title: Water-soluble superparamagnetic magnetite nanoparticles with biocompatible coating for enhanced magnetic resonance imaging.
abstract: Ultrasmall superparamagnetic Fe(3)O(4) nanoparticles (USIRONs) were synthesized by a novel, easily scalable chemical reduction of colloidal iron hydroxide under hydrothermal conditions. The average crystallite size (5.1 ± 0.5 nm) and good crystallinity of the samples were supported by HR-TEM analysis and the saturation magnetization value (47 emu g(-1)). Vitamin C, used as a chemical reducing agent, also served as a capping agent in the oxidized form (dehydroascorbic acid, DHAA) to impart nanoparticles with exceptional solubility and stability in water, PBS buffer, and cell culture medium. Detailed physicochemical analysis of the USIRON suspensions provided insight into the magnetic ordering phenomena within the colloid, arising from the formation of uniform clusters displaying a hydrodynamic size of 41 nm. Phantom experiments on the contrast agent (clinical 3 T MRI scanner) revealed an enhanced r(2)/r(1) ratio of 36.4 (r(1)= 5 s(-1) mM(-1) and r(2)= 182 s(-1) mM(-1)) when compared to the clinically approved agents. The potential of the DHAA-Fe(3)O(4) nanoparticles as negative contrast agents for MRI with optimal hydrodynamic size for extended blood circulation times was confirmed by strong contrast observed in T(2)- and T(2)*-weighted images. The cell tests performed with primary human immune-competent cells confirmed the excellent biocompatibility of USIRONs.
authors.affiliation: Chair Institute of Inorganic and Materials Chemistry, University of Cologne, D-50939 Cologne, Germany.
authors.forename: Lisong
authors.initials: L
authors.lastname: Xiao
authors.forename: Jiangtian
authors.initials: J
authors.lastname: Li
authors.forename: Dermot F
authors.initials: DF
authors.lastname: Brougham
authors.forename: Eoin K
authors.initials: EK
authors.lastname: Fox
authors.forename: Neus
authors.initials: N
authors.lastname: Feliu
authors.forename: Alexey
authors.initials: A
authors.lastname: Bushmelev
authors.forename: Annette
authors.initials: A
authors.lastname: Schmidt
authors.forename: Natascha
authors.initials: N
authors.lastname: Mertens
authors.forename: Fabian
authors.initials: F
authors.lastname: Kiessling
authors.forename: Martin
authors.initials: M
authors.lastname: Valldor
authors.forename: Bengt
authors.initials: B
authors.lastname: Fadeel
authors.forename: Sanjay
authors.initials: S
authors.lastname: Mathur
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002470:Cell Survival / Q000187:drug effects; D003287:Contrast Media / Q000737:chemistry* / Q000633:toxicity; D003683:Dehydroascorbic Acid / Q000737:chemistry; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000187:drug effects; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D008958:Models, Molecular; D008968:Molecular Conformation; D012995:Solubility; D013535:Suspensions; D014867:Water / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D003287:Contrast Media; D058185:Magnetite Nanoparticles; D013535:Suspensions; D014867:Water; D003683:Dehydroascorbic Acid