title: Probing interfacial equilibration in microsphere crystals formed by DNA-directed assembly.
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.
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Pennsylvania, 220 S. 33rd St., Philadelphia, Pennsylvania 19104, USA.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Kim
authors.forename: Raynaldo
authors.initials: R
authors.lastname: Scarlett
authors.forename: Paul L
authors.initials: PL
authors.lastname: Biancaniello
authors.forename: Talid
authors.initials: T
authors.lastname: Sinno
authors.forename: John C
authors.initials: JC
authors.lastname: Crocker
mesh_terms: D002616:Chemical Engineering / Q000379:methods; D003460:Crystallization; D004247:DNA / Q000737:chemistry*; D008863:Microspheres; D049329:Nanostructures; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D004247:DNA