Observing the Growth of Complex Nanoscale Materials in Real Time

Interview conducted by Stuart MilneJun 19 2015

Nathan Gianneschi, associate professor of chemistry and biochemistry at UC San Diego, talks to AZoNano about the visualization and growth of “nanoscale” chemical complexes in real time.

Could you please provide our readers with a brief overview of your research?

Our work involves the development of new approaches for preparing and characterizing soft, functional materials. In general, these materials are organic polymers and organic polymeric nanoparticles.

As part of this work, we are very interested in capturing the materials as they perform in solution in real time. This is a tremendous challenge because the available techniques for imaging particles at this length scale are limited.

Therefore, in recent years we have worked closely with scientists at Pacific Northwest National Lab to develop liquid cell TEM for the purpose of imaging organic materials at the nanoscale in liquids.

The paper published in the Journal of the American Chemical Society, shows how this is possible with a material that is nicely crystalline in nature, meaning we can more easily prove that they have formed. We used this as a model system for assembly of organic structures, and hope to translate what we learned here to other organic structures. However, to achieve this, we used a material that also contains metals to help generate highly ordered frameworks. The challenge now is whether this indeed translates to less ordered architectures.

Why is it important for researchers and industry to visualize the growth of nanoscale chemical complexes in real time?

Many materials are governed by the kinetics of their formation. That is, the way the materials are made, can sometimes determine how they look and how they perform. In these cases, there is a strong interest in learning in detail how a process goes from beginning to end on a particle by particle basis. If one can understand the process, then we may be better able to control it, thereby controlling the outcome and ultimately the function of the materials themselves.

The UC San Diego chemists observed the growth of complex organic-inorganic hybrid materials in real time, providing an unprecedented understanding of their formation. Image Credits: Joseph Patterson, UC San Diego

How was this breakthrough made possible?

We used a specially made holder, capable of maintaining liquids within a tiny chamber, within the high vacuum of the electron microscope. That means the electrons can pass through a sample as you image the materials in what is close to their natural state - i.e. in this case, in solution. The holder is a commercially available tool, that interfaces with the electron microscope. With that in hand, we were able to optimize the imaging conditions such that low electron doses can be employed. This is critical so that we do not damage the sample as we observe it.

Where did the research initially start and how did it develop to this point?

For us, it started with trying to image low contrast organic materials that are subject to beam damage. This effort was inspired by initial conversations with Nigel Browning and James Evans now at PNNL. They believed this kind of experiment could be done, and we had interesting materials in hand to give it a try. From there we were able to recruit some talented grad students and postdocs to make this happen. Dr. Patterson came on as a postdoc with excellent experience in the synthesis of polymeric nanomaterials, as well as a strong interest in characterizing them by other TEM methods. He went headlong into this challenge and is a key part of our collaboration with the Cohen lab who are experts in the metal-organic frameworks that we studied.

How do you see this shaping nanomaterial research in the future?

These materials are already of great interest in catalysis and in the storage of small molecules for energy applications. We believe that with a better understanding of how they form, one could feasibly induce the materials to take one morphology over the other, either optimizing catalytic properties or some other property during formation.

What are the next steps for you and your team in developing this further?

We aim to extend this strategy to imaging interactions between purely organic and/or biological matter. Now that we know these kinds of materials can survive and grow under these conditions, a whole world is opening up to us, and to many other researchers all over the world.

About Nathan Gianneschi

Nathan C. Gianneschi received his B.Sc(Hons) at the University of Adelaide in 1999. In 2005 he completed his Ph.D at Northwestern University. Following a Dow Chemical postdoctoral fellowship at The Scripps Research Institute, in 2008 he became a professor at the University of California, San Diego. The Gianneschi group takes an interdisciplinary approach to nanomaterials research with a focus on multifunctional materials with interests that include biomedical applications, programmed interactions with biomolecules and cells, and basic research into nanoscale materials design, synthesis and characterization. For this work he has been awarded the NIH Director's New Innovator Award, the NIH Director's Transformative Research Award and the White House's highest honor for young scientists and engineers with a Presidential Early Career Award for Scientists and Engineers. Prof. Gianneschi was awarded a Drefus Foundation Fellowship, is a Kavli Fellow of the National Academy of Sciences, and is an Alfred P. Sloan Foundation Fellow.