Preparation And Application Of Silica-based Separation Carriers With Atomic Layer Deposition

Silica-based separation carriers, with the advantages of high mechanical strength, controllable pore morphology, specific surface, good chemical and thermal stability and abundant surface reactive groups, became ideal matrix of separation carriers, and been widely used in chromatography, catalysis and environmental science and other fields.There are liquid phase reaction, self assembly, supercritical fluids and atomic layer deposition methods to produce bonding silica gel. Compared with other methods, atomic layer deposition is more predominant because of it avoiding the organic solvents and easy to carry out. Moreover, it is more convenient to get the production in short time with higher surface coverage of organic functional groups. Therefore, this method described here offers an economic and environmental benign approach for mass production of silica-based separation carriers.This work was focus on the silica gel surface modification. Using atomic layer deposition method, we prepared phenyl and epoxy propyl bonded silica. We further prepared strong cation exchange chromatography packing and restricted access matrix sorbents. The detailed contents of this thesis are as follows:Phenyl bonded silica was prepared successfully with atomic layer deposition using porous silica microspheres as matrix. Benzene sulfonic acid bonded silica was prepared through sulfonation of the silica matrix, which was applied to detection of melamine in raw milk. The peaks of melamine and the impurities in raw milk couldn't be baseline separation on the solid phase of propane sulfonic acid bonded silica, which seriously affected the quantitative detection of melamine in the raw milk, while on the benzene sulfonic acid bonded silica, they achieved completely baseline separation. Compared with liquid phase method, the surface coverage of benzene sulfonic acid bonded silica prepared via atomic layer deposition was much higher, therefore the retention time of melamine was longer, resolution between melamine peak and the impurity peak was greater, which reflected the advantage of chemical bonding silica packing prepared via atomic layer deposition.Epoxy propyl bonded silica was prepared successfully with atomic layer deposition using porous silica microspheres as matrix too. On this basis we prepared a novel restricted access matrix sorbents with diol groups on the external surface and 3-Aminophenylboronic acid group on the internal surface. The suitable aperture of this material ensures protein and other biological macromolecules could not enter the pore, and surface hydrophilic diol ensure biological macromolecules did not occur irreversible degeneration and adsorption on the outer surface of the sorbents. Meanwhile, 3-Aminophenylboronic acid group on the internal surface would adsorb on cis-dihydroxy compounds. We systematic studied the performance of the novel restricted access matrix sorbents, using bovine serum albumin as a protein model and three kinds of catecholamine drugs as model of cis-dihydroxy compounds. This work was followed by fabrication of a novel magnetic restricted access matrix sorbents using Fe3O4-SiO2 magnetic microspheres. The magnetic restricted access sorbents had the advantages of both restricted access matrix and magnetic material, which to facilitate or automate procedures. This would help us to develop a novel solid phase extraction approach with advancing efficiency, thus innovating the operating mode and opening up a quick and efficient approach of solid phase extraction of small molecular compounds from biological samples.