Assembling Coated Nanocubes

Abstract

Chemistry For many applications of nanoparticles, it is desirable that they assemble into periodic structures or even crystallize. Knorowski and Travesset used a theoretical model to explore the effect of DNA coatings on phase diagrams for nanocube assembly. Previous studies have focused mainly on the assembly of hard cubes. The authors explored this case, as well as hard cubes (about 12 or 18 nm across) coated with single-stranded DNA strands lacking complementary ends (an f-star polymer) and pairs of nanocubes with complementary ends. The hard nanocube system evolved from a simple cubic (sc) packing to a triclinic phase for the f-star coating at isotropic pressure. For anisotropic osmotic pressures, body-centered cubic (bcc) ordering occurred, but the cubes developed a complex orientational ordering. For complementary DNA coatings, the results depended on strand length, with short strands creating face-to-face hybridization and sc lattices and longer strands creating a bcc packing. More complex ordering than the f-star system developed at high osmotic pressure . Because polymer coatings could be polymerized, it may be possible to use such phase behavior to direct nanocube assembly. J. Am. Chem. Soc. 136 , 10.1021/ja406241n (2014).