Seminar: Stimuli-Response in Polymeric systems; from Energy Applications to Biological Phenomena
Dr. Aykut Erbas
UNAM Conference Hall
25.01.2018 3:40 pm
25.01.2018 5:00 pm
Polymers are one of the most versatile building blocks to construct stimuli-‐responsive soft matter for scientists and nature, thanks to their structural and chemical diversity. While scientists use their tailorable properties to design functional and hybrid materials, nature facilitates them for organization and adaptability. However, everything comes at a cost. The heterogeneities in the zoo of polymers bring complexity, particularly when we need to know their physiochemical responses to distortions, which are essential to design robust materials and resolve certain biological questions quantitatively. Yet, to make life even harder, most synthetic and biological polymeric systems of interest carry ionic groups that can interact beyond inter-‐atomic distances. These long-‐ range interactions are cumbersome to treat analytically alone and necessitate computational solutions. Along with these lines, in the first part of my talk, I will discuss the electro-‐mechanical responses of polyelectrolyte networks (i.e., hydrogels), which are not only excellent materials for filtration and electrolyte applications but also quite abundant in living organisms. The extensive computational simulations demonstrate that mechanical deformation of chains constituting the hydrogel leads to enhanced ionic correlations and allow an “energy conversion” process. Ionic conductivity in these networks exhibits strong non-‐linearity regardless of solvent properties, similar to ionic diodes. In the second part, I will change gear and discuss the role of ionic interactions in ligand dissociation kinetics by specifically focusing on the experiments and simulations of facilitated disassociation of transcription factors from single-‐DNA-‐binding sites. The research shows that weak inter-‐molecular interactions can be a key factor in regulatory networks and thus for some biotechnological applications. I will conclude my talk with future prospects to improve and control ionic motion in polymer matrices, and with some preliminary computational results on chromatin segregation in eukaryotic cell nuclei.
About the Speaker
Dr. Aykut Erbas received his Ph.D. in Physics from Technical University Munich (TUM) -‐ Germany in 2011 under the advisory of Roland R. Netz. During his graduate studies, he worked on peptide-‐ surface interactions and single-‐molecule friction. His thesis work revealed the contributions of cooperative rupture of hydrogen bonds on molecular mobility. Later he moved to the University of North Carolina -‐ Chapel Hill, Chemistry Department, to research polymer dynamics with Michael Rubinstein. Since 2014, Dr. Erbas has been a research fellow at Northwestern University’s Material Science & Engineering Department in various centers dedicated to designing bio-‐inspired energy systems with Monica Olvera de la Cruz. In his research, Dr. Erbas utilizes computational simulations and theoretical models, and collaborates with various experimental groups to explore phenomena in charged polymeric systems, including hydrogels, ionic liquids, amphiphilic peptides. In addition to his materials-‐oriented studies, he also researches DNA-‐protein interactions and in vivo chromatin conformations with John F. Marko, a pioneering biophysicist on DNA mechanics.