Atomic force microscopy images of artificial ion channels. (Image courtesy of Bing Gong, University at Buffal)

Taking a new stab at developing medical device technologies inspired by nature, an international team of researchers has created synthetic pores that mimic the activity of cellular ion channels. These channels play a vital role in human health by severely restricting the types of materials allowed to enter cells.

Permeable to potassium ions and water, the fabricated pores are not permeable to other ions such as sodium and lithium ions. While common in nature, such extreme selectivity is unprecedented for synthetic structures, remarks University at Buffalo chemistry professor Bing Gong, who led the study. Based on the scientists' ability to fabricate selective pores, the project could pave the wave for an array of medical device applications, such as tumor-killing technologies.

"The idea for this research originated from the biological world, from our hope to mimic biological structures, and we were thrilled by the results," says Gong, whose research appears in in Nature Communications. "We have created the first quantitatively confirmed synthetic water channel. Few synthetic pores are so highly selective."

To create the synthetic pores, the researchers learned how to force donut-shaped molecules, called rigid macrocycles, to pile on top of one another. The scientists then stitched these stacks of molecules together using hydrogen bonding. The resulting structure was a nanotube with a pore less than a nanometer in diameter.

"This nanotube can be viewed as a stack of many, many rings," comments Xiao Cheng Zeng, University of Nebraska-Lincoln Ameritas University professor of chemistry and one of the study's senior authors. "The rings come together through a process called self-assembly, and it's very precise. It's the first synthetic nanotube that has a very uniform diameter. It's actually a subnanometer tube. It's about 8.8 angstroms."

The next step in the research is to tune the structure of the pores to allow different materials to selectively pass through and to determine what qualities govern the transport of materials through the pores, Gong notes.