| Research on mesoporous materials is an interdisciplinary topic that has attracted tremendous interest internationally. Based on the chemical composition of the porous wall, they can be divided into two categories, siliceous and non-siliceous materials, among which the siliceous materials can be further classified into tranditional silica mesoporous materials and emerging periodic mesoporous organosilicas(PMO). The synthesis and the formation mechanism of inorganic silica mesoporous materials have already been well-developed; however, there is still a substantial lack of development in terms of their applications. As a kind of organic-inorganic hybrid material with fully open mesopores, PMOs can be introduced with a wide range of functional groups inside the inorganic framework to enrich their properties while maintaining mesopores highly ordered, which is mostly the focus of their research nowadays. In addition to these two kinds of siliceous mesoporous materials, there are kinds of non-siliceous materials in the mesporous family, including metal oxides, metal and nonmetal compounds. The synthesis of most non-siliceous materials has shown be more difficult than that of the siliceous materials, therefore further development and expansion of their synthetic technology and composition are strongly required. In view of the above research situation, three parts of research work have been done in this thesis:Part I:Traditional silica mesoporous materials were functionalized with fluorescent cascades to explore their applications in multiplexed bioassay, sensors, multiplexed drug delivery and monitoring, controlled drug release and so on. The details are as follows:1. Dual Foster resonance energy transfer (FRET) dye pairs were introduced into the pore channels of mesoporous silica nanoparticles in the form of oligosilicate fluorescent dots via a novel doping method. The2.5nm pore channels of the nanoparticles offers the optimal space for the FRET pairs, which greatly improve the energy transfer between them.Thus, both of the dyes can be excited via a single excitation wavelength. Abundant fluorescent signals were obtained by simply varying the doping ratio of the two dyes in the nanoparticles. These multicolour silica nanoparticles provide a robust system for multiplexed bioassay.2. A new kind of ratiometric pH sensor based on mesoporous silica nanoparticles was constructed for the first time by the incorporation of FRET dye pairs fuorescein isothiocyanate (FITC) and rhodamine B isothiocyanate (RBITC) into the pore channels of mesoporous silica nanoparticles through a co-condensation with tetraethylorthosilicate (TEOS). In this sensor, FITC acts as the pH sensitive dye and RBITC as the reference dye. Because of the effective energy transfer between them, both of their emissions can be obtained via a single excitation wavelength and the intensity ratio of the two emissions varied with the change of pH values, allowing the detection of pH in a ratiometric manner. Moreover, the ordered mesopores facilitate the accessibility of analyte to the indicator. Thus, a good sensing capability of the mesoporous nanoparticle is obtained. Further investigation shows the sensitivity and pH sensing-range can be varied by simply doping the dual-FRET dye pairs with different ratios and this nanosensor has a good reversibility.3. A novel monodisperse core-shell silica nanosphere composed of a fluorescent solid core and a mesoporous shell has been successfully fabricated. These nanospheres exhibit multifluorescent signals under a single-wavelength excitation as a result of the solid silica core that is doped with three kinds of dyes and that can produce effective fluorescence resonance energy transfer. The fluorescent signal of a single nanosphere is about700times brighter than its constituent fluorophores. X-ray diffraction, transmission electron microscopy, and N2adsorption-desorption isotherms reveal that these nanospheres possess abundant mesopores in the shell. Combining the advantages of extremely bright multifluorescent signals excited with a single wavelength and an abundant mesoporous system, this core-shell silica nanosphere is designed for the simultaneous monitoring of fluorescence of in vivo multiple-target drug transport. Experiments on drug loading and release in addition to studies on cell uptake reveal that these nanospheres not only show good drug storage and sustained release capacity but also demonstrate biocompatibility and mutlifluorescent labeling capacity for biological systems.4. We build a drug delivery and light triggered release platform that possess both diagnostic and therapeutic functions, obtained by grafting the surface of mesoporous silica nanoparticles (MSNPs) with ruthenium dipyridophenazine (dppz) complexes, which can simultaneously act as luminescence probes of DNA structure and as anticancer agents. This nanomaterial displays enhanced luminescent properties relative to the ruthenium(II) dppz complex in a homogenous phase and the ruthenium complex can be released from the surface of the nanoparticles under irradiation with visible light followed by binding to DNA with high affinity, acting as a DNA targeting motif, leading to cytotoxicity to cancer cells. Meanwhile, the mesopores of the nanoparticles allows the loading of additional kinds of drug molecules like paclitaxel, which can be capped by ruthenium dppz complexes and released with them under visible light irradiation, giving a synergistic therapy.Part Ⅱ:A new kind of PMO material were synthesized by introducing athoxysilyl-modified carbon-dots into the inorganic framework, which realizing an effective combination of the fluorescence properties of carbon-dots and mesoporous structures. Along with a good morphology, this hybrid material is of promising applications in the fields of biotechnology and biomedicine. In addition, with the increase in the doping amount of the carbon dots in the framwork, both the single-photon fluorescence and the two-photon fluorescence show gradually red-shift. Thus, multifluorescence was obtained via simply varying the doping amount of carbon-dots, which is a novel property that the carbon dots do not possess when dispersed in solution.Part III:Three new kinds of titanium-oxo clusters have been synthesized:FTOC-1:Ti4O3(O’Pr)6(ηi5-O2CC5H4)Fe (C5H4CO2-η5)2,FTOC-2:Ti6O6(OiPr)6(η5-O2CC5H4)Fe(η5-C5H5)6,FTOC-3:Ti6O6(O’Pr)6(η5-O2CC5H4)Fe(η5-C5H5)6.Their structures and properties were well studied. In addition, FTOC-3with the best crystal morphology and yields was used to sythesize mesoporous Fe/Ti/O composites, for which a good crystallinity and mesoporous structures were obtained. This study is expected to provide a new strategy to synthesize kinds of novel non-siliceous mesoporous materials. |
PDF Full Text Request