Sinan Keten

Dept. of Civil & Environmental Engineering and Mechanical Engineering

Northwestern University

Wednesday, February 4, 2015, 4 PM EST

Title: Tuning the entropic spring to dictate order and functionality in polymer conjugated peptide biomaterials

Abstract: Hybrid peptide-polymer conjugates have the potential to combine the advantages of natural proteins and synthetic polymers, resulting in biomaterials with improved stability, controlled assembly, and tailored functionalities. However, the effect of polymer conjugation on peptide structural organization and functionality, along with the behavior of polymers at the interface with biomolecules remain to be fully understood. This talk will summarize our recent efforts towards establishing a modeling framework to design entropic forces in helix-polymer conjugates and polymer-conjugated peptide nanotubes to achieve hierarchical self-assembling systems with predictable order. The first part of the talk will discuss how self-assembly principles found in biology, combined with polymer physics concepts can be used to create artificial membranes that mimic certain features of ion channels. Thermodynamics and kinetics aspects of self-assembly and how it governs the growth and stacking sequences of peptide nanotubes will be discussed, along with its implications for nanoscale transport. The second part of the talk will review advances related to modeling polymer conjugated coiled coils at relevant length and time scales. Atomistic simulations combined with sampling techniques will be presented to discuss the energy landscapes governing coiled-coil stability, revealing cascades of events governing disassembly. This will be followed by a discussion of mechanisms through which polymers can stabilize small proteins, such as shielding of solvents, and how specific peptide sequences can reciprocate by altering polymer conformations. Correlations between mechanical and thermal stability of peptides will be discussed. Finally, coarse-grained simulations will provide insight into how the location of polymer attachment changes entropic forces and higher-level organization in helix bundle assemblies. Our findings set the stage for a materials-by-design capability towards dictating complex topologies of polymer-peptide conjugate systems.

Biosketch: Sinan Keten is an Assistant Professor of Civil & Environmental Engineering and Mechanical Engineering at Northwestern University. He joined Northwestern University faculty in 2010 after obtaining his Ph.D. in Civil & Environmental Engineering from MIT. His research expertise lies in computational materials science and mechanics with an emphasis on biological and bioinspired systems. He has made original contributions to elucidating structure-property relationships in biological materials such as spider silk, which is one of the toughest materials known, and nanocellulose, which is nature’s most abundant structural building block. His most notable contributions have involved theoretical calculations and multi-scale simulations that have explained how biological nanostructured materials achieve strength and toughness through important molecular level size and geometric effects. He has published 42 articles in journals such as Nature Materials, PNAS, and Nano Letters that have been cited in over 1000 scientific articles, and highlighted in mainstream media, Science, and Nature Physics. Dr. Keten currently serves as the principal investigator for research projects funded by the National Science Foundation (The Materials Genome Initiative), Office of Naval Research, and Army Research Office. He has given numerous invited lectures and keynotes around the world and has received awards from the Materials Research Society and the American Society of Mechanical Engineers. Dr. Keten is also actively involved in creating new web-based educational tools that facilitate training of students and researchers in mechanics, materials and computational engineering.

Video-conference link: https://nibibvcsportal.nibib.nih.gov/flex.html?roomdirect.html&key=Gt8c6VLrqcTr&vd=1

— You will be directed to install the “Vidyo” video conferencing software if you have not done so already.  Please do this in advance of the colloquium.)

Iwona Jasiuk, UIUC

Stavros Thomopoulos, Washington University

IµBEAM colloquium series coordinators

Markus Buehler, MIT

Guy Genin, Washington University

IµBEAM working group co-leads