Kimberly Weirich, Assistant Professor, Clemson University

"Capillary-induced biopolymer network formation and remodeling"

Abstract:

From the drawing of fluids through thin tubes and flow through porous media to inducing fiber aggregation, capillarity underlies a range of processes from transport to self-assembly. Recently, protein condensates, which have properties of liquids, have emerged as important in regulating biological cellular organization. Based on their liquid properties, it has been hypothesized that the interactions of condensates with cellular surfaces, such as membranes and filaments, could induce mechanical deformations or higher-order structure formation via capillary-like interactions. A critical class of self-assembled cellular materials is the cytoskeleton, which is comprised of filaments canonically known to be cross-linked together by proteins into networks and bundles. The microstructure of these assemblies is particularly important, since the different microstructures each support particular physiological functions. Here, we show that protein condensates adsorb on actin filaments, evocative of drops of simple liquids on fibers. We investigate the condensate spreading and measure contact angle that condensates make with actin bundles. We find that condensates at the intersection of bundles cause capillary bridges which induce network remodeling, highlighting the role of capillarity in biological self-assembly. Understanding this bundling mechanism further could expand our toolkit for making self-assembled soft materials.

Bio:

Kim Weirich is an interdisciplinary researcher in experimental soft matter and biological materials, with focuses in self-organization and unusual mechanics in soft materials inspired by biology. She joined the faculty of Materials Science and Engineering at Clemson University in 2020 and is a Clemson University School of Health Research Faculty Scholar.  She has a Ph.D. in Biomolecular Science and Engineering and undergraduate degrees in Physics and Linguistics from the University of California, Santa Barbara. Before joining Clemson University, Kim was a Postdoctoral Scholar at the University of Chicago in the James Franck Institute and the Pritzker School of Molecular Engineering.