Authors: Anthony J. Kim, John C. Crocker, Paul L. Biancaniello, Raynaldo Scarlett, Talid Sinno
Publication Date: November 30, 2008
Journal: Nature Materials
Citation: A. Kim#, R. T. Scarlett#, P. Biancaniello, T. Sinno, and J. C. Crocker, Probing interfacial equilibration in microsphere crystals formed by DNA-directed assembly, Nature Materials, 8 (2009) 52-55. (# – equal contributions by Crocker and Sinno students)
Abstract: DNA is the premier material for directing nanoscale self-assembly, having been used to produce many complex forms. Recently, DNA has been used to direct colloids and nanoparticles into novel crystalline structures, providing a potential route to fabricating meta-materials with unique optical properties. Although theory has sought the crystal phases that minimize total free energy, kinetic barriers remain essentially unstudied. Here we study interfacial equilibration in a DNA-directed microsphere self-assembly system and carry out corresponding detailed simulations. We introduce a single-nucleotide difference in the DNA strands on two mixed microsphere species, which generates a free-energy penalty for inserting ‘impurity’ spheres into a ‘host’ sphere crystal, resulting in a reproducible segregation coefficient. Comparison with simulation reveals that, under our experimental conditions, particles can equilibrate only with a few nearest neighbours before burial by the growth front, posing a potential impediment to the growth of complex structures.