A two-step method to engineer the self-assembly of large colloidal crystals using DNA-programmed interactions

Recent work has shown that a wide variety of crystalline structures can be self-assembled from DNA-coated colloids. However, making large, monodisperse, single crystals with high yield remains an unsolved challenge despite it being a crucial step in moving colloidal self-assembly from fundamental science to practical applications, like the assembly of photonic or plasmonic devices. In this talk, I will present a simple two-step method for making large single crystals from DNA-coated colloids, which decouples nucleation and growth. First, we use microfluidics to create an emulsion of droplets filled with DNA-coated colloids and slowly lower the temperature, leading to the nucleation and growth of a single colloidal crystal in each droplet. The size of these crystals is dictated by the number of particles contained in each droplet and can therefore be finely tuned. Next, we recover the single crystals by breaking the emulsion and use them as seeds to grow much larger single crystals than have been previously possible, including single crystals with millions of particles that can be seen by the naked eye.