ruojie Sha, Yoel Ohayon, Nadrian Seeman, Paul Chaikin We present a novel mechanism for the selective creation of irreversible bonds between DNA nanotiles in the presence of a DNA template of complementary joined DNA tiles. The hybridisation transition of DNA sticky ends is highly concentration dependent. While immobilised on a template, adjacent DNA tiles are subject to a greatly increased local concentration ($10^{12}$), as compared to free tiles in solution. This reduces the entropy penalty for sticky end hybridisation and shifts the hybridisation transition to higher temperatures. We have developed a tile-template model consisting of two DNA tiles with sticky ends that will, at room temperature, only react when attached to template tiles and which can be bound irreversibly via an UV crosslinkable nucleobase substitute. The selectivity is high and the irreversible crosslinking is enhanced by a factor of roughly 100. [Preview Abstract] |
Wednesday, March 20, 2013 1:03PM - 1:15PM |
N30.00010: DNA Photo Lithography with Cinnamate-based Photo-Bio-Nano-Glue Lang Feng, Minfeng Li, Joy Romulus, Ruojie Sha, John Royer, Kun-Ta Wu, Qin Xu, Nadrian Seeman, Marcus Weck, Paul Chaikin We present a technique to make patterned functional surfaces, using a cinnamate photo cross-linker and photolithography. We have designed and modified a complementary set of single DNA strands to incorporate a pair of opposing cinnamate molecules. On exposure to 360nm UV, the cinnamate makes a highly specific covalent bond permanently linking only the complementary strands containing the cinnamates. We have studied this specific and efficient crosslinking with cinnamate-containing DNA in solution and on particles. UV addressability allows us to pattern surfaces functionally. The entire surface is coated with a DNA sequence A incorporating cinnamate. DNA strands A'B with one end containing a complementary cinnamated sequence A' attached to another sequence B, are then hybridized to the surface. UV photolithography is used to bind the A'B strand in a specific pattern. The system is heated and the unbound DNA is washed away. The pattern is then observed by thermo-reversibly hybridizing either fluorescently dyed B' strands complementary to B, or colloids coated with B' strands. Our techniques can be used to reversibly and/or permanently bind, via DNA linkers, an assortment of molecules, proteins and nanostructures. Potential applications range from advanced self-assembly, such as templated self-replication schemes recently reported [1], to designed physical and chemical patterns, to high-resolution multi-functional DNA surfaces for genetic detection or DNA computing. [1] Tong, W et al, Nature, 478, 225-228(2011) [Preview Abstract] |
Wednesday, March 20, 2013 1:15PM - 1:27PM |
N30.00011: Controlling the temperature-dependent assembly of DNA-coated colloids with toehold exchange William Rogers, Jesse Collins, Vinothan Manoharan DNA is increasingly being used as a tool for directing the self-assembly of particle-based systems. The transient bridging of grafted, complementary DNA strands induces specific, attractive interactions that can direct nanoparticles or colloids to form clusters, ordered crystal lattices, or other interesting structures. In most cases, the DNA-induced binding strength is a monotonic and near exponential function of temperature, resulting in a single, narrow temperature window for equilibrium assembly that may frustrate efforts to make multicomponent or hierarchical structures. Here, we present and quantitatively demonstrate a new approach to controlling the temperature dependence of DNA-induced colloidal interactions using toehold exchange hybridization, a concept borrowed from dynamic DNA nanotechnology. These competitive hybridization pathways allow additional control over the thermodynamics of bridge formation and provide a simple way to engineer novel temperature dependences that need not be exponential or monotonic. This additional functionality will be useful in the rational design of new multicomponent, hierarchical, or reconfigurable self-assembling systems. [Preview Abstract] |
Wednesday, March 20, 2013 1:27PM - 1:39PM |
N30.00012: Colloidal Clusters via Short, Specific, and Isotropic DNA Interactions Jesse W. Collins, Vinothan N. Manoharan Many of the material systems scientists have successfully described using statistical mechanics have a number of distinct chemical species that does not scale with the total number of particles. Do any different equilibrium phenomena emerge in systems of a much wider variety of chemical species? We investigate the case in which the number of chemical species is equal or very nearly equal the total number of particles. We coat microspheres with short and specific DNA strands, and observe small numbers of these spheres at a time self-assemble using various forms of microscopy, including holography for 3-D particle positions and fluorescence for species identification. We have learned some simple rules that modulate the energy landscape of these particles. The relative chirality of substructures, including pairs of trimers, varies for each local minima on the landscape of small clusters like the ones we observe. If the ground state structure is rigid, the higher energy local minima structures are generally soft. Although our experiments are limited to about 6 particles, ideas from graph theory and statistical mechanics suggest that much larger numbers of short-ranged, specific and chemically isotropic spheres can robustly assemble into rigid ground state clusters as well. [Preview Abstract] |
Wednesday, March 20, 2013 1:39PM - 1:51PM |
N30.00013: Phases and Dynamics of Self-Assembled DNA Programmed Nanocubes Christopher Knorowski, Alex Travesset Systems of Nanoparticles grafted with complementary DNA strands have been shown to self-assemble into an array of superlattices. In this talk, we extend our previous model [1], which successfully predicted equilibrium phases and dynamics of assembly for spherical Nanoparticles [1,2] without fitting parameters, to the case of nanocubes. We show that the phase diagram consists of bcc and sc lattices, depending on DNA length. The bcc lattices are either rotator and orientational glass or cubatic. For temperatures above the DNA melting temperature, the system is equivalent to f-star polymer systems, and consist of bcc, also with rotator, orientational glass or cubatic orientational order as well as sc. We also provide a characterization of the dynamics, including the role of topological defects in crystal nucleation and growth. \\[4pt] [1] C. Knorowski {\em et al.}, Phys. Rev. Lett. {\bf 106}, 215501 (2011)\\[0pt] [2] C. Knorowski and A. Travesset, Soft Matter. {\bf Advance Article} (2012) DOI: 10.1039/c2sm26832a [Preview Abstract] |
Wednesday, March 20, 2013 1:51PM - 2:03PM |
N30.00014: Assembly of tetrahedral gold nanoclusters from binary colloidal mixtures Nicholas B. Schade, Dazhi ``Peter'' Sun, Miranda C. Holmes-Cerfon, Elizabeth R. Chen, Emily W. Gehrels, Jonathan A. Fan, Oleg Gang, Vinothan N. Manoharan We experimentally investigate the structures that form when colloidal gold nanospheres cluster around smaller spheres. We use nanoparticles coated with complementary DNA sequences to assemble the clusters, and we observe them under electron microscopy. Previous experiments using polystyrene microspheres indicate that a 90\% yield of tetrahedral clusters is possible near a critical diameter ratio; random sphere parking serves as a useful model for understanding this phenomenon. Here we examine how this approach can be scaled down by an order of magnitude in size, using gold building blocks. We study how this method can be used to assemble tetrahedral plasmonic resonators in order to create a bulk, isotropic, optical metamaterial. [Preview Abstract] |
Wednesday, March 20, 2013 2:03PM - 2:15PM |
N30.00015: Field-directed assembly of colloidal ellipsoids Peter J. Beltramo, Eric M. Furst Self-assembly of colloidal building blocks into ordered structures has become a rapidly evolving area of research due to the novel properties (thermal transport, photonic, electromagnetic) imparted by periodicity.\footnote{M. Grzelczak et al. ACS Nano, \textbf{4}, 3591 (2010)} Assembly of anisotropic particles presents numerous challenges, namely kinetic arrest at high particle volume fractions due to glassy dynamics. This prevents the realization of theoretically predicted close-packed phases.\footnote{A. Donev et al. Phys. Rev. Let., \textbf{92}, 255506 (2004); P. Pfleiderer et al. Phys. Rev. E, \textbf{75} 020402 (2007) } In this work, we use AC electric fields to align dilute polystyrene ellipsoidal particles in suspension and a drying front to concentrate the particles into orientationally ordered thin films. Results using several aspect ratio particles are presented. The dilute electrokinetic properties which enable this field-directed assembly are characterized by dielectric spectroscopy and electrophoretic mobility measurements. Light scattering is used to evaluate the frequency and field strength dependence of particle alignment. Finally, the nanomechanical and phononic properties of the films are evaluated by Brillouin light scattering. [Preview Abstract] |
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