The world’s smallest tubes could one day stream beneficial molecules into our cells – completely leak-free

Researchers at Johns Hopkins University have created self-assembling, leak-free nanotubes that can be used to install tubes in our cells.

The nanotubes, which appear as thin green lines, are attached to the cells. Image credits Shulman Lab/Johns Hopkins University.

Leak-free pipes are something everyone who’s ever had a plumbing problem swears by. And while our bathrooms and kitchens have to wait for these tubes to become available, researchers at Johns Hopkins University have developed a way to make sure the nanotubes they’re developing avoid any and all leaks.

They add that these tubes, which are self-assembled from nanotubes and self-repair, can be connected to various biological structures in our bodies. As such, their discovery brings us one step closer to one day developing networks of nanotubes that can deliver needed drugs or other molecules to specific cells in our bodies.

mini delivery

said Rebecca Schulman, a fellow professor of chemical and biomolecular engineering at Johns Hopkins University who co-led the research. “In our case, we can also connect these tubes to different end points to form something like plumbing.”

The results are based on experiments the team conducted using tubes about seven nanometers in diameter and several microns long. Their work builds on well-established techniques to reuse bits of DNA as building blocks, growing and repairing tubes while allowing them to connect to specific structures in the body. While previous research has designed similar structures known as nanopores, those that have focused on transporting molecules across artificial cellular membranes.

Where these nanopores are like fixtures to allow tubes to pass through the wall, the nanotubes are the tubes themselves, connecting these fixtures to other equipment such as storage tanks or pumps.

“Constructing a long tube of pores could allow molecules not only to cross the pores of the membrane that holds the molecules inside a chamber or cell, but also to direct these molecules after they leave the cell,” Schulman said. “We have been able to build tubes that extend from pores much longer than those built before which could make transporting molecules along the ‘highways’ of the nanotubes much closer to reality.”

Nanotubes are made of strands of DNA woven together. But this tissue leaves small gaps between individual DNA molecules. Despite their small size, it wasn’t clear if these gaps would make the tubes unable to transport molecules without some of them leaking.

The study focused on answering this question. The team performed the equivalent of capping one end of the pipe and pouring water through the other end to check for leaks and flow rates inside the pipes. The caps were made of special DNA “plugs”, and then the tubes were filled with a solution of fluorescent particles, which could be traced more easily. During the experiment, the team monitored the shapes of the tubes, how they connected to the specific nano-pins, and the flow rate of the fluorescent solution inside them.

The team reports that the tubes are in fact leak-free. The results also showed that these tubes could be used to transport molecules across an artificial membrane.

“Now we can call this more of a plumbing system, because we direct the flow of certain materials or particles over much longer distances using these channels,” Lee told me. “We are able to control when to stop this flow by using another DNA structure that specifically binds to those channels to stop this transport, acting as a valve or stopper.”

Since this technology is still in its infancy, it is still difficult to estimate how it will develop in the future. For now, the team is confident that these nanotubes can be used to study and treat diseases such as cancer by delivering specific molecules to affected cells.

Going forward, the team will look at how the tubes interact with both artificial and natural cells.

The paper “Non-leaky end-to-end transport of small molecules through micron-length DNA nanochannels” was published in the magazine science progress.