Ferrimagnetic microspheres 20-30 μm in diameter are useful as thermoseeds for hyperthermia of cancers, especially for those located at deep parts of the body, since they are entrapped in the capillary bed of the tumors and heat cancers locally by hysteresis loss of the ferrimagnetic materials, when they are implanted into the tumors through blood vessels and then placed under an alternating magnetic field. In the present study, preparation of magnetite (Fe3O4) microspheres 20-30 μm in diameter was attempted by melting powders in high-frequency induction thermal plasma and a precipitation from solution. The microspheres 20-30 μm in size as-prepared by melting powders in high-frequency induction thermal plasma were composed of a large amount of magnetite and a small amount of wustite (FeO), and those subsequently heat-treated at 600°C for 1 h under 0.05 atm were fully composed of magnetite 1 μm in size. The saturation magnetization (Ms) and coercive force (Hc) of the heat-treated microspheres were 92 emu·g-1 and 50 Oe, respectively. The heat-treated microspheres showed the heat generation, 10 W·g-1, under 300 Oe and 100 kHz. On the other hand, the microspheres 20-30 μm in diameter as-prepared by a precipitation from solution consisted of β-FeOOH, and those subsequently heat-treated at 600°C for 1 h in 70CO2+30H2 atmosphere consisted of magnetite 50 nm in size. The Ms and Hc of the heat-treated microspheres were 53 emu·g-1 and 156 Oe, respectively. The heat-treated microspheres showed the heat generation, 41 W·g-1, under 300 Oe and 100 kHz. It can be concluded from these results that the microspheres prepared by a precipitation from solution and subsequently heat-treated at 600°C for 1 h in 70CO2+30H2 atmosphere can be a promising candidate of thermoseeds for hyperthermia of cancer.
|ジャーナル||Key Engineering Materials|
|出版ステータス||Published - 2002 1月 1|
|イベント||14th International Symposium on Ceramics in Medicine-Annual Meeting of the International Society for Ceramics in Medicine BIOCERAMICS'01 (ISCM) - Palm Springs, CA, United States|
継続期間: 2001 11月 14 → 2001 11月 17
ASJC Scopus subject areas