Los tubos, visibles en verde claro, tienen unos siete nanómetros de diámetro, unas dos millones de veces más pequeños que una hormiga, y varias micras de largo, aproximadamente la longitud de una partícula de polvo. Crédito: Universidad Johns Hopkins
La plomería más pequeña del mundo podría potencialmente canalizar drogas a células humanas individuales.
Trabajando en tuberías microscópicas de apenas una millonésima del ancho de un cabello humano, los investigadores de la Universidad Johns Hopkins han desarrollado un método para proteger estas tuberías más pequeñas incluso de las fugas más pequeñas.
Una tubería sin fugas construida a partir de nanotubos que se autoensamblan y se autorreparan y que pueden unirse a diferentes bioestructuras es un gran paso hacia el desarrollo de una red de nanotubos que algún día podría transportar medicamentos, proteínas y moléculas especializadas a células específicas del cuerpo humano. Las medidas muy precisas se describieron recientemente en Los científicos progresan.
Tubos sin fugas fabricados con nanotubos que se autoensamblan, se autorreparan y pueden conectarse a diferentes bioestructuras. Este video muestra estos nanotubos «moviéndose». Crédito: Universidad Johns Hopkins
“Este estudio sugiere fuertemente que es posible construir nanotubos sin fugas utilizando estas técnicas simples de autoensamblaje, donde mezclamos moléculas en una solución y simplemente dejamos que formen la estructura que queramos”, dijo Rebecca Schulman, socia. profesor de ingeniería química y biomolecular que codirigió la investigación. «En nuestro caso, también podemos unir estos tubos a diferentes puntos finales para formar algo así como una tubería».
Los científicos utilizaron tubos de varias micras de largo, o del tamaño aproximado de una partícula de polvo, y con un diámetro de siete nanómetros, o unas dos millones de veces más pequeños que una hormiga.
La tecnología se basa en una técnica existente que reutiliza[{» attribute=»»>DNA fragments as building blocks to grow and repair the tubes while allowing them to seek out and connect to specific structures.
Similar structures have been created in earlier experiments to create smaller structures known as nanopores. These designs concentrate on DNA nanopores’ ability to regulate the transport of molecules through lab-grown lipid membranes that resemble cell membranes.
However, if nanotubes are like pipes, nanopores are like short pipe fittings that cannot reach other tubes, tanks, or equipment on their own. To solve these kinds of issues, Schulman’s team specializes in bio-inspired nanotechnology.
“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 form using DNA strands that are woven between different double helices. Their structures have small gaps like Chinese finger traps. Because of the extremely small dimensions, scientists had not been able to test whether the tubes could transport molecules for longer distances without leaking or whether molecules could slip through their wall gaps.
Yi Li, a doctoral graduate from Johns Hopkins’ chemical and biomolecular engineering department who co-led the study, performed the nano-equivalent of capping the end of a pipe and turning on a faucet to make sure no water leaks out. Yi capped the ends of the tubes with special DNA “corks,” and ran a solution of fluorescent molecules through them to track leaks and influx rates.
By precisely measuring the shape of the tubes, how their biomolecules connected to specific nanopores, and how fast the fluorescent solution flowed, the team demonstrated how the tubes moved molecules into tiny, lab-grown sacks resembling a cell’s membrane. The glowing molecules slid through like water down a chute.
“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.”
DNA nanotubes could help scientists gain a better understanding of how neurons interact with one another. Researchers could also use them to study diseases like cancer, and the functions of the body’s more than 200 types of cells.
Next, the team will conduct additional studies with synthetic and real cells, as well as with different types of molecules.
Reference: “Leakless end-to-end transport of small molecules through micron-length DNA nanochannels” by Yi Li, Christopher Maffeo, Himanshu Joshi, Aleksei Aksimentiev, Brice Ménard and Rebecca Schulman, 7 September 2022, Science Advances.
DOI: 10.1126/sciadv.abq4834
The study was funded by the National Science Foundation, the United States Department of Energy, and the Defense Advanced Research Projects Agency.