Programmable Nanofabrication of Nanoparticle Assemblies of arbitrarily Shapes on DNA Templates

We present a method for producing metallic structures with nanoscale dimensions and programmable design. Rectangular ``DNA origami'' structures ($\sim $90x70nm) were modified to have uniquely coded binding sites and adsorbed onto silicon dioxide substrates. Gold nanoparticles functionalized with a complimentary DNA sequence were attached to these binding sites in a highly controllable fashion. The seed nanoparticles were then enlarged (and even fused, if desired) by a silver reduction chemistry. Using this method we constructed a variety of metallic structures, including parallel wires, H-shapes, and rings. Due to the flexibility of the design and the multiply parallel nature of the method, these structures may offer great promise for plasmonic applications.