Topological viscoelasticity: when DNA nanostars build loopy networks

Breakthrough demonstrates a link between these topological structures to unique hydrogel material properties.

Using a combination of experiments and simulations, researchers from the School’s Institute for Condensed Matter and Complex Systems investigated the material properties of hydrogels made of DNA building blocks, called ‘nanostars’.

The team used experimentally-validated simulations to accurately quantify the internal structure of the gels, and then employed experiments to test simulation-based predictions on how the gels’ elasticity depended on varying DNA concentration.  

They discovered that DNA nanostars formed long-lived, interpenetrating networks that had never been seen nor conjectured before. The DNA nanostars created a ‘network-within-a-network’ with loops that interlinked each other and thus presented non-trivial ‘topology’.

The crux of the findings was the demonstration of a link between these complex topological structures and the material properties of the gels. The team also observed similar structures in other network-forming materials, including ice.

The group hopes that their research will pave the way for a new concept in the science of complex fluids, such as gels, pastes, soaps, and other liquids, which fall into the category of ‘topological viscoelasticity’, where the topology of the microscopic network determines its material properties.

Dr Yair Augusto Gutierrez Fosado from the School's Computational Materials Physics research group said:

This significant result enhances our understanding of the connection between the macroscopic mechanical properties of a network, with mathematically rigorous quantities, such as topological invariants. We believe that 'topological viscoelasticity' will be a central theme in rheology of complex fluids in the future.