Total synthesis of colloidal matter

Atoms serve as an inspiration for colloidal self-assembly, whereby building blocks can combine and confer endless functionality using a few design principles, including directionality, valence and reversible binding. Tetrahedral structures inspired by the bonding of carbon atoms have long been targeted as candidates for metamaterials and are now becoming accessible through molecular mimetic colloidal building blocks. Beyond carbon mimics, increasingly complex particles are being synthesized that can be arranged in their own periodic table and used to generate forms of matter unique to colloidal systems. This Review presents a framework to describe the synthesis of these micrometre-scale colloids, in which the fundamental constituents are either combined through interparticle reactions or transformed through intraparticle reactions, in analogy to molecules in traditional synthetic chemistry. We build on this framework to illustrate how unique particle shape and surface chemistry leads to diverse assembly routes for these colloidal building blocks. Myriad complex colloidal particles have been engineered to investigate the growth of microscopic architectures from the bottom up. This Review provides a framework for the synthesis of such particles using an analogy to traditional total synthesis, describing how elementary particles are combined and transformed into new forms of colloidal matter.