Surface engineering of Co and FeCo nanoparticles for biomedical application

Abstract

Monodisperse Co, Fe, and FeCo nanoparticles are prepared via thermal decomposition of metal carbonyls in the presence of aluminium alkyls, yielding air-stable magnetic metal nanoparticles after surface passivation. The particles are characterized by electron microscopy (SEM, TEM, ESI), electron spectroscopy (MIES, UPS, and XPS) and x-ray absorption spectroscopy (EXAFS). The particles are peptized by surfactants to form stable magnetic fluids in various organic media and water, exhibiting a high volume concentration and a high saturation magnetization. In view of potential biomedical applications of the particles, several procedures for surface modification are presented, including peptization by functional organic molecules, silanization, and in situ polymerization.

Nanostructured Materials Preparation via Condensation Ways

“…These materials have a broad spectrum of practical applications. They are obtained using various approaches including RF-discharge plasma, chemical vapour deposition (CVD) [438], thermolysis of cobalt or iron carbonyls in the presence of surfactants [439][440][441]. The ferromagnetic behaviour of such optically transparent magnetic plastics corresponds to a multidomain magnetite structure; therefore, they could find use in magneto-optical technology (see, for example, Ref.…”

Biofunctional Composites of Polysaccharides Containing Inorganic Nanoparticles

“…Other magnetic nanoparticles include metal alloy nanoparticles (e.g. FePt, FeCo, and CoPt 3 ) (Behrens et al, 2006;Gu et al, 2003;Martins et al, 2007) and metallic nanoparticles (e.g. Co and Ni) (D. Zeisberger et al 2007).…”

Surface modification of metallic Co nanoparticles

“…Co nanoparticles were coated by hydrolysis of tetraethoxysilane (TEOS), a method related to the Sto¨ber process [12]. In brief, Co particles peptized with oleic acid in toluene were coated with silica via the base-catalyzed hydrolysis of TEOS under argon atmosphere [11]. The surface of the Co particles exhibited an affinity toward silica, and, in contrast to Au and Ag particles, no primer was applied to promote the deposition and adhesion of silica on the Co particles.…”

“…Due to the high saturation magnetization and the high magnetophoretic mobility, microspheres equipped with magnetic metal nanoparticles can be made much smaller than commonly used ones containing iron oxide. Silica microspheres containing Co particles could be prepared by applying a two-step procedure [11]: firstly, the pre-stabilized Co particles were treated with 3-aminopropyl silane and active silica, followed by the ammonia-catalysed hydrolysis of TEOS in a second step. The resulting uniform silica spheres were about 520 nm in size exhibiting a saturation magnetization of 21 A m 2 /kg ( Fig.…”

“…Dextran coating of iron oxide nanoparticles, for example, has been widely studied due to its biocompatibility and its surface properties such as its hydrophilic character. When colloidal solutions of L-cysteine ethyl ester-modified Co nanoparticles in ethanol were reacted with dextran (molecular weight 10,000) or carbomethoxydextran nanoparticle aggregates covered by the polysaccharide were formed [11]. The TEM images display the formation of aggregates of 9-nm-sized Co particles (Fig.…”