title: Direct coating of gold nanoparticles with silica by a seeded polymerization technique.
abstract: Gold nanoparticles prepared through a conventional citrate-reduction method were directly coated with silica by means of a seeded polymerization technique based on the Stöber method. The method required no surface modification. The addition of tetraethylorthosilicate and water prior to ammonia was found to be critical to obtain a proper coating. The silica shell thickness was varied from 30 to 90 nm for TEOS concentrations of 0.0005-0.02 M at 10.9 M of water and 0.4 M of ammonia. The optical spectra of the core-shell gold-silica composite particles agreed with predictions of Mie theory.
authors.affiliation: Department of Chemical Engineering, Graduate School of Engineering, Tohoku University, Aoba, Aramaki-aza, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Mine
authors.forename: Akira
authors.initials: A
authors.lastname: Yamada
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Mikio
authors.initials: M
authors.lastname: Konno
authors.forename: Luis M
authors.initials: LM
authors.lastname: Liz-Marzán