Innovative 'Mega Library' Gives Materials Engineers New Hope

An innovative tool for discovering new materials has shown promise for materials engineers. 

Throughout history, civilizations have been known by the tools they created and left behind. To create those tools, engineers in every era have had to access materials to accomplish their goals. In the modern era, this often led innovators to craft their own unique materials. 

A study from the Proceedings of the National Academy of Sciences (PNAS) explained how one tool could be making that task easier for modern engineers. A team from Northwestern University created a way to rapidly test billions of nanoparticles for a specific use. 

“When utilizing traditional methods to identify new materials, we have barely scratched the surface of what is possible,” said Northwestern’s Chad A. Mirkin. Mirkin served as the study’s corresponding author, and he's a global authority in nanotechnology research and its applications. “This research provides proof-of-concept—that this powerful approach to discovery science works.”

Going smaller rather than bigger

The new tool uses a megalibrary of nanoparticles. Those megalibraries work as a collection of varied structures encoded at specific sites on a surface, the researchers explained.

Using a technique developed by Mirkin, the libraries put hundreds of thousands of pyramidal tips on individual polymer dots. These "dots" are loaded with a variety of metal salts. Once researchers heat the dots, they reduce to metal atoms that form a single nanoparticle at a distinct and fixed composition and size.

Rather than "think big" with materials -- as other researcher teams have done -- Mirkin said going small gave the Northwestern team a distinct advantage.

“By going small, we create two advantages in high throughput materials discovery,” said Mirkin. 

“First, we can pack millions of features into square-centimeter areas, creating a path for making the largest and most complex libraries, to date. Second, by working at the sub-100 nanometer-length scale, size can become a library parameter, and much of the action, for example, in the field of catalysis, is on this length scale," he continued.

How the megalibrary could be used

Northwestern has already had some luck in putting this megalibrary to the test. They partnered with the United States Air Force Research Laboratory, part of the  U.S. Air Force Center of Excellence for Advanced Bioprogrammable Nanomaterials at Northwestern.

The megalibrary and an in situ Raman spectroscopy-based screening technique called ARES helped the researchers identify a new gold-copper catalyst. It can be used as a catalyst for synthesizing single-walled nanotubes made of carbon.

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Carbon nanotubing has risen to popularity in nanotechnology and nano-engineering. They're light, flexible, and incredibly strong. They've been used in everything from drug delivery to additives in plastics. 

“We were able to rapidly zero in on an optimal composition that produced the highest nanotube yield much faster than using conventional methods,” said Benji Maruyama, a study co-author from the Air Force Research Laboratory.

“The findings suggest we may have the ultimate discovery tool—a potential game changer in materials discovery.”