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.