Biological Assembly Of Hybrid Inorganic Nanomaterials Preprint PDF Download

"A powerful strategy for the synthesis of functional nanomaterials involves the assembly of both inorganic and organic nanostructured components to result in a hybrid material with intrinsically tailored properties. Achieving desired hybrid material structure, function, and reproducibility necessitates the investigation of methods to establish and preserve monodispersity, chemical functionality, and required properties within the component nanomaterials. Described herein is work on biological and synthetic nanostructures as potential building blocks for nanostructured materials by design.In the first part of this thesis we present our investigation into the functional properties and chemical control of two bio-organic materials: tobacco mosaic virus coat protein and the reversibly photoswitchable protein Dronpa. Attachment of a hexahistidine tag to tobacco mosaic virus coat protein by genetic engineering resulted in unprecedented assembly behavior for the coat protein, forming nanostructured rafts, nanofibers, and hexagonally packed disks in addition to structures normally observed for the wild-type coat protein. The type of assembly formed was controlled by the addition of ethanol or nickel(II)-nitrilotriacetic acid, enabling the modified protein to serve as a reliable template for the future preparation of hybrid nanostructured materials. Scanning tunnelling microscopy and spectroscopy obtained of Dronpa monolayers on gold allowed us to define the relationships between Dronpa fluorescence switching, orientation, and conductance. Modification of Dronpa with a hexahistidine tag resulted in better self-assembled monolayers of Dronpa, and also demonstrated the influence of molecular orientation on protein conductivity. Recent applications of magnetic iron oxide nanoparticles for separation, catalysis, and magnetic imaging have stimulated interest in the synthesis and modification of ultrasmall water-soluble iron oxide nanoparticles (the topic of Chapters 4 and 5) as components for the preparation of functional materials. In response, an efficient ligand exchange method for the synthesis of aqueous stable magnetic iron oxide nanoparticles was developed to yield monodisperse nanoparticles functionalized with the small, highly charged ligands dopamine and Tiron. Motivated by the need to better understand the nature of ligand binding to iron oxide, model benzoic acid derivatives and catechol-based ligands were reacted with oleic acid stabilized iron oxide nanoparticles. Fourier transform infrared spectroscopy was used to examine the ligand exchange, purification, and the resulting complexes. The correlations observed between features in the obtained spectra and solubility of the ligand-stabilized nanoparticles enabled the assignment of binding modes for the series of model ligands--which will assist in the rational design of custom ligands for iron oxide. Advances in monodispersity, chemical control, reaction monitoring, and knowledge gained regarding the structure-functional relationships of the bio-organic and inorganic materials examined in this work will assist in the design of future hybrid inorganic-organic nanostructured materials. " --