title: Aqueous dispersions of magnetite nanoparticles with NH3+ surfaces for magnetic manipulations of biomolecules and MRI contrast agents.
abstract: In the current study, amine surface modified iron-oxide nanoparticles of 6 nm diameter without polymer coating were fabricated in an aqueous solution by organic acid modification as an adherent following chemical coprecipitation. Structure and the superparamagnetic property of magnetite nanoparticles were characterized by selected area electron diffraction (SAED) and superconducting quantum interference measurement device (SQUID). X-ray photoelectron spectrometer (XPS) and zeta potential measurements revealed cationic surface mostly decorated with terminal -NH(3)(+). This feature enables them to function as a magnetic carrier for nucleotides via electrostatic interaction. In addition, Fe(3)O(4)/trypsin conjugates with well-preserved functional activity was demonstrated. The nanoparticles displayed excellent in vitro biocompatibility. The NMR and the in vitro MRI measurements showed significantly reduced water proton relaxation times of both T(1) and T(2). Significantly reduced T(2) and T(2)*-weighted signal intensity were observed in a 1.5 T clinical MR imager. In vivo imaging contrast effect showed a fast and prolonged inverse contrast effect in the liver that lasted for more than 1 week. In addition, it was found that the spherical Fe(3)O(4) assembled as rod-like configuration through an aging process in aqueous solution at room temperature. Interestingly, TEM observation of the liver tissue revealed the rod-like shape but not the spherical-type nanoparticles being taken up by the Kupffer cells 120 h after tail vein infusion. Combining these results, we have demonstrated the potential applications of the newly synthesized magnetite nanoparticles in a broad spectrum of biomedical applications.
authors.affiliation: Department of Dentistry and Institute of Oral Medicine, National Cheng Kung University, Tainan, Taiwan. dshieh@mail.ncku.edu.tw
authors.forename: Dar-Bin
authors.initials: DB
authors.lastname: Shieh
authors.forename: Fong-Yu
authors.initials: FY
authors.lastname: Cheng
authors.forename: Chia-Hao
authors.initials: CH
authors.lastname: Su
authors.forename: Chen-Sheng
authors.initials: CS
authors.lastname: Yeh
authors.forename: Ming-Ting
authors.initials: MT
authors.lastname: Wu
authors.forename: Ya-Na
authors.initials: YN
authors.lastname: Wu
authors.forename: Chiau-Yuang
authors.initials: CY
authors.lastname: Tsai
authors.forename: Chao-Liang
authors.initials: CL
authors.lastname: Wu
authors.forename: Dong-Hwang
authors.initials: DH
authors.lastname: Chen
authors.forename: Chen-Hsi
authors.initials: CH
authors.lastname: Chou
mesh_terms: D000818:Animals; D001704:Biopolymers / Q000032:analysis / Q000737:chemistry; D019556:COS Cells; D002522:Chlorocebus aethiops; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D003102:Colloids / Q000737:chemistry; D003287:Contrast Media / Q000737:chemistry*; D007089:Image Enhancement / Q000379:methods; D018189:Immunomagnetic Separation / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008422:Materials Testing; D008846:Micromanipulation / Q000379:methods*; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012996:Solutions; D014867:Water / Q000737:chemistry
chemical_list: D001704:Biopolymers; D020099:Coated Materials, Biocompatible; D003102:Colloids; D003287:Contrast Media; D000644:Quaternary Ammonium Compounds; D012996:Solutions; D014867:Water