Preparation of uniform sized metal-organic nanocomposites using tobacco mosaic virus.

摘要

A series of studies were conducted to determine the mechanism governing the biogenic metal mineralization process on the biotemplate, Tobacco Mosaic Virus (TMV). One aim of the studies was to investigate the how the metal precursor binding on the TMV surface functionalities affected the metal coating on the TMV. The TMV and surface functionalized silica, combined with quantitative precursor uptake analysis, served as toolkits for exploring the metal precursor uptake on surface moieties leading to the highly controlled metal coverage on TMV. The resulting thin metal layering on the biotemplate was tested for potential application as conductive nanowires.;The results from studying the metal precursor uptake on the biotemplate are used to test the hypothesis about the positive correlation between surface-bound metal precursor amounts and final metal coverage on biotemplates after reduction. As a model system, the quantitative analysis methodology of Pd(II) and Au(III) uptake on TMV was developed by using a UV-Vis spectrometer. A series of solutions were prepared by fixing surface-bound Pd(II) or Au(III) precursors to the biotemplates, and varying the free suspension precursor concentration in the medium. The resulting solutions were subsequently reduced by the addition of reducing agents. The results suggest that enhancing the surface-bound precursors on the TMV is important for improving the metal coating on templates after reduction.;Biotemplates contain intrinsic limitations due to their structural weakness and mixed surface functionalities that make it difficult to investigate precursor interaction with a single type functional group. The binding of the metal precursor on a single surface functional group was investigated using surface functionalized silica. Pd(II) sorption on surface functionalized silica nanoparticles was utilized as a testing tool to investigate the multiple Pd(II) uptake on thiol moieties. The results suggest that palladium precursors on thiol propagate palladium layers without adding external reducing agents.;By exploring the aforementioned theoretical speculations, new biogenic metallization process is proposed by demonstrating the Pd layer growth on TMV without externally added reducers. Unlike the conventional approach of using external reducing agents to form the metal coating on TMV that result in inefficient coating of the metal on the TMV, the external reducer-free palladium mineralization on the TMV demonstrates essentially 100% coating of the Pd on TMV. Conductivity measurement of Pd coated-TMV is summarized.