Dimer Crystallization of Proteomimetic Colloidal Chiral C-Shapes by Steric Pathway Selection in Slowly Crowded Enantiopure Monolayers

Inspired by crystals of dimerized proteins, we lithographically create monodisperse proteomimetic colloidal particles, or "proteoids". We show that 2D Brownian systems of certain chiral C-shaped proteoids can self-assemble into dimer crystals when slowly crowded. Using depletion attractions, we form long-lived enantiopure Brownian monolayers of mobile, microscopic, polymeric proteoids that are dispersed in water and have nearly hard in-plane interactions. Adding a circular head to an achiral C-shape yields a chiral proteoid. This head sterically blocks one of two pathways for chiral dimerization, leading to enantiopure lock-and-key dimerization. Complementary corrugations in the chiral dimers that form also lead to ordering of these dimers into crystals. Using optical microscopy, we reveal that tautomerization translocation reactions (TTRs) enable monomer defects to be expelled from growing crystallites. We lithographically mutate the location of the circular head on the proteoid and show that even small changes can significantly affect the primitive vectors of the dimer crystals. Thus, remarkably, the equivalent of a quinary level of protein self-assembly can be achieved by simply crowding certain shape-designed hard proteoids in the presence of entropic Brownian fluctuations.