| Magnetic nanoparticles have shown broad application prospects in biomedical fieldincluding magnetic resonance imaging （MRI）, immune detection, targeted drug delivery,cellular and bio-molecular separation, because of their good biocompatibility, lowtoxicity and unique magnetic properties. Therefore, they have attracted great interest inrecent years. Meanwhile, mesoporous silica nanoparticles （MSNs） have been emerging asa promising carrier for gene therapy, drug delivery, and biomedical imaging, due to theirlarge surface area and pore volume, uniform pore size, good biocompatibility andwell-defined surface properties for modification. In this thesis, different morphology ofmagnetic/mesoporous silica nanomaterials were synthesized by different methods, thenthe surface of the mesoporous silica shell was modified with environmental responsivepolymers and fluorescent dye. The biocompatibility assessment, MRI studies, drugloading and release researches were carried out for the resulting multifunctionalizedmagnetic/mesoporous silica nanomaterials. There are four chapters in this thesis.In chapter1, the recent development in the research of the mesoporous silica, magneticiron oxide nanomaterials and the magnetic mesoporous silica nanocomposites issummarized. The main research significance of the whole work is also proposed in theend.In chapter2, three kinds of α-Fe2O3nanoparticles with different morphology and sizewere synthesized, then the surface of the nanoparticles was in turn coated with a densesilica layer and a mesporous silica shell, and at last, the magnetic/mesoporous silicananospheres （Fe3O4@SiO2@mSiO2, abbreviated as MMSN） were obtained after in-situreduction. The characterization results showed that the MMSNs have a uniform morphology, good dispersion, and high surface area and pore volume. After the initiatorwas anchored on the surface of the mesporous silica shell, the atom transfer radicalpolymerization （ATRP） was carried out on the MMSN surface for the growth of polymerchains to prepare the temperature responsive MMSN-poly（N-isopropylacrylamide）（PNIPAM） and pH responsive MMSN-poly（acrylic acid）（PAA） nanocomposites. Atroom temperature, these two kinds of materials can be well dispersed in water, and theycan be easily manipulated by an external magnetic field. The results3-（4,5-dimethylthiazol）-2-diphenyltetrazolium bromide assays show that they have lowcytotoxicity, which indicates their good biocompatibility. We also tested the dispersionbehavior of MMNS-PNIPAM in water at different temperature, and this material showedgood sensitive effect to temperature. In vitro experiments revealed that the MMNS-PAAdisplayed an excellent MRI enhancement effect on cancer cells. In addition,MMNS-PAA showed a high loading capacity for anticancer drug doxorubicinhydrochloride （DOX）. The drug release of DOX-loaded MNNS-PAA were investigatedin PBS buffer at different pH （pH=7.4,6.3and5.2）, and the results showed that the drugloaded nanocomposites have good stability in normal physiological buffer and fast drugrelease in acidic environments, which are ideal properties for in vivo drug carriers.Therefore, MNNS-PAA nanocomposites have great potential to be used as drug carriersfor diagnostic and therapic applications.In chapter3, well-dispersed β-FeOOH nanorods were synthesized by a hydrothermalmethod, then the hollow core/magnetic and mesoporous double shell nanostructures（HMMNSs） were successfully synthesized by an in-situ decomposition/reductionapproach using β-FeOOH nanonods as templates. The resulting HMMNSs weresubsequently conjugated with fluoresceine isothiocyanate （FITC） and PAA to explore thepotentials of this material for biomedical application. The T2-weighted MRI contrasteffect of the obtained HMMNS-FITC/PAA was studied, and the specific relaxivity （r2） ofMMSN-PAA was calculated to be75.88Fe mM-1s-1, which indicated thatHMMNS-FITC/PAA can be used as a good T2contrast agent.In chapter4, the important results obtained in this work are summarized. |
PDF Full Text Request