Tiny protein coils may help researchers develop molecular electronics or solar cells

Washington, August 18 : A team of chemists have succeeded in making a layer of tiny protein coils attached to a surface, much like miniature bedsprings in a frame, which is made of stable and very pure helices that can help researchers develop molecular electronics or solar cells.

The coils were developed by physical chemists at the Department of Energy's Pacific Northwest National Laboratory in the US, by using a "soft-landing" technique that disperses the tiny protein coils onto a waiting surface.

The small proteins called peptides are of a variety that normally take the shape of a coiled spring or helix in gas phase.

The method used by PNNL's Julia Laskin and Peng Wang delivered ultra-pure helical peptides to the surface and trapped them there.

"Controlling the conformation of peptides is not easy. Our previous studies showed that soft-landing can be used to prepare ultrapure peptide layers on substrates," said Laskin.

"The question we faced was, in addition to controlling purity, can we also control the structure of the molecules? We showed we could," she added.

Researchers have been trying to make thin films of helical peptides for many years.

Because the peptides line up in an orderly fashion, the overall chemical nature of the thin films make them useful for a variety of technological applications.

They can be modified with light sensitive molecules and turned into components of solar cells; or designed to change shape when a current is applied for molecular electronics. Also, the helices themselves can be used to elicit cues about how proteins function.

After making the thin films out of generic peptides previously, Laskin and Wang wanted to use this method to make a film out of helical peptides, and compare it with a more common method called electrospray.

Depositing the peptides with soft-landing, the chemists found that nearly all of them alighted as helices. In addition, they could chemically connect the helices to the surface using a related technique called reactive-landing.

When the chemists treated the thin layer with sound waves to test how easily the peptides fell off or changed shape, they found that some loosely bound peptides fell off, but those remaining maintained their helical forms.

"They formed a nicely organized, beautiful layer," said Wang.

Next, the team would like to create thin peptide layers using different support surfaces and a different mix of peptide shapes, to learn how to control the design of the thin films precisely.

"We found an interesting pathway to conduct different types of chemical reactions between complex molecules and substrates that will potentially enable us to prepare materials that cannot be made by standard methods," said Laskin.

ANI