Time-dependent rheology of enzymatically-active composites of DNA and dextran
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Excerpt of abstract: Polymer topology has been shown to play a principal role in the rheology and miscibility of polymer composites. At the same time, active materials, which undergo bulk rheological changes driven by macromolecular rearrangement and restructuring, are the topic of intense investigation. Here, we design polymer composites comprising entangled ring DNA and dextran polymers, and measure the dependence of rheological properties on the ratio of the two polymers. To push the composites out of equilibrium we incorporate enzymes that convert DNA rings to linear fragments and measure the time-dependent rheological properties of the topologically-active DNA-dextran composites during enzymatic activity. The bulk linear viscoelastic moduli that we measure show that composites undergo shear thickening and thinning over time, with the timescale and magnitude of the rheological changes dependent on the DNA:dextran ratio. Our system combines the tunability and versatility of polymer composites with the power of topologically-distinct DNA and enzymatic reactions to create topologically-active polymeric fluids that can be used for diverse applications from drug delivery, to filtration to infrastructure repair.