Carnegie Mellon Chemists Create DNA-style Helical Inorganic Supercrystals
By Ben Panko
In new research, Carnegie Mellon University chemists synthesized complex gold supercrystals with arrangements resembling the iconic helical structure of DNA. The work, published today in the journal Nature, highlights new promise for the precise design and engineering of supercrystals.
One can think of supercrystals like LEGO blocks, said chemistry Ph.D. candidate Yingwei Li, who was lead author on the study. Li works in the research group of Professor of Chemistry Rongchao Jin, who has pioneered the synthesis of gold nanoparticles with precise numbers of atoms. In this latest study from the group, Li and her collaborators brought Jin’s approach to supercrystals. These macroscopic crystals are built piece-by-piece out of nanoparticles or nanoclusters, allowing for the possibility of creating meticulously tailored materials with a variety of different properties.
The researchers synthesized gold nanoclusters in two varieties based on a dimeric structure, which comprises two roughly spherical parts combined. The homodimeric nanoclusters had two largely identical component parts, and these nanoclusters arranged themselves into familiar layered superstructures, Li said. But the heterodimeric nanoclusters behaved far differently.
"To our surprise, the heterodimeric nanoclusters self-assemble into double- and quadruple-helical superstructures," Li said.
The helical structure of DNA has long been a model for constructing particle assemblies, the researchers noted, but getting inorganic nanoclusters to form such structures has been challenging. A complex series of atomic interactions and bonding help nucleotides form DNA helices, a feature purely inorganic particles are not able to use.
However, by carefully crystallizing heterodimeric nanoclusters, Li and her collaborators were able to leverage the natural attractions between molecules called Van der Waals interactions to create the inorganic helices.
"Our work demonstrates a new principle of constructing supercrystal materials, and the resulting exquisite supercrystals may lead to other discoveries of functionality," Li said.
Li and her co-authors are now working on closely studying the properties of these newly created supercrystals and how they could potentially be used.
Other authors on this study included Tatsuya Higaki of Carnegie Mellon, Meng Zhou and He Wang of the University of Miami and Yongbo Song of Anhui Medical University in China.
Funding for this research was provided by grants from the National Science Foundation (DMR-1808675) and the U.S. Air Force Office of Scientific Research (FA9550-17-1-0099).