New structures self-assemble from DNA-encased nanocubes

Self-assembly is often used in nanotechnology to produce nanostructured materials. One self-assembly method attaches complementary strands of DNA to individual gold nanoparticles to create DNA-functionalized gold nanoparticles (DNA-AuNPs). The DNA strands encasing the nanoparticles direct the formation of various superlattice structures.

Although most studies employ spherical DNA-AuNPs, these nanoparticles can be anisotropic particle shapes, such as cubes. Zhang et al. used coarse-grained molecular dynamics simulations to study the self-assembly of cubic DNA-AuNPs.

They found the hybridization of the DNA strands caused the nanocubes to spontaneously self-assemble into two new cubic superlattice structures not attainable with spherical particles, a plastic body-centered tetragonal structure and a compositionally disordered plastic body-centered tetragonal structure, as well as a simple cubic structure that has previously been observed with spherical DNA-AuNPs.

These new shapes are created by the interplay between the anisotropic nanoparticle shape and the arrangement of the DNA strands. Changing properties of the DNA strands on the nanoparticles can change the superstructure shape. Calculations showed that longer and more flexible DNA strands can transform a superstructure from a simple cubic shape to a plastic body-centered tetragonal shape.

“Our results may serve as a guide for self-assembly experiments on DNA-functionalized cubic nanoparticles,” said author Yunhan Zhang. “These results can also be extended to DNA-functionalized nanoparticles with various compositions, shapes, and sizes, and have important consequences for the rational design of self-assembled structures based on geometric considerations.”

Next, the authors will study DNA-functionalized nanoparticles with less symmetry than cubes, such as tetrahedra, which may yield even more superlattice structures.

Source: “Shape-induced crystallization of binary DNA-functionalized nanocubes,” by Yunhan Zhang, Giuliana Giunta, Haojun Liang, and Marjolein Dijkstra, Journal of Chemical Physics (2023). The article can be accessed at https://doi.org/10.1063/5.0148139 .