Seeing more deeply into nanomaterials

New 3D imaging tool reveals engineered and self-assembled nanoparticle lattices with highest resolution yet—7nm—about 1/100,000 of the width of a human hair

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 the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Columbia University 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 on April 7, 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.

Read more on the BNL website

Image: An artist’s impression of how the researchers used x-ray tomography as a magnifying lens to see into the inner structure of nanomaterials

We all love science!

#LightSourceSelfie from users of the Australian Light Source

Marta Krasowska (Associate Professor), Sarah Otto (PhD Student) and Stephanie MacWilliams (Early Career Researcher) are scientists based at the University of South Australia. They share a passion for soft matter research and conduct experiments at ANSTO’s Australian Synchrotron. Their research questions relate to structural ordering in soft matter and its relevance in applications such as food, personal care products, biomaterials and pharmaceuticals.

In their #LightSourceSelfie, Marta, Sarah and Stephanie discuss what attracted them to this area of research, how they felt the first time they conducted experiments at the Australian Synchrotron, the support they receive from the team based at the facility, their top tips for surviving night shifts and how their research will benefit from the new BioSAX beamline, which is part of the synchrotron’s major upgrade. When it came to single words to describe their research, they agreed on “Challenging, unpredictable and super rewarding!”

Unravelling the molecular structure, self-assembly, and properties of a cephalopod protein variant

Cephalopods, such as the loliginid in Figure 1A, are known for their remarkable ability to rapidly change the color and appearance of their skin. These capabilities are enabled in part by unique structural proteins called reflectins, which play essential roles in optical behavior of cephalopod skin cells. Moreover, reflectins have demonstrated exciting potential as functional materials within the context of biophotonic and bioelectronic systems. Given reflectins’ demonstrated significance from both fundamental biology and applications perspectives, some research effort has been devoted to resolving their three-dimensional (3D) structures. However, the peculiar sequence composition of reflectins has made them extremely sensitive to subtle changes in environmental conditions and prone to aggregation, thus significantly complicating the study of their structure-function relationships and precluding their definitive molecular-level structural characterization. In this work, we have elucidated the structure of a reflectin variant at the molecular level, demonstrated a robust methodology for controlling its assembly and optical properties.

We began our studies by rationally selecting a prototypical reflectin variant (RfA1TV) by using a bioinformatics-guided approach (Figure 1B). Next, we not only produced the variant in high yield and purity but also optimized conditions for maintaining this protein in a monomeric state (Figure 1C). We then probed the protein with small angle X-ray scattering (SAXS) using the Austrian SAXS beamline at the Elettra Synchrotron Laboratory in Trieste, Italy. For this purpose, a well-dispersed solution of RfA1TV was prepared in a low-pH buffer and transferred into a glass capillary, which was positioned in the path of an incident X-ray beam. The X-rays scattered by the solution-borne RfA1TV molecules formed a 2-D pattern on a Pilatus3 1M detector (Figure 1D). Subsequently, radial averaging and image calibration of the two-dimensional data furnished corresponding one-dimensional curves, which were further processed, analyzed, and correlated with other experiments to obtain insight into the protein’s geometry (Figure 1E).

Read more on the Elettra website

Image: (A) A camera image of a Doryteuthis pealeii squid. (B) An illustration of the selection of the prototypical truncated reflectin variant (RfA1TV) from full-length Doryteuthis pealeii reflectin A1. (C) A digital camera image of a solution of primarily monomeric RfA1TV (Upper) and a corresponding cartoon of RfA1TV monomers (Lower Inset). (D) An illustration of the SAXS analysis of the reflectin variant, wherein incident X-rays are scattered by the solution-borne proteins to furnish a corresponding scattering pattern. (E)The 3D structure of RfA1TV (random coils – gray, helices – orange, β-strands – purple). 

Credit: This figure has been adapted from M. J. Umerani*, P. Pratakshya* et al.Proc. Natl. Acad. Sci. U.S.A 117, 32891-32901 (2020).