Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session U31: Focus Session: Assembly & Function of Biomimetic & Bioinspired Materials III |
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Sponsoring Units: DMP DPOLY DBIO Chair: Shengfeng Cheng, Sandia National Laboratories Room: 339 |
Thursday, March 21, 2013 11:15AM - 11:27AM |
U31.00001: Multiscale self-assembly of DNA-functionalized nanoparticles and cationic phospholipids Sunita Srivastava, Dmytro Nykypanchuk, Oleg Gang Cationic phospholipids (CLs) when mixed with oppositely charged biomolecules exhibit rich structural diversity including lamellar, inverted hexagonal, honeycomb and rectangular columnar phases. Our study explores how CLs can be used to control the organization of nanoparticles (NP) and their ligands on molecular and nano scales by tuning lipid composition. We utilized a synchrotron-based x-ray scattering to probe in-situ electrostatic assembly of double stranded (ds) DNA-functionalized nanoparticles with cationic phospholipids. The assembly of the DNA-NP and CLs is driven by attraction between negatively charged ds-DNA and positively charged CLs. We investigated the role of DNA length, lipid charge density and charge ratio on structural behavior of the assembly. Interplay of electrostatic interaction and curvature effects results in hierarchical organizations in which DNA-NP and CLs exhibit lamellar and hexagonal phases at different length scales. [Preview Abstract] |
Thursday, March 21, 2013 11:27AM - 11:39AM |
U31.00002: Revealing Structural Transformations during Crystallization of DNA-Nanoparticle Assemblies Yugang Zhang, Fang Lu, Daniel van der Lelie, Oleg Gang Nanoparticle assembly via sequence-specific DNA recognition emerges as a powerful strategy for the fabrication of nanoparticle (NP)-based crystalline materials. Generally, a delicate thermal annealing is essential for the crystallization of NPs from kinetically trapped disordered states. Due to the complex coupling between interactions, entropic and chain effects in these systems, the crystallization pathway remains an intricate and open question. Herein, we present an experimental study of the crystallization process for DNA-directed nanoparticle assembly systems using synchrotron-based small angle x-ray scattering (SAXS). We demonstrated the effects of two crystallization-dominant factors, namely, temperature and volume fraction, on the structural transformation and order development. By combining a single component and binary systems we uncovered the evolution of global and local particle arrangements, such as correlation length, compositional disorder and coordination number, during the phase transformation. Research was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. [Preview Abstract] |
Thursday, March 21, 2013 11:39AM - 11:51AM |
U31.00003: Modeling Lattice Structures of DNA-Coated Nanoparticles with Tetrahedral Linkers Joshua Neitzel, Oleg Gang, Francis Starr Much attention has recently focused on using DNA as a linking agent to engineer nanoparticle (NP) lattices with specific geometries. There has been success generating a broad range of crystal symmetries, but the formation of a tetrahedral or diamond lattice has been particularly challenging. We use molecular simulations to examine a combination of NP uniformly coated with DNA that connect via linking units that incorporate tetrahedral structure. We test the stability of spherical NP-DNA complexes with tetrahedral linkers in a 1:1 ratio, which allow for a variety of lattices, including a diamond structure. Previously postulated interpenetrating diamond lattices are also possible. [Preview Abstract] |
Thursday, March 21, 2013 11:51AM - 12:03PM |
U31.00004: Directed assembly of hierarchical light-harvesting complexes using virus capsid scaffolds and DNA origami tiles Debin Wang, Stacy Capehart, Suchetan Pal, Minghui Liu, Jolene Lau, Hao Yan, Matthew Francis, Jim DeYoreo Directed assembly of nanostructures with molecular precision is of great importance to develop an insightful understanding of assembly pathways and dynamics as well as to derive new functionalities. In this work, we explore the use of virus capsids and DNA origami tiles as 3D scaffolds and 2D templates for directed assembly of light-harvesting molecules and plasmonic gold nanoparticles to achieve tunable photoemission. Bacteriophage MS2 virus capsids with well-defined spherical macromolecular structures are genetically modified to provide predictable steric arrangements of light-harvesting molecules. DNA origami tiles act as programmable planar templates to provide higher-order organization of oligonucleotide-functionalized light-harvesting capsids and plasmonic gold nanoparticles. The direct observation of distance dependent photoluminescence emission is carried out by our correlative approach combining atomic force microscopy and confocal fluorescence microscopy, which is in good agreement with our numerical simulation and theoretical calculation. This work will facilitate the construction of multicomponent biological-metal hybrid plasmonic nanostructures for nanophotonics and biosensing applications. [Preview Abstract] |
Thursday, March 21, 2013 12:03PM - 12:39PM |
U31.00005: Shape Remodeling Assemblies in Biologically Inspired Materials Invited Speaker: Cyrus Safinya Much of our research is inspired by, and directed at, understanding the formation of novel structures (both relatively static and highly dynamic) with distinct shapes and morphologies observed in charged biological systems. The structures, in turn, often correlate to specific functions. For example, charged nanoscale tubules and rods and their assemblies are of interest in a range of applications, including as templates for hierarchical nanostructures, encapsulation systems, and biosensors. A series of studies will be described on charged biological assemblies exhibiting ``molecularly-triggered'' dynamical shape changes. In particular, we will focus on protein and lipid based nanotubule formation through small molecule stimuli-induced shape remodeling events. The systems include invertible protein nanotubes from two-state tubulin-protein building blocks and lipid nanotubes and nanorods from curvature stabilizing lipids (mimicking membrane curvature generating proteins). [Preview Abstract] |
Thursday, March 21, 2013 12:39PM - 12:51PM |
U31.00006: Visualizing DNA Nanoparticle Motion under Graphene Liquid Cell TEM Qian Chen, Jessica Smith, Jungwon Park, Somin Lee, Alex Zettl, Paul Alivisatos We think of a simple colloidal nanocrystal as one type of artificial atoms. They mutually interact, cluster into artificial molecules, and further arrange into macroscopically functional artificial solids. The ``atomic'' resolution dynamics of this bottom-up strategy in materials design is studied here in a system of artificial molecules composed of DNA and nanoparticle. The observation of dynamics in their liquid environment is recently enabled by graphene liquid cell transmission electron microscopy (TEM). In comparison to conventional TEM, wherein the assembled 3D artificial structures are dried out during sample preparation and thus are collapsed, this graphene liquid cell introduces a special local liquid structure that retains the conformations as well as the dynamics of the assemblies. In situ imaging of correlated motions of DNA and nanoparticle provides insights into the design principles of artificial nanocrystal molecules and solids linked by DNA. [Preview Abstract] |
Thursday, March 21, 2013 12:51PM - 1:03PM |
U31.00007: Controlling Assembly and Crystallization of S-layers on Diblock Copolymer Patterns Ilja Gunkel, Magal{\'I} Lingenfelder, Bart Stel, Xiaodan Gu, Thomas Russell, James DeYoreo Block copolymers (BCPs) self-assemble into arrays of nanoscopic morphologies, including lamellar, cylindrical, and spherical microdomains, that serve as ideal templates for the fabrication of nanostructured materials. The size of the microdomains is a function of the polymer size so tuning the copolymer's molecular weight allows for a precise control over the dimension of the BCP morphologies. Moreover, the heterogeneous chemical nature of BCPs allows them to be used as templates for well-defined protein adsorption. Here, we used nanoscopic BCP patterns as templates to study the assembly of S-layer proteins SbpA from Lysinibacillus sphaericus (ATCC 4525) by in-situ Atomic Force Microscopy (AFM). The templates were formed by polystyrene-b-poly(ethylene oxide) BCPs of various molecular weights after spin coating on solid surfaces and subsequent controlled solvent-vapor annealing. Our results show that by controlling the chemical contrast in templates of different geometry and periodicity, protein assemblies could be directed exclusively to the hydrophobic domains of the template. More importantly, our high-resolution AFM measurements indicate that the proteins crystallized in their native lattice while following the structure of the underlying template by preferential adsorption. [Preview Abstract] |
Thursday, March 21, 2013 1:03PM - 1:15PM |
U31.00008: Structural control in model microtubule self-assembly Shengfeng Cheng, Mark Stevens Being able to control the structure formed in self-assembly is the goal of many nanoscience studies. Here we explore various ways to control the structure of self-assembled tubules. We have previously developed a model wedge-shaped monomer that can self-assemble into tubule structures. We now add chirality and a lock-and-key mechanism to the model to enhance structural control of the self-assembly. Previously, we found that helical tubes are frequently formed despite the fact that chiral symmetry is not present in the monomer. We now identify the physical origin of helicity as the large overlap in the energy distributions between nonhelical and helical tubes. The helical tubes typically undergo a twist deformation that lowers the energy substantially. We find that a modification of the location of binding sites on the bottom and top surfaces of the wedge into a lock-and-key configuration leads to a better control of the helicity and twist deformation of the assembled tubes. Better control occurs when the interaction strength between the vertical binding sites is stronger than that between the lateral ones. We can also control the pitch of the helicity by adjusting the location of binding sites on the lateral surfaces of the monomer. Our results shed new light on the structure of in vitro microtubules formed with various numbers of protofilaments of tubulins, which also exhibit twisted structures when the number is different from 13. [Preview Abstract] |
Thursday, March 21, 2013 1:15PM - 1:27PM |
U31.00009: Self-folding polyhedra and analogies to biomolecular assembly Shivendra Pandey, Govind Menon, David Gracias We detail model studies aimed at uncovering design principles that govern the self-assembly of polyhedral structures from two-dimensional precursors using surface tension forces. For a given polyhedron, there are a very large number of two-dimensional precursor nets that can be utilized, and remarkably many of these will self-assemble but with varying yields. We uncovered design rules that suggest striking analogies to biomolecular assembly such as observed in proteins and viruses. For example our studies revealed that the compactness of two-dimensional nets determines the yield of self-folding polyhedra and that certain intermediates and pathways were preferred. Consequently, a search algorithm was implemented to screen the large numbers of nets (e.g. 2.3 million for the truncated octahedron) and find high-yielding precursors. This assembly process represents a model system that can be utilized to design and then visualize self-assembly processes. The model system, design rules and findings will be discussed. References: S. Pandey, M. Ewing, A. Kunas, N. Nguyen, D. H. Gracias and G. Menon, Algorithmic design of self-folding polyhedra, \textit{PNAS }108, 50, 19885-19890 (2011). [Preview Abstract] |
Thursday, March 21, 2013 1:27PM - 1:39PM |
U31.00010: Functional quantum dot-protein nano bio-assembly for superior light harvesting applications Evren Mutlugun, Urartu Ozgur Safak Seker, Pedro Ludwig Hernandez- Martinez, Vijay Kumar Sharma, Vladimir Lesnyak, Nikolai Gaponik, Alexander Eychmuller, Hilmi Volkan Demir The formation of functional bio-assemblies is crucial for the advanced biophotonic applications. In this work, we formed a nano bio-assembly, consisting of green fluorescent protein (GFP) and inorganic quantum dots (QDs), to employ as an excitonic biofunctional composite to use for light harvesting and biosensing applications. Using QDs as donor molecules with the acceptor GFP in the formed bio-assembly, we observed up-to 15-fold enhancement on the GFP emission, mediated by the strong nonradiative energy transfer. The lifetime modifications of the donor-acceptor pair were studied as a function of the number of proteins per quantum dot, and in good agreement with the proposed theoretical model based on the excitonic interaction among the species. Apart from the light harvesting system, a biosensing medium was also established, facilitated by the enzymatic activity destructing the light harvesting complex. The energy transferring QD-GFP complex was controllably modified by the addition of trypsin, by destroying the bond in between the QD-GFP complex, as verified by the observation of lifetime modifications. In summary, we developed functional excitonic nano-bio-assemblies, which we believe will open up new possibilities for advanced biophotonic applications. [Preview Abstract] |
Thursday, March 21, 2013 1:39PM - 1:51PM |
U31.00011: Controlling size and patchiness of soft nanoparticles via kinetically arrested co-assembly of block copolymers Jose Santos, Margarita Herrera-Alonso Engineering patchy particles from block copolymers provides an effective route for the preparation of nanoparticles with surface heterogeneity and unique properties. In the current work, co-assembly of block copolymers amphiphiles with distinct macromolecular architectures under kinetically arrested conditions was used to control the size and patchiness of polymeric nanoparticles. The block copolymer mixture is composed of linear and linear-dendritic polymeric amphiphiles, the later of which provides pre-assembled ``patches'' with well-controlled dimensions and chemical functionality. Parameters including but not limited to the molecular diffusity of the amphiphiles and the kinetics of self-assembly were found to play an important role on the control of the particle size and formation of the patches. The patchy particles are stable for several months and its stability against protein/blood plasma solutions can be tuned. We will also discuss the use of these constructs to probe nanoparticle-cell interactions. [Preview Abstract] |
Thursday, March 21, 2013 1:51PM - 2:03PM |
U31.00012: Structural color of butterflies: The case of Papilio butterflies Beom-Jin Yoon, Jung Ok Park, Mohan Srinivasarao The term ``structural color'' is often used to describe color produced by a material possessing periodic variations in refractive index, which is commonly observed in many species of butterflies. Papilio butterflies commonly have multilayered bowl structures on their wing scales but the resulting colorations are different each other. Papilio ulysses has blue colored wing and Papilio palinurus shows green coloration on its wing, while Papilio blumei has green coloration on the wing scales but display a blue colored tail. We investigated the structures of the scale on the wings of Papilio butterflies using focused ion beam milling and analyzed the structural origin of the structural color from each Papilio butterfly. The coloration mechanism was attributed to the combination of the multilayer reflection from different feature size coupled with additive color mixing. [Preview Abstract] |
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