Colloids with valence and specific directional bonding

• Published in: Nature (London) 2012-11, Vol.491 (7422), p.51-55
• Main Authors: Wang, Yufeng, Wang, Yu, Breed, Dana R., Manoharan, Vinothan N., Feng, Lang, Hollingsworth, Andrew D., Weck, Marcus, Pine, David J.
• Format: Article
• Language: English
• Subjects: 639/301/923/916; 639/638/298/923/966; Amidines - chemistry; Applied sciences; Atoms & subatomic particles; Biotin - chemistry; Chemical bonds; Chemical properties; Colloids; Colloids - chemical synthesis; Colloids - chemistry; Deoxyribonucleic acid; Design; DNA; DNA - chemical synthesis; DNA - chemistry; DNA - ultrastructure; Emulsion polymerization; Exact sciences and technology; Humanities and Social Sciences; Kinetics; Methods; Microscopy, Confocal; Microspheres; multidisciplinary; Organic polymers; Physicochemistry of polymers; Polymerization; Polymers with particular structures; Polystyrenes - chemistry; Preparation, kinetics, thermodynamics, mechanism and catalysts; Science; Silicon wafers; Surface Properties; Surfactants; Symmetry; Valence
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature11564

The ability to design and assemble three-dimensional structures from colloidal particles is limited by the absence of specific directional bonds. As a result, complex or low-coordination structures, common in atomic and molecular systems, are rare in the colloidal domain. Here we demonstrate a general method for creating the colloidal analogues of atoms with valence: colloidal particles with chemically distinct surface patches that imitate hybridized atomic orbitals, including sp , sp 2 , sp 3 , sp 3 d , sp 3 d 2 and sp 3 d 3 . Functionalized with DNA with single-stranded sticky ends, patches on different particles can form highly directional bonds through programmable, specific and reversible DNA hybridization. These features allow the particles to self-assemble into ‘colloidal molecules’ with triangular, tetrahedral and other bonding symmetries, and should also give access to a rich variety of new microstructured colloidal materials. A general method of creating colloidal particles that can self-assemble into ‘colloidal molecules’ is described: surface patches with well-defined symmetries are functionalized using DNA with single-stranded sticky ends and imitate hybridized atomic orbitals to form highly directional bonds. New bonds take colloidal self-assembly to new levels Chemists routinely use atoms that can form directional bonds to assemble complex and useful molecular structures. But larger colloidal particles have proved less conducive to rational assembly because they lack specific directional bonds. David Pine and colleagues now report a way around this problem that could lead to the creation of a rich variety of new micro-structured colloidal materials with technologically useful properties. Using microsphere clusters as intermediates, they create colloidal particles with chemically distinct and precisely located 'sticky patches' on the surface — up to 7 per particle — that enable specific and highly directional bonding. Using this system, they assemble 'colloidal molecules' exhibiting a wide range of bonding symmetries.