| Due to the advantages of high surface area, well-defined pore structure, tunable pore sizes, easy modification, optical transparency, chemical stability and biocompatibility, mesoporous silicas have a potential application in the adsorption, separation, catalysis, recognition and drug-controlled release. But with the development of technology, research of mesoporous materials is no longer confined to the traditional single-function, and is expected to integrate multiple functions in a single system, such as optics, electricity, magnetism and so on. This thesis launched a series of studies which focused on the synthesis and application of multifunctional mesoporous materials. The main results are as follows:1. Ferric chloride was chosen as an iron source. Fe3O4magnetic nanoparticles were prepared using a solvothermal reaction. Magnetic core-shell mesoporous materials were fabricated by using a sol-gel technology and surfactant template method. Thiol-functionalized magnetic mesoporous materials (Thiol-MMM) can sequentially adsorb toxic phenolic compounds and heavy metal ions, which effectively combine the high transmission performance of magnetic materials with high adsorption properties of mesoporous materials. The structural properties of Thiol-MMM were characterized by XRD, SEM, TEM, BET and so on. A systematic study was carried out on adsorbent dosages, solution pH, contact time, ionic strength and interfering organic and inorganic pollutants in order to optimize the adsorption behaviors of phenolic compounds and heavy metal ions on Thiol-MMM. Experimental results showed that optimum adsorption pH was3-5. The adsorption equilibrations for the pollutants can achieve within30minutes. Adsorption capacity increased with increasing of initial concentration, but decreased with increasing of ionic strength. Interfering pollutants had little impact on the adsorption effect. The adsorption process was well described by the Langmuir and Freundlich equation. The maximum adsorption amount of4-Me-2,6-DNP on Thiol-MMM was144.78mg g-1. After Thiol-MMM was treated with a fast ion-exchange method using NH4NO3, the maximum adsorption capacity was185.19mg g-1for Hg2+and114.7mg g-1for Pb2+. The Thiol-MMM could be easily removed from solution within1minute.2. A novel "all-in-one" material was synthesized by immobilization of a Rhodamine fluorescent probe in the surface of magnetic core-shell mesoporous materials by using surface modification technology. The transformation of spiro and open-loop structure in Rhodamine was used to achieve the rapid detection, high-efficient adsorption and removal of toxic Hg2+RhB-functionalized magnetic mesoporous materials (RhB-MMM) showed excellent fluorescence sensitivity and selectivity towards Hg2+over other metal ions (Cu2+, Pb2+, Ag+, Co2+, Zn2+, Ni2+, Mn2+, Cd2+, Mg2+, Na+). Upon the addition of Hg2+, an overall emission change of16-fold was observed, and the detection limit of Hg2+was as low as10ppb. The adsorption process of Hg2+on the RhB-MMM was well described by the Langmuir equation. The equilibrium could be established within5minutes and the adsorption capacity was21.05mg g-1. Hg2+adsorbed RhB-MMM could be easily separated from the solution within1minute by adding an external magnetic field, and the concentration of Hg2+ions in the solution could be reduced to less than0.05ppm.3. A pH-responsive drug carrier (MN-FA-Fc) was fabricated by immobilization of multiple functions in the surface of magnetic core-shell mesoporous silica materials by using surface modification technology, which simultaneously realized induced target delivery, promoted cellular uptake and controlled drug release. The inner Fe3O4core endowed the material with magnetic properties, which can be used in magnetic induced target delivery, and the outer mesoporous shell could adsorb and store DOX in its mesopores. Ferrocene Schiff base linker was linked to the orifices of the mesopores to implement pH-dependent self-release. The linkers remained intact at neutral pH, however, the Schiff base bond breaked by hydrolysis at acidic pH. Because the cancer cells have a weak acidic pH, hydrolysis of the Schiff base group removes the nanovalves and releases the trapped DOX to kill the cancer cells. Bioactive small molecule FA was chosen as specific recognition group because some tumors expressed a high affinity to it, which could improve the target capability, promote the uptake of MN-FA-Fc by cancer cells, and further heighten the curative effect. In order to evaluate the feasibility of MN-FA-Fc in the biomedicine field, intracellular localization, endocytosis and cytotoxicity test were demonstrated by LSCM, TEM and flow cytometry. Experimental results showed that Drug carrier MN-FA-Fc exhibited almost no cytotoxicity towards MCF-7cells. Binding activity of MN-FA-Fc is consistent with FA receptor, which could be enriched at the position of cancerous lesion. Simultaneous internal pH stimulus induced DOX self-release from MN-FA-Fc, which shows an effective cell-killing effect.4. Three metallorganic surfactant FcC11Me3Br, FcC11Et3Br and FcC11PyBr were synthesized. The surfactant contained a terminal ferrocene moiety was used as a structure-directing agent and iron precursor to fabricate mesoporous silica material by using the hybrid organic-inorganic self-assembly approach. After simple oxidation, the obtained magnetic mesoporous silica material (MMS) had a high surface area and a narrow pore distribution. The saturation magnetization of the MMS was affected by the oxidation temperature. Experimental results showed that a mid-range temperature (300℃) was considered to be the optimum reaction condition. The generated Fe2O3was dispersed evenly inside the channels of the mesoporous host. MMS-300was found to have an ideal catalytic ability to quickly degrade several dyes from water under visible light irradiation. The removal rate of the dyes reached99%(Rhodamine B) and100%(Methylene Blue), and the catalyst MMS-300could be recycled many times without the loss of activity. MMS successfully integrates adsorption, photocatalytic degradation, magnetic removal and reuse.5. A quinoline derivative-based surfactant QAC12Et3Br was synthesized. The surfactant was used as a structure-directing agent to fabricate mesoporous silica material by using the hybrid organic-inorganic self-assembly approach. The fluorescent mesoporous material (FMM) was prepared via confining coordinate complex assembly in porous silicate channels. The quinoline moiety coordinated with Al3+in the FMM to give a bright blue-green fluorescence. Meanwhile, the silica nanochannels, which protect the included coordination complex assemblies, have an excellent compatibility with PMMA. Transparent fluorescent polymer bulks with various shapes (film and rod-like) were successfully fabricated. Furthermore, the fluorescence of FMM could be selectively quenched by PPi, so FMM could be used as a high performance sensing material. Experimental results showed that the fluorescence spectrum of FMM solution had a strong emission peak. While the fluorescence of FMM was gradually quenched by titrating PPi, due to metal-to-ligand charge transfer was destroyed. Other biologically relevant species such as Cl-, Br-, I-, NO3-, NO2-, ClO3-, HSO3-, ClO4-, SCN-, SO42-, S2O32-and ATP did not give any observable response. |
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