Electrochemical Investigation And Application Of Vertically Oriented Silica Mesochannels

Ordered silica-based mesoporous materials consist of a periodic and regular arrangement of well-defined mesopores and amorphous inorganic framework structures. They are usually highly porous, with high specific surface areas, stable structure and good biocompatibility. Besides, the inner surface and outer surface of the channels can be modified with different chemical groups and functional biomolecules. These advantages make them ideal earriers of protein, gene and drug molecules, etc. In this paper, vertically ordered mesoporous silica channel arrays were synthesized on conductive substrates and mass transfer of charged species in the channels was studied by electrochemical methods. Besides, the channels were used to immobilize protein and then electron transfer kinetics of the protein were studied.In Part1, Chapter1, the influence of electric double layer on mass transport in nanochannels was introduced. The synthesis and modification of mesoporous silica materials in different form (powder and film) and the preparation of their modified electrodes were reviewed. The application of mesoporous silica materials in enzyme immobilization was simply summarized.In Part2, Chapter2, mesoporous silica film (MSF) with highly ordered1D-channel array perpendicular to ITO substrate was synthesized by a simple Stober-solution growth approach. The pore size was about2.3nm. After chemical modification of channels with NH4+groups, the surface charge was converted from negative to positive. The charge effect of MSF was studied for the first time and permselectivity of MSF towards probe molecules with different size and charge was discussed in detail. Besides, based on the size effect and charge effect of nanochannels, the influence of solution ionic strength on the permselectivity of MSF was detected and a sensor with smart interface was designed, which can turn "on" or "off by changing solution conditions.In Part3, Chapter3, the application of MSF/ITO electrode in protein immobilization was discussed. Microperoxidase-11(MP-11) was chosen because its dimension was comparable to the pore size. It was demonstrated for the first time that monomers of microperoxidase-11could be selectively adsorbed into the MSF channels via physical adsorption, constructing the MP-11/MSF/ITO electrodes. Furthermore, thermodynamic and kinetic processes of adsorption as well as the electron transfer kinetics of MP-11were discussed.