Written by AZoNano May 4 2016

New Tool Helps Visualize Nanoscale ChemicalReactions in LiquidsPublished on May 4, 2016 at 11:07 AM

An innovative tool developed by UC San Diego chemistsenables researchers to visualize mixing processes orchemical reactions occurring in liquids at the nanoscale.

By mixing combinations of gold nanoparticles (yellow arrows) with other nanoscalecrystals (blue arrows) in the LCTEM (at left), the chemists showed their techniqueworks. Images by Lucas Parent, UC San Diego

Traditionally, researchers have been using transmission electron microscopy (TEM) toview nanoscale structures, but this method can only record static images and requiresthe samples to be frozen or dried, and placed inside a vacuum chamber forvisualization. Consequently, researchers were not able to view ‘nanoscale’ chemicalreactions or living processes, such as the contraction and growth within the living cellsof small fibers, nanoscale protrusions that are critical in the movement and division ofcells, or the changes induced by a chemical process in a liquid.

Being able to look at nanoscale chemical gradients and reactions asthey take place is just such a fundamental tool in biology, chemistryand all of material science. With this new tool, we’ll be able to lookat the kinetics and dynamics of chemical interactions that we’ve

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Gianneschi led the research team, which described this latest development in a paperpublished on the Microscopy and Microanalysis journal.

However, with new advancements in Liquid Cell TEM (LCTEM), scientists are nowable to record videos of nanoscale objects present in liquids. A drawback of thismethod is that it lacks the ability to manage the mixing of solutions, a prerequisitewhen viewing and studying the reaction of two chemicals or the effect of a drug on aliving cell.

In order to address this issue, Joseph Patterson, a postdoctoral researcher inGianneschi laboratory, in collaboration with researchers at Pacific Northwest NationalLaboratory and SCIENION AG in Germany, has developed a tool and a techniquethrough which researchers can now deposit small amounts of liquid, approximately 50trillionths of a liter, inside the LCTEM’s viewing area.

never been able to see before.

Nathan Gianneschi, Professor of Chemistry and Biochemistry, UCSan Diego

As chemists, we could only really analyze the end products or bulksolution changes, or image at low resolution because we couldnever see events directly occur at the nanoscale.

Nathan Gianneschi, Professor of Chemistry and Biochemistry, UCSan Diego

With this technique, we can view multiple components mixedtogether at the nanoscale within liquids, so, for example, one couldlook at biological materials and perhaps see how they respond to adrug. That was never possible before. The benefits to basicresearch are huge. We will now be able to directly see the growth atthe nanoscale of all kinds of things, like natural fibers ormicrotubules.

There’s a lot of interest on the part of researchers in understandinghow the surfaces of nanoparticles affect chemical reactions or how

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Although the tool is yet to be used for viewing nanoscale chemical reactions in a liquid,the UC San Diego team has demonstrated that the method works by mixing acombination of nanoscale crystals and gold nanoparticles suspended in a solution.

While the novel tool will not enable scientists to see molecules in solution, Gianneschiexplained that scientists would be able to view the effect of chemical reactionsoccurring on materials that are five billionths of a meter or larger than 5 nm.

UC San Diego and SCIENION AG have jointly applied for a patent to license the newtool and technique. Other co-authors of the paper include Lucas Parent of UC SanDiego; James Evans of Pacific Northwest National Laboratory; Holger Eickhoff, JoshuaCantlon, and Guido Bared of SCIENION AG in Berlin.

The research was funded by grants from the U.S. Air Force Office of ScientificResearch and the U.S. Army Research Office.

nanoscale defects on the surfaces of materials develop. We canfinally look at the interfaces on nanostructures so that we canoptimize the development of new kinds of catalysts, paints andsuspensions.

Nathan Gianneschi, Professor of Chemistry and Biochemistry, UCSan Diego

What we’ve demonstrated is the proof of concept, but that’s whatwe’ll be doing next.

Nathan Gianneschi, Professor of Chemistry and Biochemistry, UCSan Diego

We won’t be observing molecules colliding, but we will be able toobserve single particles and collections of them, on the nanometerlength scale. Observing these kinds of processes has been one ofthe key challenges in the field of nanoscience.

Nathan Gianneschi, Professor of Chemistry and Biochemistry, UCSan Diego

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