title: Development of iron-doped silicon nanoparticles as bimodal imaging agents.
abstract: We demonstrate the synthesis of water-soluble allylamine-terminated Fe-doped Si (Si(xFe)) nanoparticles as bimodal agents for optical and magnetic imaging. The preparation involves the synthesis of a single-source iron-containing precursor, Na(4)Si(4) with x% Fe (x = 1, 5, 10), and its subsequent reaction with NH(4)Br to produce hydrogen-terminated Si(xFe) nanoparticles. The hydrogen-capped nanoparticles are further terminated with allylamine via thermal hydrosilylation. Transmission electron microscopy indicates that the average particle diameter is ∼3.0 ± 1.0 nm. The Si(5Fe) nanoparticles show strong photoluminescence quantum yield in water (∼10%) with significant T(2) contrast (r(2)/r(1) value of 4.31). Electron paramagnetic resonance and Mössbauer spectroscopies indicate that iron in the nanoparticles is in the +3 oxidation state. Analysis of cytotoxicity using the resazurin assay on HepG2 liver cells indicates that the particles have minimal toxicity.
authors.affiliation: Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, USA.
authors.forename: Mani P
authors.initials: MP
authors.lastname: Singh
authors.forename: Tonya M
authors.initials: TM
authors.lastname: Atkins
authors.forename: Elayaraja
authors.initials: E
authors.lastname: Muthuswamy
authors.forename: Saeed
authors.initials: S
authors.lastname: Kamali
authors.forename: Chuqiao
authors.initials: C
authors.lastname: Tu
authors.forename: Angelique Y
authors.initials: AY
authors.lastname: Louie
authors.forename: Susan M
authors.initials: SM
authors.lastname: Kauzlarich
mesh_terms: D045744:Cell Line, Tumor; D003287:Contrast Media / Q000138:chemical synthesis*; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007501:Iron / Q000737:chemistry; D008113:Liver Neoplasms / Q000473:pathology*; D008856:Microscopy, Fluorescence / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry; D012825:Silicon / Q000737:chemistry*
chemical_list: D003287:Contrast Media; D007501:Iron; D012825:Silicon