Connecting microscale stresses to macromolecular motion in entangled ring-linear DNA blends

Ring polymers, as well as mixtures of ring and linear polymers, are ubiquitous in nature yet still poorly understood. Due to the lack of free ends in ring polymers, the motion and dynamics of entangled rings is complex and distinctly different than their linear chain counterparts. As such, the dynamics of entangled blends of ring and linear polymers remain a topic of fervent debate. Here, we use DNA - which occurs naturally in rings and linear forms - as a model system to investigate highly entangled ring-linear blends. To elucidate the dynamics of these blends, we demonstrate a novel technique that combines optical tweezers microrheology with fluorescence imaging and differential dynamic microscopy. This technique enables us to directly image single polymers while performing active microrheology. As a result, we show that it is possible to unambiguously connect the stresses induced by both linear and nonlinear strains to the corresponding macromolecular deformations and network rearrangement in ring-linear polymer blends.