Functionalization Of Mesoporous SBA-15Materials And Their Application In Humidity Sensor And Drug Delivery

Since the discovery of MCM-41-type ordered mesoporous silica (MS) by Mobilcorporation scientists in1992, there has been large amount of research conducted onthe controlled syntheses and applications of MS. Great endeavors have been made inthe control of particle size, pore diameter, morphology, structure, surface propertiesand functionalization of MS to develop their applications in the fields of catalysis,adsorption, sensor, optics, etc. In particular, biomedical application research onmesoporous silica materials has received great attention in the last few years.Mesoporous silica materials have been intensively suggested for use in controlleddrug/gene release and as delivery carriers, biosensors, enzyme supporters.Meanwhile, the biological effects of mesoporous silica materials at different levelsfrom molecule, cell, blood to organ/tissue, involving cytotoxicity, biodegradability,blood compatibility, are also drawing increasing attention and have become currenthot topics in mesoporous silica materials. In this thesis, we synthesized several kindsof functional mesoporous SBA-15materials and discussed their application inhumidity sensor and drug delivery.Mesoporous silica material is an attractive material for many sensingapplications because of its ordered mesoporous structure, uniform pore diametersand numbers of available hydroxyl and/or silanol sites. In the second chapter, wepresent a simple and effective route for the synthesis of a highly efficient humiditysensing material of KCl-doped SBA-15. Their structure was characterized bylow-angle XRD, N2adsorption-desorption and TEM, these tests indicated that theordered mesoporous structure of SBA-15was maintained by the doping of KCl. Bysimply controlling the contents of KCl, the linearity correlation between impedance and RH can be easily controlled. Of all these samples, K-SBA-15-0.5presented themaximum humidity sensitive property, better linearity and shorter response-recovery.The abundant dissociation of KCl at high relative humidity played an important rolein improving the humidity sensitive properties of these materials.Dendrimers are tree-like highly branched macromolecules that possess uniquethree-dimensional architectures. In order to combine the advantages of both thedendrimer and the mesoporous silica material, PAMAM dendrimers up to the thirdgeneration have been attached to the surface of the channels of SBA-15mesoporoussilica material via multistep synthesis. Detailed characterization of the hybridmaterials was performed in order to confirm the linkage and homogeneousdistribution of dendrimers along the mesoporous silica material. The new hybridmaterials prepared in this work have been tested as host matrices for the preparationof drug delivery systems using ibuprofen as a model drug.Seutellaria baiealensis Georgi is an effective traditional chinese medicine, it hasthe functions of dispelling wind-heat to reduce fever and detoxifcating. Due to it'slarge polarity, low liposolubility as well as water-solubility, baiealin has poorperformance in oral absorption, bioavailability and stability, which influence theexertion it's clinical effects. In order to improve its bioavailability, it is necessary toprepare the sustained release tablets. In the fourth chapter, amino-groups have beenattached to the internal surface of the channels of SBA-15mesoporous silicamaterials via co-condensation method. The hybrid materials synthesized has beentest as controlled delivery systems, adsorption and in vitro release assays werecarried out using baiealin as a model drug. Detailed characterization of the hybridmaterials reveal that specific surface area, mesoporous pore system and the amountof amino-groups have an effect on the drug loads and sustained drug releaseproperties.Periodic mesoporous organosilicas (PMOs) prepared by surfactant-directedpolycondensation of bridged organosilane precursors are promising for a variety ofnext-generation functional materials, because their large surface areas, well-definednanoporous structures and the structural diversity of organosilica frameworks are advantageous for their expanding potential applications. In the fifth chapter,PMO-CH3-NH2hybrid material was synthesized via co-condensation of bis-1,2-(triethoxysilyl) ethane and (3-aminopropyl) diethoxymethylsilane using P123astemplate. Detailed characterization of the hybrid materials was performed in order toconfirm the grafting of amine and methyl within the channel of mesoporous silicaand the maitaining of P6mm ordered structure. The hybrid material has a largeadsorption amount of bilirubin because of the interaction between aminne/methyland bilirubin molecules and the hydrophobic properties of the internal channels.