Synthetic channel with a strong preference for potassium ions offers rapid transport through artificial membrane

March 9, 2018, Agency for Science, Technology and Research (A*STAR), Singapore
Synthetic channel with a strong preference for potassium ions offers rapid transport through artificial membrane
This scanning electron microscope image shows that the artificial ion channels self-assemble into fibers. Credit: American Chemical Society

Artificial ion channels developed by A*STAR researchers could pave the way for new kinds of antibacterial agents and biomedical sensors.

Ion channels are biochemical superhighways that enable ions of metals such as and sodium to zoom in and out of cells. Crucially, the channels are typically very selective, allowing only one type of ion through and barring others. For example, the naturally-occurring KcsA can transport 100 million ions per second, and only lets one sodium ion through for every 10,000 .

"But protein-based are costly and difficult to manipulate," says Huaqiang Zeng at the A*STAR Institute of Bioengineering and Nanotechnology. "Synthetic versions are therefore being developed to mimic and eventually surpass the functions exhibited by naturally-occurring protein channels." However, it has been difficult to develop artificial channels that have a strong selectivity for potassium over sodium ions.

Zeng and colleagues have now developed ion channels that offer rapid potassium ion transport, with a selectivity that is among the highest reported for any artificial ion channel. The channel is formed from a series of identical molecules that stack on top of one another. Each molecule contains three components. At one end is a crown ether, a large ring of carbon and oxygen atoms; in the middle is an amino acid, which contains chemical groups that allow the molecules to stack in a specific pattern; and at the other end is a long, carbon-based 'tail'. These molecules can self-assemble so that the crown ether rings line up to form a tube, which acts as an ion channel.

The researchers created a library of molecules using various amino acids, different lengths of alkyl chains, and crown ethers that contained five or six oxygen atoms. Then they formed membranes from the stacked channels, and tested their ion transport properties.

The most selective channel they studied contained a crown ether with five , a phenylalanine amino acid, and an alkyl chain containing eight carbon atoms. This could transport 30 million ions per second, and was about ten times more selective for potassium ion than . This offers a much better performance than previous artificial potassium ion channels based on crown ethers or other molecular scaffolds.

The ' three components can be readily altered to fine-tune the channels' properties, so Zeng is optimistic that his team can improve their performance further. They hope to test their optimized systems in medical applications, such as antibacterial agents or hair growth promoters.

Explore further: Structural and dynamic differences between selective and non-selective ion channels

More information: Changliang Ren et al. Combinatorial Evolution of Fast-Conducting Highly Selective K+-Channels via Modularly Tunable Directional Assembly of Crown Ethers, Journal of the American Chemical Society (2017). DOI: 10.1021/jacs.7b04335

Related Stories

Stop and go in the potassium channel

October 11, 2017

Cells need openings in the cell membrane in order to make exchanges with their environment. These openings are closable portals in which the signals are transported in the form of ions. Private lecturer Dr. Indra Schröder ...

Study reveals how nanochannels select potassium ions

August 25, 2015

(—One of the mysteries in biology is how cells can selectively diffuse potassium across a membrane. Biological systems rely on a delicate balance between these potassium and sodium ion concentrations in the surrounding ...

Studying dynamics of ion channels

May 18, 2015

Scientists from the Vaziri lab at the Vienna Biocenter, together with colleagues at the Institute for Biophysical Dynamics at the University of Chicago, have developed a method using infrared spectroscopy and atomistic modeling ...

Synthetic nanochannels for iodide transport

June 8, 2017

Exchange of iodide (iodine ions) between bloodstream and cells is crucial for the health of several organs and its malfunctioning is linked to goiter, hypo- and hyperthyroidism, breast cancer, and gastric cancer. Researchers ...

Recommended for you

Archaeologists discover Incan tomb in Peru

February 16, 2019

Peruvian archaeologists discovered an Incan tomb in the north of the country where an elite member of the pre-Columbian empire was buried, one of the investigators announced Friday.

Where is the universe hiding its missing mass?

February 15, 2019

Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the "normal" matter in the Universe. New results from NASA's Chandra X-ray Observatory may have helped them ...

What rising seas mean for local economies

February 15, 2019

Impacts from climate change are not always easy to see. But for many local businesses in coastal communities across the United States, the evidence is right outside their doors—or in their parking lots.

The friendly extortioner takes it all

February 15, 2019

Cooperating with other people makes many things easier. However, competition is also a characteristic aspect of our society. In their struggle for contracts and positions, people have to be more successful than their competitors ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Mar 09, 2018
Looks like an excellent prospect for some sort of chemical evolution strategy.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.