Depletion-Induced Tunable Assembly of Complementary Platonic Solids

Multicomponent self-assembly has been explored to create novel metamaterials from nanoparticles of different sizes and compositions, but the assembly of nanoparticles with complementary shapes remains rare. Recent binary assemblies were mediated by DNA base pairing or induced by solvent evaporation. Here, we introduce depletion-induced self-assembly (DISA) as a novel approach to constructing tunable binary lattices. In situ structural analysis in the real and reciprocal spaces demonstrates DISA of a binary mixture of octahedra and tetrahedra into extended supercrystals with Fm3m symmetry. The interparticle distance, adjustable by depletant concentration, offers a versatile method for assembling nanoparticles into ordered structures while they remain dispersed in a liquid phase. We show that DISA can control the packing fraction of such binary supercrystals between phi = 0.37 and phi = 0.66, much lower than dense packing in the dry state. These findings highlight DISA's potential for creating complex and highly ordered metamaterials with tailored properties.