Chemical engineers at Penn State have accidentally discovered a new and versatile way to make nanofibers. During an experiment, one of the researchers "left his fingerprints on a piece of research equipment that had been secured with Super Glue and nanofibers appeared." And the team was able to reproduce this process with a variety of fake fingerprints made from salt of other substances found on fingers. And they were able to build not only nanofibers, but also nano-sized flat sheets or spheres. This new method will first be used in medical applications such as drug delivery.
Here is an introduction to this new technology.
The new technique is based on the way forensic scientists develop fingerprints from a crime scene and is easier and more versatile than either of the current methods, templates or electrospinning, used commercially to make nanofibers. The first nanofibers generated by the technique are made from the basic ingredient of Super Glue, cyanoacrylate, which is a biologically-compatible material already used in liquid sutures, spheres for drug delivery and in experimental cancer treatment. However, the researchers say that other materials, like cyanoacrylate, that form solid polymers when nudged by a catalyst could potentially also be used in the process.
Dr. Henry C. Foley, professor of chemical engineering who directed the project, says, "The new technique is so versatile that it allows us not only to make nano-scale fibers but also nano-sized flat sheets, spheres and even wrinkled sheets that look tortellini-like."
And here is how this discovery was made.
One of the researchers, Pratik Mankidy, had accidentally left his fingerprints on a piece of research equipment that had been secured with Super Glue and nanofibers appeared. Putting two and two together, the researchers set out to discover what constituents of fingerprints trigger the cyanoacrylate polymerization on the ridges of fingerprints.
They made synthetic fingerprints from a mixture of a known polymer initiator, common table salt in water, and a non-initiator, linoleic acid, found on fingers. Then they exposed the fake prints to cyanoacrylate fuming. Sure enough, they got nanofibers similar to the ones Mankidy's fingerprints had generated accidentally.
For more information, below is a picture of fumed and reversed fumed fingerprints (Photo credit: Greg Greico, Penn State) and here is a link to other photos of this new nanofiber fabrication technique.
And the illustration below shows a "tortellini-like polymer film obtained by initiation with sodium hydroxide" (Credit: The Royal Society of Chemistry).
This research work has been published as an advanced article by Chemical Communications under the name "Facile Catalytic Growth of Cyanoacrylate Nanofibers" (January 26, 2006). It is available to subscribers from this link.
Sources: Penn State University news release, January 26, 2006; and various web sites
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