Capsids under compression

Icosahedral shells play important functional roles in many systems, including protein-shelled viruses, bacterial microcompartments, and synthetic nanocages. The reversible self-assembly process that leads to formation of such shells has been extensively studied during the past two decades, both theoretically and experimentally. In comparison, we have relatively little knowledge of their disassembly, in particular when disassembly is driven by mechanical forcing. In this talk we use dynamical Monte Carlo simulations to investigate icosahedral shells undergoing compression between two parallel walls. We particularly focus on the onset and propagation of cracks leading to shell disassembly. We quantify the increase in brittleness of the shells with the subunit stiffness and we follow the inhomogeneous nucleation and interaction of the propagating cracks under steady load. Finally, we apply cyclic load to the shells and measure the degree of recovery after the load is removed.