In this dissertation, I developed a Pd seeding method in association with electroless plating, to successfully metallize both lambda DNA and DNA origami templates on different surfaces. On mica surfaces, this method offered a fast, simple process, and the ability to obtain a relatively high yield of metallized DNA nanostructures. When using lambda DNA as the templates, I studied the effect of Pd(II) activation time on the seed height and density, and an optimal activation time between 10 and 30 min was obtained. Based on the Pd seeds formed on DNA, as well as a Pd electroless plating solution, continuous Pd nanowires that had an average diameter of ~28 nm were formed with good selectivity on lambda DNA. The selected Pd activation time was also applied to metallize "T"-shape DNA origami, and Au coated branched nanostructures with a length between 200-250 nm, and wire diameters of ~40 nm were also fabricated. In addition, I found that the addition of Mg2+ ion into the reducing agent and electroless plating solution could benefit the surface retention of Pd seeded DNA and Au plated DNA structures. This work indicated that DNA molecules were promising templates to fabricate metal nanostructures; moreover, the formation of Au metallized branched nanostructures showed progress towards nanodevice fabrication using DNA origami. Silicon surfaces were also used as the substrates for DNA metallization. More complex circular circuit DNA origami templates were used. To obtain high enough seed density, multiple Pd seeding steps were applied which showed good selectivity and the seeded DNA origami remained on the surface after seeding steps. I used distribution analysis of seed height to study the effect of seeding steps on both average height and the uniformity of the Pd seeds. Four-repeated palladium seedings were confirmed to be optimal by the AFM images, seed height distribution analysis, and Au electroless plating results. Both Au and Cu metallized circular circuit design DNA origami were successfully obtained with high yield and good selectivity. The structures were maintained well after metallization, and the average diameters of Au and Cu samples were ~32 nm and 40 nm, respectively. Electrical conductivity measurements were done on these Au and Cu samples, both of which showed ohmic behavior. This is the first work to demonstrate the conductivity of Cu metallized DNA templates. In addition, the resistivities were calculated based on the measured resistance and the size of the metallized structures. My work shows promising progress with metallized DNA and DNA origami templates. The resulting metal nanostructures may find use as conducting interconnects for nanoscale objects as well as in surface enhanced Raman scattering analysis.

Nanomaterials display interesting physical and chemical properties depending on their shape, size and composition. Self assembly is an intriguing route to producing nanomaterials with controllable compositions and morphologies. DNA has been used to guide the self assembly of materials, resulting in: (1) metal nanowires; (2) metal or semiconductor nanorods; (3) carbon nanotubes; and (4) semiconductor, metal or biological nanoparticles. My work expands the range of DNA templated nanomaterials and develops novel ways of using DNA to pattern nanostructures on surfaces. I have performed the first synthesis of silver nanorods on single stranded DNA, an attractive material for localizing DNA coupled nanostructures through hybridization. I have demonstrated an ionic surface masking protocol to reduce ~70% of non specific metal deposition (a pervasive problem) during electroless plating of DNA with silver or copper. I have designed and constructed discrete three branched DNA junctions as scaffolding for self assembling three terminal, individually gateable nanotransistors. I have labeled these DNA structures with single streptavidin molecules, as a model for the placement of semiconductor nanocrystals at the junctions. Moreover, I have shown selective silver and copper plating of branched DNA constructs, with crystallinity that depends on plating conditions. I have fabricated DNA templated nickel nanostructures on surfaces and demonstrated their reversible interaction with a histidine labeled protein, as a model system for patterning histidine tagged nanostructures on surfaces. Previous methods were limited to decorating DNA scaffolds using streptavidin-biotin interactions. Finally, I have developed DNA shadow nanolithography, which uses angled thin film deposition and anisotropic etching to transfer patterns of surface aligned DNA onto substrates as nanoscale trenches with linewidths <30 nm. Nanotrenches can be post processed with microfabrication methods to modify their properties; I have constructed metal lines and nanopores from such trenches. This dissertation summarizes the principles and methods for synthesis and characterization of DNA templated nanomaterials. These biologically templated constructs may be useful in the fabrication of self assembled chemical and electrical sensors, and as structural materials for nanofabrication and nanopatterning on surfaces.