Mechanical response of a simple DNA nanostar hydrogel: symptoms of disorder and glassy emergence of solidity

TL;DR

This study investigates the mechanical properties of a simple DNA nanostar hydrogel, revealing disorder-related symptoms and a glass transition, with implications for understanding and designing DNA-based bulk materials.

Contribution

The paper introduces a systematic method combining rheology, microrheology, modeling, and thermodynamics to analyze the mechanical response of disordered DNA hydrogels, highlighting the role of disorder and glass transition.

Findings

Deviations from Maxwell behaviour indicate disorder effects.

Solid-like behaviour observed at high temperatures suggests a glass transition.

Method applicable to complex DNA materials.

Abstract

DNA self-assembly is a well-understood nanotechnology to obtain extremely ordered structures from the nanometer to up to the hundred of microns scale. By contrast, DNA hydrogels rely on the disordered assembly of DNA building blocks to reach macroscopic volumes. However, in order to hold the promise of DNA bulk materials, the sequence designer needs a systematic understanding of how macroscopic properties emerge from disorder. Here, we show a method to study systematically the mechanical response of a simple DNA nanostar hydrogel. This method mobilises bulk rheology, dynamic light scattering microrheology, mechanical modeling, as well as thermodynamic calculation and DNA sequence alteration. At low temperatures, we demonstrate a systematic deviation from Maxwell behaviour that is symptomatic of disordered materials. At temperatures much higher than the percolation of the DNA network, we characterise a surprising solid behaviour that we attribute to a glass transition. Our results show the importance of disorder in DNA materials. Furthermore, the method we showcase in this article can be widely applied to more complex DNA materials.