Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session E5: Physics at Bio-Nano Interface IFocus
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Sponsoring Units: DBIO DPOLY Chair: Binquan Luan, IBM T. J. Watson Research Center Room: 264 |
Tuesday, March 14, 2017 8:00AM - 8:36AM |
E5.00001: Bioelectronic Sensors and Devices Invited Speaker: Mark Reed Nanoscale electronic devices have recently enabled the ability to controllably probe biological systems, from the molecular to the cellular level, opening up new applications and understanding of biological function and response. This talk reviews some of the advances in the field, ranging from diagnostic and therapeutic applications, to cellular manipulation and response, to the emulation of biological response. In diagnostics, integrated nanodevice biosensors compatible with CMOS technology have achieved unprecedented sensitivity, enabling a wide range of label-free biochemical and macromolecule sensing applications down to femtomolar concentrations. These systems have demonstrated integrated assays of biomarkers at clinically important concentrations for both diagnostics and as a quantitative tool for drug design and discovery. Cellular level response can also be observed, including immune response function and dynamics. Finally, the field is beginning to create devices that emulate function, and the demonstration of a solid state artificial ion channel will be discussed. [Preview Abstract] |
Tuesday, March 14, 2017 8:36AM - 8:48AM |
E5.00002: Transport of Proteins through Nanopores Binquan Luan In biological cells, a malfunctioned protein (such as misfolded or damaged) is degraded by a protease in which an unfoldase actively drags the protein into a nanopore-like structure and then a peptidase cuts the linearized protein into small fragments (i.e. a recycling process). Mimicking this biological process, many experimental studies have focused on the transport of proteins through a biological protein pore or a synthetic solid-state nanopore. Potentially, the nanopore-based sensors can provide a platform for interrogating proteins that might be disease-related or be targeted by a new drug molecule. The single-profile of a protein chain inside an extremely small nanopore might even permit the sequencing of the protein. Here, through all-atom molecular dynamics simulations, I will show various types of protein transport through a nanopore and reveal the nanoscale mechanics/energetics that plays an important role governing the protein transport. [Preview Abstract] |
Tuesday, March 14, 2017 8:48AM - 9:00AM |
E5.00003: Amphiphilic gold nanoparticles as modulators of lipid membrane fusion Mukarram Tahir, Alfredo Alexander-Katz The fusion of lipid membranes is central to biological functions like inter-cellular transport and signaling and is coordinated by proteins of the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) superfamily. We utilize molecular dynamics simulations to demonstrate that gold nanoparticles functionalized with a mixed-monolayer of hydrophobic and hydrophilic alkanethiol ligands can act as synthetic analogues of these fusion proteins and mediate lipid membrane fusion by catalyzing the formation of a toroidal stalk between adjacent membranes and enabling the formation of a fusion pore upon influx of Ca$^{2+}$ into the exterior solvent. The fusion pathway enabled by these synthetic nanostructures is analogous to the regulated fast fusion pathway observed during synaptic vesicle fusion; it therefore provides novel physical insights into this important biological process while also being relevant in a number of single-cell therapeutic applications. [Preview Abstract] |
Tuesday, March 14, 2017 9:00AM - 9:12AM |
E5.00004: First step in developing SWNT nano-sensor for C17.2 neural stem cells. Tetyana Ignatova, Massooma Pirbhai, Swetha Chandrasekar, Slava V. Rotkin, Sabrina Jedlicka Nanomaterials are widely used for biomedical applications and diagnostics, including as drug and gene delivery agents, imaging objects, and biosensors. As single-wall carbon nanotubes (SWNTs) possess a size similar to intracellular components, including fibrillar proteins and some organelles, the potential for use in a wide variety of intracellular applications is significant. However, implementation of an SWNT based nano-sensor is difficult due to lack of understanding of SWNT-cell interaction on both the cellular and molecular level. In this study, C17.2 neural stem cells have been tested after uptake of SWNTs wrapped with ssDNA over a wide variety of time periods, allowing for broad localization of SWNTs inside of the cells over long time periods. The localization data is being used to develop a predictive model of how, upon uptake of SWNT, the cytoskeleton and other cellular structures of the adherent cells is perturbed. [Preview Abstract] |
Tuesday, March 14, 2017 9:12AM - 9:24AM |
E5.00005: Self-Assembly of Protein Nanostructures to Enhance Biosensor Sensitivity Bradley Olsen, Xuehui Dong, Allie Obermeyer The Langmuir adsorption isotherm predicts that the number of bound species on a surface at a given concentration will be directly proportional to the number of binding sites on the surface. Therefore, the number of binding events in a biosensor may be increased at a given analyte concentration if the surface density of binding domains is increased. Here, we demonstrate the formation of block copolymers where one block is a human IgG antibody or a nanobody and self-assemble these molecules into nanostructured films with a high density of binding sites. The type of nanostructure formed and the rate of transport through the protein-polymer layers are explored as a function of coil fraction of the protein-polymer conjugate block copolymers, showing optima for transport and assembly that depend upon the identity of the protein. For small enough analytes, binding to the antibodies and nanobodies is linear with film thickness, indicating that the entire film is accessible. Consistent with the enhanced number of binding sites and the prediction of the Langmuir isotherm, the films improve sensitivity by several orders of magnitude relative to chemisorbed protein layers used in current sensor designs. Current research is integrating this new material technology into prototype sensors. [Preview Abstract] |
Tuesday, March 14, 2017 9:24AM - 9:36AM |
E5.00006: Structure of water and ice next to graphene Saranshu Singla, Emmanuel Anim-Danso, Ahmad Islam, Yen Ngo, Steve Kim, Rajesh Naik, Ali Dhinojwala Graphene, due to its excellent electrical, mechanical and optical properties, has become a material of increasing interest in many applications, where it comes in contact with water, ions, polymers and biomolecules. The knowledge of the molecular level interactions of graphene with these molecules is the key to optimizing performance; for example, the band gap of graphene can be tuned by means of water adsorption. However, lack of surface sensitive experimental techniques has led to limited understanding of molecular level interactions. Here, we report a study of the graphene-water interface using surface sensitive sum frequency generation (SFG) spectroscopy. The strong interactions between graphene and water lead to enhanced ordering of water molecules at the graphene-water interface. We also use the graphene-water system as a model to understand the heterogeneous ice nucleation on soot particles in the atmosphere. Future work will focus on extending this study to more complex systems including graphene and biopolymers. [Preview Abstract] |
Tuesday, March 14, 2017 9:36AM - 9:48AM |
E5.00007: Thickness-dependent dielectric breakdown and nanopore creation on sub-10-nm-thick SiN membranes in KCl aqueous solution Itaru Yanagi, Koji Fujisaki, Hirotaka Hamamura, Kenichi Takeda Recently, dielectric breakdown of solid-state membranes in solution has come to be known as a powerful method for fabricating nanopore sensors. This method has enabled stable fabrication of nanopores down to sub-2 nm in diameter, which can be used to detect the sizes and structures of small molecules. Until now, the behavior of dielectric breakdown for nanopore creation in SiN membranes with thicknesses of less than 10 nm has not been studied, while thinner nanopore membranes are preferable for nanopore sensors in terms of spatial resolution. In the present study, the thickness dependence of the dielectric breakdown of sub-10-nm-thick SiN membranes in solution was investigated using a method developed herein called “gradually increased voltage pulse injection.” The increment in leakage current through the membrane at the breakdown was found to become smaller with a decrease in the thickness of the membrane, which resulted in the creation of smaller nanopores. In addition, the electric field for dielectric breakdown drastically decreased when the thickness of the membrane was less than 5 nm. These breakdown behaviors are quite similar to those observed in gate insulators of metal-oxide-semiconductor (MOS) devices. [Preview Abstract] |
Tuesday, March 14, 2017 9:48AM - 10:00AM |
E5.00008: Confronting with single-molecule and FCS measurements mobility within membranes taken from red blood cells Hyun-Sook Jang, Steve Granick This talk will show aspects of complex, anomalous diffusion of phospholipids within membranes extracted from red blood cells (RBC). Isolated after osmotic bursting, we have formed supported bilayers of these extracted membranes on colloidal and flat surfaces while retaining a high fraction of the native protein content. The nature of these supported bilayers appears to be surprisingly faithful to the native RBC state. This study may shed light on the function of support membranes for membrane-based sensors when they respond to external stimuli such as ions and ATP. [Preview Abstract] |
Tuesday, March 14, 2017 10:00AM - 10:12AM |
E5.00009: Fabrication of unique 3D microparticles in non-rectangular microchannels with flow lithography Sung Min Nam, Kibeom Kim, Wook Park, Wonhee Lee Invention of flow lithography has offered a simple yet effective method of fabricating micro-particles. However particles produced with conventional techniques were largely limited to 2-dimensional shapes projected to form a column. We proposed inexpensive and simple soft-lithography techniques to fabricate micro-channels with various cross-sectional shapes. The non-rectangular channels are then used to fabricate micro-particles using flow lithography resulting in interesting 3D shapes such as tetrahedrals or half-pyramids. In addition, a microfluidic device capable of fabricating multi-layered micro-particles was developed. On-chip PDMS valves are used to trap and position the particle at the precise location in microchannel with varying cross-section. Multilayer particles are generated by sequential monomer exchange and polymerization along the channel. While conventional multi-layered particles made with droplet generators require their layer materials be dissolved in immiscible fluids, the new method allows diverse choice of materials, not limited to their diffusibility. The multilayer 3D particles can be applied in areas such as drug delivery and tissue engineering. [Preview Abstract] |
Tuesday, March 14, 2017 10:12AM - 10:24AM |
E5.00010: Impedimetric Zika and Dengue Biosensor based on Functionalized Graphene Oxide Wrapped Silica Particles Seon-Ah Jin, Ernesto E. Marinero, Lia A. Stanciu Stanciu, Shishir Poudyal, Richard J. Kuhn A composite of 3-Aminopropyltriethoxysilane (APTES) functionalized graphene oxide (APTES-GO) wrapped on SiO2 particles (SiO2@APTES-GO) was prepared via self-assembly. Transmission electron microscopy (TEM) and ATR-Fourier Transform Infrared spectroscopy (ATR-FTIR) confirmed wrapping of the SiO2 particles by the APTES-GO sheets. An impedimetric biosensor was constructed and used to sensitively detect Zika and dengue DNA and RNA via primer hybridization using different oligonucleotide sequences. The results demonstrate that the SiO2@APTES-GO electrode materials provide enhanced RNA detection sensitivity with selectivity and detection limit (1 femto-Molar), compared to both APTES-GO and APTES-SiO2. The three-dimensional structure, higher contact area, electrical properties and the ability for rapid hybridization offered by the SiO2@APTES-GO resulted in a successful design of a Zika and dengue biosensor with the lowest detection limit reported to date. We are in the process of developing a platform for multiple viral detection for point-of-care diagnostics for arthropode borne viral infectious diseases. [Preview Abstract] |
Tuesday, March 14, 2017 10:24AM - 10:36AM |
E5.00011: Electrophoretic ratcheting of spherical particles in a simple microfluidic device: making particles move against the direction of the net electric field Hanyang Wang, Gary Slater, Hendrick Haan We examine the electrophoresis of spherical particles in microfluidic devices made of alternating wells and narrow channels – a type of system previously used to separate DNA molecules. Using computer simulations, we first show why it should be possible to separate particles having the same free-solution mobility using these systems in DC fields. Interestingly, in some of the systems we studied, the mobility shows an inversion as the field intensity is increased: while small particles have higher mobilities at low fields, the situation is reversed at high fields with the larger particles then moving faster. The resulting nonlinearity allows us to use asymmetric AC electric fields to build a ratchet in which particles have a net size-dependent velocity in the presence of an unbiased (zero-mean) AC field. Exploiting the inversion mentioned above, we show how to build pulsed field sequences that make particles move against the net field (an example of negative mobility). Finally, we demonstrate that it is possible to use these pulsed fields to make particles of different sizes move in opposite directions even though their charge have the same sign. Potential uses of these idea are discussed. [Preview Abstract] |
Tuesday, March 14, 2017 10:36AM - 10:48AM |
E5.00012: Shape Effect of Magnetic Nanoparticles on Hyperthermia Applications Jeotikanta Mohapatra, F. Zeng, K. Elkins, N. Poudyal, K. Gandha, J. Ping Liu Magnetic Fe$_{\mathrm{3}}$O$_{\mathrm{4}}$ nanoparticles (NPs) are extensively studied for their applications in advanced technologies. Incorporation of different transition metal ions and control of their sizes from nanometre to submicron scale are the keys for the magnetic property manipulation. We have investigated an alternative approach to optimize the magnetic properties by tailoring the shape of the NPs based on the observation that anisotropy of the NPs plays a crucial role in defining the magnetic characteristics. To synthesize monodisperse Fe$_{\mathrm{3}}$O$_{\mathrm{4}}$ NPs we have modified the conventional thermal decomposition to a `solvent-less' synthesis approach where long chain amine/acid acts as reducing and surface functionalizing agent. Various shapes like spheres, rods, octahedrons and cubes are obtained through simple alteration in reaction conditions. Octahedral and cube shaped Fe$_{\mathrm{3}}$O$_{\mathrm{4}}$ NPs exhibit bulk magnetization (92 emu/g) value due to the reduced surface spin disorder. These anisotropic NPs serve better in hyperthermia applications compared to the conventional spherical NPs. The cube and octahedron NPs show significantly higher SAR value, making them a potential candidate for hyperthermia treatment. [Preview Abstract] |
Tuesday, March 14, 2017 10:48AM - 11:00AM |
E5.00013: Characterization of Peptide/Surface Interactions for MoS2, Graphene, and Silica. Andrew Stroud, Pedro Derosa, Rajiv Berry, Gary Leuty, Chris Muratore Surface-binding peptides are increasingly being used to functionalize inorganic interfaces for bio sensing and 3D-printed bio-engineered applications. In this study, classical molecular dynamics was used to identify the structural characteristics of peptide sequences that selectively mediate the binding of graphene and molybdenum disulfide (MoS2) to glass. These three surfaces were exposed to two peptide sequences in aqueous solution. The binding ability of the polypeptides, HSSYWYAFNNKT (P1) and HLLQPTQNPFRN (HLL), toward each surface was compared by calculating binding enthalpies and tracking the positions of critical amino acid residues during the simulations to determine which residues bonded to each surface. For graphene and MoS2, the strongest-binding residues contained aromatic rings. Notably, these amino acids were found within the bulk water layer above the silica surface. Conversely, charged residues bound to silica did not show strong binding to MoS2 or graphene. The relevance of this finding is that as the list of residues that are found to bind to silica is different from those that bind to MoS2 or graphene, such polypeptides can simultaneously bind to both surfaces, acting as a mediator for the 3D printing of 2D materials on glass. [Preview Abstract] |
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