Binary Protein Crystals for the Assembly of Inorganic Nanoparticle Superlattices

Biomolecules can act as functional templates for the organization of inorganic particles. Here we use two protein containers, engineered with opposite surface charge, as building blocks for the construction of a new type of biohybrid material. Binary structures with crystalline order were obtained, adopting a tetragonal lattice. Moreover, the cavity of the engineered protein containers can be filled with inorganic nanoparticles. The controlled assembly of these protein–nanoparticle composites yields highly ordered binary nanoparticle superlattices as free-standing crystals, with up to a few hundred micrometers in size. Because the structure and lattice parameters of the protein–nanoparticle crystals are independent of their nanoparticle cargo, the binary protein material may serve as a generally applicable matrix for the assembly of a variety of nanoparticles types.