Prepareation Of Two Kinds Of Self-assembled Nanostructures Containing Au Nanopaticles And Silk Fibroin Respectively

The past 20 years or so have witnessed an explosion of relatively inexpensive analytical tools, such as scanning probe microscopies, for interrogating and manipulating materials on the nanometer length scale. At the same time, several previously unrelated fields such as electrical engineering and biology have begun to focus on understanding and controlling physical and chemical phenomena on this length scale, typically 1 to 100 nm. Scientists have learned how to control the size and shape of a wide variety of materials at the atomic or molecular level. And in the process, they have uncovered interesting and potentially useful properties, many of them unanticipated. The field is going to blossom and turn into a major force in science over the next tens of years.Nanoparticles are considered to be a new state of matter whose properties depend not only on the chemical composition, but also on the size and shape. Such properties are of interest for applications in optical data storage, ultrafast data communications systems, and solar energy conversion. To be sure, chemists are used to working on the nanometer scale. But making an organic compound using traditional synthetic chemistry is not an example of nanotechnology. By contrast, the use of self-assembly techniques to make small molecular components coalesce into a macrocyclic molecule having multinanometer dimensions can legitimately be considered nanotechnology.Bottom-up approach was utilized to prepare self-assembled nanostructures on the basis of octa（aminopropyl）silsesquioxane octahydrochloride （POSS-NH₃⁺） and gold nanoparticles. Self-organized nanocomposites of functionalized gold nanoparticles coated with carboxylate groups （Au-COO^-） with POSS-NH₃⁺ were prepared via electrostatic interaction between carboxylate groups and ammonium cations under mild basic conditions. Subsequent chemical reaction between the reactive ion couples well-defined in the nanocomposites generated amide bonds between the two components. Porous nanocomposites were accomplished by precipitation of the POSS-NH₃⁺ modified polystyrene （PS） latex particles and Au-COO^- followed by removal of the PS particles via tetrahydrofuran （THF） extraction.Successive deposition of POSS-NH₃⁺ and Au-COO^- on glass substrates alternatively under mild basic conditions led to systematic buildup of gold colloidal multilayers. Driving force of the self-assembly was electrostatic interaction between ammonium cations of POSS-NH₃⁺ and carboxylate anions on Au-COO^-. A linear increase of surface plasmon resonance of Au-COO^- with the deposited bilayers indicated the multilayer manipulation was reproducible. Microporous nanocomposites of Pd and Au nanoparticles were generated by utilizing electrostatic interaction between oppositely charged Au-COO^- and spherical aggregates of Pd nanoparticles （Pd-NH₃⁺） stabilized and cross-linked by POSS-NH₃⁺. Amide bonds were formed between the reactive ion couples well-defined in the Pd-Au colloidal nanocomposites during a subsequent chemical reaction to produce more stable nanocomposites with improved chemical and physical properties.Diverse silk fibroin （SF）/silica （SiO₂） hybrids were prepared via sol-gel reaction for the purpose of depositing a thin layer of SF on fabric surfaces. Structures and morphologies of the hybrids were visualized with atomic force microscopy （AFM）, and transmission electron microscopy （TEM）. Porous network nanostructure of the nanohybrid with the feed weight ratio of SF/TEOS=7/3 （NanohybridⅡ） was observed with isolated SiO₂ nanoparticles dispersing in the SF network. The SiO₂ nanoparticles acted as physical anchoring sites of the SF molecules. Subsequent self-assembly of the SF molecules with the assistance and restriction of the SiO₂ nanoparticles generated the porous SF network. The typical size of the SiO₂ nanoparticles is 20.8±3.4 nm, and the diameter of SF threadlike branches is 16.7±2.0 nm. Coating of cotton fabrics with NanohybridⅡwas attempted so as to achieve silklike properties by nanosol coating. The coated cotton fabrics demonstrated improvement in their water repellency. A new and facile approach of surface dyeing was developed for cotton and nylon fabrics coated with a novel porous silk fibroin （SF）/silica （SiO₂） nanohybrid. Actually, dyeing of the fabrics occurred in the very thin nanohybrid layers exclusively while the main body of the fabrics remained intact on the whole. With the assistance of the large surface areas of the porous nanohybrid, dye uptake of the coated fabrics dyed with Acid Red GSF or Disperse Cation Red SD-GRL was enhanced substantially compared with that of the uncoated fabrics as a control. Moreover, dye uptake increased with the SF content in the hybrid, indicating that the SF moiety played a significant role for the surface dyeing process. Color fastness to water of both the dyestuffs was much higher for the coated cotton fabrics compared with that of the uncoated ones. Similar results were obtained for the nanohybrid coated nylon fabrics dyed with Disperse Cation Red SD-GRL as those of the coated cotton fabrics. Introduction of the novel nanohybrid to the fabrics in this work opens up new vistas for finishing of fabrics with nanomaterials to achieve unique chemical and physical properties.