Frederick A. Heberle, PhD, Biology & Soft Matter Oak Ridge National Laboratory
Lipid organization in complex biomimetic membranes: Insight from Scattering & SimulationThe 3-dimensional architecture of biological membranes has functional consequences for living cells. In the outer leaflet of the plasma membrane, lipids are thought to organize into ordered yet fluid domains, with diverse evidence supporting participation of these “rafts” in membrane processes including protein sorting and signaling. Cells also actively maintain an asymmetric distribution of different lipid types between the plasma membrane’s inner and outer leaflets, resulting in transmembrane differences in fluidity and charge density. Despite intense interest, the fundamental mechanisms controlling raft size and morphology, as well as coupling between leaflets of different composition, remain elusive. The precise determination of phase-separated and asymmetric bilayer structure is a crucial step toward a deeper understanding of these mechanisms. To this end, small-angle neutron and X-ray scattering are powerful biophysical tools for interrogating both lateral and transverse bilayer structure with sub-nanometer resolution. Molecular dynamics simulations probe further still, providing a glimpse of membrane organization with atomic detail. In this talk, I will describe new approaches for combining experimental and computational data to obtain a detailed structural picture of complex biomimetic membranes.
Professor Yossi Weizmann, University of Chicago
Synthetic Nucleic Acid Topology and Colloidal LEGO-Like Nanoparticles for Biological and Plasmonic Applications
Polina Anikeeva, PhD, MatSci and Eng, MIT
Probing Neural Function with Electronic, Optical & Magnetic MaterialsMammalian nervous system contains billions of neurons that exchange electrical, chemical and mechanical signals. Our ability to study this complexity is limited by the lack of technologies available for interrogating neural circuits across their diverse signaling modalities without inducing a foreign-body reaction. My talk will describe neural interface strategies pursued in my group aimed at mimicking the materials properties and transduction mechanisms of the nervous system. Specifically, I will discuss (1) Fiber-based probes for multifunctional interfaces with the brain and spinal cord circuits; (2) Magnetic nanotransducers for minimally invasive neural stimulation; and (3) Active scaffolds for neural tissue engineering and interrogation.
Fiber-drawing methods can be applied to create multifunctional polymer-based probes capable of simultaneous electrical, optical, and chemical probing of neural tissues in freely moving subjects. Similar engineering principles enable ultra-flexible miniature fiber-probes with geometries inspired by nerves, which permit simultaneous optical excitation and recording of neural activity in the spinal cord allowing for optical control of lower limb movement. Furthermore, fiber-based fabrication can be extended to design of scaffolds that direct neural growth and activity facilitating repair of damaged nerves.
Molecular mechanisms of action potential firing inspire the development of materials-based strategies for direct manipulation of ion transport across neuronal membranes. For example, hysteretic heat dissipation by magnetic nanomaterials can be used to remotely trigger activity of neurons expressing heat-sensitive ion channels. Since the alternating magnetic fields in the low radiofrequency range interact minimally with the biological tissues, the magnetic nanoparticles injected into the brain can act as transducers of wireless magnetothermal deep brain stimulation. Similarly, local hysteretic heating allows magnetic nanoparticles to disrupt protein aggregates associated with neurodegenerative disorders.
The Tuesday JFI Seminar - Suri Vaikuntanathan, Department of Chemistry, University of Chicago
Non-equilibrium Pathways for Self Assembly and OrganizationNonequilibrium forces can drive specific and novel pathways to modulate self-assembly and organization. The close connection between energy dissipation and organization is particularly apparent in biology. Indeed, it has been demonstrated that nonequilibrium forces are crucial for the functioning of biochemical processes responsible for error correction, adaptation and timing of events in the cell cycle. However, unlike the behavior and characteristics of equilibrium systems, where no energy is dissipated, general principles governing fluctuations about a steady state or the steady state itself in far-from-equilibrium conditions are just being discovered. In my talk, I describe how tools from non-equilibrium statistical mechanics can be used to direct self assembly far-from-equilibrium, engineer novel spatiotemporal correlations in active liquids, and finally support properties such as ultra sensitivity in non-equilibrium biochemical networks. These results provide a framework for uncovering fundamental design principles of organization in non-equilibrium chemical and biological processes.
For further information please contact Brenda Thomas at 773-702-7156 or by email at firstname.lastname@example.org. You may contact the Host, Aaron Dinner at 773-702-2330 or via email to email@example.com.
IME Special Seminar: Antoine Georges
Quantum Materials: Bridging Physical Mechanisms, Simple Models and Realistic ComputationsQuantum Materials display competing phases with fascinating physical properties, which result from the multiple degrees of freedom in presence (charge, spin, orbital, lattice) and from strong electronic correlations. In this talk, I will show how computational methods aimed at the quantum many-body problem can be combined with realistic electronic structure methods in order to shed light on these physical properties, help identify relevant mechanisms and formulate simple effective models. This will be mostly illustrated by rare-earth nickelates, a family of materials displaying a metal-insulator transition which can be controlled by strain, gating or light, pulses.
Professor Bryan Dickinson, University of Chicago
Molecular Imaging and Evolutionary Approaches to Probe and Control Biology
The Tuesday JFI Seminar - Dr. Sho Yaida, Department of Chemistry, Duke University
Novel Phase Transition within Amorphous Solids"Glassy materials are omnipresent in everyday life from windows to plastics to piles of sand. Yet our understanding of both their (equilibrium) liquid and (out-of-equilibrium) solid phases lags far behind that of crystalline counterparts. Recent advances are rapidly changing the ways in which we understand these common-yet-physically-enigmatic materials. This talk overviews one such advance -- the discovery of the Gardner phase transition from normal to marginally-stable glasses. Our work in particular indicates that such a transition, first found in abstract infinite-dimensional models, can survive down to the three-dimensional world. This transition reinforces the overriding role of rugged free-energy landscapes that dictate physics of glassy systems, with tangible consequences on jamming, yielding, and beyond.
For further information please contact Brenda Thomas at 773-702-7156 or by email at firstname.lastname@example.org. You may also contact the Host, Arvind Murugan at 773-834-3146 or via email at email@example.com."