Topologically Active Polymers
Davide Michieletto (University of Edinburgh)
Polymer physics successfully describes most of the polymeric materials that we encounter everyday. In spite of this, it heavily relies on the assumption that polymers do not change topology (or architecture) in time or that, if they do alter their morphology, they do so in equilibrium. This assumption spectacularly fails for DNA in vivo, which is constantly topologically re-arranged by ATP-consuming proteins within the cell nucleus.
Inspired by this, here I will discuss some non-equilibrium complex fluids in which DNA topology is selectively altered in time by proteins. I argue that solutions of « topologically active” polymers can display unconventional viscoelastic behaviours and can be conveniently realised using solutions of DNA functionalised by certain families of vitally important proteins.
More specifically, in this talk I will present some results using both theory/simulations and experiments on the microrheology of entangled DNA undergoing digestion by restriction enzymes and ligation by ligase. I will try to convince you that that we can harness these topological processes to design complex fluids with exotic and time-varying viscoelastic behaviours.