Study On The Preparation And Drug-loading Property Of Magnetic Hollow Materials

Magnetic hollow structure materials have received more and more attention in thebiomedicine, immobilizing enzyme, controlled drug delivery and targeted drug, andmany other fields, due to their unique profile structure and excellent properties, suchas large surface area, hollow structure, good permeability and magnetism property,and so on. In order to improve the drug efficacy and decrease the side effect, targeteddrug and controlled drug delivery have become a focused subject in the various fieldsof biomedicine and medicine, therefore, many researchers have paid more attention tothe synthesis and application of magnetic hollow structure materials.In the paper, precursors are assembled, adsorbed and deposited on the giventemplate via chemical reaction, the shell layer is thus constructed on the templatesurface. The magnetic hollow nanospheres are obtained by means of calcining oretching templates, and the drug delivery property of magnetic hollow nanospheres areinvestigated.In the second chapter, the preparation and in situ modification of Fe₃O₄@CaCO₃nanoparticles are examined, the Fe₃O₄@CaCO₃nanoparticles as the templates areenvironment-friendly, moreover, we can obtain the hollow structure with magneticproperty by dissolving the CaCO₃, which enlarges the application field ofFe₃O₄@CaCO₃nanoparticles. The obtained Fe₃O₄@CaCO₃nanoparticles are uniformwith an average diameter of80nm. TEM and HRTEM measurements demonstratethat Fe₃O₄nanoparticles are successfully embedded in the CaCO₃particles, formingthe core-shell structure of Fe₃O₄@CaCO₃. The contact angle result of oleicacid-modified Fe₃O₄@CaCO₃composite nanoparticles is hydrophobic (108.5o), whichfacilitate the achievement of magnetic hollow PMMA nanospheres.In the third chapter, we develop a facile method to prepare the core–shellFe₃O₄@CaCO₃@PMMA nanospheres via in situ emulsion polymerization in thepresence of oleic acid-modified Fe₃O₄@CaCO₃composite nanoparticles, and themagnetic hollow PMMA nanospheres are obtained by etching the template of CaCO₃.TEM images show that the magnetic hollow PMMA nanospheres with a shellthickness of10nm possess a perfect spherical profile. The resultant magnetic hollowPMMA nanospheres possess magnetic properties and large cavities structure, and itcould bring about potential applications in the various fields of controlled release,drug delivery, targeted drug and so on. In the fourth chapter, we develop a novel approach to prepare of raspberry-likemonodisperse hollow hybrid nanospheres with γ-Fe2O₃@SiO₂particles as shell by thesol-gel process, which is based on the principle of the electrostatic interactionbetween negatively charged silica and positively charged polystyrene. With thismethod, a series of raspberry-like magnetic hollow silica nanospheres with differentmorphology and structure are successfully synthesized by the variation of thesesynthesis conditions including the amount of NH4OH, TEOS, Fe₃O₄, and the addingtime of PS. TEM images indicate that monodisperse magnetic hollow nanospherespossess perfect spherical profile and large cavities, SEM images exhibit that theNH4OH content plays a key role in forming the papillar surface morphology and theporous shells of hollow spheres, and the average diameter of Fe₃O₄@SiO₂nanoparticles increase with the increasing NH4OH content. It is also found that theadding time of PS templates have an effect on the forming of hollow structure.Moreover, the drug delivery experiment results demonstrate that the magnetic hollownanospheres possess a slower release rate.In the fifth chapter, magnetic protein microcapsules are prepared by dispersing oilin aqueous solution of protein with an ultrasonic technique. The hydrophobiccompounds (drug, magnetic nanoparticles) are easily loaded in the microcapsules bydissolution in the oil phase before sonication. A series of magnetic proteinmicrocapsules are successfully prepared, the different synthesis conditions includingdifferent power amplitudes, protein concentrations, ultrasonical pattern, magneticcontent are systematically investigated. And the optimal synthesis conditions are250W of power amplitudes,3wt%of protein concentrations, pulse-ultrasonicalpattern, the obtained magnetic protein microcapsules possess a narrow sizedistribution and an average diameter of4.3μm.In the sixth chapter, a new approach is reported to synthesize MFI zeolites(silicalite-1, ZSM-5), which possesses a fast crystallization rate and hierarchicalmesopores in the presence of CO₂-in-water emulsions, and mesoporosity is formedwithout organotemplate comparing to the conventional synthesis method. A series ofhierarchical mesopores ZSM-5zeolite with different morphology are successfullysynthesized in the presence of CO₂-in-water emulsions, the different synthesisconditions including silica alumina molar ratio, stirring time and compressed CO₂pressure are systemically examined to discuss the influence of these conditions on the morphology of ZSM-5zeolite. Interestingly, SEM images exhibit that the hierarchicalmesopores ZSM-5-S zeolite possess a uniform chain-like crystal morphology,whereas ZSM-5(conventional) display a monodisperse crystal morphology. Based onthe SEM images, it is observed that the length of chain-like crystal morphologyincreases with the decreasing of silica alumina molar ratio, stirring time also have aneffect on the morphology of ZSM-5-S zeolite. And these influence factors play theimportant roles in the formation of the chain-like crystal morphology.