Biomedical and Chemical Engineering Research Seminar Series

Multi-scale simulations of soft matter: from block copolymers to biomolecular condensates

Abstract: Polymers are ubiquitous in both synthetic and biological materials and underlie technologies as diverse as surfactants, adhesives, proteins and DNA. One of the defining features of all polymeric materials is that they are characterized by a wide range of length scales, often involving phenomena that span nanometers to microns. In this talk, I describe recent efforts by my group to develop multi-scale simulations of polymeric materials that can link monomeric to mesoscopic length scales. In the first part of the talk, I describe a new "multi-representation" simulation method where particle-based and field-theoretic simulations are linked together into a unified framework. Notably, this multi-representation approach leverages the formal equivalence between particle and field-based models and involves no approximation. The utility of this approach is illustrated by examining the self-assembly of complex sphere phases in block copolymer melts. In the second part of the talk, I demonstrate how these multi-representation simulations can be extended to explain the phase separation of biomolecular condensates. Our approach can recapitulate recent experimental data on prion-like domains and can resolve how subtle modifications to the amino acid sequence can modulate their phase behavior. Finally, we examine the phase separation of chromatin and how post-translational modifications to histone proteins can lead to transitions between liquid-like and solid-like behavior. Taken together, this work demonstrates that multi-resolution can unlock new insights into the multi-scale physics that characterize synthetic and biological polymers.

Bio: Joshua Lequieu is an Assistant Professor of Chemical and Biological Engineering at Drexel University. His research is focused on the theory and simulation of polymers and biological macromolecules such as proteins and DNA. He received a B.S. in Chemical Engineering from Cornell University, and a Ph.D. in Molecular Engineering from the University of Chicago under the guidance of Juan J. de Pablo. Following a postdoc in the Materials Research Lab at the University of California, Santa Barbara with Glenn H. Fredrickson, he joined Drexel University in 2020. He is the recipient of the 2019 Edward J. Kramer Prize in Materials, the 2021 Charles E. Kaufman Foundation New Investigator Award, and the 2021 Outstanding Teaching Award from Drexel University.

https://www.lequieulab.org/