Novel sol-gel nanoporous materials, nanocomposites and their applications in bioscience

Transparent, nanoporous silica materials have been prepared successfully via the acid-catalyzed hydrolysis and condensation of tetramethyl orthosilicate using the nonsurfactant templated sol-gel process. The synthetic conditions have been systematically studied and optimized. The effects of template and synthetic process, especially template removal steps on pore structure, have been investigated. The composition and pore structures were thoroughly characterized with various spectroscopic and microscopic methods such as IR, TGA, SEM, TEM and BET. The obtained nanoporous materials usually exhibit high surface area, large pore volume and narrowly distributed pore diameter. The porosity can be fine tuned to a certain extent simply by adjusting the template concentration. The convenient synthesis, as well as the distinctive structure and physical-chemical properties, render these sol-gel materials suitable for a wide range of potential applications, such as chemical and biological sensors, catalysts, drug delivery and functional coatings. Because of excellent biocompatibility of this novel sol-gel technology, the method was used to study behaviors of encapsulated biospecies in silica matrix within a confined space. We call such nanoporous materials "rigid matrix artificial chaperone" because they mediate protein folding process in many aspects like a chaperone. In the studies included in this thesis, cytochrome c, hemoglobin, myoglobin as well as amyloid [beta] peptide were encapsulated in sol-gel nanoporous silica matrix with controlled pore size. Then their folding-unfolding and aggregation behaviors were investigated by a variety of analytical methods, such as fluorescence spectroscopy, circular dichroism and resonance Raman spectroscopy. It was found that the size of pore had great effects on the folding and aggregation process of those encapsulated biospecies. In the second part of this thesis, the synthesis, processing and characterization of hybrid nanocomposites and their applications in dental materials are described. Two approaches have been developed to achieve homogenous hybrid nanocomposites: the first approach involves the use of vinyl modified silica nanoparticle as inorganic component and the other one employs nanoporous silica particle as inorganic filler. The materials synthesized by both of these two approaches demonstrated promising potential in dental applications.