Magnetic SiO2 gel microspheres for arterial embolization hyperthermia.
We have prepared magnetic SiO(2) microspheres with a diameter of 20-30 µm as thermoseeds for hyperthermia of cancer. These were prepared by directly introducing preformed magnetic iron oxide nanoparticles (IONPs) into microspheres of a SiO(2) gel matrix derived from the hydrolysis of tetramethoxysilane (TMOS) in a water-in-oil (W/O) emulsion. Dimethylformamide (DMF) was used as a stabilizer, methanol (CH(3)OH) as a dispersant and ammonia (NH(4)OH) as the catalyst for the formation of the spherical particles in the aqueous phase of the W/O emulsion. The magnetic IONPs were synthesized hydrochemically in an aqueous system composed of ferrous chloride, sodium nitrate and sodium hydroxide. Mono-dispersed magnetic SiO(2) gel microspheres with a diameter of approximately 20 µm were successfully obtained by adding a determined amount of solution with a molar ratio of TMOS/DMF/CH(3)OH/H(2)O/NH(4)OH = 1:1.4:9:20:0.03 to kerosene with a surfactant (sorbitan monooleate/sorbitan monostearate = 3:1 by weight ratio) that was 30 wt% of the total amount of the oil phase. These were estimated to contain up to 60 wt% of IONPs that consisted mainly of Fe(3)O(4) and showed a higher specific absorption rate (SAR = 27.9-43.8 W g(-1)) than that of the starting IONPs (SAR = 25.3 W g(-1)) under an alternating current magnetic field of 300 Oe and 100 kHz.
Graduate School of Biomedical Engineering, Tohoku University, 6-6-11-1306-1, Aramaki-Aoba, Aoba-ku, Sendai 980-8579, Japan. zhixia@ecei.tohoku.ac.jp
Zhixia
Z
Li
Masakazu
M
Kawashita
Norio
N
Araki
Michihide
M
Mitsumori
Masahiro
M
Hiraoka
Masaaki
M
Doi
D004574:Electromagnetic Fields; D004621:Embolization, Therapeutic / Q000379:methods*; D006490:Hemostatics / Q000138:chemical synthesis* / Q000627:therapeutic use; D006979:Hyperthermia, Induced / Q000379:methods*; D008280:Magnetics / Q000379:methods; D008422:Materials Testing; D008863:Microspheres; D012822:Silicon Dioxide / Q000737:chemistry* / Q000528:radiation effects*
D006490:Hemostatics; D012822:Silicon Dioxide