Self-assembly of photonic crystals by controlling the nucleation and growth of DNA-coated colloids

Abstract

DNA-coated colloids can self-assemble into an incredible diversity of crystal structures, but their applications have been limited by poor understanding and control over the crystallization dynamics. To address this challenge, we use microfluidics to quantify the kinetics of DNA-programmed self-assembly along the entire crystallization pathway, from thermally activated nucleation through reaction-limited and diffusion-limited phases of crystal growth. Our detailed measurements of the temperature and concentration dependence of the kinetics at all stages of crystallization provide a stringent test of classical theories of nucleation and growth. After accounting for the finite rolling and sliding rates of micrometer-sized DNA-coated colloids, we show that modified versions of these classical theories predict the absolute nucleation and growth rates with quantitative accuracy. We conclude by applying our model to design and demonstrate protocols for assembling large single crystals with pronounced structural coloration, an essential step in creating next-generation optical metamaterials from colloids.

Self-Assembly of DNA-Grafted Colloids: A Review of Challenges

“…DNA grafted particles hold great promise as a tool to create programmed structures [ 6 , 29 , 32 , 48 ]. Ever since the first demonstration of the assembly of DNA-grafted nanoparticles into crystalline structure, by Mirkin [ 30 ] and Alivisatos [ 31 ], there has been extensive research around the possibilities offered by the self-assembly of DNA-grafted particles [ 32 , 33 ], as well as to develop a microscopic understanding of various mechanisms involved [ 49 , 50 , 51 , 52 , 53 , 54 ]. In principle, any target structures can be created using these building blocks, if the particles are functionalized with complementary strands of user defined sequences.…”

“…This problem is further aggravated with the increasing size of the colloids. Several studies have modeled the effective interaction between DNA-grafted particles [ 49 , 52 , 53 , 54 , 104 , 105 , 106 ], and it is found that the melting transition of DNA-grafted particles is much steeper than the melting of DNA-strands in solution (see Figure 4 ). Broadly speaking, there are two different approaches taken towards softening of this sharp temperature dependence.…”

“…Researchers have tried to experimentally probe the interaction potential in a system of DNA-coated particles, and relate it to various design parameters such as sequence, length and areal density of the grafts [ 49 ]. Additionally, there are several theoretical and computational investigations to pinpoint the effect of these system parameters on the dynamics and thermodynamics of the assembly process [ 50 , 52 , 105 ].However, a complete understanding of the assembly pathways and the effect of these parameters on the assembly dynamics is still to be developed. Using predictive tools and simulations, to gain the conceptual insights, would help in obtaining design elements that could avoid kinetic arrest and lead to successful assemblies.…”

A simple method to reprogram the binding specificity of DNA-coated colloids that crystallize

“…Because DNA-coated microparticles (Fig. 1a) have sizes comparable to the wavelength of visible light, they are particularly promising building blocks for the self-assembly of photonic bandgap materials [14,15,16,29], with applications in optical wave guides, lasers, and various light-harvesting technologies. DNA-coated microparticles are also useful as model systems for self-assembly, both in [17] and out of equilibrium [18,19].…”

“…When biotin-streptavidin chemistry is used to attach single-stranded DNA to particles, the particles tend to hit-and-stick and become kinetically trapped in fractal-like aggregates, even at temperatures at which the DNA-mediated interactions are reversible [21,22]. Attaching DNA to particles using strategies based on strain-promoted click chemistry [24,25,26] produce DNA-coated colloids that crystallize [27,28,29]. However, these click-chemistry-based methods are timeconsuming and require specialized knowledge of synthetic chemistry, which stands in the way of the widespread use of DNA-coated colloids.…”