title: Antiferromagnetic iron nanocolloids: a new generation in vivo T1 MRI contrast agent.
abstract: A novel T1 agent, antiferromagnetic α-iron oxide-hydroxide (α-FeOOH) nanocolloids with a diameter of 2-3 nm, has been successfully prepared. These nanocolloids, together with a post synthetic strategy performed in mesoporous silica, are a great improvement over the low T1-weighted contrast common in traditional magnetic silica nanocomposites. The intrinsic antiferromagnetic goethite (α-FeOOH) shows very low magnetization (M(z)) of 0.05 emu g(-1) at H = 2 T at 300 K (0.0006 emu g(-1) for FeOOH/WMSN-PEG), which is 2 orders of magnitude smaller than any current ultrasmall iron oxide NPs (>5 emu g(-1)) reported to date, hence ensuring the low r2 (∝ Mz) (7.64 mM(-1) s(-1)) and r2/r1 ratio (2.03) at 4.7 T. These biodegradable α-FeOOH nanocolloids also demonstrate excellent in vitro cellular imaging and in vivo MR vascular and urinary trace imaging capability with outstanding biocompatibility, which is exceptionally well secreted by the kidney and not the liver as with most nanoparticles, opening up a new avenue for designing powerful antiferromagnetic iron T1 contrast agents.
authors.affiliation: Department of Chemistry, National Taiwan University , Taipei, Taiwan.
authors.forename: Yung-Kang
authors.initials: YK
authors.lastname: Peng
authors.forename: Chien-Liang
authors.initials: CL
authors.lastname: Liu
authors.forename: Hsieh-Chih
authors.initials: HC
authors.lastname: Chen
authors.forename: Shang-Wei
authors.initials: SW
authors.lastname: Chou
authors.forename: Wei-Hsuan
authors.initials: WH
authors.lastname: Tseng
authors.forename: Yu-Jui
authors.initials: YJ
authors.lastname: Tseng
authors.forename: Chia-Cheng
authors.initials: CC
authors.lastname: Kang
authors.forename: Jong-Kai
authors.initials: JK
authors.lastname: Hsiao
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
mesh_terms: D003102:Colloids; D003287:Contrast Media; D007501:Iron / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D053768:Metal Nanoparticles; D046529:Microscopy, Electron, Transmission
chemical_list: D003102:Colloids; D003287:Contrast Media; D007501:Iron