Defect size and cross-linker properties controlled fracture of biopolymer networks

Abstract

Damage in cytoskeleton can occur frequently during processes like cell migration and division. However, the question of how the presence of micro-cracks affects the deformation and fracture response of such bio-filament networks remains unclear. Here, we report a computational study to address this unsettling issue where large deformation and thermal fluctuations of individual biopolymers, as well as the forced breaking of crosslinks between them, have all been taken into account. It was found that the introduction of micro-cracks could alter the fracture path inside the network, change its ductility and actually result in an increased fracture energy of the material. More interestingly, we showed that on average the maximum fracture resistance will be achieved when the crack length is a few times of the network pore size, highlighting the flaw insensitive nature of such materials. Finally, the network fracture energy was observed to increase with the linear stiffness of crosslinking molecules monotonically but reach its minimum at an intermediate rotational stiffness value. In addition to enhancing our understanding of how cytoskeleton performs different cellular duties, findings here could also provide useful information for the development of high performance biological materials in the future.