Seeing more deeply into nanomaterials
Date:
April 13, 2022
Source:
Columbia University School of Engineering and Applied Science
Summary:
Researchers have overcome imaging the inside of a novel material
self- assembled from nanoparticles with seven nanometer resolution,
about 1/ 100,000 of the width of a human hair. The researchers
now showcase the power of their new high-resolution x-ray imaging
technique to reveal the inner structure of the nanomaterial.
FULL STORY ==========================================================================
From designing new biomaterials to novel photonic devices, new
materials built through a process called bottom-up nanofabrication,
or self-assembly, are opening up pathways to new technologies with
properties tuned at the nanoscale.
However, to fully unlock the potential of these new materials,
researchers need to "see" into their tiny creations so that they can
control the design and fabrication in order to enable the material's
desired properties.
==========================================================================
This has been a complex challenge that researchers from Columbia
Engineering and the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have overcome for the first time, imaging the inside of a
novel material self- assembled from nanoparticles with seven nanometer resolution, about 1/100,000 of the width of a human hair. In a new paper published April 6, 2022, in Science,the researchers showcase the power
of their new high-resolution x-ray imaging technique to reveal the inner structure of the nanomaterial.
The team designed the new nanomaterial using DNA as a programmable
construction material, which enables them to create novel engineered
materials for catalysis, optics, and extreme environments. During the
creation process of these materials, the different building blocks made
of DNA and nanoparticles shift into place on their own based on a defined "blueprint" -- called a template -- designed by the researchers. However,
to image and exploit these tiny structures with x-rays, they needed to
convert them into inorganic materials that could withstand x-rays while providing useful functionality. For the first time, the researchers
could see the details, including the imperfections within their newly
arranged nanomaterials.
"While our DNA-based assembly of nanomaterials offers a tremendous
level of control to fine-tune the properties we desire, they don't form
perfect structures that correspond fully to the blueprint. Thus, without detailed 3D imaging with single-particle resolution, it is impossible
to understand how to design effective self-assembled systems, how to
tune the assembly process, and to what degree a material's performance
is affected by imperfections," said corresponding author Oleg Gang,
professor of chemical engineering and of applied physics and materials
science at Columbia Engineering, and a scientist at Brookhaven's Center
for Functional Nanomaterials (CFN).
Creating new nanostructures at Columbia and Brookhaven labs As a DOE
Office of Science user facility, the CFN offers a wide range of tools
for creating and investigating novel nanomaterials. It was at the labs of
the CFN and at Columbia Engineering where Gang and his team first built
and studied new nanostructures. Using both DNA-based assembly as a new fabrication tool at the nanoscale and precise templating with inorganic materials that can coat DNA and nanoparticles, the researchers were able
to demonstrate a novel type of complex 3D architecture.
========================================================================== "When I joined the research team five years ago, we had studied the
surface of our assemblies really well, but the surface is only skin
deep. If you can't go further, you'll never see that there's a blood
system or bones underneath.
Since the assembly inside our materials drives their performance,
we wanted to go deeper to figure out how it worked," said Aaron Noam
Michelson, first author of the study who was a PhD student with Gang
and is now a postdoc at the CFN.
And deeper the team went, collaborating with the researchers at the
Hard X-ray Nanoprobe (HXN) beamline at the National Synchrotron Light
Source II (NSLS-II), another DOE Office of Science user facility located
at Brookhaven Lab. NSLS-II enables researchers to study materials with nanoscale resolution and exquisite sensitivity by providing ultrabright
light ranging from infrared to hard x- rays.
"At NSLS-II, we have many tools that can be used to learn more about
a material depending on what you are interested in. What made HXN
interesting for Oleg and his work was that you can see the actual spatial relationships between objects within the structure at the nanoscale. But,
at that time when we first talked about this research, 'seeing into'
these tiny structures was already at the limit of what the beamline
could do," said Hanfei Yan, also a corresponding author of the study
and a beamline scientist at HXN.
Overcoming hurdles To push through this challenge, the researchers
discussed the various hurdles they needed to overcome. At the CFN and
Columbia, the team had to figure out how they could build the structures
with desired organization and how to convert them into an inorganic
replica that can withstand powerful x-ray beams, while at NSLS-II the researchers had to tune the beamline by improving the resolution, data acquisition, and many other technical details.
==========================================================================
"I think the best way to describe our progress is in terms of
performance. When we first tried to take data at HXN, it took us three
days and we got part of a data set. The second time we did this, it
took us two days, and we got most of a whole data set, but our sample
got destroyed in the process. By the third time it took a little over
24 hours, and we got a full data set. Each of these steps was about six
months apart," said Michelson.
Yan added: "Now we can finish it in a single day. The technique is mature enough that we also offer it to other users who would want to use our
beamline to investigate their sample. Seeing into samples on this scale is interesting for fields such as microelectronics and battery research." Leveraging Brookhaven's beamline The team leveraged the beamline's
abilities in two ways. They not only measured the phase contrast of the
x-rays passing through the samples, but they also collected the x-ray fluorescence -- the emitted light -- from the sample. By measuring the
phase contrast, the researchers could better distinguish the foreground
from the background of their sample.
"Measuring the data was only half the battle; now we needed to translate
the data into meaningful information about order and imperfection of self-assembled systems. We wanted to understand what type of defects can
occur in these systems and what is their origin. Until this point, this information was only available through computation. Now we can really see
this experimentally, which is super exciting and, literally, eye-opening
for the future development of complex designed nanomaterials," said Gang.
New software tools to manage data Together, the researchers developed
new software tools to help untangle the large amount of data into chunks
that could be processed and understood. One major challenge was being
able to validate the resolution they achieved. The iterative process
that finally led to the groundbreaking new resolution stretched over
several months before the team had verified the resolution through both standard analysis and machine-learning approaches.
"It took my whole PhD to get here but I personally feel very gratified
for being part of this collaboration. I was able to get involved in every
step of the way from making the samples to running the beamline. All the
new skills I have learned on this journey will be useful for everything
that lies ahead," said Michelson.
Next steps Even though the team has reached this impressive milestone,
they are far from done. They already set their sights on the next steps
to further push the boundaries of the possible.
"Now that we have gone through the data analysis process, we plan to make
this part easier and faster for future projects, especially when further beamline improvements enable us to collect data even faster. The analysis
is currently the bottleneck when doing high-resolution tomography work
at HXN," said Yan.
Gang added, "Aside from continuing to push the performance of the
beamline, we also plan to use this new technique to dive deeper into
the relationships between defects and properties of our materials. We
plan to design more complex nanomaterials using DNA self-assembly that
can be studied using HXN. In this way we can see how well the structure
is built internally and connect this to the process of the assembly. We
are developing a new bottom-up fabrication platform that we would not
be able to image without this new capability." By understanding this connection between material's properties and the assembly process, the researchers hope to unlock the path to fine-tuning these materials for
future applications in designed nanomaterials for batteries and catalysis,
for light manipulation, and for desired mechanical responses.
========================================================================== Story Source: Materials provided by Columbia_University_School_of_Engineering_and_Applied Science. Original
written by Holly Evarts. Note: Content may be edited for style and length.
========================================================================== Journal Reference:
1. Aaron Michelson, Brian Minevich, Hamed Emamy, Xiaojing Huang,
Yong S.
Chu, Hanfei Yan, Oleg Gang. Three-dimensional visualization of
nanoparticle lattices and multimaterial frameworks. Science, 2022;
376 (6589): 203 DOI: 10.1126/science.abk0463 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/04/220413161747.htm
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