Synthesis Of Magnetic Mesoporous Composite Nanospheres As Drug Carriers

Fe₃O₄nanoparticles （NPs） are superparamagnetic and high saturationmagnetization. Mesoporous SiO₂has high surface area. The magneticmesoporous nanospheres which are composed of mesoprous SiO₂shell andmagnetic Fe₃O₄core have potencial application in drug transportation, catalystand etc. In this paper, Fe₃O₄@SiO₂@mSiO₂nanospheres were prepared bysonochemical method, and were used as drug carriers. The loading releaseproperties of the magnetic mesoporous nanospheres were investigated. Themain content of this paper is as follows：1. Fe₃O₄NPs were prepared with solvothermal method. The experimentalresults showed that the morphology of the product was greatly influenced bysolvent and the presence of sodium citrate etc. The products had broad sizedistribution when EG was used as solvent. If EG and DEG were used assolvent, the prepared products had norrow size distribution, excellentcontrollability, good dispersion and antioxidation, and a saturatemagnetization of77.8emu/g. The sample produced prepared with EG and ethylenediamine as the solvent was small nanograins with a size of30nm. Theantioxidation ability of the product decreased obviously when sodium citratewas added.2. Combining ultrasonic wave and the St ber method, Fe₃O₄@SiO₂NPswere prepared, which was formed through the hydrolysis and polymerizationof tetraethoxysilane （TEOS） on the surface of Fe₃O₄NPs. The Fe₃O₄@SiO₂NPs prepared by this method had homogeneous SiO₂shell and gooddispersion. The result showed that increasing the TEOS dosage or prolongingthe reaction time could result in the increase of the shell thickness. In addition,the shell thickness would decrease with the increasing of ultrasonic power.3. In the synthesis of mesoporous SiO₂, cetyltriethylammonium bromide（CTAB） was used as the porogenic agent. The Fe₃O₄@SiO₂@mSiO₂CTABcomposites were prepared through the hydrolysis and polymerization of TEOSon the surface of Fe₃O₄@SiO₂. Hydrochloric acid ethanol solution wereemployed to extract CTAB, and then got the target product ofFe₃O₄@SiO₂@mSiO₂nanocomposites （MSs）. The MSs had high surface area（628m2/g）, high pore volume （0.45cm3/g） and norrow pore size distribution,（4.2nm）. The magnetization of the MSs was24.8emu/g.4.3（aminopropyl） triethoxysilane （APTES） was used as surfacemodification agent to prepare Fe₃O₄@SiO₂@mSiO₂NH₂（MSs NH₂） whichhas a surface area of167m2/g. Ibuprofen was chosen to test the loading abilityof MSs and MSs NH₂in different pH condition. The experimental results demonstrated that the carrying capacity of MSs and MSs NH₂were290mg/gand159mg/g, and the loading effciency were0.46mg·m2and0.95mg·m2,respectively. The MSs NH₂had better sustained release effect than MSs inneutral condition, and the release percent was about50%in80hours. Adiffusion controlled release mechanism is proposed.