Researchers at Johns Hopkins University have devised self-assembling nano-scale pipes that are leak-free and can be used to install plumbing in our cells.
Leak-free piping is something anyone who has ever had a plumbing problem would swear by. And while our bathrooms and kitchens will have to wait until such pipes are available, researchers at Johns Hopkins University have developed a way to ensure that the nanoscale piping they are developing avoids any leaks.
These tubes, which self-assemble from nanotubes and repair themselves, can be connected to various biological structures in our bodies, they add. As such, their discovery one day brings us closer to developing networks of nanotubes that can deliver drugs or other molecules needed by specific cells in our bodies.
Delivery in miniature
“This study strongly suggests that it is possible to build non-leaking nanotubes using these simple self-assembly techniques, in which we mix the molecules into a solution and let them form the structure we want,” said Rebecca Schulman, an associate professor of chemical engineering. and biomolecular at Johns Hopkins who co-directed the research. “In our case, we can also connect these pipes to different end points to form something like a plumbing system.”
The results are based on experiments conducted by the team using tubes approximately seven nanometers in diameter and several microns long. Their work relies on established techniques to reuse DNA fragments as building blocks, grow and repair tubes allowing them to connect to specific structures in the body. While previous research had designed similar structures known as nanopores, those have focused on transporting molecules across artificial cell membranes.
Where these nanopores are like fittings to allow tubes to pass through a wall, the nanotubes are the tubes 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 pass through the pore of a membrane that contained the molecules inside a chamber or cell, but also to direct where those molecules go after they leave the cell,” he said. said Schulman. “We have been able to build tubes that extend out of the pores much longer than those that were built before they could bring the transport of molecules along the nanotube ‘highways’ close to reality.”
Nanotubes are made up of strands of DNA woven together. But this texture leaves small gaps between individual DNA molecules. Although they are very small in size, it was unclear whether these gaps would leave the tubes unable to carry molecules without some leaking.
The study focused on answering this question. The team performed the equivalent of plugging one end of the pipe and pouring water through the other to check for leaks and flow rates within the pipes. The caps were made of special DNA “caps” and the tubes were then filled with a solution of fluorescent molecules, which could be more easily traced. 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 pipes are, in fact, leak-free. The results also showed that these tubes can be used to transport molecules across an artificial membrane.
“We can now call it more of a hydraulic system, because we are directing the flow of certain materials or molecules over much longer distances using these channels,” Li said. “We can control when to stop this flow by using another DNA structure that binds very specifically to those channels to stop this transport, functioning as a valve or a plug.”
As this technology is still in its infancy, it is still difficult to estimate how it will evolve 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 certain molecules to affected cells.
Moving forward, the team will investigate how the tubes interact with synthetic and natural cells.
The article “Lossless end-to-end transport of small molecules through micron-long DNA nanochannels” was published in the journal Science advances.
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