Coarse-Grained Simulation of Active Cytoskeletal Composites for Rational Material Design

We present coarse-grained agent-based simulations of active cytoskeletal protein composites. Combining reconstituted structural proteins and molecular motors in vitro has enabled the creation of novel classes of active materials that exhibit rich dynamics such as large scale, self-driven contractility. Strategically harnessing such systems for a specific task requires detailed understanding of composition-property relationships. These systems’ complex dynamics and spatial heterogeneity make them difficult to model with continuum mechanics, and the often large persistence lengths of cytoskeletal proteins make them difficult to simulate with conventional molecular dynamics because of the short time steps required. We will present techniques for spatial and temporal coarse-graining of simulations of active cytoskeletal composites (ACCs), with a focus on blends of filamentous actin, microtubules, and myosin II minifilaments. We will quantitatively compare the behavior of our simulations to the large-scale contractility and dynamics observed in experiments, while also discussing the utility of our simulations in calibrating experimental post-processing tools by providing a well defined ground truth.