Directed Assembly of Periodic Materials from Protein and Oligonucleotide-Modified Nanoparticle Building Blocks**

In 1996 we reported a method for utilizing DNA and its synthetically programmable sequence recognition properties to assemble nanoparticles functionalized with oligonucleotides into preconceived architectures (Figure 1 B).[1] Since that initial report, our research group and many others have shown that this strategy[2±8] and off-shoots of it that rely on protein ± receptor and antibody ± antigen interactions[9±12] can be used to generate a wide range of architectures with many unusual and, in some cases, useful chemical and physical properties. Since proteins and certain protein receptors can be functionalized with oligonucleotides, one, in principle, could Figure 1. Schematic representation of DNA-directed assembly of Au nanoparticles and streptavidin. A) Assembly of oligonucleotide-functionalized streptavidin and Au nanoparticles (Au ± STV assembly). B) Assembly of oligonucleotide-functionalized Au nanoparticles (Au ± Au assembly). Note that 1 and 4 have the same DNA sequence.