Colloidal atoms and molecules*

We describe two new types of colloidal particles that greatly expand the kinds of colloids and nanoparticles that are available for self-assembly. The first type, called colloidal molecules, consists of clusters of microspheres and/or nanospheres that take on well-defined geometries such as dumbbells, triangles, tetrahedra, octahedral, \textit{etc}. With these, we explore new two and three-dimensional phases, including dumbbells at a planar interface, and three-dimensional assemblies of tetrahedra. The second type, called colloidal atoms, consists of nearly spherical particles with a specific number of symmetrically-placed patches on their surface. These patches have symmetries similar to the colloidal molecules described above. The patches can be functionalized with single-stranded DNA that interacts specifically with complementary strands on other particles forming a network or crystal of colloidal particles.