Quasicrystals are ordered but non-repetitive crystalline structures, with patterns similar to mosaic structures, that have puzzled the scientific community for a long time. The existence of quasicrystals has been an enigma for decades and their discovery was worthy of the Nobel Prize.
Now, a team of researchers from the Cooperative Research Center in Biomaterials CIC biomaGUNE (Basque Country), the International Institute of Nanotechnology at Northwestern University, and the University of Michigan (both in the USA) has unveiled a novel methodology for designing colloidal quasicrystals using DNA. This pioneering study in the field of nanotechnology is published in the journal Nature Materials.
The study shows that the programmable nature of DNA can be harnessed to design and assemble quasicrystals deliberately.
“It is very difficult to prepare particles with this geometry in sizes around 100 nm and with a good enough size uniformity to generate these quasicrystalline structures,” explains one of the authors, CIC biomaGUNE’s Ikerbasque professor Luis Liz Marzán.
“While there are now several examples known, discovered in nature or through serendipitous paths, our research demystifies their formation and, more importantly, shows how we can harness the programmable nature of DNA to design and assemble quasicrystals deliberately,” says co-author Chad Mirkin of Northwestern University.
The research stemmed from a proposal by the Basque center’s Bionanoplasmonics group, pioneers in developing methods for manufacturing and modifying the surface of nanoparticles to enhance their application possibilities: “We had precisely found a way to synthesize nanoparticles with decahedral geometry—particles with ten sides—and with enough quality to address this study,” says Liz Marzán.
Importance of geometry
“The decahedral geometry is essential in this case due to the pentagonal symmetry it implies,” he adds. “Pentagons are essential geometric elements in quasicrystals and this is what has allowed us to reach these very special materials.”
On the other hand, the group led by Professor Sharon Glotzer at the University of Michigan had already predicted the first quasicrystal of nanoparticle layers in 2009: “In our original simulation of the quasicrystal, the arrangement of the decahedrons left very small spaces between them. Here, DNA would fill those gaps.”
An innovative approach opens new paths for design at the nanoscale, according to its creators.
The study focused on the assembly of decahedral nanoparticles using DNA as a guiding structure, in a colloidal medium: “That is, in a non-homogeneous medium where particles are suspended in a fluid,” explains Liz Marzán.
Through a combination of computer simulations and experiments, the team has discovered something extraordinary: these decahedral nanoparticles can organize themselves to form quasicrystalline structures with fascinating pentagonal and hexagonal motifs (penta and hexacoordinated), culminating in the creation of a dodecagonal quasicrystal.
A robust quasicrystalline structure
“Decahedral nanoparticles have a characteristic quintuple symmetry that challenges conventional norms of periodic mosaics,” explains Professor Mirkin. Leveraging the programmable capabilities of DNA, we have been able to direct the assembly of these nanoparticles into a robust quasicrystalline structure.
The research team has functionalized decahedral gold nanoparticles with short double-stranded DNA and applied a precisely controlled cooling process to facilitate the assembly. “We have attached DNA chains to the nanoparticles, to direct their ordering, even reversibly because it is temperature-sensitive,” says Liz Marzán.
Decahedral gold nanoparticles have been functionalized with short DNA and a precisely controlled cooling process applied to facilitate the assembly.
The resulting quasicrystalline superlattices have shown a mid-range quasiperiodic order, with rigorous structural analysis confirming the presence of a twelve-fold symmetry and a triangular-square mosaic pattern, distinctive features of a dodecagonal quasicrystal.
“Thanks to the engineering of colloidal quasicrystals, we have achieved a major milestone in the field of nanoscience. Our work not only sheds light on the design and creation of intricate nano-scale structures, but also opens up a world of possibilities for advanced materials and innovative nanotechnological applications,” declared the CIC biomaGUNE professor.
“The implications of this advance are far-reaching, as it offers a possible model for the controlled synthesis of other complex structures that were previously considered unattainable,” the researchers indicate. As the scientific community delves into the unlimited prospects of programmable matter, this research paves the way for transformative advances and applications in various scientific fields.
Source: MiMub in Spanish
