磁性二氧化硅纳米粒子的制备及性能

为了克服磁性四氧化三铁纳米粒子易团聚、易氧化、耐酸性差等缺点,提高其在催化剂、靶向药物载体、生物分离、核磁共振成像、磁热疗等领域的利用效率,采用共沉淀法合成了四氧化三铁纳米粒子,然后以其为核用Stber法制备出二氧化硅包覆四氧化三铁的复合纳米粒子.对包覆前及包覆后的磁性纳米粒子分别进行了X射线衍射、透射电子显微镜、振动样品磁强计的表征,并研究了二氧化硅的包覆对四氧化三铁纳米粒子磁性和耐酸性的影响.实验结果表明:磁性四氧化三铁及磁性二氧化硅纳米粒子的粒径分别为约20 nm和40 nm;磁性四氧化三铁的磁饱和强度为5.7 emu/g,磁性二氧化硅纳米粒子的磁饱和强度也达到5.1 emu/g;此外,在稍微降低磁性的条件下,表面二氧化硅的包覆显著改善了四氧化三铁纳米粒子的分散性和耐酸性.

Preparation and properties of magnetic silica nanoparticles

To overcome the deficiency of magnetic ferroferric oxide nanoparticles such as agglomeration, oxidation and bad acid resistance, and to improve its use efficiency in the fields of catalyst, targeting drug delivery, bioseparation, magnetic resonance imaging and magnetic mediated hyperthermia, magnetic ferroferric oxide nanoparticles were synthesized by a co-precipitation process, and employed as the core to prepare magnetic silica nanoparticles. The nanoparticles were characterized by X-ray diffraction, transmission electron microscope and vibrating sample magnetometer. Besides, the magnetism and the acid resistance of nanoparticles were investigated. The particle sizes of the obtained magnetic ferrosoferric oxide and magnetic silica nanoparticles are about 20 and 40 nm, and their magnetic saturation in- tensity is 5.7 emu/g and 5.1 emu/g respectively. In addition, the dispersibility and the acid resistance are significantly improved by the silica coating of magnetic ferrosoferric oxide nanoparticles with merely a slight decrease of the magnetic saturation intensity.