“The additional covalent bonds prevent double-helices from unwinding, hence the objects become stronger,” said Dietz.

They created the additional covalent bonds with UV radiation after the self-assembly is completed.

“UV irradiation can cause two adjacent T-bases to react with each other,” said Dietz. “Normally, in cells that’s a nuisance and needs to be repaired. But for our nanostructures it is an easy fix to increase the stability.”

More durable DNA nanostructures able to withstand temperatures up to 90 degrees Celsius open up new applications. And not only are the structures more durable, says Dietz, but the process also leads to high yield, practically defect-free self-assembly at low cost. 

“With more durable objects you can go into much harsher conditions,” said Dietz. “Among such ‘harsh conditions’ are in vivo conditions.”

Dietz doesn’t see any show-stoppers. “Most of the general challenges that apply to all have been addressed, so one can now focus on solving application-specific challenges,” said Dietz. “So you could say, with the craftsmanship sufficiently mature now, we can move on to build those devices.”

Along these lines, Dietz and his colleagues will be looking at biomedical applications that can use these nanostructures in their future research.

He added: “We are looking to figure out how organisms react to DNA nanostructures, immunogenicity, toxicity, body distribution, look into cell/tissue targeting; some work has been done into this direction but there are many open questions.”