The Preparation And Heat Effect Under Alternating Magnetic Field Of γ-Fe₂O₃Magnetic Nanoparticles

Magnetic nanoparticles have received much attention for their applications in various fields of medical care such as drug delivery system, cancer therapy, magnetic resonance imaging, tissue repair and cell separation. Local hyperthermia treatment of cancers is to inject the magnetic thermoseeds into the tumour area of patient. The heating of cancer area containing the implanted thermoseeds to elevate temperatures in an external alternating-current magnetic field, induce apoptosis of tumour cells. In particular, nanoparticles of magnetic y-Fe2O3, which are representative magnetic materials, have become perfect thermoseeds for local hyperthermia treatment of cancers with the super magnetic and inductive heating property.The y-Fe2O3magnetic nanaoparticles were prepared by oxidation of Fe3O4nanoparticles in the air,chemical co-precipitation and sol-gel method.The y-Fe2O3nanoparticles with different magnetic properties were prepared by oxidation of Fe3O4nanoparticles in the air. The size and structures of particles were analyzed by means of XRD, TEM and SEM. The results indicated that the particles are about5-20nm well-crystallized cubic particles with high purity and narrow particles size distribution. The potential of the y-Fe2O3nanoparticles was evaluated for localized hyperthermia treatment of cancers. The saturation magnetization Ms and coercivity He of y-Fe2O3nanoparticles were67.37emu/g and0Oe respectively. Exposed in the alternating current magnetic field for8min, the temperatures of physiological saline suspension containing γ-Fe2O3nanoparticles with concentration of20mg/ml were52.3℃. The y-Fe2O3nanoparticles would be useful as good thermoseeds for localized hyperthermia treatment of cancers.The y-Fe2O3nanoparticles with different magnetic properties were prepared by chemical co-precipitation. The size and structures of particles were analyzed by means of XRD and SEM. The results show that the particles prepared under5℃、10℃and20℃are rod-like y-Fe2O3nanoparticles with aspect ratio about5well-crystallized cubic particles with high purity and narrow particles size distribution. As the temperature increases, the rod-like structure disappears. The temperature of y-Fe2O3nanoparticles that is prepared under60℃co-precipitation temperature is best. The temperature that y-Fe2O3nanoparticles physiological salt water aqueous suspensions with concentration of50mg-ml-1reached is64℃in the alternating-current magnetic field for4min, and they can be used as thermoseeds for local hyperthermia treatment of cancers. The saturation magnetization Ms and coercivity He of y-Fe2O3nanoparticles were45.53emu/g and165Oe respectively. Nanoparticles γ-Fe2O3were prepared by using the Sol-Gel method. system. The samples were characterized by XRD and SEM. The thermal stability of the γ-Fe2O3samples was investigated. The results show that the average diameter of particles is30-50nm and that the structure ofNanocrystal γ-Fe2O3has a good stability. he saturation magnetization Ms and coercivity He of γ-Fe2O3nanoparticles prepared by Sol-Gel method is61.78emu·g-1and65Oe respectively under the optimum conditions of Fe(NO3)3:CH2OHCH2OH value at1:15and heated at300℃for2h. Exposed in the alternating current magnetic field for10min, the temperatures of physiological saline suspension containing γ-Fe2O3nanoparticles with concentration of50mg/ml were48.5℃. They can be used as thermoseeds for local hyperthermia treatment of cancers.