Abstract

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.

Degree

PhD

College and Department

Physical and Mathematical Sciences; Chemistry and Biochemistry

Rights

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