title: Characterization of superparamagnetic iron oxide coated with silicone used as contrast agent for magnetic resonance image for the gastrointestinal tract.
abstract: The present work is a report of the characterization of superparamagnetic iron oxide nanoparticles coated with silicone used as a contrast agent in magnetic resonance imaging of the gastrointestinal tract. The hydrodynamic size of the contrast agent is 281.2 nm, where it was determined by transmission electron microscopy and a Fe3O4 crystalline structure was identified by X-ray diffraction, also confirmed by Mössbauer Spectroscopy. The blocking temperature of 190 K was determined from magnetic measurements based on the Zero Field Cooled and Field Cooled methods. The hysteresis loops were measured at different temperatures below and above the blocking temperature. Ferromagnetic resonance analysis indicated the superparamagnetic nature of the nanoparticles and a strong temperature dependence of the peak-to-peak linewidth deltaH(pp), giromagnetic factor g, number of spins N(s) and relaxation time T2 were observed. This behavior can be attributed to an increase in the superexchange interaction.
authors.affiliation: Instituto de Ensino e Pesquisa, Hospital Israelita Albert Einstein IIEPAE, 05651-901 São Paulo, Brazil.
authors.forename: L F
authors.initials: LF
authors.lastname: Gamarra
authors.forename: J B
authors.initials: JB
authors.lastname: Mamani
authors.forename: S M
authors.initials: SM
authors.lastname: Carneiro
authors.forename: J D
authors.initials: JD
authors.lastname: Fabris
authors.forename: R V
authors.initials: RV
authors.lastname: Ferreira
authors.forename: R Z
authors.initials: RZ
authors.lastname: Domingues
authors.forename: D R
authors.initials: DR
authors.lastname: Cornejo
authors.forename: W M
authors.initials: WM
authors.lastname: Pontuschka
authors.forename: E Júnior
authors.initials: EJ
authors.lastname: Amaro
mesh_terms: D003287:Contrast Media; D005290:Ferric Compounds / Q000737:chemistry*; D041981:Gastrointestinal Tract / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D046529:Microscopy, Electron, Transmission; D012828:Silicones / Q000737:chemistry*; D015204:Spectroscopy, Mossbauer
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D012828:Silicones; C000499:ferric oxide