Assembly of three-dimensional binary superlattices from multi-flavored particles

Abstract

Binary superlattices constructed from nano- or micron-sized colloidal particles have a wide variety of applications, including the design of advanced materials. Self-assembly of such crystals from their constituent colloids can be achieved in practice by, among other means, the functionalization of colloid surfaces with single-stranded DNA sequences. However, when driven by DNA, this assembly is traditionally premised on the pairwise interaction between a single DNA sequence and its complement, and often relies on particle size asymmetry to entropically control the crystalline arrangement of its constituents. The recently proposed "multi-flavoring" motif for DNA functionalization, wherein multiple distinct strands of DNA are grafted in different ratios to different colloids, can be used to experimentally realize a binary mixture in which all pairwise interactions are independently controllable. In this work, we use various computational methods, including molecular dynamics and Wang-Landau Monte Carlo simulations, to study a multi-flavored binary system of micron-sized DNA-functionalized particles modeled implicitly by Fermi-Jagla pairwise interactions. We show how self-assembly of such systems can be controlled in a purely enthalpic manner, and by tuning only the interactions between like particles, demonstrate assembly into various morphologies. Although polymorphism is present over a wide range of pairwise interaction strengths, we show that careful selection of interactions can lead to the generation of pure compositionally ordered crystals. Additionally, we show how the crystal composition changes with the like-pair interaction strengths, and how the solution stoichiometry affects the assembled structures.

Using symmetry to elucidate the importance of stoichiometry in colloidal crystal assembly

“…The interaction potentials considered here are very general, but experimental schemes for realization of such interactions in multicomponent systems exist using multi-flavored DFPs. These DFP systems are not limited to two dimensions, and simulations and experiments in both two 18,55 and three 57,58 dimensions have been performed on these systems to show the capacity of simple pairwise models to capture DFP assembly effects. They additionally demonstrate the feasibility of fine-tuning interactions in multicomponent mixtures as necessary to achieve self-assembly of particular structures.…”

Size-dependent thermodynamic structural selection in colloidal crystallization

“…The observed phenomenon may therefore be applicable to a variety of systems and may help to explain transformation and polymorph selection mechanisms during their nucleation and growth processes. For example, in 3D, the micrometer-sized particle system studied here produces CsCl and CuAu structures ( 20 ) analogous to the square and hexagonal structures considered in this work. Experimental and simulation evidence in a similar system ( 6 ) provides evidence of transformations, indicating that they occur in a diffusionless fashion similar to the transformations considered here.…”

Role of Entropy in Colloidal Self-Assembly

“…This process usually arises from weak and non-covalent interactions and finds suitable applications in nanotechnology, microelectronics, and photonics [ 11 ]. Ordering can be directed by physical characteristics of the particles or via the application of external triggers (e.g., electric and/or magnetic fields, or pressure) [ 12 ], or by functionalizing the particle surface [ 13 , 14 ]. For example, an external shear force can cause unidirectional ordering of lamellar bilayers formed by a polymeric surfactant, resulting in the formation of anisotropic hydrogels, which can be used as artificial muscles [ 15 ].…”