Assembling inorganic nanomaterials using tobacco mosaic virus templates
A series of methodologies has been researched and utilized with the intent to create functional devices from biologically nanostructured materials. The Tobacco mosaic virus (TMV) was chosen as a model biological template to investigate a series of approaches for the practical use of biological nanotemplates. Three specific achievements using TMV templates are discussed. First, the deposition of silica on the surface of TMV has been achieved at a higher pH (5-7) as a means to enhance its usefulness as a template for the synthesis of nanostructures. Electron energy loss spectroscopy definitively showed the presence of a silica shell on the surface of the TMV while small angle X-ray scattering differentiated between silica-coated TMV and silica particles in the presence of uncoated TMV. The TMV-templated silica coatings were found to enhance the stability to the virus particle in methanol at conditions that would ordinarily disrupt the assembled particle. Silica-coated TMV virions were shown to be applicable as templates for the deposition of platinum and palladium nanoparticles with particle density comparable to the deposition on the TMV2cys. Secondly, additional TMV templates were designed and created through PCR-based site-directed mutagenesis to include cysteine point mutations along the inner channel of the coat protein. The templates were then utilized for the spatially controllable growth of nickel and cobalt nanoparticles within the inner channel. Particle density was shown to vary with mutation location and catalyst concentration. Finally, high area nickel and cobalt surfaces were assembled using genetically modified TMV1cys templates. TMV templates engineered to encode unique cysteine residues were self-assembled onto gold patterned surfaces in a vertically oriented fashion, producing an order of magnitude increase in surface area. Electroless deposition of metals onto surface assembled virus templates produced uniform coatings up to 40 nm thick. Within a nickel-zinc battery system, the incorporation of virus-assembled electrode surfaces more than doubled the total electrode capacity. Combined these investigations demonstrate the versatility of the TMV template in achieving the successful construction and application of nanomaterials.
Harris, Purdue University.
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