Fabrication, Characterization And Drug Delivery Application Of Composite Hollow Magnetic Particles

Magnetic iron oxide nanoparticles (MIONPs) could be widely used inbiomedical areas after surface modifying or coating. However, how tobroaden the application of MIONPs in drug delivery and how to reducetheir intrinsic biological toxicity are the focuses in recent research. Byconsidering all above reasons, this thesis focuses on fabricating thebiocompatible polymer coated magnetite (Fe3O4) nanoparticles, andevaluating their toxicity and preliminary application in drug delivery. Thethesis is composed by the following parts:1. Hollow magnetite particles were prepared with tunable size andstructure by employing ethylene glycol (EG) as solvent and reducingagent, Iron(III) chloride hexahydrate (FeCl3·6H2O) as only ferric ionresource and anhydrous sodium acetate (NaAc) as alkalinestructure-directing reagent. The influences of reaction time, molar ratio ofreactants on the size, morphology, crystal structure and magneticproperties of hollow Fe3O4nanoparticles had been carefully investigated.By combination of all characterization data analysis of SEM, TEM, XRDand VSM, the results were concluded as follows: the hollow Fe3O4hadbeen prepared with an average size of about222nm and its saturationmagnetization (Ms) was125.00emu·g-1, moreover, the Fe3O4nanoparticles demonstrated obvious hollow structure and fine crystalstructure of spinel phase of magnetite.2. The polyacrylic acid (PAA) was coated on the surface of(3-aminopropyl) triethoxysilane (APTES)-modified Fe3O4nanoparticlesby chemical cross-linking method. Then the composite nanoparticleswere characterized with various means of SEM, TEM, XRD, FourierTransform Infrared spectroscopy（FTIR）、Thermogravimetry（TG）andVSM. The major results were as follows: the thermogravimetry analysisshowed that the composite nanoparticles had presented a weight loss of25.2%caused by PAA coating, thus it could be roughly estimated that themass ratio (W/W) of PAA coating onto Fe3O4was about40%in thehollow magnetic Fe3O4@PAA nanocomposites. What’s more, the MsValue of Fe3O4@PAA nanoparticles decreased as compared to that of pristine Fe3O4nanoparticles. The Ms decrease was attributed to both theinterlayer of APTES and surface layer of PAA coating. Nevertheless, themagnetic response property of the composites was still excellent.3. The performances of toxicity and model drug delivery of theFe3O4@PAA nanoparticles were further investigated. The toxicitycomparison between the hollow Fe3O4nanoparticles and the Fe3O4@PAAnanoparticles to saccharomycetes had revealed that the medial lethalconcentration and half lethal time of Fe3O4nanoparticles were0.100g/Land1hour, respectively. While there was no distinct toxic effect of1.00g/L Fe3O4@PAA nanoparticles on saccharomycetes after its exposure for8hours. The results implied that the cytotoxicity of the composites hadbeen evidently reduced after PAA-coating. As a result, the composites’biocompatibility was greatly improved as they are applied in drugdelivery.In the experiment of model drug rhodamine6G (R6G) delivery ofFe3O4@PAA nanoparticles, the results were shown as follows: Themaximum adsorptive capacity was reached1011mg R6G per1.00g ofthe Fe3O4@PAA nanoparticles when the adsorptive temperature was30°C, the adsorptive time was30min and the adsorptive concentrationwas0.15×10-1mol/L in pH=7.4PBS buffer. Moreover, the optimal drugreleasing rate was achieved93.0%in pH=7.4PBS solution after14hours.The releasing rate could also be satisfying in acidic condition, although itwas only about86.5%. The above results indicated that acceptable lowertoxicity and superior drug delivery properties were endowed with theFe3O4@PAA composite nanoparticles.