Researchers at Johns Hopkins University have devised self-assembling, nano-scale pipes that are leak-free and can be used to install plumbing into our cells.

Leak-free piping is something everyone who’s ever had a plumbing issue would swear by. And while our bathrooms and kitchens will have to wait until such pipes become available, researchers at Johns Hopkins University have developed a way to ensure that nano-scale piping they are developing avoids any and all leaks.

These pipes, which self-assemble from nanotubes and self-repair, can be connected to various biological structures in our bodies, they add. As such, their discovery brings us one step closer to one day developing nanotube networks that can deliver drugs or other needed molecules to specific cells in our bodies.

Miniature delivery

“This study suggests very strongly that it’s feasible to build nanotubes that don’t leak using these easy techniques for self-assembly, where we mix molecules in a solution and just let them form the structure we want,” said Rebecca Schulman, an associate professor of chemical and biomolecular engineering at Johns Hopkins who co-led the research. “In our case, we can also attach these tubes to different endpoints to form something like plumbing.”

The findings are based on experiments the team ran using tubes that are around seven nanometers in diameter and several microns long. Their work builds on established techniques of repurposing bits of DNA as building blocks, growing and repairing the tubes while allowing them to connect to specific structures in the body. While previous research had designed similar structures known as nanopores, those focused on transporting molecules through artificial cellular membranes.

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

“Building a long tube from a pore could allow molecules not only to cross the pore of a membrane that held the molecules inside a chamber or cell, but also to direct where those molecules go after leaving the cell,” Schulman said. “We were able to build tubes extending from pores much longer than those that had been built before that could bring the transport of molecules along nanotube ‘highways’ close to reality.”

The nanotubes are formed from strands of DNA that are woven together. But this weave leaves tiny gaps in between individual DNA molecules. Although they are very small in size, it was unclear whether these gaps would leave the tubes unable to transport molecules without some leaking out.

The study focused on answering this question. The team performed the equivalent of capping one end of the tube and pouring water through the other to check for leaks and flow rates inside the tubes. The caps were made of special DNA “corks”, and the tubes were then filled with a solution of fluorescent molecules, which could be more readily tracked. During the experiment, the team monitored the shapes of the tubes, how they connected to specific nanopores, 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 can be used to transport molecules through an artificial membrane.

“Now we can call this more of a plumbing system, because we’re directing the flow of certain materials or molecules across much longer distances using these channels,” Li said. “We are able to control when to stop this flow using another DNA structure that very specifically binds to those channels to stop this transport, working as a valve or a plug.”

As this technology is still in its infancy, it is still hard to estimate how it will evolve in the future. For now, the team is confident that these nano-pipes can be used to study and treat diseases like cancer by delivering certain molecules to affected cells.

Going forward, the team will be investigating how the tubes interact with both synthetic and natural cells.

The paper “Leakless end-to-end transport of small molecules through micron-length DNA nanochannels” has been published in the journal Science Advances.