Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session D42: Biomolecular Solution AssemblyInvited Live Streamed
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Sponsoring Units: DPOLY Chair: Darrin Pochan, University of Delaware Room: McCormick Place W-375A |
Monday, March 14, 2022 3:00PM - 3:36PM |
D42.00001: The Effect of Chemistry, Sequence, and Architecture on Complex Coacervation Invited Speaker: Sarah L Perry Complex coacervation is an associative liquid-liquid phase separation phenomenon with a long history of use in a variety of industries, and relevance to new classes of ‘membraneless organelles’ in cells. Coacervate assembly is largely driven by electrostatic attraction coupled with the entropic release of bound counterions and the restructuring of water. We harness model polymer systems to explore the ways in which factors such as the chemical identity (i.e., charge group, polymer backbone chemistry), the patterning or distribution of charges, and the overall size and architecture of the complexing polyelectrolytes modulate the phase behavior of the system. Our experimental efforts are supported by the parallel development of computational approaches to model and predict the phase behavior of coacervate materials. Our goal is to establish molecular-level design rules to facilitate the tailored creation of materials based on complex coacervation that can both illuminate self-assembly phenomena found in nature, and find utility across a wide range of real-world applications. |
Monday, March 14, 2022 3:36PM - 4:12PM |
D42.00002: Self-assembly of Helical Peptide Filaments and Tubes Invited Speaker: Vincent Conticello The rich functional properties of biologically derived helical assemblies provide inspiration for the de novo design of synthetic analogues, which, unconstrained by evolution, can be designed to perform unique functions under conditions that differ from those that commonly occur in the native biological environment. Biologically derived helical protein assemblies encompass a diversity of functional roles that would be desirable to emulate in synthetic systems, including controlled release and delivery, cargo transport, locomotion, energy transduction, and signal transduction and actuation. However, it remains difficult, if not impossible, to achieve this level of structural and functional control, thus far, for synthetic assemblies. |
Monday, March 14, 2022 4:12PM - 4:48PM |
D42.00003: Controlling liquid-liquid phase separation of nucleic acid motifs via programmable biochemical reactions Invited Speaker: Elisa Franco The toolkit of DNA nanotechnology has recently provided a framework to design and build motifs for liquid-liquid phase separation (LLPS). Using DNA nanotechnology we are exploring the mechanisms and design rules by which condensates can be controlled through chemical reactions. We focus on multivalent, star-shaped DNA motifs whose interactions can be designed by engineering single stranded domains (sticky ends). I will describe, by theory and experiment, how modification of the structure of DNA nanostars affects their macroscopic condensation kinetics. By changing the various domains of the DNA monomer we achieve a predictable growth profile of the condensates. Further, we obtain reversible dynamic control of condensate formation and dissolution by utilizing DNA strand displacement reactions that deactivate or reactivate the DNA monomer interaction domains. By changing DNA monomer design and sequence makeup, we explore the tunability of these reactions under different conditions. Our approach may be useful to build synthetic membraneless organelles whose formation can be temporally controlled via chemical reactions. |
Monday, March 14, 2022 4:48PM - 5:24PM |
D42.00004: Integrating protein and peptide self-assembly with DNA nanotechnology Invited Speaker: Nicholas Stephanopoulos The ability to design materials that mimic the complexity and functionality of biological systems is a long standing goal of nanotechnology, with applications in medicine, energy, and fundamental science. Biological molecules such as proteins, peptides, and DNA possess a rich palette of self-assembly motifs and chemical functional diversity, and are attractive building blocks for the synthesis of such nanomaterials. DNA provides unparalleled programmability to build nanostructures, but the resulting materials are limited to the chemical and physical properties of oligonucleotides. Proteins and peptides, by contrast, have a much greater palette of functionality and chemical diversity, but are more difficult to program into arbitrarily complex nanostructures. In this talk, we will describe research in creating hybrid materials that incorporate proteins and peptides with DNA nanotechnology to create various assemblies (cages, nanofibers, addressable nanobots, and 3D crystals) with a high degree of programmability and nanoscale resolution. Key to these endeavors will be (bio)molecular design, chemistry for linking components in a site-specific fashion, and the tuning of multiple self-assembly "modes" to create hybrid structures. Although the talk will focus on the fundamental chemistry and self-assembly of these systems, we will also discuss potential applications in areas such as targeted cargo delivery, biomaterials for regenerative medicine, and synthesis of virus- and antibody-mimetic nanostructures. |
Monday, March 14, 2022 5:24PM - 6:00PM |
D42.00005: Towards programmable assembly via geometric frustration Invited Speaker: Gregory M Grason Geometric frustration is most often associated with the disruption of long-range order and proliferation of defects in the bulk state of a self-organizing system. Soft and self-assembled materials, on the other hand, are able to tolerate some measure of local misfit due to frustration, allowing imperfect order to extend over at least some finite range. This talk focuses on theoretical frameworks for exploiting geometrically-frustrated assemblies (GFAs) to realize size-controlled, self-limiting assembly. In GFAs self-assembling elements (e.g. particles, macromolecules, proteins) favor local packing motifs that are incompatible with uniform global order in the assembly. While concepts of GFA have been used to describe a broad range of soft matter structures, from self-twisting protein filament bundles, chiral membranes, to spherical shells, current challenges focus on exploiting the scale-dependent thermodynamics of GFA to design and realize new classes of intentionally ill-fitting assemblies that target equilibrium architectures with well-defined dimensions on length scales that extend far beyond the size of the building blocks. In this talk, I describe some of the emerging principles and ongoing efforts to engineer the intra-assembly stress propagation and thermodynamic self-limitation in assemblies through the shape, interaction and flexibility of those building blocks. A generic feature of soft GFA systems, are mechanisms of frustration escape, structural modes that limit the maximum range of self-limitation, which in turn define key design features frustrated building blocks that extend the range of accessible self-limiting size well beyond the few-particle size. |
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