American researchers are applying the techniques used to test DNA to create a new tool that can rapidly test millions of different nanoparticles at one time to zero in on the best particle for a specific use.
Using five metallic elements (gold, silver, cobalt, copper and nickel), the engineers and scientists from Northwestern University in Chicago have developed an array of unique structures by varying every elemental combination.
Some of the compositions can be found in nature, but more than half of them have never existed before on Earth. And when pictured using high-powered imaging techniques, the nanoparticles appear like an array of colorful Easter eggs, each compositional element contributing to the palette.
“As scientists, we’ve only just begun to investigate what materials can be made on the nanoscale,” said the study leader Professor Chad Mirkin, a world leader in nanotechnology research and its application.
“Screening a million potentially useful nanoparticles, for example, could take several lifetimes. Once optimised, our tool will enable researchers to pick the winner much faster than conventional methods. We have the ultimate discovery tool.”
Using a technique called Dip-Pen Nanolithography, Mirkin and his team deposited onto a surface individual polymer 'dots', each loaded with different metal salts of interest. The researchers then heated the polymer dots, reducing the salts to metal atoms and forming a single nanoparticle. The size of the polymer dot can be varied to change the size of the final nanoparticle.
Mirkin said control of both size and composition of nanoparticles is very important, and having demonstrated control, the researchers used the tool to systematically generate a library of 31 nanostructures using the five different metals.
They can now study these nanoparticles as well as build other useful combinatorial libraries consisting of billions of structures that subtly differ in size and composition.
Mirkin says these structures may become the next materials that power fuel cells, efficiently harvest solar energy and convert it into useful fuels, and catalyse reactions that take low-value feedstocks from the petroleum industry and turn them into high-value products useful in the chemical and pharmaceutical industries.
[A combinatorial library of polyelemental nanoparticles was developed using Dip-Pen Nanolithography. Image: Peng-Cheng Chen/James Hedrick]
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