Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session S05: Biomaterials and Nanotechnology IFocus Recordings Available
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Sponsoring Units: DBIO DPOLY Chair: Sebastian Sensale, Duke University Room: McCormick Place W-178A |
Thursday, March 17, 2022 8:00AM - 8:12AM |
S05.00001: Toward a minimal DNA origami for seeding tiled DNA nanotube bundles and patterning silos Sarah A Webster, Deborah K Fygenson Using DNA origami, a self-assembly method for building arbitrary and highly addressable structures out of DNA, we designed what we believe to be the shortest possible seed for nucleating tiled DNA nanotubes from either end; 75% the size of the smallest seed described in the literature. It consistently forms with high yield (70%) and nucleates nanotubes from both ends equally well. This seed’s small size makes it less costly to produce and easier to incorporate into hierarchical assemblies. Here we explore strategies for building seed clusters of well-defined size and shape (triangular and square) and seed rafts (with extended hexagonal or square lattice structure) for nucleating nanotube bundles. |
Thursday, March 17, 2022 8:12AM - 8:24AM |
S05.00002: Nanoscale characterization of DNA binding on gold nanostars via quantitative EELS spectral imaging Sang hyun Bae, Kwahun Lee, Teri W Odom, Pinshane Y Huang, Susanna Monti Nanoconstructs of organic ligands conjugated onto inorganic nanoparticles are capitalized heavily as drug or biomolecule delivery vehicles. A notable candidate is DNA-conjugated gold nanostar, a complex anisotropic nanoparticle1. Ligand loading on nanoparticle surface has been shown to be strongly affected by curvature2, but conventional characterization techniques lack the spatial resolution to study local dependence of ligand binding on anisotropic nanoparticles3. Here, we directly visualize and quantify local distribution of DNA ligands on gold nanostars with few nm resolution, without any labeling or ligand removal. By combining quantitative scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) spectral mapping, we find a twofold increase in ligand density with respect to increase in surface curvature, indicating corressponding higher DNA binding. Our results elucidate the role of nanoscale steric interactions in molecular binding to metal nanoparticles and can be used to probe nanoscale variations in biomolecule loading on inorganic nanocarriers. |
Thursday, March 17, 2022 8:24AM - 8:36AM |
S05.00003: Optimizing Communication Speeds in DNA Origami Nanodevices Sebastian Sensale, Pranav Sharma, Gaurav Arya In the last decade, dynamic DNA origami structures have shown great promise for the transport of signals and cargo at the nanoscale. While the diffusion coefficient of these structures is usually large, the strand exchange mechanisms used for communicating signals or cargo across structures make the overall process reaction limited, leading to slow operation speeds. In this talk, a kinetic theory to estimate the stepping rate constant of communicating DNA origami nanostructures of arbitrary lengths is introduced. This theory, in agreement with experimental measurements, is used to optimize communication among DNA origami nanostructures, suggesting there is still room to substantially improve the operation rates of strand exchange-mediated devices. While our theory is presented in the context of DNA nanotechnology, the expressions for the stepping rates introduced hereby are broadly applicable to diverse systems, providing new ways to characterize natural communication processes and optimize the rate of signal propagation for sensing and computing applications in systems where reaction and diffusion are the dominating forces. |
Thursday, March 17, 2022 8:36AM - 9:12AM |
S05.00004: Self-Assembly of Nanoscale Architectures with DNA Invited Speaker: Grigory Tikhomirov Nature has evolved to self-assemble complex functional architectures in a sustainable bottom-up way. From bacteria to humans, biological systems arise from a common set of atomically precise nanoscale building blocks such as proteins that give rise to complex functions such as sensing, computation, and actuation. In contrast, most human-made devices are composed of building blocks with much less precision, and are assembled through a top-down process which is highly inflexible and unsustainable. Drawbacks aside, these devices are highly useful and can often surpass their biological counterparts (e.g., computers playing chess). This success is largely due to a systematic and modular engineering approach where simple but well-understood components such as transistors are put together in a programmable way. Is it possible to develop a new approach to building complex devices that combines the strengths of biomolecular self-assembly and systematic engineering? In this talk I will discuss recent work towards this goal using DNA as a nanoscale, programmable building block [1-4]. However, despite being the most programmable molecule for information processing, DNA lacks the basic physical attributes required for building high performance electronic devices. I will discuss ongoing work towards a new type of nanoscale building blocks in which DNA can be flexibly replaced with other materials such as metals and semiconductors. These nanoscale modules can be designed to self-assemble into a variety of plasmonic, photonic, and electronic architectures unattainable with any current nanofabrication techniques. This novel approach integrates the advantages of natural bottom-up assembly and engineered top-down programming and may lead to a host of new intelligent devices for technology and medicine. |
Thursday, March 17, 2022 9:12AM - 9:24AM |
S05.00005: Seeing the Forces: Single Avalanching Upconverting Nanoparticles as Ultrasensitive Local Force Transducers Natalie Fardian-Melamed, Changhwan Lee, Hye Sun Park, Ayelet Teitelboim, Kevin WC Kwock, Tom P Darlington, Bruce Cohen, Emory Chan, Sang Hwan Nam, Yung Doug Suh, P. James Schuck It has recently been demonstrated that ensembles of upconverting nanoparticles (UCNPs) exhibit changes in their emission spectra due to applied stress [1, 2]. Avalanching UCNPs (ANPs) [3], possessing steeply nonlinear optical responses, are ideally suited for sensing minute changes in their environments, as small perturbations are expected to usher large changes in signal. Because ANPs absorb and emit tissue-penetrating near-infrared (NIR) light, they are uniquely positioned for sensing within biological cells and fluids. To characterize and understand the response of these ANPs to local stress, it is important to study their mechano-opto-physics on a single particle level. Utilizing a custom designed combined AFM and inverted optical microscope system, we correlate sub-nano-Newton applied forces and observable changes in hyperspectral optical signals for isolated single UCNPs, demonstrating their potential as local force sensors. |
Thursday, March 17, 2022 9:24AM - 9:36AM |
S05.00006: Grafted Polymer Architecture as a Tool to Inform Mechanisms of Polymer-Cell Membrane Interactions Joseph Hassler, Adelyn Crabtree, Frank S Bates, Benjamin Hackel, Timothy P Lodge Amphiphilic poly(ethylene oxide)-b-poly(propylene oxide) (PEO-b-PPO) block polymers interact with phospholipid bilayers and have been shown to stabilize cell membranes under stress. In this work, we seek to study the mechanisms of polymer-lipid interactions by leveraging known structure-property relationships of graft polymers. We developed a grafting-through approach to synthesize grafted, block amphiphiles with PEO and PPO side chains. Bulk crystallization and aqueous micellization behavior were investigated over a range of molecular weights and compositions to assess differences between grafted and linear block polymers. Select grafted polymers, chosen to address mechanistic structure-function hypotheses, were evaluated for polymer-lipid binding via pulsed-field gradient NMR and for membrane stabilization of cells under stress via a macromolecular release assay. |
Thursday, March 17, 2022 9:36AM - 9:48AM |
S05.00007: Fabrication strategies of peptide rigid rods with computationally designed coiled-coils Yi Shi, Rui Guo, Jeffery G Saven, Christopher J Kloxin, Darrin J Pochan Peptide rigid rods were constructed via thiol-Michael or copper-catalyzed alkyne-azide cycloaddition (CuAAc) 'click' conjugation reactions with tetrameric coiled-coils. These polymer chains are a new class of bio-inspired materials with well-defined nanostructures that display extremely high molecular rigidity and readily form liquid crystals in solution as well as shear-thinning behavior. The building blocks for the rigid rod polymer chains are homotetrameric peptide coiled coil nanoparticles, also called 'bundlemers'. The peptides that constitute the bundlemer particles are computationally designed so that the specific amino acid sequences can be controlled and include non-natural amino acids. Since the sequences are designed and are not taken from any natural protein sequences, one can arbitrarily design building block attributes. Of particular focus is our ability to create bundlemer building blocks with designed net charge. The presentation will discuss results from bundlemer building blocks with a wide range of charge characteristics that all have the same size, shape (i.e., nanocylinders that are 2 by 4 nanometers), and functionality to be linked together to form rigid rod polymers. The solution behavior of the coiled coil building blocks with net charge ranging from highly negatively charged through highly postitively charged will be discussed as well as the behavior of rigid rod polymer chains made from conjugating the building blocks together through click chemistry. |
Thursday, March 17, 2022 9:48AM - 10:00AM |
S05.00008: Nanoparticles Functionalized with Bundlemers and Bundlemer Rods Matthew G Langenstein, Darrin J Pochan Bundlemers are monodisperse nanoparticles, also known as coiled coils, created by the solution assembly of computationally designed peptides. The peptides are designed to self-assemble into homotetrameric, antiparallel coiled coils and consequently display desired surface functionality. This rare combination of monodispersity and tunability make bundlemers excellent building blocks for more complex nanostructures. Recently, we have used ‘click’ chemistry functionalized bundlemers as macromonomers to create rigid rods, extremely high aspect ratio hybrid covalent-supramolecular polymers with extreme persistence lengths and aspect ratios/diameters similar to single wall carbon nanotubes. By incorporating substrate-binding terminal residues, we can design bundlemers to assemble with preferred orientation on a substrate to produce bundlemer brushes through either a grafting to approach, e.g., coupling bundlemer rods directly to a substrate through functionalized termini, or a grafting from approach, e.g., using a template layer of bundlemers as reaction sites for subsequent bundlemer coupling or assembly. Results surrounding bundlemer rod brushes on SiO2 substrates, both nanoparticle as well as flat substrates, through DOPA terminated bundlemers will be discussed. |
Thursday, March 17, 2022 10:00AM - 10:12AM |
S05.00009: Citric Acid-modified Hydroxyapatite Nanoparticles as an Antibiotic Protein Carrier Ruibo Hu, Nita Sahai Hydroxyapatite nanoparticles (HAp NPs) are widely used as protein and drug delivery systems since HAP has excellent biocompatibility. During the protein loading process, HAp NPs may change the secondary structures of the proteins, which may affect their biological functions. Using citric acid (CA) to functionalize HAp NPs is a good approach to increase the loading capacity of positively-charged proteins, such as lysozyme, which is an antimicrobial. However, the influence of CA concentration and aging time on HAP NP morphology, surface charge, lysozyme loading capacity, and lysozyme conformation are still not fully understood. Herein, CA-functionalized HAp NPs (CA-HAp NPs) were synthesized, characterized, and loaded with antimicrobial protein, lysozyme. We observed that a higher concentration of CA leads to a greater negative surface charge of HAp NPs, which increases lysozyme loading capacity while maintaining its biological function during the adsorption/release process. The lysozyme-loaded CA HAp NPs developed here have potential applications as antimicrobial fillers in dental composites used for restoratives and wider protein delivery applications for various other biomedical applications. |
Thursday, March 17, 2022 10:12AM - 10:24AM |
S05.00010: Biomimetic porous calcium phosphate nanoparticles with lithium ions incorporation induce osteogenic stem cell differentiation in vitro and in vivo Sara Romanazzo, Iman Roohani Calcium phosphates (CP) are inorganic compounds naturally found in approximately 60% of all human bones in form of semi crystalline carbonated hydroxyapatite nanocrystals, and responsible for bone regeneration. Due to their osteoconductive and chemical similarity to inorganic part of the bone, CP have been widely used as the backbone formulation to fabricate synthetic bone grafts for treatment of bone defects [1]. Here in, we have developed a novel type of CP nanoparticles (CaP), by mimicking bone forming precursors particles involved in bone mineralisation process. CaP are amorphous and porous with hospitable structure to be doped with various bioactive elements or incorporated with large and small biomolecules. Moreover, to promote vascularisation, which is a crucial step in bone repair, we have incorporated a trace amount of lithium ions between calcium and phosphate atoms of CaP, labelled as Li-CaP [2]. |
Thursday, March 17, 2022 10:24AM - 10:36AM |
S05.00011: Using Phytoglycogen Nanoparticles to Improve the Water Solubility of Bioactive Compounds Nicholas van Heijst, Michael Grossutti, Jay Leitch, Ciaran Henry, John R Dutcher Phytoglycogen (PG) is a naturally occurring, dendrimeric polysaccharide produced as compact nanoparticles in the kernels of sweet corn. PG nanoparticles are soft, porous, digestible and nontoxic, which makes them ideally suited for applications in human health and nutrition. Many bioactive compounds suffer from poor water solubility, and enhancement of their bioavailability is a major challenge for industry. We have explored improving the solubility of the insoluble carotenoid astaxanthin (ASX) through association with PG as a gateway to enhanced bioavailability. We have developed a technique that incorporates roto-evaporation and freeze-drying to create a dehydrated ASX-PG powder that is readily dispersed in water and creates stable dispersions of ASX-PG at concentrations that exceed the solubility limit of ASX in water by many orders of magnitude. We use ultraviolet-visible (UV-Vis) spectroscopy to characterize the aggregation state of the ASX-PG dispersions, and surface plasmon resonance imaging (SPRi) to quantify the degree of binding between ASX-PG and a PG-functionalized SPR sensor surface. Our results demonstrate that PG is an effective solubilizing agent for ASX. |
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