Fig. 1.
DNA-coated colloids follow a dynamic pathway to crystallization characterized by three distinct regimes: nucleation, growth, and equilibrium coexistence. (A) A binary mixture of 600-nm-diameter colloidal particles that interact by direct hybridization of complementary DNA sequences. (B) The resultant interactions are temperature dependent, forming a colloidal gas phase at high temperature, an ordered crystal phase at intermediate temperature, and a disordered gel phase when quenched to low temperatures. (C) The binary mixture forms crystals with a copper–gold lattice structure. Bright-field and fluorescence micrographs (Top Insets) show the (100) and (111) planes (Bottom Insets), as well as the crystal facets. (D) Micrographs of water droplets containing DNA-coated particles show the dynamics of nucleation and growth, as seen in the time series. (E) Time-lapse micrographs of a single droplet show the full dynamic pathway to crystallization, which proceeds through multiple stages: 1) nucleation from a metastable gas; 2) early-stage growth; 3) detection of a crystal followed by late-stage growth; and, 4) eventually, equilibrium coexistence between crystal and gas. (F) We extract the crystal mole fraction as a function of time for each droplet individually. Points show data for a single droplet, and the orange curve shows a model of growth described in the main text (Eq. 2). The crystal mole fraction is defined as the number of particles in the crystal, , divided by the total number of particles per droplet. Gray lines show trajectories of other droplets in the same experiment. Data are for a colloid concentration of 1% (vol/vol).