Mechanics of smiflexible polymer chains under confinements

摘要

Physical properties of macromolecules and polymers in complex environments are usually influencedby external conditions such as geometrical confinements and applied forces. Polymers ingeometrical confinements that are smaller than their unconfined molecular sizes are of great significancein fields from polymeric liquid crystals to biological structures including cytoskeleton, stressfibres, nucleosomes and viruses. In this study, we use the wormlike chain model to theoreticallyinvestigate the force-extension relations of semiflexible polymer chains constrained by a) a slab-likeconfinement, where the polymer chain is sandwiched between two parallel impenetrable wall, orthe two ends of the chain are tethered to the opposing walls; b) a tube-like confinement, which isrealized when the polymer is bounded along two directions; c) a full 3D confinement, which refersto a fully-bounded subspace of R3 such as a box or a sphere. Brownian dynamics simulations,based on a recently developed generalized bead-rod model (Wang and Gao, J. Chem. Phys., 123:2005, 084906), are performed to verify the theoretical results of force-extension behavior of confinedpolymer chains. Applications in modelling the mechanical behaviors of F-actin bundles, such asstress fibers, and modelling the stability of molecular adhesion mediated by polymer repellers andligand-receptor bonds are discussed.