title: Cubic Silica-Coated and Amine-Functionalized FeCo Nanoparticles with High Saturation Magnetization.
abstract: By systematically varying the reaction parameters in a liquid-phase reduction reaction, large FeCo nanocubes with tunable body diagonal lengths of 175, 350, and 450 nm were synthesized. The nanocubes were initially stabilized with poly(vinyl pyrrolidone) (PVP) and then coated with a relatively thin layer of silica (~55 nm thick), which allowed them to retain their cubic shape. The magnetization curves showed that the PVP-stabilized nanocubes exhibited a high saturation magnetization of 167 ± 4 emu/g. The saturation magnetization, however, decreased upon coating with silica to 146 ± 13 emu/g for the particles with 350 and 450 nm FeCo cores and 48 ± 1 emu/g for the particles with 175 nm FeCo cores. The silica-coated FeCo nanocubes were then functionalized with 3-(aminopropyl)-trimethoxysilane (APTMS), and a layer of surface-bound nanoparticle was generated by exposing the resultant amine-functionalized nanocubes to self-assembled monolayers (SAMs) on gold terminated with carboxylic-acid groups.
authors.affiliation: Department of Chemistry and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204, United States.
authors.forename: Arati G
authors.initials: AG
authors.lastname: Kolhatkar
authors.affiliation: Department of Electrical and Computer Engineering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204, United States.
authors.forename: Ivan
authors.initials: I
authors.lastname: Nekrashevich
authors.affiliation: Department of Electrical and Computer Engineering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204, United States ; Department of Chemical and Biomolecular Engineering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204, United States ; Department of Chemistry and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204, United States.
authors.forename: Dmitri
authors.initials: D
authors.lastname: Litvinov
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204, United States.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Willson
authors.affiliation: Department of Chemistry and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204, United States.
authors.forename: T Randall
authors.initials: TR
authors.lastname: Lee
keywords: FeCo; amine-functionalized; biosensor; cubic; nanocube; nanoparticle; saturation magnetization; silica-coated