Paper Number
SM46 

Session
Polymer Solutions and Melts

Title
Single molecule dynamics of DNA comb polymers

Presentation Date and Time
October 15, 2015 (Thursday) 8:40

Track / Room
Track 2 / Constellation D

Authors (Click on name to view author profile)

1. Schroeder, Charles M. (University of Illinois at Urbana-Champaign, Chemical & Biomolecular Engineering)
2. Mai, Danielle J. (University of Illinois at Urbana-Champaign, Chemical & Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Charles M. Schroeder and Danielle J. Mai
Chemical & Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801

Speaker / Presenter 
Schroeder, Charles M.

Text of Abstract
We report the synthesis and direct observation of branched DNA polymers. We developed a two-step synthesis method to generate branched polymers for single molecule visualization. Here, we use a graft-onto synthesis method by linking side branches onto DNA backbones, thereby producing star, H-shaped, and comb-shaped polymers. In these experiments, DNA-based branched polymers are designed to contain short branches (1-10 kilobase pairs) and long backbones (10-30 kilobase pairs), where the branches and backbones are monodisperse and the branch distribution can be controlled in an average sense. Following synthesis, we utilize single-color or dual-color single molecule fluorescence microscopy (SMFM) to observe the dynamics of these molecules, in particular by tracking the side branches and backbones independently. In this way, our imaging method allows for characterization of these materials at the single molecule level, including quantification of polymer contour length and branch distributions for varying synthetic conditions. Moving beyond characterization, we study the dynamics of single branched polymers in flow using a molecular rheology approach. In one experiment, we utilize precision microfluidics to study the relaxation of branched DNA from high stretch. Here, we directly observe conformational relaxation dynamics of single chains by characterizing backbone relaxation from high stretch, and we find that the relaxation of branched polymers is a strong function of the number of branches and position of branch points along the main chain backbone. In a second experiment, we also observe the transient and steady-state dynamics of single branched polymers in planar extensional flow. Overall, our work aims to probe the impact of branching on the dynamics of polymers in dilute and concentrated solutions, thereby providing a molecular-level understanding of the dynamics of topologically complex polymers in flow.