title: Nonlinear microrheology reveals entanglement-driven molecular-level viscoelasticity of concentrated DNA.
abstract: We optically drive a trapped microscale probe through entangled DNA at rates up to 100× the disentanglement rate (Wi≈100), then remove the trap and track subsequent probe recoil motion. We identify a unique crossover to the nonlinear regime at Wi≈20. Recoil dynamics display rate-dependent dilation and complex power-law healing of the reptation tube. The force response during strain exhibits key nonlinear features such as shear thinning and yielding with power-law rate dependence. Our results, distinctly nonclassical and in accord with recent theoretical predictions, reveal molecular dynamics governed by individual stress-dependent entanglements rather than chain stretching.
authors.affiliation: Department of Physics, University of San Diego, San Diego, California 92110, USA.
authors.forename: Cole D
authors.initials: CD
authors.lastname: Chapman
authors.affiliation: Department of Physics, University of California San Diego, La Jolla, California 92093, USA.
authors.forename: Rae M
authors.initials: RM
authors.lastname: Robertson-Anderson
mesh_terms: D004247:DNA / Q000737:chemistry*; D008863:Microspheres; D008956:Models, Chemical; D017711:Nonlinear Dynamics; D012212:Rheology; D055682:Viscoelastic Substances / Q000737:chemistry*
chemical_list: D055682:Viscoelastic Substances; D004247:DNA