Classical nucleation and growth of DNA-programmed colloidal crystallization

Colloidal particles coated with DNA can self-assemble into an amazing diversity of ordered structures; yet the dynamic pathways leading from the disordered state to the ordered state are comparatively unexplored. In this talk, I will present some of the first direct measurements of nucleation and growth of DNA-programmed crystallization. We use a microfluidic droplet-based technique to quantify the pathway to crystallization in hundreds of individual droplets simultaneously. We find that nucleation is governed by a single temperature-dependent free-energy barrier. The nucleation rate changes by orders of magnitude over 0.5 degrees and follows the predictions of classical nucleation theory. We also find that the rate of crystal growth is determined by a balance between the rate at which particles diffuse to the growing crystal surface and the rate at which they unbind from the crystal interface. Together, these results provide an explanation for why it’s been difficult to crystallize DNA-coated particles, and suggest ways to control the nucleation and growth rates to design new assembly pathways that yield large, single crystals.