title: Ultra-small, uniform, and single bcc-phased Fe(x)Co(1-x)/graphitic shell nanocrystals for T1 magnetic resonance imaging contrast agents.
abstract: We have synthesized ultra-small and uniform Fe(x)Co(1-x)/graphitic carbon shell (Fe(x)Co(1-x)/GC) nanocrystals (x=0.13, 0.36, 0.42, 0.50, 0.56, and 0.62, respectively) with average diameters of <4 nm by thermal decomposition of metal precursors in approximately 60 nm MCM-41 and methane CVD. The composition of the Fe(x)Co(1-x)/GC nanocrystals can be tuned by changing the Fe:Co ratios of the metal precursors. The Fe(x)Co(1-x)/GC nanocrystals show superparamagnetic properties at room temperature. The Fe(0.50)Co(0.50)/GC, Fe(0.56)Co(0.44)/GC, and Fe(0.62)Co(0.38)/GC nanocrystals have a single bcc FeCo structure, whereas the Fe(0.13)Co(0.87)/GC, Fe(0.36)Co(0.64)/GC, and Fe(0.42)Co(0.58)/GC nanocrystals have a mixed structure of bcc FeCo and fcc Co. The single bcc-phased Fe(x)Co(1-x)/GC nanocrystals functionalized with phospholipid-poly(ethylene glycol) (PL-PEG) in phosphate buffered saline (PBS) are demonstrated to be excellent T(1) MRI contrast agents.
authors.affiliation: Department of Chemistry and Inorganic and Bio-Materials Center of BK21, Sogang University, Seoul, 121-742, Korea.
authors.forename: In Ae
authors.initials: IA
authors.lastname: Choi
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Da Jeong
authors.initials: DJ
authors.lastname: Kim
authors.forename: Mou
authors.initials: M
authors.lastname: Pal
authors.forename: Jee-Hyun
authors.initials: JH
authors.lastname: Cho
authors.forename: Kyujoon
authors.initials: K
authors.lastname: Lee
authors.forename: Myung-Hwa
authors.initials: MH
authors.lastname: Jung
authors.forename: Chulhyun
authors.initials: C
authors.lastname: Lee
authors.forename: Won Seok
authors.initials: WS
authors.lastname: Seo
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D003287:Contrast Media; D006108:Graphite / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles
chemical_list: D003287:Contrast Media; D003035:Cobalt; D006108:Graphite; D007501:Iron