Preparation And Properties Of Fe₃O₄ Based Multifunctional Nano-core-shell Structure

Magnetic core-shell structure multifunctional nanomaterials have become a research hotspot of new nanomaterials due to their multiple specific functions,and play a major role in a wide range of fields.Under the background of this research,this thesis focuses on the preparation and properties of multifunctional nanoparticles with core-nuclear shell structure based on magnetic Fe₃O₄.Fe₃O₄@SiO₂ and Fe₃O₄@SiO₂@HAP core-shell composite nanoparticles are prepared in the laboratory.Before the preparation of magnetic Fe₃O₄ based multifunctional composite nanoparticles,pure Fe₃O₄ and SiO₂ nanoparticles were synthesized first.The hydrothermal method?the first method?and the coprecipitation method?the second method?were used to prepare the target product,and the experimental target products prepared by the two methods were characterized by X-ray diffractometry and transmission electron microscopy.The nanoparticles can be successfully prepared and have good superparamagnetism with a particle size of about 20 nm.By comparing the two synthetic methods,it is found that the magnetic Fe₃O₄ nanoparticles prepared by the coprecipitation method are prone to agglomeration,which is not conducive to subsequent synthesis of multilayer composite nanoparticles.Then the experimental conditions?heat treatment temperature,heat treatment time,ammonia water consumption?which affect the synthesis of Fe₃O₄ nanoparticles were analyzed,and the optimal reaction conditions for the preparation of Fe₃O₄ nanoparticles were obtained.SiO₂ nanoparticles were prepared by self-assembly synthesis method,and the prepared nanoparticles were uniform in particle size.Then,X-ray diffraction analysis and transmission electrons were performed on SiO₂ nanoparticles synthesized under different experimental conditions?such as temperature,heat treatment time and ethanol content?.Microscopic analysis led to the best preparation conditions.Based on the previous two steps,the optimal experimental conditions were used to coat the surface of magnetic Fe₃O₄ nanoparticles to prepare Fe₃O₄@SiO₂ core-shell composite nanoparticles.The synthesized nanoparticles were found to have the core-shell structure,SiO₂ can be uniformly coated on the outside of the Fe₃O₄ nanoparticles,and can exhibit certain magnetic properties,but the magnetic saturation strength is weakened,indicating that the outer shell layer can weaken the magnetic properties.Finally,the Fe₃O₄@SiO₂ nanoparticles were coated once again.This time,hydroxyapatite was used as the coating layer to synthesize Fe₃O₄@SiO₂@HAP nanoparticles.The composite nanoparticles core-shells of this core-shell structure were found through analysis.The layer does not react between the layers,and the outer layer evenly covers the surface.It exhibits good biocompatibility in the in vitro simulated body fluid?SBF?test.It is found by external magnetic field test,Fe₃O₄@SiO₂@HAP The core-shell nanoparticles exhibit magnetic properties,and the saturation magnetization is weaker than that of Fe₃O₄@SiO₂,indicating that the magnetic attenuation of the core Fe₃O₄ increases with the increase of the number of outer shell layers.Therefore,the magnetic properties and biocompatibility of Fe₃O₄@SiO₂@HAP core-shell nanoparticles can make it a good application potential in the biomedical field as a targeted drug delivery carrier.It was found through analysis that the Fe₃O₄@SiO₂ particles prepared in the laboratory have obvious core-shell structure,and the particle size is larger than that of pure ferroferric oxide,which is between 42nm to 55nm,and the magnetic strength is 34.8emu/g.Fe₃O₄@SiO₂@HAP nanoparticle,the nanoparticle also has a core-shell structure,the particle size is increased,about 65nm,magnetic strength is 24.6emu/g,and simulated body fluid?SBF?detection by nanoparticles.It was found that the hydroxyapatite layer on the outer surface can express biological activity,making Fe₃O₄@SiO₂@HAP have good biocompatibility and is a good carrier for targeted drug delivery in vivo.