title: Direct Fabrication of Monodisperse Silica Nanorings from Hollow Spheres - A Template for Core-Shell Nanorings.
abstract: We report a new type of nanosphere colloidal lithography to directly fabricate monodisperse silica (SiO2) nanorings by means of reactive ion etching of hollow SiO2 spheres. Detailed TEM, SEM, and AFM structural analysis is complemented by a model describing the geometrical transition from hollow sphere to ring during the etching process. The resulting silica nanorings can be readily redispersed in solution and subsequently serve as universal templates for the synthesis of ring-shaped core-shell nanostructures. As an example we used silica nanorings (with diameter of ∼200 nm) to create a novel plasmonic nanoparticle topology, a silica-Au core-shell nanoring, by self-assembly of Au nanoparticles (<20 nm) on the ring's surface. Spectroscopic measurements and finite difference time domain simulations reveal high quality factor multipolar and antibonding surface plasmon resonances in the near-infrared. By loading different types of nanoparticles on the silica core, hybrid and multifunctional composite nanoring structures could be realized for applications such as MRI contrast enhancement, catalysis, drug delivery, plasmonic and magnetic hyperthermia, photoacoustic imaging, and biochemical sensing.
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200D, B-3001 Leuven, Belgium.
authors.forename: Kuo
authors.initials: K
authors.lastname: Zhong
authors.affiliation: IMEC, Kapeldreef 75, B-3001 Leuven, Belgium.|Laboratory of Solid-State Physics and Magnetism, Department of Physics and Astronomy, KU Leuven , Celestijnenlaan 200D, B-3001 Leuven, Belgium.
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Li
authors.affiliation: Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven , Celestijnenlaan 200D, B-3001 Leuven, Belgium.
authors.forename: Liwang
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200D, B-3001 Leuven, Belgium.
authors.forename: Ward
authors.initials: W
authors.lastname: Brullot
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200D, B-3001 Leuven, Belgium.
authors.forename: Maarten
authors.initials: M
authors.lastname: Bloemen
authors.affiliation: Laboratory of Solid-State Physics and Magnetism, Department of Physics and Astronomy, KU Leuven , Celestijnenlaan 200D, B-3001 Leuven, Belgium.
authors.forename: Alexander
authors.initials: A
authors.lastname: Volodin
authors.affiliation: Laboratory of Bio-inspired Smart Interface Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Song
authors.affiliation: IMEC, Kapeldreef 75, B-3001 Leuven, Belgium.|Laboratory of Solid-State Physics and Magnetism, Department of Physics and Astronomy, KU Leuven , Celestijnenlaan 200D, B-3001 Leuven, Belgium.
authors.forename: Pol
authors.initials: P
authors.lastname: Van Dorpe
authors.affiliation: IMEC, Kapeldreef 75, B-3001 Leuven, Belgium.|Laboratory of Solid-State Physics and Magnetism, Department of Physics and Astronomy, KU Leuven , Celestijnenlaan 200D, B-3001 Leuven, Belgium.
authors.forename: Niels
authors.initials: N
authors.lastname: Verellen
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200D, B-3001 Leuven, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Clays
mesh_terms: D008280:Magnetics; D054118:Nanospheres; D049329:Nanostructures; D012822:Silicon Dioxide; D020349:Surface Plasmon Resonance
chemical_list: D012822:Silicon Dioxide
keywords: antibonding; colloidal lithography; hollow spheres; nanoring; reactive ion etching; self-assembled plasmonic nanoparticles; templates