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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/4111

Title: Silane ligand exchange to make hydrophobic superparamagnetic nanoparticles water-dispersible
Authors: De Palma, Randy
Peeters, Sara
Van Bael, Margriet
Bonroy, Kristien
Laureyn, Wim
Borghs, Gustaaf
Maes, Guido
Issue Date: 2007
Citation: CHEMISTRY OF MATERIALS, 19(7). p. 1821-1831
Abstract: Ferrite magnetic nanoparticles (MNPs) were functionalized with a variety of silanes bearing different functional endgroups to render them stable with respect to aggregation and keep them well-dispersed in aqueous media. The MNPs were prepared by the thermal decomposition method, widely used for the synthesis of monodisperse nanoparticles with controllable size. This method makes use of a hydrophobic surfactant to passivate the surface, which results in nanoparticles that are solely dispersible in nonpolar solvents. For use in biological applications, these nanoparticles need to be made water-dispersible. Therefore, a new procedure was developed on the basis of the exchange of the hydrophobic surface ligands with silanes bearing different endgroups to decorate ferrite magnetic nanoparticles with diverse functionalities . By this means, we could easily determine the influence of the endgroup on the nanoparticle stability and water-dispersibility. Amino-, carboxylic acid- and poly(ethylene glycol)-terminated silanes were found to render the MNPs highly stable and water-dispersible because of electrostatic and/or steric repulsion. The silane molecules were also found to form a protective layer against mild acid and alkaline environments. The ligand exchange on the nanoparticle surface was thoroughly characterized using SQUID, TEM, XPS, DLS, TGA, FTIR, UV-vis, and zeta potential measurements. The presented approach provides a generic strategy to functionalize magnetic ferrite nanoparticles and to form stable dispersions in aqueous media, which facilitates the use of these magnetic nanoparticles in biological applications.
Notes: IMEC, MCP ART, B-3001 Louvain, Belgium. Catholic Univ Louvain, B-3001 Louvain, Belgium. Hasselt Univ, Inst Mat Res, Lab Inorgan & Phys Chem, B-3590 Diepenbeek, Belgium. IMEC Div IMOMEC, B-3590 Diepenbeek, Belgium.De Palma, R, IMEC, MCP ART, Kapeldreef 75, B-3001 Louvain, Belgium.Randy.Depalma@imec.be
URI: http://hdl.handle.net/1942/4111
DOI: 10.1021/cm0628000
ISI #: 000245208100039
ISSN: 0897-4756
Category: A1
Type: Journal Contribution
Validation: ecoom, 2008
Appears in Collections: Research publications

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