Self-assembling bio-inspired nanotubes discovered

Original news release was first published at EurekAlert.

We still have ways to go when it comes to reliable nanotechnology. It is already being used in modern computer parts and variety of consumer electronics, as well as water-resistant fabrics. However, consistent production of more sophisticated nanostructures is still proving extremely difficult. Nanotubes with diameter of a few bilionths of a meter would enable advanced applications, such as injecting cancer-fighting drugs directly into cells, or removing salt from seawater, but some serious precision is required for mass production of such miniscule structures.

Progress has been made, though. Researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory have discovered a family of polymers that spontaneously assemble into hollow crystalline nanotubes upon being placed in water. These tubes can even be adjusted to a diameter between 5 and 10 nanometers, depending on the length of the polymer chain. They are made out of two chemically disctinct bars which form a molecular tile ring, bundling up into nanotubes up to 100 nanometers long.

“This points to a new way we can use synthetic polymers to create complex nanostructures in a very precise way,” says Ron Zuckermann, who directs the Biological Nanostructures Facility in Berkeley Lab’s Molecular Foundry, where much of this research was conducted.

Zuckermann has also suggested that the adjustable diameter of the tubes could theoratically allow for advanced filtration and desalination technologies. It is the kind of functionality that resembles proteins found in nature, but made out of durable materials. There is still research to be done to determine how exactly these tubes are formed, but Berkeley Lab’s findings have cleared up a lot of questions regarding their structure. This information could reveal new design principles, helping us put together complex nanostructures in the future.

What makes these nanotubes stand out, is that they are created without the approaches traditionally used in nanotechnology, mainly electrostatic interactions or hydrogen bond networks. Zuckerman added: “You wouldn’t expect something as intricate as this could be created without these crutches, but it turns out the chemical interactions that hold these nanotubes together are very simple. What’s special here is that the two peptoid blocks are chemically distinct, yet almost exactly the same size, which allows the chains to pack together in a very regular way. These insights could help us design useful nanotubes and other structures that are rugged and tunable – and which have uniform structures.”