Materials scientists, led by a team at the Department of Energy's Pacific Northwest National Laboratory, design a tiny tube that rolls up and zips closed. The hollow nanotubes are reportedly thousands of times smaller than a strand of human hair and could help with water filtration, tissue engineering and many other applications. The tubes were inspired by protein structures called microtubules that reside in cells, according to PNNL's Chun-Long Chen.
"The structure of the cell is so beautiful," says Chen, a materials chemist who conceived of and directed the project. "We wanted to create a synthetic system that mimics the microtubule structure and is stable enough for a variety of technical applications."
Microtubules are tiny hollow tubes that help keep DNA organized during cell division and form highways for shuttling contents around in the cell. These cellular roads are composed of long chains of proteins that come together into a rigid, but hollow, tube. Microtubules have a uniform but dynamic structure, and they inspire scientists like Chen.
Chen's group hopes to use tiny hollow tubes like microtubules to create a robust water filtration system that would catch salt or other molecules inside and let pure water escape out the other end. In addition, they want to monitor how stem cells adapt to different environments by studying how the cells change while they grow on these tubes.
The researchers, however, can't use microtubules themselves for these projects. Microtubules are susceptible to temperature changes and microbes. The team set about making a synthetic version of microtubules using protein-like molecules called peptoids. Like proteins, peptoids are composed of a repeating pattern of building blocks with slight variations, but peptoids are more stable. These new nanotubes form in a unique way. First, small peptoid particles come together to form a sheet. Then the sheet closes at one end and rolls into a seamless tube.
"Nature has offered us all kinds of beautiful examples," says Chen. "Fish can take in water from the sea without having to worry about high salt conditions. If we could mimic this behavior by building artificial cell membranes containing these nanotubes, we could solve some of the big problems facing our world today."
The work was supported by the Department of Energy Office of Science, PNNL and the National Science Foundation of China.
For more information, visit: www.pnnl.gov