Core shell particles consisting of cobalt ferrite and silica as model ferrofluids [CoFe2O4–SiO2 core shell particles]

Wagner, Joachim; Autenrieth, Tina; Hempelmann, Rolf

doi:10.1016/s0304-8853(02)00729-1

Cited by 101 publications

(61 citation statements)

References 6 publications

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“…Nanoparticles of different materials (Mulvaney et al 2000;Graf et al 2003;Jana et al 2007), in particular noble metals (Au, Liz-Marzán et al 1996;Buining et al 1997;Ag, Hardikar & Matijevic 2000;Han et al 2008), fluorescent quantum dots (CdSe/ZnS, Gerion et al 2001;Nann & Mulvaney 2004;Darbandi et al 2005), phosphorescent (Ehlert et al 2008) and magnetic nanoparticles (e.g. Fe, Ohmori & Matijevic 1993;Co, Kobayashi et al 2003; CoFe 2 O 4 , Wagner et al 2002) and particles of different shapes have been coated with silica shells.…”

Section: (D) Polymer Coatingsmentioning

confidence: 99%

Surface modification, functionalization and bioconjugation of colloidal inorganic nanoparticles

Sperling

Parak

2010

Phil. Trans. R. Soc. A.

1,378

1,092

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Inorganic colloidal nanoparticles are very small, nanoscale objects with inorganic cores that are dispersed in a solvent. Depending on the material they consist of, nanoparticles can possess a number of different properties such as high electron density and strong optical absorption (e.g. metal particles, in particular Au), photoluminescence in the form of fluorescence (semiconductor quantum dots, e.g. CdSe or CdTe) or phosphorescence (doped oxide materials, e.g. Y 2 O 3 ), or magnetic moment (e.g. iron oxide or cobalt nanoparticles). Prerequisite for every possible application is the proper surface functionalization of such nanoparticles, which determines their interaction with the environment. These interactions ultimately affect the colloidal stability of the particles, and may yield to a controlled assembly or to the delivery of nanoparticles to a target, e.g. by appropriate functional molecules on the particle surface. This work aims to review different strategies of surface modification and functionalization of inorganic colloidal nanoparticles with a special focus on the material systems gold and semiconductor nanoparticles, such as CdSe/ZnS. However, the discussed strategies are often of general nature and apply in the same way to nanoparticles of other materials.

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Section: (D) Polymer Coatingsmentioning

confidence: 99%

Surface modification, functionalization and bioconjugation of colloidal inorganic nanoparticles

Sperling

Parak

2010

Phil. Trans. R. Soc. A.

1,378

1,092

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“…The colloidal particles were prepared in a two-step synthesis that is described in detail elsewhere (Wagner et al, 2002). First, the magnetic core consisting of cobalt ferrite is precipitated from stoichiometric amounts of the corresponding cobalt and iron salts, according to Massart's method (Massart, 1981).…”

Section: Synthesis Of the Core-shell Colloidsmentioning

confidence: 99%

The dynamic behavior of magnetic colloids in suspension

Autenrieth¹,

Robert

Wagner

et al. 2007

J Appl Cryst

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The dynamic behavior of magnetic colloidal particles in suspension is investigated. The particles of the core-shell colloid consist of a cobalt ferrite core embedded in a silica shell and are stabilized by surface charges. As the suspension is strongly opaque to visible light, it can not be probed by dynamic light scattering techniques as a result of strong multiple scattering as well as absorption effects. Therefore, the static and dynamic behavior is probed with small-angle X-ray scattering and X-ray photon correlation spectroscopy (XPCS), respectively. Using XPCS, we are able to study the diffusion coefficient of an opaque colloidal system as a function of the scattering vector. In this paper, we report on the behavior of the colloidal system in the absence of an external magnetic field, meaning that the magnetic moments of the particles are oriented randomly. We find no evidence for magnetic interactions in the static data, while the dynamic XPCS data deviate very significantly from the predictions of model calculations.

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“…Details are published elsewhere. 5 The core-shell structure becomes evident from the smallangle X-ray scattering (SAXS) of a highly dilute suspension (Fig. 1).…”

Section: Preparation and Characterizationmentioning

confidence: 99%

Cobalt ferrite–silica core–shell colloids: a magnetic Yukawa system

Autenrieth

Wagner

Hempelmann

et al. 2004

Applied Organom Chemis

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Colloidal core-shell particles consisting of a magnetic cobalt ferrite core surrounded by a silica shell are prepared via precipitation and a subsequent modified Stöber synthesis. The resulting particles with narrow size distribution interact due to weakly acidic surface groups at the silica shell via a screened Coulomb or Yukawa potential in addition to the magnetic dipole-dipole interaction of the magnetic cores.The structural characterization of the particles is done by transmission electron microscopy and small-angle X-ray scattering (SAXS), and the potential parameters of the electrostatic monopole and magnetic dipole-dipole interactions are determined by laser Doppler electrophoresis and magnetogranulometry, respectively.Owing to the interaction potential, the particles self-organize to a liquid-like ordered structure as determined by SAXS. The magnetic dipole-dipole interaction becomes evident from the anisotropic scattering pattern in the presence of an external magnetic field.

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Core shell particles consisting of cobalt ferrite and silica as model ferrofluids [CoFe2O4–SiO2 core shell particles]

Cited by 101 publications

References 6 publications

Surface modification, functionalization and bioconjugation of colloidal inorganic nanoparticles

Surface modification, functionalization and bioconjugation of colloidal inorganic nanoparticles

The dynamic behavior of magnetic colloids in suspension

Cobalt ferrite–silica core–shell colloids: a magnetic Yukawa system

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