Measuring structural parameters of crosslinked and entangled semiflexible polymer networks with single-filament tracing

TL;DR

This study uses programmable DNA nanotubes to measure structural properties of polymer networks, revealing the influence of filament stiffness and interactions, and suggesting models need to include inter-filament interactions.

Contribution

It introduces a method using DNA nanotubes to systematically study how filament stiffness and interactions affect measurements in polymer networks.

Findings

Filament stiffness influences measured network parameters.

Steric interaction models are insufficient alone.

Inter-filament interactions significantly affect network behavior.

Abstract

Single-filament tracing has been a valuable tool to directly determine geometrical and mechanical properties of entangled polymer networks. However, systematically verifying how the stiffness of the tracer filament or its molecular interactions with the surrounding network impacts the measurement of these parameters has not been possible with the established experimental systems. Here, we use mechanically programmable DNA nanotubes embedded in crosslinked and entangled F-actin networks, as well as in synthetic DNA networks, in order to measure fundamental, structural network properties like tube width and mesh size with respect to the stiffness of the tracers. While we confirm some predictions derived from models based purely on steric interactions, our results indicate that these models should be expanded to account for additional inter-filament interactions, thus describing the behavior of real polymer networks.