Templated Gold Nanoparticle Assembly On Two-Dimensional Protein Crystals

Nature has evolved the ability to efficiently construct complex, nanoscale architectures in self-assembling biological systems, and this provides synthetic nanotechnology with insightful paradigms and functional fabrication platforms. Two-dimensional crystals of the protein streptavidin exhibit tunable crystalline lattice structures and the ability to control interactions between colloidal nanoparticles and the protein monolayer through electrostatic and specific receptor-ligand mechanisms. Furthermore, these highly-ordered protein monolayers can be grown at both the air/water interface and on a solid substrate. Using the C222 crystal form of streptavidin, we demonstrate that this protein system can be manipulated to template the assembly of ordered gold nanoparticle arrays. We examine experimental conditions (e.g., pH, ionic strength, nanoparticle size) which promote the assembly process to yield nanoparticle arrays with longer-range order. Our work shows that the streptavidin protein system is a novel platform for the “bottom-up” fabrication of highly-organized arrays of inorganic nanomaterials.