Biopolymer Networks: Simulations of Rigid Rods Connected by Wormlike Chains

The cytoskeleton of cells is a composite network of filaments ranging from stiff rod-like microtubules to semiflexible actin filaments that together play a crucial role in cell structure and mechanics. The collective dynamics of these cytoskeletal filaments with different mechanical properties are yet to be understood completely. To model such a strongly heterogeneous composite, we simulate networks of \textit{rigid} rods connected by \textit{flexible} linkers (wormlike chains). We extract elastic moduli by quasistatic deformations at varying filament densities and analyze the crossover between cross-link dominated and rod dominated regimes. In particular, we are interested in the asymptotic stress dependence of the \textit{differential modulus}. The simulations are accompanied by rheological experiments on networks of \textit{microtubules} (MTs) cross-linked by double-stranded \textit{DNA} of variable length (cf. talk Meenakshi Prabhune).