title: In vitro heat generation by ferrimagnetic maghemite microspheres for hyperthermic treatment of cancer under an alternating magnetic field.
abstract: Ferrimagnetic materials can be expected to be useful as thermo seeds for hyperthermic treatment of cancer, especially where the cancer is located in deep parts of body, as they can generate heat by magnetic hysteretic loss when they are placed in an alternating magnetic field. Recently, it was reported that ferrimagnetic maghemite (gamma-Fe2O3) microspheres 20-30 microm in diameter prepared in aqueous solution can show excellent heat generating ability. However, these microspheres have many cracks on their surfaces. In this study, the preparation conditions for the microspheres was further optimized in order to obtain crack-free ferrimagnetic microspheres, and the in vitro heat generation of the obtained microspheres was measured in an agar phantom under an alternating magnetic field. Crack-free gamma-Fe2O3 microspheres 20-30 microm in diameter were obtained successfully. Their saturation magnetization and coercive force were 68 emu g(-1) and 198 Oe, respectively. Their heat generation under an alternating magnetic field of 300 Oe at 100 kHz was estimated to be 42 W g(-1). The microspheres showed in vitro heat generation when they were dispersed in an agar phantom and placed under an alternating magnetic field. It is believed that these microspheres may be useful for the in situ hyperthermic treatment of cancer.
authors.affiliation: Photonics and Electronics Science and Engineering Center, Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan. kawashita@kuee.kyoto-u.ac.jp
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kawashita
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Domi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Saito
authors.forename: Masaaki
authors.initials: M
authors.lastname: Aoki
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Ebisawa
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kokubo
authors.forename: Takashi
authors.initials: T
authors.lastname: Saito
authors.forename: Mikio
authors.initials: M
authors.lastname: Takano
authors.forename: Norio
authors.initials: N
authors.lastname: Araki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hiraoka
mesh_terms: D000362:Agar; D004574:Electromagnetic Fields; D004867:Equipment Design; D005290:Ferric Compounds / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D006979:Hyperthermia, Induced; D008280:Magnetics; D008422:Materials Testing; D008863:Microspheres; D015233:Models, Statistical; D009369:Neoplasms / Q000628:therapy*; D019047:Phantoms, Imaging; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D005290:Ferric Compounds; D014867:Water; C000499:ferric oxide; D000362:Agar