title: Monodispersed core-shell Fe3O4@Au nanoparticles.
abstract: The ability to synthesize and assemble monodispersed core-shell nanoparticles is important for exploring the unique properties of nanoscale core, shell, or their combinations in technological applications. This paper describes findings of an investigation of the synthesis and assembly of core (Fe(3)O(4))-shell (Au) nanoparticles with high monodispersity. Fe(3)O(4) nanoparticles of selected sizes were used as seeding materials for the reduction of gold precursors to produce gold-coated Fe(3)O(4) nanoparticles (Fe(3)O(4)@Au). Experimental data from both physical and chemical determinations of the changes in particle size, surface plasmon resonance optical band, core-shell composition, surface reactivity, and magnetic properties have confirmed the formation of the core-shell nanostructure. The interfacial reactivity of a combination of ligand-exchanging and interparticle cross-linking was exploited for molecularly mediated thin film assembly of the core-shell nanoparticles. The SQUID data reveal a decrease in magnetization and blocking temperature and an increase in coercivity for Fe(3)O(4)@Au, reflecting the decreased coupling of the magnetic moments as a result of the increased interparticle spacing by both gold and capping shells. Implications of the findings to the design of interfacial reactivities via core-shell nanocomposites for magnetic, catalytic, and biological applications are also briefly discussed.
authors.affiliation: Department of Chemistry, State University of New York at Binghamton, Binghamton, New York 13902, USA.
authors.forename: Lingyan
authors.initials: L
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Luo
authors.forename: Quan
authors.initials: Q
authors.lastname: Fan
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Suzuki
authors.forename: Itsuko S
authors.initials: IS
authors.lastname: Suzuki
authors.forename: Mark H
authors.initials: MH
authors.lastname: Engelhard
authors.forename: Yuehe
authors.initials: Y
authors.lastname: Lin
authors.forename: Nam
authors.initials: N
authors.lastname: Kim
authors.forename: Jian Q
authors.initials: JQ
authors.lastname: Wang
authors.forename: Chuan-Jian
authors.initials: CJ
authors.lastname: Zhong
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008280:Magnetics; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide; D006046:Gold